2. Review of Literature
Ramachandran & Nair, 1988 studied the flora of Cannanore, which is the Kannur district of Kerala state. The total area of study was about 3670 sq.km, including the present northern Wayanad taluk area, which was once the part of Cannanore but now belongs to the Wayanad district. The region has three natural divisions: the lowlands, the midlands and the highlands. Thirteen exploration trips of duration 15-20 days were conducted in different seasons during five years. Every species was collected in their flowering and fruiting stages, and detailed field notes were noted. Further critical studies were done with authentic materials and expert opinions. According to (Champion & Seth, 1968) there are three types of forests in the area: tropical evergreen, tropical semievergreen and tropical moist deciduous types. Chandrasekaran, 1960 recognized two types, climax type and secondary type. The flora of the study area accounts for 1132 species of angiosperms in 658 genera and 157 families. Fabaceae (sensa lato) is the dominant family in the study area. Gymnosperms are represented by 2 species belonging to 2 genera and 2 families. From the total endemic angiosperms of Peninsular India, 15 species belonging to 12 genera under 10 families were collected during the study. 9 species which were known only from the type or other very old collections were relocated. The flora of Cannanore shows marked affinity with the flora of Sri Lanka, having a number of species common to both. Mohanan & Henry, 1994 conducted a study and prepared a report on the flora of Thiruvananthapuram district in Kerala. A systematic botanical exploration was conducted for five years with field observations. The study results in collecting 1270 species in 710 genera under 163 families. Among the total flora, 939 species were dicots, 328 were monocots, and 3 were gymnosperms. The Leguminosae and Gramineae families are the first and second largest families, respectively. Tea, rubber, teak, and cashew plantations, jungle woods like Artocarpus hirsutus, Artocarpus heterophyllus and soft wood like Pithecellobium monadelphum can be seen in the area. The study resulted in the discovery of two new species Cinnamomum chemungianum (Lauraceae) and Syzygium parameswaranii (Myrtaceae) and two new varieties Eria muscicola (Lindl.) Lindl. var. ponmudiana (Orchidaceae) and Exacum courtallense Arn. var. boneccordiana (Gentlanaceae). During the study, Eragrostis cumingii Steud. (Poaceae) and Exacum walkesi Griseb. (Gentianaceae) are recorded for the first time from India. Species such as Aphyllorchis montana (Thw.) Reichb. f. (Orchidaceae), Asplenium affine Sw. forma affine (Aspliniaceae) and Malaxis latifolia Sm. (Orchidaceae) are recorded first time from Kerala. Actinodaphne campanulata Hook.f var. obtusa Gamble, Clematis bourdillonii Dunn, Cinnamomum travancoricum Gamble, Eria muscicola (Lindl.) Lindl. var. brevillnglus Joseph & Chandras and Ochlandra ebracteate Raizada & Chatterjee are endemic to Thiruvananthapuram. Several rare and threatened species was also observed during the study.
Sasidharan et al., 1994 conducted botanical studies in the medicinal plant conservation areas (MPCAs) in Kerala. Among 7 MPCAs in Kerala, 5 of them were explored in the study: Athirapally, Peechi, Silent Valley, Periya and Eravikulam. Specimens were collected in their generative stages, and data were recorded. Herbarium specimens were prepared and identified with the help of standard literature and by comparing with authentic specimens. Belt transects were laid and enumerated species in the transects were carried out as per the design provided by the FRLHT (The Foundation for Revitalisation of Local Health Traditions). About 1% of the area in each MPCA was covered by transects. Among the five MPCAS, two are located in the Moist deciduous forests (Athirapally and Peechi), two in the Evergreen forests (Silent Valley and Periya), and one in the Shola-Grasslands (Eravikulam). In Athirapally, 238 species under 186 genera were recorded. Fabaceae and Poaceae, with 26 species each, are the largest families. Peechi records 215 species under 167 genera and 67 families. Fabaceae, with 30 species, is the largest family in Peechi. In Silent Valley, 343 species under 270 genera and 104 families were recorded. Orchidaceae is the largest family with 25 species. In Periya, 234 species under 195 genera and 81 families were recorded. Rubiaceae with 16 species is the largest family. Eravikulam records 201 species under 154 genera and 72 families. Orchidaceae, with 18 species, is the largest. Among the five MPCAs, Peechi dominates with 107 species of medicinal plants, followed by Athirapally with 95 species. In Silent Valley, the medicinal plants are 59, while at Periya, it is 33. The lowest number (23) is at Eravikulam as many of the species have not been evaluated for their medicinal properties. Among the MPCAs, the highest number of endemics (78) is recorded from Silent Valley, followed by 67 at Periya, 57 at Eravikulam, 42 at Athirapally, and 12 from Peechi. Silent Valley, Periya and Eravikulam are relatively undisturbed with a smaller number of exotic weeds. Peechi and Athirapally are disturbed areas with many exotic weeds, and they are under severe biotic pressure. Regarding species diversity, Silent Valley ranks first with 343 species, with 22.7% endemic species. The number of Rare and Threatened species is more in Periya, Silent Valley, and Eravikulam, with 12, 8 and 7 species, respectively, while in Athirapally, there are 3 species, and in Peechi there is only one. In general, the MPCAs in the Evergreen forests at Silent Valley and Periya exhibit a greater species diversity.
Jose et al., 1994 studied the structural, floristic, and edaphic attributes of the grassland-shola forests of Eravikulam National Park in the Idukki district of Kerala. The study area was selected based on visual observations on floristic composition and density, which caused the selection of a representative grassland-shola forest type of the Rajamallay area in the Eravikulam National Park. 50 quadrats of 10 X 10 m size were established in shola forest, GBH of all trees and shrubs were measured and recorded. Species-area relationships, structural attributes, phytosociological parameters, Importance Value Index (IVI) and Diversity Indices were calculated from the Sholas. Ten quadrats of 1 X 1 m were laid in grasslands near the sholas to study the species diversity and biomass productivity. Soil samples were collected to characterize the soil profile development and the result showed a reddish-brown surface horizon and a very dusky red lower horizon. The difference between the grassland and shola profiles was statistically not significant. From shola forests, 942 stems of at least 10 cm GBH, belonging to 53 species were encountered, which is equivalent to a density of 1884/ ha. The species having the highest density was Pithecellobium subcoriaceum Thw. Grasses were mainly represented in the peripheral region of sholas, where light availability to the ground floor is comparatively high. A continuance canopy from under-shrubs to shrubs and then to larger shola trees, with no marked differentiation was observed in the shola vegetation. Four species were encountered from the grassland, in which Arundinella vaginata showed a high degree of dominance. Biomass accumulation of grasslands ranged from 471 to 633 g/m2. Regarding structural features of vegetation, Eravikulam shola forests were superior to the mid and low-elevation forests of the Western Ghats.
Mohan Kumar et al., 1994 studied the diversity, structure, and standing stock of wood in the home gardens of Kerala. Out of 61 thaluks, 17 taluks were randomly selected from nine districts throughout Kerala. Detailed house-hold surveys were performed among individual farmers belonging to the small (below 0.4 ha), medium (0.4 to 2 ha), and large (> 2.0 ha) holding size categories. Farmers were identified through a stratified random process. A total of 252 farmers were surveyed, five in each category from any given thaluk during the years 1991 and 1992. General information on crop and livestock production enterprises was gathered, and all scattered trees and shrubs on the homestead and border trees, except palms and rubber, were enumerated. For palms and rubber, their mean height, girth and frequency were recorded. In total, 127 woody species were encountered. Coconut and arecanut were the most dominant components of the home gardens of the entire state. Smaller holdings had a higher density of trees per unit area. Physiognomically, home gardens exhibit a multi-tiered canopy structure that is somewhat similar to that of tropical evergreen forests. Medium-sized holdings registered the least value for Simpson's index, which may be due to the focus of medium holders on cash crops like coconut, rubber, cacao, and spices. The density-based Shannon-Wiener diversity index (H') suggested low to moderate levels of floristic diversity. The mean number of individuals exhibited no marked variation among the thaluks. Coastal areas show relatively lower values of Simpson's diversity index and equitability, while midlands exhibited higher diversity functions. Major species were represented in all size-classes, suggesting that home gardens are dynamic as well as sustainable land use systems. The frequency distribution of homestead trees indicates that farmers prefer timber trees such as Ailanthus and teak. The Sorensen's similarity indexes show moderately high similarity for different tree species encountered on the homesteads. Homegarden size is, by and large, a function of the population density. The northern thaluks, having relatively lower population densities, had relatively larger home gardens. No clearcut planting pattern was recognized in the home gardens of Kerala. The average standing stock of commercial timber ranged from 6.6 to 50.8 m3/ ha and fuel wood volume was of the order of 23 to 86 m3/ha. This shows that a good amount of society's wood demands are met from the homesteads. Palms were the dominant component of standing commercial timber and fuel wood volumes.
Chandrashekara, 1996 studied the ecology of Bambusa arudinacea (Retz.) Willd. growing in teak plantations of the Kariem-muriem reserve of the Nilambur Forest Division, in KeraIa where the natural forests were tropical moist deciduous. Bamboo clump distribution and clump size were analyzed at different distances from the water course. Three convenient types of bamboo distribution were recognized: Type A - having 3 or more clumps per 400 m2; Type B having 1-3 clumps per 400 m2; Type C, having 0-3 clumps per 400 m2. Phytosociological studies of herbs, shrubs, trees, seedlings, and saplings were done using standard methods. The biomass of teak was measured by a non-destructive volume estimation method, while biomass estimation in bamboo was based on destructive sampling. The biomass of herbs, shrubs, and tree seedlings was determined separately by harvesting above-ground biomass from October-November 1992. Shrubs, seedlings, saplings, and mature trees of species showed higher values for density, basal area and species diversity index in site C, herbs were denser and had more basal cover in site A and more species diversity in site B. The density of teak did not show any significant difference among the three site types, but its basal area was significantly higher in site C. In case of bamboo, the highest values for density and basal area were recorded in site A. For each site, the contribution of teak to the total above-ground biomass was generally higher. Nutrient concentrations were generally highest in leaves and lowest in main branches. Enrichment quotients of potassium and nitrogen were significantly higher in bamboo than in teak. However, teak had higher enrichment ratios for calcium.
Renuka et al., 1996 studied the palm resources of Kerala and their utilisation. As part of the study, frequent visits were made to the forest areas of Western Ghats and other palm-growing habitats. Herbarium specimens were prepared, field observations were noted, and detailed enquiries were made with the local people. Kerala has 10 genera and 21 species in its palm wealth. Of these Cocos nucifera (coconut), Areca catechu (arecanut) and Elaeis guineensis (oil palm) are widely cultivated. Another 13 different genera are cultivated as ornamental palms. The only rattan genus in Kerala, Calamus, is widely used in the furniture industry. Genus like Arenga, Bentinckia and Pinanga occur in evergreen forests. Phoenix is seen in grasslands at high elevation. Borassus and Corypha are semi-wild palms seen in open areas and are often cultivated. Caryota has a wider distribution and is seen in evergreen, semievergreen, and moist deciduous forests. Except Phoenix and Pinanga all other palms are single stemmed. Of the 6 subfamilies of Palmae family, only three subfamilies are represented in Kerala; namely Coryphoideae, Calamoideae and Arecoideae. The fibro-vascular tissue of the palms is valuable for woody constructional material and provides the brush fibre. The tough leathery leaf blades of a number of palms are used in thatching, basket weaving, plaiting and wickerwork, handicrafts, fodder and green manure. Leaflet blades of some species like Borassus flabellifer and Corypha umbraculifera are used for writing manuscripts in ancient times. The main edible products obtained from palms include parts of fruits and seed, the tender apical portions of stem and storage products and secretions such as starch, fats or sugars from other parts. The sweet toddy is consumed fresh as a beverage or converted into various useful products such as palm-sugar, arrack, candy, vinegar etc. Palms are also used for landscaping and agroforestry purposes. Loss of habitat and over-exploitation are the major threats to palms. As Arenga wightii, Bentinckia condapanna and Pinanga dicksonii are much restricted in distribution, destruction of evergreen forests is affecting the growth of their population.
Gopalan, 1997 studied the plant diversity in Agastyamalai hills, situated at the southern end of Western Ghats and falls within the hilly tracts of Tirunelveli-Kattabomman and Kanniyakumari districts of Tamil Nadu and Thiruvananthapuram district of Kerala. The western slope in Kerala has an area of 180 sq. km with two wildlife sanctuaries: Neyyar (128 sq.km) and Peppara (53 sq.km) wildlife sanctuary. Agastyamalai has a forest cover of 2000 sq.km and harbours 2000 flowering plants, including 100 endemic and 50 rare and endangered species. The floristic diversity and complexity make it a rich gene pool region. More than 30 new taxa have been discovered here in recent years. Aenhenrva agastyamalayana Gopalan and Janakia arayalpathra J. Joseph & V. Chandras. are two new genera discovered. 157 families are represented in the region. Several Sri Lankan species, which were so far considered to be endemic to Sri Lanka have also been collected in these forests. The region is known for rare plants that are still widely used in ayurvedic medicines. Besides valuable timber trees, revenue is being collected from the sale of minor forest produce. The Kani tribes inhabiting in the area collect honey, Cinnamomum bark, resin of white dammar, black dammar, bark for red dye from Morinda tinctoria Roxb. and fruits of Garcinia spp. Commercial cash crops such as coffee, tea, rubber, pepper, and cardamom are grown on large scale in the hill slopes. Hydel/irrigation projects, cultivation of plantation crops, increase in a number of pilgrims, and the visitors intentional fire to the seasonal dry forests had caused a loss of biodiversity in the area. Also, there are many threatened animal species in the area in which the tiger is the apex of a complex biotype. The social and environmental values that the area provides are yet to be fully assessed.
Sajeev & Sasidharan, 1997 studied the ethnobotanical observations on the tribals of Chinnar Wildlife Sanctuary in the Idukki district of Kerala. The sanctuary occupies and area of 90.44 km2. The vegetation types are dry deciduous forests (dominant in the sanctuary), moist deciduous forests, semi-evergreen forests, grasslands, and shoal forests. The tribals in the sanctuary are Hill Pulayas and Muthuvans, living at 11 settlements. Ethnobotanical details were collected from the tribal medical practitioners from 1994 to 1996, and the voucher specimens were prepared. 64 plant species used by the tribals for various purposes were observed. Among the 64 species, 55 were used as medicinal plants, 3 as fiber-yielding, 2 as fish poison and 3 as food plants. Of the 55 medicinal plants, 8 species were used to heal cuts and wounds, 6 as anodyne, 4 as antidote to poison, 4 against skin diseases, 4 anti-dysenteric, 2 as antipyretic and 2 insect repellents.
Vivekananthan et al., 1997 studied the plant diversity in Nilgiri Biosphere Reserve, Southern India. A good amount of biodiversity occurs here mainly due to the significant geographical location (Trijunction of western Ghats) and the proximity of the tri-seas (the Arabian sea, the Bay of Bengal, and the Indian Ocean). All the important forest types in southern India, from scrub jungles to wet evergreen forests and others that are peculiar to the region. About 80% of flowering plants reported from the Western Ghats (3187/4000) appear to occur in the Nilgiri Biosphere Reserve. The genus Baeolepis Decne.ex Moq. (Periplocaceae) is exclusively endemic to the Nilgiris. Silentvalleya V.J Nair et al. is the other genus endemic to Silent Valley, an integral part of the biosphere reserve. Out of the 1932 taxa of flowering plants endemic to Peninsular India, about 818 (25%) are found in the Nilgiris and adjoining areas.
Chandrashekara et al., 1998 studied the plant diversity in different forest types of Kerala by laying out a permanent sample plot in four different forests. They are the tropical montane forest (shola forest) at Mannavan Shola in Munnar Forest Division, the tropical evergreen forest at Pothumala in Nemmara Forest Division, the moist deciduous forest at Channakkad in Trichur Forest Division, and the dry deciduous forest at Chinnar Wildlife Sanctuary in Eravikulam Wildlife Sanctuary Division. The plot was of 1-ha in size and was subdivided into 100 quadrats 10 m x 10 m in size, with quadrats permanently marked. In each permanent plot, tree tagging and identification were carried out in three stages by marking all trees above 30.1 cm girth at breast height (GBH) as mature trees, with GBH ranging from 10.1 cm to 30.0 cm as saplings and plants with less than 10 cm girth and less than 1 m height as tree seedlings. Most of the trees species were identified in the field, while others were identified by referring the herbaria. The relative density, relative frequency, relative dominance and the Importance Value Index (IVI) of species were calculated. Stands quality of shola and wet evergreen forests was determined using RISQ (Ramakrishnan index of Stand Quality) equation. The Mannavan shola natural forest and dry deciduous forest plot site was noticed without major disturbance. Almost all species in the moist deciduous forest and dry deciduous forest plots are widely distributed in the Indian subcontinent. Among the four plots, shola and wet evergreen forest plots are species-rich and comparable to many tropical wet evergreen forests. The lowest species diversity was recorded in dry deciduous forests indicating the dominance of one or two species in the tree community.
Varghese & Menon, 1998 studied a variety of trees, grasses, shrubs, and herbs in the moist mixed deciduous forests of Agasthyamalai region of Kerala. Terminalia paniculata and Pterocarpus marsupium are the dominant species, and co-dominants vary from locality to locality. Species diversity, stand density and basal area cover are lower in hilltop regions and higher for valleys. Compared to the moist deciduous of the Western Ghats, the Agasthyamalai part of Kerala showed comparatively lower basal area cover, species diversity, and evenness.
Manilal & Raveendrakumar, 1998 studied the additions to the flora of Kerala since Gamble (1935). Gamble's ‘Flora of the Presidency of Madras’ (19 I 5-35) was usually consulted by general taxonomists and students for the study and identification of flowering plants of Kerala. Since then, a large number of new species and records were reported. Information about all the new taxa, new records, and new combinations of angiosperms reported from Kerala (since Gamble), is collected and provided in the literature. This includes 625 new taxa coming under 103 different families, which have been published by various workers since Gamble. Of these, 240 are new additions to the world flora. This includes six new genera, 193 new species, 3 new sub-species and 41 new varieties. An analysis of the percentage of new reports from Kerala since Gamble reveals that Orchidaceae (118.9 %), Zingiberaceae (88.2 %) and Araceae (69.2 %) show a very high increase in number. The maximum number of reports are from Silent Valley in Palakkad district (36), Chandanathode in Kannur district (33) and Thenmala in Kollam district (21). The new reports were chiefly from forest areas and high ranges of Western Ghats.
Sasidharan, 1998 studied the flora of the Periyar Tiger Reserve along the Western Ghats in Idukki District of Kerala. The Tiger Reserve has an area of 777 km2. The floristic study resulted in the collection and description of 1965 taxa of flowering plants, which belong to 823 genera under 151 families. Dicotyledons dominate the area, with 1440 species under 128 families, and 525 species were monocotyledons, which comes under 23 families. The Poaceae family dominate with 168 species. Among 151 families, 34 families are represented by only one species each. Among the 1965 species of flowering plants, 515 (26%) are endemic to Southern Western Ghats. Orchidaceae family holds the highest number of endemic species (55 sp.) in the Tiger Reserve. One hundred fifty species in the study area belonging to various threat categories. Among the plants studied, 4 species were new records for India and 14 were new records for Kerala. Species Habenaria periyarensis Sasi. was newly described. The results show that Periyar Tiger Reserve is home to diverse flora. The flora in the Reserve has the richest account of grass flora in the state and has high number of Orchids reported from a district.
Ecology and management of sacred groves in Kerala was studied by Chandrashekara & Sankar, 1998. Based on management systems, three sacred groves, namely Sri Bhagavathi Kavu at Iringole (managed by a temple trust in association with the Devaswom Board), Sri Shangukulangara Bhagavathi Kavu at Sree Narayana Puram (managed by a committee comprising of a group of families) and a Sarpa kavu at Ollur (managed by an individual owner) were selected for the study. The phytosociological analysis was done for trees. Stakeholders, their interests, and the conservation and management of sacred groves were identified based on surveys and semi-structured interviews. A number of 51, 17 and 24 tree species were recorded from Iringole Kavu, S.N. Puram, and Ollur Kavu, respectively. Values of stem density and basal area of mature trees were higher in S.N. Puram Kavu, but in the case of sapling and seedling phases these values were more in Iringole Kavu. The one managed by an individual family (Ollur Kavu) is highly disturbed, indicated by the low stem density of mature trees and poor regeneration potential. Of the 73 tree species recorded from the three sacred groves, 13 are endemic to South western Ghats, three are endemic to Western Ghats and one is endemic to peninsular India. Myristica malabarica, Nothopegia beddomei and Antiaris toxicaria are rare and threatened species while Aporosa bourdillonii is a vulnerable species found from the groves.
Sasidharan. N, 1999 studied about the flora of Chinnar Wildlife Sanctuary, which is located along the rain shadow region of the Western Ghats in Idukki district of Kerala. The vegetation of the Sanctuary is classified into six types according to (Champion & Seth, 1968)and (Chandrasekaran, 1960) classification. Dry deciduous forest and scrub jungle are the two main forest types in the study area, and together, they constitute about 50% of the total forest area. Extensive field trips were conducted periodically during 1994-1998. The study documented 965 species of flowering plants from the study area, which constitutes 24% of the total flowering plants in Western Ghats. The species belong to 578 genera under 135 families. Dicotyledons are represented with 794 species, 82.3% of the flora of the study area and monocotyledons are represented with 171 species constituting 17.7% of the flora of the study area. There is only one species representing the Gymnosperm. The first and second dominant families in the study area are Fabaceae and Poaceae respectively. 41 families are represented with one species each. About 335 medicinal plants are present in the sanctuary, and many are used by tribes in crude form. Ipomoea mombassana collected from the Sanctuary is a new record to India. Albizia lathamii a critically endangered species from the sanctuary is the first recollection after the type collection. Chrysopogon velutinum and Theriophonum sivaganganum are new records to the flora of Kerala. Among the 5 centres of endemism in the Southern Western Ghats, the study area falls within the Anamalai-High Ranges. There are 114 peninsular Indian endemics in the study area. Poaceae is the largest family with 12 endemics and the genus Impatiens is the largest endemic genus with 9 species. Flora of the sanctuary has more resemblance to the Deccan-Carnatic elements rather than that of the wet regions of the Western Ghats. The large number of families and genera with fewer number of species and low percentage of endemism leads to the assumption that the vegetation of the sanctuary is highly disturbed.
Jacob John & M. Achuthan Nair, 1999 worked on crop-tree inventory of the home gardens of Thiruvananthapuram district of southern Kerala. The different trees and crops grown in the homesteads were documented through personal interviews and visual identification. Frequency and percentage analysis was done using the data. The average size of home gardens surveyed was 0.33 ha per holding. Tuber crops (46.3 % of total plants) predominated among the crop categories, among that Cassava (64.19 % of total tuber crops) was most commonly grown and banana was mostly cultivated fruit. Rubber has been noticed in homesteads as a tree crop. The tree density increases land holding size of an individual decreases.
Varghese et al., 1999 studied the structure, composition, and diversity of the tropical wet evergreen forest of the Agasthyamalai region of Kerala. Plots of 0.1 ha size were established in four regions, namely the Bonaccord locality (around 600 m), Karamana locality (around 800 m), third from Athirumalai (at 1000 m), and the fourth from Chemmunjimottai region (1200 m). All tree species above 10 cm dbh (at 1.3 m) were enumerated. The data was analyzed for percentage frequency, nature of vegetation, species association, family importance value, maturity index, species distribution, and similarity index. Species richness was calculated using Margalef (Rl) index, and species diversity of trees was determined using Shannon's index. Pielou's index was used to estimate species evenness or equitability. Density, abundance, percentage frequency, and basal area show the wide ecological amplitude of Mesua nagassarium especially in higher altitudes of the study area. The species association and mean IVI show the association of the Mesua-Cullenia- Dimocarpus series, in which Mesua nagassarium dominates at high altitudes, Cullenia exarillata middle and Dimocarpus longan low altitudes. The heterogeneous nature of vegetation, species evenness and diversity decrease from low to high altitudes. Agasthyamalai has comparatively high species per unit area and stand density. High species richness, medium diversity, and low equitability are the features of its vegetation.
Sasidharan N, 1999 studied the floristic diversity of Shenduruny forest in the Western Ghats part of Kerala. Vegetation of the sanctuary falls into five major groups. Specimen samples in generative stages of three years in different seasons were collected. This resulted in the collection of 951 species of flowering plants in 118 families. Leguminosae and Orchidaceae families dominate the sanctuary, with 70 species each. Of 951 species, 310 are endemic to western ghats. 100 rare and threatened species were collected. Two new species were described. 9 species that were considered to be ‘possibly extinct’ are found to be still surviving in the sanctuary.
Varghese & Menon, 1999 studied the floristic composition, dynamics, and diversity of Myristica Swamp forests of Agasthyamalai region of Kerala. Myristica swamp forest was found within 100-500 m range. Random sampling through the census quadrat method were adopted in seven places and different analysis was conducted. 18 species of 12 families were recorded in the area. Species Gymnacranthera farquhariana shows high density. Due to the edaphic conditions and dense stilt root system, the stand density (520 trees/ha) was low when compared to other forest types. Gymnacranthera farquhariana (3.00) and Myristica malabarica (2.50) are the most abundant species. Gymnacranthera farquhariana, Myristica dactyloides and Knema attenuata have percentage frequency of 40.00 and more, showing a heterogeneous nature. None of the species show regular distribution. Four species that show random distribution are Myristica dactyloides, Myristica fatua, Persea macrantha and Knema attenuata and all other 14 species show contiguous distribution. The association is mainly between Gymnacranthera-Knema and Persea. Myristicaceae records the highest Family Importance Value (FIV). Compared to other forest types of southern western Ghats, Myristica swamps show low stand density, medium basal area, low maturity index value, very low species richness and medium diversity. Some pockets of swamps in the valleys of low altitude are under tremendous biotic pressure.
Stand structural diversity and dynamics in natural forests of Kerala was studied by Chandrashekara et al., 2002. A total of 60 sites were selected in common forest types of state like, tropical montane forest (shola forest), wet evergreen forest, semi-evergreen forest, moist deciduous forest, and dry deciduous forest and also in all geographical regions of the State. The number of sites was determined primarily based on the relative proportion of area covered by it in the state and the accessibility to the site for regular and frequent monitoring. In order to determine the size of the plot species-area curves were drawn for each forest type. In each permanent plot, tree tagging and identification was carried out. Most of the tree, shrub and herb species were identified in the field, while others were identified with the help of regional floras and referring the herbaria. Relative density, relative frequency, and relative dominance, Importance Value Index (IVI), species richness (Menhinick’s index), relative abundance (Shannon-Wiener index), and Fisher’s α were calculated. In these plots, a total of 21,239 trees were marked in which 20,524 trees represent 327species while another 715 individuals are yet to be identified. Species-level basic information such as the location of trees in plots, girth distribution pattern and frequency of distribution in the different forest has been generated. Cluster analysis shows divergence among the habitats with respect to species composition.
Sasidharan, 2002 conducted detailed research and prepared a report on the floristic diversity in the Parambikulam Wildlife Sanctuary, in Palakkad district of Kerala. The sanctuary is part of the Anamalai Hills and has an area of 274 km2. Intensive seasonal floristic collections were made during 1998-2001. Field data were recorded, and specimens were collected. The collected specimens were preserved or pressed immediately and critically studied with relevant literatures and compared with authentic specimens. The sanctuary is situated in the northern end of the Anamalai subunit of the Western Ghats, the most hotspot region with respect to species diversity and endemism. 1432 species of angiosperms under 753 genera belonging to 140 families were collected, forming about 35% of the flora of Kerala. Dicotyledons are represented by 1,119 species under 120 families, while monocotyledons by 313 species under 20 families. Fabaceae, with 116 species, is the largest family and Ficus with 20 species is the largest genus. Among the 140 families, 31 dicot and three monocot families are represented by a single species each. Among the 1432 species, 653 are herbs, 359 species are trees, 268 are shrubs, and 152 are climbers. Maximum collections were recorded from the Sungam Range, followed by Karimala Range, due to the diverse habitats in these two Ranges. Among the 60 endemic genera of peninsular India, 13 were collected from the sanctuary. Haplothismia, Utleria and Pseudoglochidion are confined to Anamalai hills. A new species, Pteroceras monsooniae was collected from the sanctuary during the study period. Orchidaceae has the highest number of endemic species (34). The genus Impatiens has 12 endemic species. Heterophragma roxburghii considered endemic to the northern region of the Deccan plateau is collected from the sanctuary. Among the 460 species of rare and threatened flowering plants recorded from Kerala, 109 were collected during the study. Teak is the major plantation in the sanctuary, occupying an area of 87 km2.
Ann E Russell, 2002 studied the relationships between crop-species diversity and soil characteristics in the Thrissur district. 50 farms were randomly selected and a paired-plot sampling design was used in the analysis. Pairing consisted of one mono- or bi-culture with one polyculture. Three forest plots were paired, each with polyculture plots in a nearby farm. Altogether, there were 70 pairs (140 plots) from 50 farms. Background information was obtained through extensive interviews with each farmer and agricultural officers. Plots of 10x10m size were established and crop species were identified and their basal area and frequency were measured from December 1996 until June 1997. Identification of plants <3.2 cm DBH and frequency were determined to compare dominance patterns among ecosystems. Study says that the agricultural plots were dominated by woody species, with the exception of monocultures of annuals. Of all 91 species found in 140 agricultural plots, 70% were woody, 14% herbaceous, 8% root, 3% shrub, 3% vine, and 2% grass crops species. Of all 49 species found in three forest plots, 88% were woody, 2% herbaceous, 4% shrubs, and 6% vines. Agricultural plots differ from forest plots in terms of basal area. Forest basal area of large stems was double that of polycultures, and composed entirely of wood.
Sharma et al., 2002 studied the biodiversity of the new Amarambalam Reserved Forests of Nilgiri Biosphere Reserve. New Amarambalam Reserved Forest is situated in Malappuram District of Kerala, covering an area of 265.57 km2. Floristic surveys were conducted concentrating on arborescent species available in the 287 sample plots of 30 m x 30 m size, laid in the different vegetation types in the study area. The reserve is the abode of all seven hill forest types of southern India, namely tropical moist deciduous, tropical semievergreen, tropical evergreen, subtropical hill forests, subtropical savannahs, montane wet temperate forests and montane wet temperate grasslands. About 9.8 per cent of the area is occupied by teak plantations and natural forests cover the remaining area. Floral, insect, bird and mammalian diversity were studied by laying sample plots in different vegetation types from 1997 to 2000. Specimens were collected, studied, and herbaria prepared. Floristic analysis of the arborescent species recorded 305 taxa, under 212 genera belonging to 73 families. The most dominant family was Euphorbiaceae (33 species). The dominant genera in the area was Litsea (7 species). 32 percent of the arborescent flora of the area is composed of endemic species.
Raj et al., 2003 studied about the grass diversity of Kerala focusing on its endemism and phytogeographical significance. A detailed taxonomic survey and field explorations were conducted for three years. Collected plants were used to make a herbarium. It is estimated that about 350 grass species belonging to 108 genera occur in Kerala, forming the largest angiosperm family (Poaceae) in the state. This represents 27% of the total grass species of India and 90% of Peninsular Indian grass flora. Ischaemum, with 36 species, and Dimeria, with 26 species are the dominant genera in the family and have a high degree of endemism in Kerala. The two endemic genera Chandrasekharania and Silentvalleya, exclusively occur in Kerala. Lower attitude ecosystems which are dominated by grass, show much diversity and endemism. The tribe Andropogoneae, with about 120 species under 32 genera forming 27% of the total grass species, has maximum diversity and endemism compared to other grass tribes in the state. Phytogeographical analysis of the grass flora of the state shows affinity with that of Myanmar, Sri Lanka, and tropical Africa including Madagascar.
Sasidharan N, 2003 reviewed the red-listed threatened tree species in Kerala. There are 4,465 taxa of flowering plants in Kerala, in which 4050 are indigenous and the rest exotics. Among the 4,465 species, 812 are tree species in which 327 are endemic to Peninsular India, and 26 are restricted to Kerala. Among 1,272 Western Ghats taxa endemic to Kerala, 483 were placed under threatened categories. Based on published literature, 497 species from Kerala belong to the Red Listed categories, including 151 tree species. The red listed tree species are assigned to categories such as: Extinct (2 species), Low Risk/near threatened (22 species) Critically Endangered (26 species), Vulnerable (38 species) and Endangered (63 species). Among the families, Myrtaceae has 20 Red Listed tree species followed by Lauraceae (16 species). Among the red listed species, 23 species are seen in the shola forests, one species (Albizia lathamii) in the dry deciduous forests and the rest in the evergreen/ semievergreen forests.
Sreedharan, 2004 study on the biodiversity of Kalliasseri panchayat in Kannur district of Kerala shows rich tree species in the area. This includes some of the rare and threatened plants. Local varieties of Mangifera indica, Cocos nucifera, Piper nigrum can be seen in the panchayat. 69 species of shrubs have been identified from Kalliasseri. 162 species of medicinal plants, 20 species of fruit crops, 29 species of vegetables, 103 species of ornamental plants have also been identified. The major cereal cultivated in the panchayat is rice. The widely cultivated tuber crops of the area are the Manihot utilissima (Tapioca), Amorphophallus companulatus, Dioscorea alata, and Ipomaea batatas. The major commercial crops of the panchayat were coconut, arecanut, pepper, and cashewnut. 9 species are endangered and 20 species are rare species in the panchayath. There were exotic plants from tropical Asiatic, American, tropical Africans and Madagascan elements found in this area.
Peyre et al., 2006 studied the dynamics of home garden, its structure and function in Kerala. A case study was carried out in two panchayats (Mundur and Puduparyaram) of Palghat district in the central part of Kerala to study the development trends in agroforestry systems. A stratified sample of 30 farm households was selected within the panchayats. The information of households were gathered from the Integrated Rural Technology Centre of Palghat district. A detailed survey on the composition and management practices in the homegardens was conducted. This results in the inventory of trees and shrubs species and the number of individuals per species. Only presence was recorded for herbs and bi-annuals. The species were classified according to their use into several categories like fruits and nuts, staple food, beverage and stimulant, spices, timber and firewood, medicinal products, religious plants, ornamentals, multipurpose species with more than four uses, and other. Rubber was the only species used exclusively as a cash crop and classified as such. During the survey oral information was collected on the management practices for individual species and the changes involved in it. The average number of species in the various homegarden types ranges from 17 to 51. Cash crops are subjected to a variety of management practices. The most intensively managed species are Cocos nucifera, Hevea brasiliensis and Areca catechu. The valuable timber species Tectona grandis receives no particular attention to increase productivity. The study shows that homegardens composition and management is gradually evolving in response to the socioeconomic dynamics. 33% of all respondents have adopted modern practices by increasingly moving towards concentrated cash crop production and use of external inputs.
Yesodharan & Sujana, 2007 studied the status of ethnomedicinal plants in the Parambikulam Wildlife Sanctuary in Kerala. The sanctuary is situated in the Palakkad district, which has major tribal communities like Kadar, Malasar, Muduvar, and Malamalasar. Expansion of agricultural land, fuel wood collection, and large number of domestic cattle maintained by the tribes impacts regeneration in the sanctuary. Anthropogenic activities and natural calamities like land slips, earthquakes, etc. are the major cause of rarity of species. A complete list of threatened medicinal plants used in the traditional system of medicine is enumerated in the study. 139 species of plants belonging to 51 different families are used in the tribal medicine of this region. Among them, 27% are included in different categories of threat. Fabaceae is the dominant family with the highest number of species used for medicinal purposes. These plants are commonly used in the form of juice, paste, infusion, and powder.
Yesodharan & Sujana, 2007 also studied the wild edible plants traditionally used by the tribes in the Parambikulam Wildlife Sanctuary in Palakkad district of Kerala. The data were collected from the tribals through rural visits and questionnaire survey. A total of 83 species of edible plants were collected, in which 82 were angiosperms and one were gymnosperm. Among the 83 species, 31 species are used for fruits, 30 leafy vegetables, 16 for seeds, 10 for rhizomes/tubers/corms and 6 as food from stem/shoot. Among wild fruits, Artocarpus heterophyllus and Mangifera indica are commonly consumed. A number of species is used as medicines, in which some are also used as food. Oxalis corniculate, Sarcostigma kleinii, Cassia obtusifolia, Ensete superbum and Terminalia bellirica are some species which were used as food as well as medicinal plants. Some plants are used to make liquors. The tribals use mushrooms and other unidentified wood inhabiting fungi and lichens as food.
Sabu & Babu, 2007 conducted a study on the floristic analysis of wetlands of Kerala. Floristic surveys were conducted in 11 major wetlands of Kerala (six coastal and five inland wetlands) and various data of species was collected through a literature survey. The present study included both inland and coastal wetlands from Thiruvananthapuram to Kannur and listed 503 true wetland species. A total of 100 species of phytoplanktons were recorded from the selected wetlands. Desmidaceae had a higher representation in the northern backwaters (Neeleswaram to Azhikode) during the monsoon season, whereas this was replaced by either Bacillariophyceae or Chlorophyceae during the post-monsoon season. The southern backwaters except Ashtamudi were dominated by Bacillariophyceae during monsoon, which got replaced by Myxophyceae during the post-monsoon season. During the pre-monsoon period Chlorophyceae, Myxophyceae and Chrysophyceae showed higher percentage incidence in the southern backwaters, whereas Bacillariophyceae showed higher incidence in the northern backwaters. A total of 725 vascular plants, which include 8 Pteridophytes and 717 Angiosperms in 81 families were recorded from the wetlands studied. The first ten dominant families are Cyperaceaae, Poaceae, Scrophulariaceae, Fabaceae, Asteraceae, Eriocaulaceae, Araceae, Convolvulaceae, Lythraceae, and Commelinaceae. In the wetland-dependent category, herbs are the dominant group. Herbaceous species dominate in all wetland areas except in the unique Myristica Swamps of Kulathupuzha and Shendurney Wildlife Sanctuary. Coastal wetlands are rich in floristic diversity, and 281 species are common in coastal and inland wetlands.
Augustine Jomy, 2008 studied the diversity, distribution, and endemism of genus Strobilanthes in high ranges of Kerala. The hilltops and understory of evergreen forests in the High ranges of Kerala and other parts of Western Ghats are well known for the Strobilanthes thickets. Altogether 43 species of Strobilanthes are known from Kerala. Of these 38 are endemic to Peninsular India, 3 are endemic to Kerala (S. dupeni, S. homotropus and S. virendrakumarana) and 2 species are exclusively endemic to Idukki District (S. homotropus and S. andersonii). 40 species of Strobilanthes are found in the High ranges of Kerala, in which most of them occur within the existing Protected Areas. 22 species and one sub-species were known to occur in Eravikulam National Park, 18 species in Anamudi Chola National Park, 27 species in Periyar Tiger Reserve, and only one species (Strobilanthes cuspidatus) in Chinnar Wildlife Sanctuary is recorded. The high ranges of Kerala is a hotspot of endemic Strobilanthes. Possible reasons may be the geographical isolation of many highland valley and gorges, altitudinal and eco-climatic zones. The largest number of species (27) within Periyar Tiger Reserve may be due to the large tract of evergreen forests and wide ranges of altitudinal variation (200 to 2016m asl). Monocarpic nature and gregarious flowering are the specialty of Strobilanthes species. The periodicity of flowering varies from annual to 16 years.
Nayar T. S et al., 2008 conducted a primary analysis of the flowering plants of Kerala based on 1303 publications. They found that 4694 species of flowering plants have been recorded so far in Kerala, under 1418 genera and 188 families. The state constitutes only 1.18% of the geographical area of India, but it accommodates 27.57% (in total, 17,023 species in India) of flowering plants occurring in the country. Out of 496 publications from 1981 - 1990, 119 papers come up with 168 new species from the state. This is due to the establishment of Botany Department at Calicut University (Malappuram district) (1968), Kerala Forest Research Institute at Peechi (Thrissur district) (1975) and Tropical Botanic Garden and Research Institute at Palode (Thiruvananthapuram district) (1978) triggered intensive botanical explorations in Kerala forests, which helped to discover this many new species. Excluding 417 cultivated and/or planted species, there are 4277 species in the state, that come under 1238 genera and 173 families. Out of 4078 indigenous species, 237 species in 47 families (5.81%) are endemic to Kerala. More than 45% (2051 spp.) of the total species are represented by nine families which accommodate more than 100 species. Rest of the families have ≤ 83 species. Impatiens is the largest genus with 78 species. There is no family endemic to Kerala. There are two monotypic genera (Silentvalleya and Haplothismia) endemic to the state. There are 199 exotic species naturalised in Kerala. Herbs constitute 50.1%, shrubs 15.8 % and trees 15.08% of the total flowering plant species of the state. Kerala is horizontally segmented into three: Southern (Thiruvananthapuram, Kollam, Alappuzha, Pathanamthitta, Idukki and Kottayam districts), Central (Eranakulam, Thrissur, and Palakkad districts) and Northern (Malappuram, Kozhikode, Wayanad, Kannur and Kasaragod districts). There are 378 species found in southern and central Kerala alone, 228 species in southern and northern Kerala alone and 36 species in central and northern Kerala alone. Out of the 4078 indigenous species, 203 species (4.97%) come under one or other IUCN red list category. 1170 species occurring in the state (27.35%) are used medicinally. There are 117 species used for softwood purposes, 146 species for extraction of tannin, 29 species for latex, 111 species for gum, 65 species for resin and 284 species for oil. There are 224 species having poisonous properties. About 1,000 species are used for basketry and as detergent, sand binder, green manure and so on. In fact in the study, floras dealing with comprehensive descriptions of species are absent. Species descriptions in many floras are scanty and repetitive. About 3,990 Malayalam names have been recorded for 1507 species (35.1%) and rest of them (3187 species) do not possess Malayalam names, possibly because the locals do not use them, not accessible to them or local names are not fully documented.
Silija et al., 2008 studied the ethnomedicinal plant knowledge of the Mullu kuruma tribe in Wayanad district, of Kerala. Out of 60 Mullu kuruma colonies, 10 colonies were randomly selected. Field work was conducted from April to June 2005 in Noolpuzha village, and the results were based on interviews. Plant specimens were collected, and herbaria was prepared. A total of 136 plants was found to be used by the tribes which involves using its different parts like leaves, roots, rhizome, inflorescence, fruit, seeds, etc for different medicinal purpose. 19 plants were used to treat asthma and other bronchial diseases, 14 for skin diseases, 13 for urinary complaints, 11 for dysentery and anaemia, 10 for inflammation, 9 for dandruff, 8 for jaundice and liver diseases, 7 for epilepsy and leucorrhoea, 6 for piles, burns and leprosy, 5 for wounds, 4 for constipation, 3 for abortifacient and malaria, 2 for migraine, and 1 for tuberculosis treatment are used by the tribes.
Sujana & Sivaperuman C, 2008 studied the status and conservation of threatened flora in selected sacred groves in coastal areas of Thrissur district of Kerala. 5 sacred groves were selected, field observations were carried out, and the neighboring people and temple worshippers were interviewed. Plants were identified with the help of standard floras, and herbarium data. The diversity index was calculated using SPDIVERS.BAS. The study revealed that sacred groves act as gene pools and are home to many rare, endangered, endemic, economically and ethno-medicinally important species. Total of 25 threatened flora were encountered consisting of 15 tree species, 6 climbers, 3 shrubs, and 1 palm. The abundance was higher in Madambath Kavu and lowest in Pipoth Kavu.
Menon et al., 2010 conducted a study about the vegetation characteristics of the Southern Secondary Moist Mixed Deciduous Forests of Thrissur district of Kerala. Four zones were selected, namely, Peechi, Vazhani, Chimmney, and Chalakudy regions. Random sampling by quadrate method (32 X 32 m) was done in five localities of each of the four zones. Data of trees, saplings, seedlings, shrubs and climbers from these quadrats and data of herbs from nested quadrats (1 X 1 m) were collected for analysis. The study resulted in the enumeration of 2919 individuals which includes 81 tree species, 21 shrubs, 58 herbs and 48 climbers. Among trees, Xylia xylocarpa dominates the study area. Shrub species was low in number due to the over dominance of Helecteres and Chromolaena species. Tree species diversity was high in the study area when compared to other forests in Western Ghats. High seedling diversity and low sapling diversity were observed in the forest which warns the decline of tree species in the future. The average species density of Thrissur district was 34 species per 0.1ha. Vazhani region has high tree density among other zones. Herb and shrub density was higher in Peechi and climber show high density in Peechi and Chalakudy region.
Mohan Kumar, 2011 studied the species richness and aboveground carbon stocks in the homegardens of central Kerala. Based on proximity to the Western Ghats and occurrence of predominant land use activity in home gardens, three districts, namely Thrissur, Palakkad and Malappuram districts were selected for the study. Two-stage stratified random sampling was employed where 10% of the panchayaths from each three districts (10 each from Thrissur and Malappuram, 8 from Palakkad) were selected randomly and approximately 30 households per panchayath were randomly selected. Common herbs, shrubs, and trees were recorded and tree biomass was computed using equations. Aboveground carbon stocks of trees were computed on the basis of the area of home garden which include 284 small size home gardens, 330 medium size, and 225 large size homegardens. Data of one panchayat from each three districts were used to compute Simpson's diversity index and for elucidating garden size vs. species richness relationships. Altogether 463 species were recorded from all selected panchayaths in the three selected districts, of which 208 were trees. Many home garden floristic elements had multiple uses such as timber, fuelwood, fodder, medicines, gums, resins, latex, etc. Floristic richness decreased in the order of medium, small, and large-sized holdings. Woody perennials accounted for a considerable proportion of the floristic spectrum in all holding size categories. Average aboveground standing stocks of carbon ranged from 16 to 36 Mg ha−1 with standard error values in the range of 0.74–2.18. The size of the gardens was a major factor affecting carbon stocks per unit area, and the number decreased in the order small > medium > large. The C stock estimates are approximations of the C sequestration potential (CSP). Therefore, increasing plant species richness increases CSP of the home-gardens. Species richness on a total home-garden area basis increased as the size of the gardens increased, but the number of species per unit area declined.
Ratheesh Narayanan, et al., 2011 studied the ethnobotanically important trees and their uses by the Kattunaikka tribe in the Wayanad Wildlife Sanctuary of Kerala. Frequent trips were carried out for plant collection in different seasons from 2006 to 2009. Specimens were identified and deposited in the herbarium. Five tribal colonies were randomly selected, and data were gathered from Kattunaikka tribal groups. A total of 101 taxa of trees under 79 genera belonging to 32 families were collected and identified. It accounts about 15% of the total tree species of Kerala. Moist deciduous forest is the dominant vegetation type. A total of 75 trees are used for various purposes such as medicines (22%), timber (20%), edible fruits (15%), Non-Timber Forest Products (11%), socio-religious (4%) and other uses (28%). 21 species are having high timber value and used for house construction materials, household articles, furniture, etc. 30 trees are used for various domestic purposes like fire wood, making toys, agricultural implements, ropes, etc. Wood of Shorea roxburghii is widely used as a source of fuelwood for cooking and making fireplaces. Crushed leaves of Casearia wynadensis and fruits of Hydnocarpus pentandra are used as fish poison.
Thomas et al., 2011 conducted a study on floristic diversity along an altitudinal gradient of Mannavan Shola forest in Kerala. The study area was segregated into three gradients based on altitudes (1900, 2100, and 2300 msl) using Trimble GEOXT 2005 software. A field survey was conducted; all mature trees, saplings, and tree seedlings were tagged and vegetation analysis was performed. 554 individuals of mature trees belonging to 40 species under 21 families were identified from the first altitude (1900 msl). 552 individuals belonging to 31 species and 15 families were identified from second altitude (2100 msl) and 234 individuals belonging to 24 species and 13 families were observed from third altitude (2300 msl). This reveals that diversity was higher in lower altitude followed by middle which may be due to eco-physiological constraints and geographical barriers. A total of 19 species were endemic to Western Ghats.
Madhusudhanan & Jayesh, 2011 studied the physico-chemical and floristic studies of Mangalavanam mangrove ecosystem in Ernakulam district of Kerala. A physiochemical analysis of water was performed using standard methods. Quantitative estimation of vegetation and leaf anatomy of mangroves was also studied. The hardness of mangrove water was 405.6 mg/L, and the average value of phosphate was 0.17 mg/L. This lower value of phosphate indicates the absence of eutrophication. 5 true mangrove species under 3 families and other mangrove associated species were identified from the study area. Acanthus ilicifolius was abundant among the true mangroves. Leaf anatomy study of Avicennia officinalis show the presence of salt gland covered by hairs and hairy nature of lower epidermis. Sclereids were present in Rhizophora mucronata species.
Ratheesh Narayanan et al., 2011 studied about the wild edible plants used by the Kattunaikka, Paniya and Kuruma tribes of Wayanad District in Kerala. Field survey was conducted from August 2001 to July 2003 and 2008-2010. 15 tribal hamlets from 5 study sites (randomly selected) were selected. 366 knowledge holders of different age groups from the three tribal groups were selected randomly from the hamlets and directly interviewed. Plant specimens were collected and herbarium vouchers were prepared. A total of 165 plants were found to be used for edible purposes by the communities. The Paniya community possesses knowledge regarding 136 taxa of wild edible plants, Kattunaikkas has knowledge of 97 taxa and the Kurumas has knowledge of 42 taxa of wild edible plants. Edible roots, tubers and rhizomes of 24 wild plant species/varieties are consumed by the tribal communities. 84 plant species are used as wild edible greens. 62 edible fruits and seeds was collected during the study, in which 33 are trees, which are usually found in the forests and hills. Paniya community successfully explored all the landscapes ranging from forests to grazing lands, but more from the habitats outside forest-thickets while the Kattunaikkas forage mostly the forests, and the Kurumas access the plantations and paddy fields.
Magesh et al., 2011 conducted studies on vegetation status, species diversity and endemism of Sulimudi forests in the Southern Western Ghats of Kerala, which is a part of Idamalayar forest range. Seasonal variation survey, phytosociological investigation and intensive field survey was carried out. GBH, IVI, density, abundance, frequency, basal area, Margalef index, Shannon and Wiener index, Simpson’s index were calculated. Trees, shrubs, lianas, climbers and herbs in the area were documented in the study. 124 species of flowering plants belonging to 114 genera and 56 families were recorded. Some site specific species like Bentinckia condapana Berry & Roxb, Euphorbia santapaui Henry are interesting features in the study area.
Vidyasagaran et al., 2011 conducted a phytosociological analysis of mangroves at Kannur district of Kerala. Six sites were selected, and a phytosociological analysis was carried out using the quadrate method. GBH of trees was measured and structural parameters were calculated using standard formulas. 12 species under 9 genera belonging to 7 families were recorded. Rhizophoraceae has maximum genera of four species. Acanthus illicifolius, Avicennia marina and Avicennia officinalis were noticed in all the study sites. The frequency was 300 individuals per hectare. Phytosociological analysis reveals highest density and maximum relative density for Acanthus illicifolius. Highest IVI was for Avicennia officinalis. Pappinisseri site has highest Shannon Weiner index and equitability, while highest Simpson's index was in Valapattanam-Madakkara and Kavvayi has lowest value for Shannon Weiner index.
Vidyasagaran & Anilkumar, 2011 conducted a study on the structural analysis of ecosystems of Attappady in Palakkad district of Kerala. It was studied using the quadrat method by establishing 20 x 20 m size quadrats with a minimum distance of 200 m size along the transect. Numerical data about the species were recorded, and various species analysis and indices were worked out. In Muthikkulam tropical west coast wet evergreen forest, 42 species belonging to 25 families were observed whereas Euphorbiaceae represented the maximum genera of 6 species. The highest density, relative density, and abundance was for Xanthophyllum arnottianum and Highest IVI was for Cullenia exarillata in the Muthikkulam forest. The rare and endemic species Vateria macrocarpa is naturally present in Muthikkulam. In the Kuruvambadi moist deciduous forest, 36 species belonging to 24 families were observed where Fabaceae and Euphorbiaceae represented the maximum genera. The highest density and relative density were for Wrightia tinctoria and the lowest were for Artocarpus hirsutus, Bauhinia malabarica, and Bombax ceiba. Wrightia tinctoria observed the highest IVI in the moist deciduous forest. In Murappalam dry deciduous forest, 27 tree species belonging to 18 families were observed, where Euphorbiaceae represented maximum genera of 4 species. The highest density was for Albizia amara, the high relative density was for Naringi crenulate and the lowest values of density and relative density was for Acacia chundra, Anogeissus latifolia and Argyreia spp. Givotia moluccana has high IVI and lowest for Pavetta spp. Murappalam dry deciduous forest show comparatively low canopy levels. The evergreen forest showed the highest diversity index followed by moist deciduous forest. Dry deciduous forest has the lowest values of all diversity indices.
Sasidharan N. & P. Sujanapal, 2011 examined and studied the species of Atuna genus in Southern Western Ghats, namely Atuna indica (Bedd.) Kosterm. and Atuna travancorica (Bedd.) Kosterm. The specimens of A. indica were first collected by Beddome from Wayanad. During the recent floristic exploration of authors, Atuna indica was recollected from two localities in northern Kerala, which caused the rediscovery of this species after the type collection, about 150 years later. Both species of Atuna were described in terms of their morphological characteristics, flowering and fruiting period, habitat, and areas of specimen examination. Atuna genu show relatively high rate of endemism. Among the eight species in the genus, five are narrow endemics and placed under various threat categories. A.cordata and A. pentangiana are restricted to Malaysia and are belonging to the Endangered category. Atuna elliptica, is a red-listed species in the Pacific region. A. indica and A. travancorica from India are restricted to the evergreen forests of southern Western Ghats and belong to ‘Endangered’ category (IUCN, 2006). Atuna travancorica, is known from Kerala and Tamil Nadu. The species has a localised distribution pattern in the Anamalai and Agasthyamali regions. The population and extent of distribution are extremely low. The extent of occurrence is less than 500 sq. km with a severely fragmented population and is facing a high risk of extinction in the wild. Atuna indica shows restricted distribution and a limited extent of occurrence than A. travancorica. This species was known only from Wayanad region and Wayanad ghats in Nilgiri hill ranges. This species faces a more serious threat than what is stated by IUCN (Endangered). The extent of occurrence is estimated to be less than 100 km2. The population is severely fragmented and known to exist in no more than five localities. This indicates that the species can be placed under the Critically Endangered category.
Manoj et al., 2012 conducted a phytosociological analysis of riparian tree species of Alakyam stream in Pariyaram, Kerala. Alakyam stream has a length of 8 km and flows in Kannur district. The study was carried out from December 2010 to June 2011 by adopting quadrate method for trees. A stratified random sampling method was used where roughly 10% sampling was conducted. Primary analysis was carried out and various parameters were measured. 63 species of trees were recorded. The highest density was for Hopea ponga, an endemic and endangered species. About 27% flora is endemic to Western Ghats and 10% belongs to RET category. Species like Hopea ponga and Hopea parviflora have high ecological importance in the area. The Alakyam stream plays a major role in the survival of these species, especially in seed disposal. Syzygium travancoricum, a critically endangered tree species is also seen along the banks of streams.
Reneela & Remesh, 2012 conducted a study on plant resources of Kerala. Among the 10, 735 plant species, the utilization potential is known only for about 1300 species (12%). Angiosperms are more explored for natural products (400 species). The secondary metabolites of plants are economically important in pharmaceuticals, aromatics, fragrances, stimulants, color or pesticides. Natural products isolated from plants are sources of oils, flavours, fragrances, resins, gums, waxes, saponins, pharmaceuticals, plant and insect growth regulators and other products. In traditional material culture, plants are used for dyes and pigments. In Kerala, different systems of medicine like Ayurveda, Sidha, Folk medicine, and Ethnomedicine are utilizing plants for curing a number of diseases. ‘Jeevani’ drug was developed by scientists at the Tropical Botanical Research Institute(TBGRI), Thiruvananthapuram, and was formed from the ethnobotanical knowledge of Kani tribes. Sustainable extraction and application of plants and marine biota will help industries produce dyes, paints, oils, resins, gums, waxes, plant and insect growth regulators, etc.
Augustine, 2012 studied the flowering plant diversity of Cardamon Hill Reserve (CHR), Southern Western Ghats, Kerala. 1044 species of flowering plants were identified in the Cardamom hill Reserve. The richness is comparable to any Protected areas in Kerala. The various 21 places of CHR are found to be floristically rich. The vegetation and floristic composition of these areas share the plant community of the other Protected areas of the high Ranges. Tracts of grasslands with scattered trees and small thickets of Strobilanthus and Psychotria were the vegetation in most of the areas. About 740 species of flowering plants were collected and identified from Mathikettan Chola, showing immense biodiversity richness.
Swarupanandan & Balasubramanyan, 2013 studied and prepared a report on ecology and conservation of five selected tree endemics of Kerala, namely Vateria macrocarpa, Dipterocarpus bourdillonii, Dysoxylum malabaricum, Anacolosa densiflora, and Gluta travancorica. Phyto-sociological and demographic studies were conducted through extensive field exploration and stratification of the distribution area. Geospatial analysis and density data were utilized to estimate population size. Reproductive phenological studies, germination ecology, and some transplantation experiments were also conducted. In Kerala Vateria macrocarpa ranges between 550 and 1,300 m altitude, and the area of occurrence is around 40 km2. The species is found in some natural forests and coffee and cardamom plantations of the Siruvani Group of plantations. In areas of 900-1300 m altitude, the species has high density, where all the life stages are well represented; therefore, this area is suitable to mark as a conservation area for the species. One hundred seedlings of V. macrocarpa were planted on the banks of a streamlet south of the Palghat Gap at Upper Moozhiyar to evaluate its survival, and it resulted in the survival of 44% of the species in 6 months. For the study of Dipterocarpus bourdillonii, the areas like Malayattur, Attappady, Achenkovil, Moozhiyar, Azhutha and Pamba were explored in the study. The population in Kerala is only around 200 trees, and suffers from selective logging. The low population size makes it ‘Critically Endangered’. The area of occurrence of Gluta travancorica in Kerala is 178 km2 and the average density is 30 tr/ha. The species can be considered ‘Low Risk, Near Threatened’. Two-hundred seedlings of the species were transplanted at Upper Moozhiyar and Nilakkal forests but because of the failure of NE monsoon in the planting year, only 20% survival was obtained after 6 months. Dysoxylum malabaricum is distributed in almost all districts in Kerala and occurs as dense patches in ecotonal semi-evergreen forests. The species is extremely rare except the known high-density areas of Moozhiyar and Sholayar (17 km2), therefore, the species may be considered ‘Endangered’. A patch of semi-evergreen forest has been identified at Moozhiyar, where the species grows gregarious and may be protected as a conservation area. Together with two more species of the same genus, this forest patch is a gene reserve for the genus Dysoxylum in Kerala. Pretreatment of seeds with bavistin can imporve germination from 50 to 70%. Two hundred seedlings of D. malabaricum were transplanted in canopy gaps at Nilakkal and Upper Moozhiyar, and only 20% survived after 6 months, due the failure of NE monsoon. Anacolosa densiflora, is an extremely rare tree recorded from Anamalai and Travancore which recorded 15 tree species in the Periyar Tiger Reserve. The species may be assigned a ‘Critically Endangered’ status. The fruits sown in nursery beds failed to germinate.
Sasidharan, 2013 conducted floristic studies in Aralam Wildlife Sanctuary in Kannur district of Kerala. The sanctuary covers an area of 55 km2 with evergreen and semi-evergreen forests as major vegetation. 1005 species of flowering plants belonging to 597 genera under 128 families and 2 sub families, have been collected and described during the study. Dicotyledons predominate the area with 818 species under 108 families and 2 sub families while monocotyledons were 186 species under 19 families. Fabaceae with 83 species is the largest family and 28 angiosperm families in the sanctuary are represented by only one species. One single species of Gymnosperm was also observed in the study area. Among 597 genera, Strobilanthes and Impatiens have maximum number of species (12 each). Out of 1005 species, 7 species are new additions to Kerala flora and 247 are new to Kannur district flora. Compared to other protected areas of Nilgiri Biosphere Reserve, the dominance of Poaceae family has low rank in Aralam Wildlife Sanctuary because of the dense evergreen tree cover. Out of the 1005 species recorded, 274 are endemic to Peninsular India and 135 are confined to Southern Western Ghats. Rubiaceae family has high number of endemic species (28 sp.) in the study area. 59 species in the sanctuary falls under various threat categories. Association of species like Dipterocarpus- Palaquium– Mesua was found in the sanctuary. Critically endangered tree Dipterocarpus bourdillonii, was observed in the Sanctuary, which is the only presence in North Kerala to Palakkad gap.
Sundarapandian et al., 2013 studied the edge effects on plant diversity in tropical forest ecosystems at Periyar Wildlife Sanctuary in the Western Ghats of India. Three study sites were selected in the forest ecosystem based on disturbance gradient. The study site I is close to the Teak plantations and human settlements and severely disturbed. Site II is a moderately disturbed forest which is subjected to occasional dry wood collections by tribal peoples. Site III is completely undisturbed natural forest. Phytosociological studies and vegetation analysis were conducted in three sub-plots of each site. Data on trees, tree seedlings, shrubs, climbers were collected. The plant samples were identified using flora books and confirmed with Regional BSI, Coimbatore. Species diversity index, the dominance of community, species richness, evenness index of community was calculated. One way ANOVA was used to test for differences among the study sites in various phytosociological characteristics. A total of 174 plant species of 135 genera and 63 families were recorded. The numbers of species were greater in the site III (undisturbed forest). The dominant family in terms of the number of species was Euphorbiaceae in site I and III whereas, Lauraceae and Euphorbiaceae in site II. The dominant tree species was Tectona grandis, Terminalia paniculata in site I and II respectively. In site III, Terminalia bellirica, Bruces javanica and Shorea gardneri shared the dominance. Site II is at forest transition level because the site is dominated by both natural species as well as plantation species such as Tectona grandis. The shrub community in site I and II was dominated by Maesa indica, in site III it was Mallotus tetracoccus. The number of species in the herbaceous community was greater in the site I. Cyrtococcum patens was the dominant species in both the study sites I and II. Whereas in site III, the dominant herbal species was Pteris biaurita. Cattle grazing and other disturbances that alter the micro climate may be the reason for single species dominance in sites I and II. The number of species of sapling populations was greater in site III. The study reveals that anthropogenic disturbance causes exotic plant invasion, reduces the species richness, and inhibits the regeneration of native species. The species richness was observed to be lower in site I in comparison to site III when considering the number and diversity indices of trees, seedlings, and saplings, but the trend was reversed when only herbs were taken into account. The lower number of tree diversity, species richness and greater herb diversity in site I could be attributed to anthropogenic disturbance, cattle grazing and other associated disturbances. Disturbance helps the establishment of rural weeds such as Lantana camara and Erysimum odoratum. Invasion of such Exotic plant resulted in the loss of local biodiversity.
Vaheeda & Uma, 2013 studied the plant diversity along the lower reaches of Bharathapuzha river in Kerala. Total 10 sites were selected along the river where the first seven sites are located in Palakkad District and remaining three are located in Malappuram district of Kerala. A survey was conducted and aquatic and wetland macrophytes were collected from the selected sites. Phyto-sociological parameters were analysed using quadrat method. The study was conducted during March to June 2011 (Pre-monsoon period). A total of 110 macrophytes under 41 families were observed in the study area of which 29 families were dicotyledons, 9 monocotyledons and 3 Pteridophytes. 81 species were typical herbs. Shannon-Weiner index of species richness showed greater diversity in Pattambi in Palakkad district and least at Chamravattam in Malappuram district. ANOVA indicated no significant diversity between the sites. Poaceae with 15 species dominated the vegetation analysed. Majority of the plants recorded in the study were either moisture loving or wetland species. The sedges and grasses contribute 23 % to the floral diversity. Saccharum spontaneum L.,Cyanadon dactylon (L) Pers. and Cyperus compressus L. were the major grasses. 25 % of the plants are alien to India. 34% of the plants recorded during the study have medicinal properties. The species richness is less compared with that of sholas of Eravikulam. The relatively low values of species richness may be due to the river water being regulated by dams, leading to reduce flow and consequent dryness, especially during the pre-monsoon period.
Rajan et al., 2013 studied the floristic diversity and associated fauna in the Vagamon hills of Kerala. The area consists of grasslands and shola forests and study was conducted during 2007-2010 by selecting random sampling sites. Vegetation analysis was done by both qualitative and quantitative methods. Qualitative methods include conducting field visits, collecting plant components, preparing herbarium, and identifying and studying them using standard floristic references. Quantitative analysis was done by using quadrate method. 286 plant species from 85 families were identified where Asteraceae family holds the most abundant species. The different analysis show that the area is rich in floristic diversity. 112 species of butterflies and 78 species of birds were also discovered from the area.
Abhilash et al., 2013 conducted an ecological analysis in the abandoned forest plantations of Kannavam in Kerala. Since 1949 no routine plantation activities were done in the area, leading to the establishment of a natural, moist deciduous forest. Quadrats of 0.1 ha were laid out pertaining to trees. Density, Basal area, Abundance, Frequency and its relative values were determined. Species richness, diversity and evenness were studied using standard indices measurement. 19 tree species were enumerated, where Tectona grandis alone constitutes 66 % of the total tree volume, high density, and basal area. Tectona grandis and Terminalia paniculata are the most frequently distributed species. 29 endemic species were recorded, of which 13 are of tree species, 4 shrubs, 5 climbers and 7 herbs. As in the case of regenerants dominant sapling is Olea dioica and in small trees Ixora brachiata, Aporusa lindleyana and Ficus hispida are the dominant regenerates. The average Shannon diversity value of Kannavam forest plantations is 2.13, similar to typical moist deciduous forests and higher than the natural forests like Aralam, Parambikulam, Andaman Islands, etc. Margaleff’s species richness index is high, which reveals its biodiversity richness. 29 Endemic plants were observed in the study area.
Arun & Shaji, 2013 studied the diversity and distribution of mangroves in Kumbalam island of Kerala. Kumbalam is a coastal region located in the east of Ernakulum district. Quadrat analysis was done, and qualitative and quantitative structures of plant community were studied. The mangrove flora comprises 7 true mangrove species, 2 semi mangrove species, and 8 species of mangrove associates. Maximum frequency, density and abundance was showed by species Acanthus ilicifolius.
Nair, 2013 conducted a comprehensive study on the socio-economic and cultural aspects of sacred groves in Kerala. Individual study reports of all 14 districts in Kerala have been prepared and the first report was on the sacred groves in Thiruvananthapuram district. Thiruvananthapuram is the southernmost district of Kerala, which has a geographical area of 2192 sq.km. The total number of sacred groves in the district was 452 and the thaluk wise number was Neyyattinkara -122, Thiruvananthapuram - 101, Nedumangadu – 66 and Chirayinkil – 163. The size of sacred grove vary from one cent to 3 acres. They were owned by different groups like Travancore Devaswam Board, public committees, government or private ownership. All three land regions (highland, midland and lowland) in the district have the same climatic condition and no marked difference is noticed in the vegetation of sacred groves except those in the low land-coastal region due to soil variations. Most of the species belong to the families Fabaceae, Rubiaceae, Euphorbiaceae, Amaranthaceae, Moraceae, Rutaceae and Liliaceae in descending order. The common species among the sacred groves were tabulated under different plant forms like trees, shrubs/herbs, and climbers, which mainly come under evergreen and semi-evergreen forest types. Rare species and species particularly seen on specific land forms were listed. The regeneration status of species was recorded by noting the pole crop and saplings. Natural regeneration is generally good in Artocarpus hirsutus, Adanenthera pavonia, Holigarna arnotiana, Apoousa lindleyana, Caryotta urens, Hydnocarpus pentandra, Struchnos nux-vomica, Machilus macrantha, Terminalia bellirica, Cinnamomum etc. which are common in almost all the sacred groves. Garcinia cambogia regenerates well in many sacred groves but mature trees are less, this may be due to its delayed growth. Regeneration of Struchnos nux-vomica is more in sacred groves of Thiruvananthapuram taluk. Diospyros peregrina and Emblica officinalis are rare in the sacred groves. Morinda tinctoria, Taberneamontana heyneana, Sterculia foetida and Borassus flabellifer are seen in many sacred groves as mature trees. Some of the trees like Alstonia scholaris, Michelia chempaka, Ficus sp., Artocarpus hirsuta, Aegle marmelos, Emblica officianalis, Mimusops elengi, Azadirachta indica, Strychnos nux-vomica are believed to be the abode of devi and therefor people adore and give special protection and consideration to these trees.
Rahees et al., 2014 studied the phytosociological analysis of the mangrove forest at Kadalundi- Vallikkunnu community reserve in Kozhikode and Malappuram districts of Kerala. It spread across 1.5 km2 situated at the Kadalundi river estuary. Species area estimation and quadrat analysis was used to study the distribution patterns of mangroves. The plant diversity analysis was calculated using different diversity indices. The mangrove flora in the study area comprises about 7 true mangrove species under 6 genera belonging to 5 families. Avicenniaceae is the largest family. Avicennia officinalis holds the highest density, frequency, and basal area value. Avicennia marina was the least diverse species. The pattern of distribution were discontinuous. Shannon index value of 2.117 shows that the study area is a high species diversity zone.
Prajeesh Parameswaran et al., 2014 conducted a study on the vascular Plants associated with wetland paddy fields (Vayals) of Wayanad District in Kerala. 34 paddy plot sites were selected from different places in Wayanad. A total of 319 species of vascular plants were recorded, with 308 Angiosperms, which is 15% of the total species reported from the district, and 11 Pteridophytes. Out of 319 species, 233 were herbs, 40 were shrubs, 17 were climbers and 29 are trees. A total of 72 families (66 Angiosperm families and 6 Pteridophyte families) were recorded and Cyperaceae (34) has the highest number of species. Apart from the widely cultivated crops and seasonal crops, six other cultivated species found near the paddy fields are Artocarpus hirsutus, Artocarpus heterophyllus, Hibiscus rosa-sinensis, Ipomoea batatas, Ipomoea turbinata and Mangifera indica. Paddy fields of these sites harbour 118 species, paddy levees harbour 150 species and 189 species were found both in paddy fields and paddy levees. The study shows that the flowering plant diversity of paddy-associated landscape is rich, and it harbours 15% of the total Angiosperm species reported from the district.
Xavier et al., 2014 conducted an ethnobotanical study of Kani tribes in Iyyavilagam of Thoduhills in Thiruvananthapuram district of Kerala. The study area was investigated through field trips from March 2012 to May 2013. At least 10 days were spent with the local people during each field survey. Collected specimens were identified and authenticated with the help of valid references. A total of seven resource persons or informants or traditional healers who have sound knowledge of the medicinal plants and practice medicine, were identified to get the ethnomedicinal information. All the reported ailments were categorized into 14 categories. The Informant Consensus Factor (Fic) was used to see if there was agreement in the use of plants in the ailment categories between the plant users in the study area. The relative importance of each plant species is reported as the use value (UV). Fidelity level (FL) was calculated to determine the most frequently used plant species for treating a particular ailment category. The Relative Importance (RI) of each remedial plant was designed. 35 plant species are used as herbal remedies to treat several ailments. Among them,16 plants were herbs, 8 were shrubs, 6 were trees and 5 climber species. Out of the 35 plant species studied 29 were dicot, 5 were monocot and 1 was a pteridophyte. Drugs are utilized in the fresh or dried state. Leafy crude drug preparations are mostly recommended as ethnomedicine. Most commonly used method of preparation was paste (48%) followed by juice (28%), raw material of plant parts like leaves, fruits, etc. (12%) and decoction (10%).The Kani traditional healers used more than two or three plant parts to prepare medicine to treat single or multiple ailments. The most commonly used species was Plumbago zeylanica, which had 13 use reports from 7 informants (UV- 1.86). The Fic values ranged from 0.70 to 1 for all ailment categories. 23 species had the highest fidelity level of 100%. Andropogon muricatus had the highest RI (92.5).
Morvin Yabesh et al., 2014 conducted an ethnobotanical study of medicinal plants used by traditional healers in the Silent valley of Palakkad district in Kerala. The study was conducted in 5 villages of Silent valley (Agali, Kottathara, Mannarkad, Padavayal, and Sholayur). The study area was investigated, and local traditional healers of 5 villages were interviewed from September 2011 to August 2013. They were requested to collect specimens of the plants they knew or to show the plant species on site. The questionnaires were used to obtain information on medicinal plants, and a field data sheet was prepared. Voucher specimens of medicinal plants in triplicate were collected, prepared and identified. All the reported ailments were categorized into 15 categories. Data analysis was done by calculating the Informant consensus factor (Fic), Use value (UV), and Fidelity level (FL). 102 ethnomedicinal plant species belonging to 53 families, in 95 genera, are commonly used for treating 52 types of ailments. Among the families, Euphorbiaceae has high number of species (7). The majority of the plant remedies were prepared by paste (39%). The most frequently used mode of remedy administration is oral ingestion (62%). The most commonly used species was Moringa oleifera (highest UV=2.62), with 21 use reports from 8 informants. It is used in the treatment of various diseases like cancer. The Fic values ranged from 0.63 to 1.00. 7 species had the highest fidelity level of 100%, most of which were used in the single ailment category with multiple informants.
Vidyasagaran et al., 2014 studied the distribution and plant diversity of mangroves on the west coast of Kerala. A team of experts visited various mangrove sites in the coastal districts of Kerala and documented information on extent, floristic diversity, structural attributes, degradation status, etc. Secondary data was collected from resource survey details of the land use board and resource map prepared at the Panchayat level and also through discussion to local experts, social workers, environmentalists, and Panchayath officials. Plant diversity was studied by the spot identification of plant species. Plant specimens of unidentified species were collected and identified with the help of taxonomists. Kannur district occupies maximum extent of mangroves (1100 ha) followed by Ernakulam (600 ha) and Kasaragod (315 ha). Similarly, minimum extend was represented by three districts, namely Malappuram (26 ha), Thiruvanthapuram (28 ha) and Thrissur (30 ha). Out of the total extent of mangroves in Kerala (2502 ha), 1313 ha are under private ownership and 1189 km belong to the State. The mangrove vegetation is mainly influenced by the halophytic adaptations. During the study, 15 pure mangroves species were recorded, belonging to 9 genera and 6 families. Rhizophoraceae represented 7 species, followed by two from families: Avicenniaceae, Sonnaraceae and Euphorbiaceae. 33 mangrove associates were identified from various locations in different districts.
The grass diversity of Vagamon hills in Kerala was studied by Mathew et al., 2014, and the area shows exceptional biodiversity. The study was carried out through field visits, and plant specimens were collected, identified, and analyzed according to their habit and conservation status. The study area is dominated by tall grasses like Cymbopogon flexuosus, Themeda cymbaria etc. Rare species like Zenkaria elegans, Arthraxon lancifolius, etc., are seen. Some grasses are used for thatching and for medicinal purposes. Out of 77 Species collected, 18 are Endemic to Peninsular India. 25 Exotics indicate the degrading nature of grasslands may be due to agricultural and other developmental programs.
Sankaran K. V et al., 2014 studied the invasive plant threats in Kerala forests. Data on the presence of Invasive Alien Plants (IAPs) was collected through road surveys during the period of 2012–2013 covering evergreen, moist deciduous, and dry deciduous forests and grasslands. There were a total of 655 observation points throughout the State. At each location, information on the IAPs in the area, intensity of their infestation and the native species and habitats impacted by these were collected. A total of 38 IAPs were located in the forests of Kerala. Of these, 10 are of high risk, 12 pose medium risk, 10 low risk and the rest 6 are of insignificant risk. These include 5 trees, 10 shrubs, 4 sub-shrubs, 13 herbs and 6 climbers. The land of origin of majority of the species was Central and South America. Most species’ introduction into the forests was intentional, and few were accidentally introduced. Forest surveillance, early detection and rapid control, manual/mechanical removal of weeds followed by planting of native species and assisted regeneration are suggested as immediate steps to control invasion and reduce impacts.
Senthilkumar et al., 2014 studied the Myristica swamp forest in Kerala as part of the project of the Indian Council of Forestry Research and Education (ICFRE) to revisit the forest types of India through rapid assessment mode to know whether there are any changes in the forests characteristics which was classified and described by Champion and Seth long before (1968). The study was conducted on the Myristica swamp forest in Kulathupuzha range of Thiruvananthapuram Division from April 2012 to March 2013. The sample point locations (geo-coordinates) were given by FSI, which falls under Mayilamoodu and Sangili sections of Kulathupuzha forest range. Ten Myristica swamps (5 in each section) were selected based on the given latitude and longitude. About 40% of the area of Kulathupuzha is occupied by various plantations, the rest is constituted by evergreen forests, grass lands, swamps, degraded forests and human habitations. Swamps are located on hill streams and in tributaries of Kulathupuzha River. Nine quadrates were laid for each point, and data on vegetation and other history was recorded for each point. Samples were collected for the entire flora observed. The species Gymnacranthera farquhariana is dominated in narrow valley swamps whereas Myristica fatua var. magnifica is dominated in flat valley swamps. It is observed that there is no change in forest type of Myristica swamp as described by Champion and Seth (1968).
Kumr K, 2015 conducted studies and provided a checklist of the vascular flora of Anamudi Shola National Park in the Idukki district of Kerala. The area includes three distinct sholas: Mannavan Shola, Pullaradi Shola, and Idivara Shola. Since 1994, regular field trips have been organized to these sholas, and plant specimens have been collected and critically studied. Herbaria were prepared using collected specimens as per standard procedure. About 674 of vascular plants, including 598 taxa of flowering plants and 76 pteridophytes, could be collected. Among 598 taxa of flowering plants, 484 taxa are dicotyledons, and 114 taxa are monocotyledons. Asteraceae (from dicots) with 42 taxa, Poaceae (from monocots) with 32 taxa, and Aspleniaceae (from pteridophytes) with 12 taxa were the largest families in their respective groups. Out of the 484 dicot taxa, 39.5% belonged to herbs, 33.7% were shrubs and 26.9% were trees. Among pteridophytes, there were more terrestrial taxa than epiphytes and lithophytes. More than 30% of plants collected during the study were restricted to the Western Ghats. Out of the total 598 angiosperm taxa, 222 were endemics. During the study, 4 species of angiosperms, which were earlier documented as ‘Possibly extinct’ could be rediscovered, and about 66 plants were reported for the first time from Kerala.
Vincy et al., 2015 compared the riparian species diversity between the main river channel and sub-watersheds of the Meenachil river basin of Kerala and studied the diversity indices and analytical features. The study mainly focused on the mainstream and five sub-watersheds namely; Kattachira, Koduvan Ar, Mannani, Payappara, and Thikovil sub-watersheds. Vegetation analysis was conducted from 2009-2012. Quadrats of size 10 × 10 m for trees; 5 × 5 m for shrubs, and 1 × 1 m for herbs were laid randomly, and different analytical features and indices were calculated. A total of 441 species belonging to 105 families were recorded. Alstonia scholaris, Artocarpus hirsutus, Chrysophyllum cainito, and Holigarna arnottiana are the most common tree species along the banks of the river. Leguminosae is the leading plant family. There is no significant difference in the diversity index of trees, herbs, and shrubs of the main stream and other selected sub watersheds. Koduvan Ar and Payappara exhibited the highest richness for trees, whereas Kattachira revealed the highest richness for herbs and shrubs. Mannani had the least species richness, which may be due to deforestation and rapid urbanization. A majority of the species show a contagious pattern of distribution. Upstream watersheds (Payappara and Thikovil) showed the greatest species diversity.
Chandrashekara UM, 2015 studied the diversity, management, and nutritive value of edible non-crop plants in home gardens of Kerala. The study was conducted in Karakkode Village. An area of 3 km x 1 km was selected and divided into a 200 m x 200 m grid. The grid intersection points were marked using GPS. Out of 90 grid intersection points, 48 represented home gardens and were selected for the study. In each of the 48 home gardens, three transects, each of 40 m x 10 m in size were marked. Each transect was divided into 16 quadrats (5 m x 5m). All the herbs and shrubs were identified. Information on edible plants, parts used, frequency of collection, and management was gathered from the home garden owners. 27 species, belonging to 22 genera and 17 families were identified as edible non-crop plants. In the 27 species, leaf is the edible part for 22 species, while in the remaining 5 species, the whole plant is edible. A significant positive correlation was noted between the number of home gardens of occurrence and number of home gardens where the species are used. No special care was given to protect and nurture the species in any home gardens. The average biomass of Cassia occidentalis was significantly more than the rest of species. The edible non-crop plants contribute substantially to protein, mineral, and crude fiber intake and are rich in calcium and iron minerals.
Vijayan et al., 2015 studied the floristic diversity and structural analysis of mangrove forests at Ayiramthengu in Kollam district of Kerala. Distribution patterns of mangroves were studied using species area estimation and quadrat analysis, in which 15 quadrats of 5x5 m in size were taken. Density, frequency, basal area, and their relative values, as well as the Importance Value Index (IVI), diversity indices, and richness of mangrove species, were calculated using standard methods. The mangrove flora comprises 9 mangrove species belonging to 6 families. Family Avicenniaceae is the largest family, and Avicennia marina sp. has the highest density, frequency, and IVI. Relative density was maximum for Avicennia marina and the lowest for Sonneratia caseolaris. Shannon-Weiner diversity index is considered as a medium to high diversity in terms of species. Landfilling, increased aquaculture, industrial developments, and housing are the major threats faced by the mangroves of Ayiramthengu.
Kiran M et al., 2015 conducted a study about the floristic diversity and structural dynamics of mangroves on the northwest coast of Kerala. The study areas selected were six different mangrove sites in Malappuram district of Kerala. Data analysis was conducted using quadrat method. GBH, density, frequency, basal area and their relative values, abundance and IVI were calculated. Plant diversity analysis was carried out using Shannon-Wiener Index, Simpson’s Index, Equitability measure, Species richness and Beta diversity. Jaccard’s cluster diagram has been done using Biodiversity Professional Ver.2 software. 11 species of true mangroves belonging to 5 families were recorded from different sites. Rhizophoraceae has the highest number of species. Among the locations, Pullooni recorded the highest number of species. Avicennia officinalis and Rhizophora mucronata were found in all the six study sites. Rhizophora apiculata and Sonneratia alba were found to be rare and confined in a single site. Avicennia officinalis has the highest density, maximum relative density, and relative frequency. Rhizophora apiculata has lowest density, minimum relative density, relative frequency and minimum value of abundance. Aegiceras corniculatum has a high abundance value. Bruguiera sexangula, which is rare in Kerala, was found in four sites. The pattern of distribution of species were discontinuous in all the locations. Mangrove at Thalakkad-Pariyapuram has the highest Shannon–Weiner index and Simpson’s index, while Mangattiri– Etrikkadavu has lowest value of these indices.
Pius OL et al., 2015 studied the diversity and conservation of Malappuram District endemic and threatened medicinal plants. Field explorations were carried out from different habitats of the district during 2008-2013, and the details of medicinal plant were also collected from authentic literature. 869 species of vascular medicinal plants were documented in the study, in which 85 of them are endemic and threatened. Among the 85 species, 50 are endemic to peninsular India. Remaining 35 are with wider distribution pattern but their population is extremely low. Out of 50 peninsular Indian endemics, 41 are restricted to Western Ghats, including 29 species found only Southern Western Ghats region. Out of 85 species, 51 are under various threat categories, including 28 Vulnerable, 11 Endangered, 7 Near Threatened, 4 Least Concern and one Critically Endangered. Major forest areas in Malappuram district come under the Nilgiri phytogeographical region of Western Ghats, which has many endemic and threatened species. The higher percentage of medicinal plants in the district shows rich traditional knowledge, and the area is also the centre of primitive tribal groups. Among the 85 endemic and threatened species, 77 (90%) are used in folk systems. 9 species in whole, root of 19 species, bark of 20 species and wood of 9 species are used for preparing medicines.
Nair, 2015 conducted a comprehensive study on the socio-economic and cultural aspects of sacred groves in Kerala, and their second report was on the sacred groves in Kollam district. The Geographical extent of Kollam district was 2491 sq. km. From available data of Social Forestry, publicity in the press, and through word of mouth, 895 sacred groves were found in the area. It covers 98 ha of vegetative cover, and Thiravoor kavu (in 2.5 Acs.) in Karunagappally is the largest sacred grove. Most sacred groves contain as many as 12-24 tree species, 10-22 shrubs and 25-34 climbers. Rare and threatened species like Myristica malabarica, Gynacranthera farquhariana, Syzygium travancoricum, etc. have been found in the sacred groves. Euphorbiaceae, Lauraceae, Fabaceae, Rubiaceae and Apocynaceae families are very well represented. The vegetation has distinctive ecological characteristics, such as clear tiers of trees, shrubs and herbs, climbers, epiphytes, parasites etc. The diversity among shrubs and herbs are comparatively low with trees. The prevalence of woody climbers is the specialty of Kollam sacred groves. Invasion of exotic weeds such as Mikania micrantha, Eupatorium odoratum, Hyptis suaveolens and Lantana camara cause threat to the biodiversity. Ficus religiosa and Ficus benghalensis are considered to be Keystone species in the sacred groves as they attract birds, mammals, reptiles and several insects also the strong winding roots of Ficus prevent soil erosion. Interference with the sacred groves been restricted culturally, which causes protection to the ecosystem of sacred groves.
Vijayakumar et al., 2015 conducted a quantitative ethnomedicinal study of plants in the Nelliyampathy hills in Palakkad district of Kerala. The study was conducted in eight villages in the area during the period from September 2011 to August 2013. Data was collected by means of interview with 66 local traditional healers of the village in different age groups. 6 field trips were organized, and a total of 60 days were spent with the local traditional healers. Voucher specimens of medicinal plants were prepared. The information was quantitatively analysed using Relative Frequency Citation (RFC) index, Use Value (UV), and Pearson correlation coefficient. 85 ethnomedicinal plant species belonging to 49 families were used in as herbal medicines for curing diseases. The Cucurbitaceae family has the highest number of species due to its wide occurrence, and the local informants knew a number of traditional uses. 54% of the ethnomedicinal plant species were herbs, 26% trees, 19% climbers, and 1% shrubs. The most frequently used medicinal plant parts were leaves. The majority of the herbal remedies were prepared by paste, and the frequently used mode of administration was through oral ingestion. Highest number of plant species were used against the cold. The highest value of RFC and highest UV was ranked for Solanum trilobatum. Pearson correlation coefficient was 0.638, indicating high positive significant association between the local importance of each species and relative importance of the use of plants.
Nair, 2016 conducted a comprehensive study on the socio-economic and cultural aspects of sacred groves in Kerala, and their third report was on the sacred groves in Kozhikode district of Kerala. The total Geographical extent of the district was 2,206 sq. km having 4 thaluks. The number of sacred groves in the district was1231 with 141 ha. of vegetative cover. Kozhikode taluk contains the maximum number of sacred groves (653) and Thamarassery thaluk has a minimum. The extent of sacred groves varies from less than 3 cents (2%) to 24 acres. Most of the sacred groves are confined to the coastal belt. 83 % of sacred groves are private ownership. Strychnos nux-vomica is the most common species. Euphorbiaceae, Rubiaceae, Fabaceae, Dipterocarpaceae, Aracaceae, Menisprmaceae and Icanthceae can be widely seen in the sacred groves. Medicinally important and rare and threatened species can be found in the groves. Shrub diversity is comparatively low. Climbers, and herbs occurrence is abundant in the area compared to southern districts. Detailed floristic exploration in 28 sacred groves in different taluks were performed. Based on the extent of area, vegetation type, and location, one-time enumeration was carried out in 27 sacred groves in the four taluks, resulting to the enumeration of 372 species, of which 143 are trees, 121 are climbers, and 108 are shrubs. Strychnos nux-vomica occurred in all the 27 sacred groves. Adenathera pavonina and Pothos scandens occur in 25 sacred groves, and Caryota urens, Chassalia ophioxyloides and Mimusops elengi is seen in 24 sacred groves. 90 species occurs only in any one of the sacred groves. Out of 372 species, 35 are Western Ghats endemics (19 trees, 5 climbers, and 11 shrubs). 44 exotic species were recorded from the sacred groves. Eight species serve as keystone species in the area. Shifting deity, encroachment, disputes on ownership, dumping waste, etc. are major threats, and awareness programmes, distribution of grants, production of quality seedlings, and conducting further research can protect the groves.
Nair, 2016 conducted a comprehensive study on the socio-economic and cultural aspects of sacred groves in Kerala, and their fourth report was on the sacred groves in Thrissur district. The geographical extent of the district was 3032 sq. km, with a forest area of 992 sq.km and 6 Taluks. A total of 970 sacred groves were recorded in the district covering an area of 32.54 ha. The vegetation is mostly evergreen types. The number of species of trees in a sacred grove range from 13-29. Some rare and threatened species, as per IUCN status and species used in Ayurvedic preparations, are observed in sacred groves. A total of 35 sacred groves from all thaluks were selected for vegetation and taxonomical study. Inside the Sacred groves, herbs were found wherever there were openings in the canopy. Among the 276 species enumerated from 35 sacred groves, 133 are trees, 87 are climbers, and 56 shrubs. The most widely occurring species are Caryota urens and Pothos scandens, which occur in 31 sacred groves followed by Chassalia ophioxyloidesthos in 27. No species is found occurring in all sacred groves. 96 species are unique to certain Sacred groves. Out of the 276 species, 29 are endemics, and tree endemism is relatively high with 17 species. 44 species were exotics. Euphorbiaceae is the most dominant family with 20 species. Threats faced by the groves include shifting deity, encroachment, disputes on ownership, dumping waste, etc. Awareness programmes, distribution of grants, production of quality seedlings, interference by the government, and conducting research on ecology and carbon sequestration in Sacred Groves are the major recommendations for conservation.
Dantas & Nanu, 2016 prepared a checklist of wild edible plants of Aralam Wildlife Sanctuary in Kerala. Aralam Wildlife Sanctuary is the northernmost sanctuary in Kerala and home to 1,005 species of plants. West Coast tropical evergreen and West Coast semi-evergreen vegetation dominate the sanctuary. Field data was collected by visiting all habitats of the sanctuary. Specimens were identified with the help of literature. A total of 43 wild edible plants were identified in the area, where Syzygium genus is the largest with 7 species. Among these wild plants, 32 are fruits, Momordica sahyadrica and Solanum torvum are used as vegetable. Phyllanthus emblica, Mangifera indica, Spondias pinnata and Baccaurea courtallensis are consumed directly and used to prepare pickles. Most of the fruits are consumed without cooking. Varieties of Garcinia gummi‐gutta are used as spices. For Dioscorea sp., tubers are consumed after cooking. Some species are grown in homesteads, but wild varieties are seen in forests.
The floristic diversity of Vallikkaattu Kaavu, a sacred grove of Kozhikode was studied by Sreeja et al., 2016. History and details of this sacred grove was collected through field visits, personal interviews with members of the temple trust, and from temple records. Plants were collected seasonally based on their flowering season, and herbaria were prepared. Medicinal uses of these plants were collected through personal interviews with local medical practitioners and renowned Ayurveda physicians of Kottakkal Arya Vaidya Sala, Malappuram, Kerala. The present conservation and endemic status of plants was listed. The sacred grove recorded 245 flowering plants belonging to 209 genera and 77 families. Among these 245 species, 75 species are herbs, 71 trees, 55 shrubs, and 44 climbers. Among the total species, 44 are endemic. There were 34 threatened plants listed. Out of the 245 species listed from this grove, 236 are medicinal, constituting 96% of the flowering plants reported from this sacred grove.
Sreejith et al., 2016 studied the tree species composition and distribution pattern in a Myristica Swamp of Sivapuram, Koothuparambu, Kannur District of Northern Kerala. An area of 5000 m2 was divided into five plots, and in each plot ten quadrats (10 X 10 m) were established for the study. Vegetation analyses were done by calculating IVI, species diversity index, and Simpson’s index of dominance, and the data were statistically tested using ANOVA. Knema attenuata and Myristica malabarica contribute about half of the total IVI. Species like Gymnacranthera canarica and Myristica fatua var. magnifica, which are believed to be essential elements for a Myristica swamp were not observed in the study area. But irrespective of the species composition, the vegetation is dominated by the family Myristicaceae and found in a swampy environment with knee roots, which can be considered a Myristica swamp. The density of trees was 806 individuals/ha and basal area was 34.25 m2/ha. Most of the trees in the study were represented with lower girth classes which results in low basal area value. The Simpson’s index of species dominance shows high value when comparing to the nearest semi-evergreen and evergreen forests. This may be due to the lower diversity and over dominance of the species of Myristicaceae. The similarity index shows that the first plot near the stream side and the last plot away from the stream share only 33% vegetation as common. The girth class shows a normal distribution pattern. In the lower girth class, Knema shows poor regeneration, while that of Myristica remains normal. Among two dominant species, Knema attenuata is widely distributed away from the stream while Myristica malabarica were concentrated along the streamside.
The diversity of herbaceous riparian flora in the lower stretch of the Bharathappuzha river of Kerala was studied by Cherullipadi et al., 2016. The taxonomic survey was conducted from 2014 to 2015 in the lower stretch of Bharathappuzha near Ponnani, Malappuram district. Riparian plants were collected and identified with standard floras. 8 sites were selected, and quadrates of 1 X 1 m were employed for quantitative data collection of herbs. This resulted in identifying 73 species in 29 families in the study area. The vegetation profile includes 73 herbs, 32 shrubs, 22 climbers, and 54 trees. The most frequent herbs are Desmodium triflorum, Emilia sonchifolia and Dactyloctenium aegyptium. The most abundant species is Brachiaria ramose. The Shannon Weiner diversity shows uniform diversity in the area.
Deepa et al., 2016 studied about the medicinal plants in the selected sacred groves of Kodungallur taluk in the Thrissur district of Kerala. They selected 4 sacred groves from Kodungallur: Ayyalath Nagayakshi Kavu, Kumaramangalath Kavu, Chemathi Kavu and Kalapparambath Kavu. Field visits were conducted during different seasons from June 2013 to February 2016. Observations like habit, phenology of the plant, colour, texture and smell of leaves, local names and local uses were noted. Analysis of floristic composition was done with the help of floral books, and herbarium sheets prepared were verified with the data of KFRI and Calicut University Herbarium (CALI). The study records 89 species of angiosperms coming under 83 genera and 43 families from all four selected groves. Of these, 20.22% are trees, 16.85% are shrubs, 42.70% are herbs and 20.22% are climbers. Leguminosae is the dominant family with 3 sub families (Papilionoideae, Caesalpinioideae, Mimosoideae). From the total plants 98.88% plants are medicinal and used in different systems of medicines such as Ayurveda, Folk, Unani, Siddha, Homoeopathy and Tibetan. Different parts of the plants such as leaves, roots, bark, latex, inflorescence, fruits, seeds, and sometimes the whole plants, are used for different medical purposes. Chassalia curviflora (Wall ex Kurz) Thw. is a common plant present in all the four groves.
Deepa et al., 2016 also studied the floristic diversities and medicinal importance of selected sacred groves in Thrissur district of Kerala. The study area includes Adipparambukavu, Daivathinkavu, Kanisherykavu, Kottaichalippattukavu, and Kottarathkavu. The floristic composition was analysed between April 2013 and September 2015 through field visits, and plants were studied with the help of floras. A total of 119 species of angiosperms under 104 genera and 51 families were collected. 8 vulnerable, 12 endemic and 3 near-threatened species were present in the groves. Hydnocarpus pentandra(Buch.-Ham.) Oken, Leea indica (Burm. f.) Merr., and Pothos scandens L. are common in the five sacred groves. All 119 species have medicinal value. 17.64% of species were herbs, 19.33% were shrubs, 41.18% were trees, and 21.85% were climbers. Fabaceae and Moraceae are the dominant families in these sacred groves. Kottarathkavu has a maximum number of endemic plants.
Deepa M.R et al., 2016 studied the rare, endemic, and medicinal plants of selected sacred groves in Chavakkad Taluk of Thrissur district in Kerala. Five sacred groves were selected for study, and they were visited during different seasons from June 2013 to December 2015. Field observations were made about plant characteristics and studied with the help of floras. Floristic composition and flowering twigs were collected and herbarium sheets were prepared. 79 angiosperm species under 70 genera and 42 families were recorded. Out of these 46. 84 % constitute trees, 15.19% were shrubs, 11.39% were herbs, and 26.58% were climbers. All 79 species have medicinal value. 8.86% of plants are endemic, another 8.86% are vulnerable, and 3.8% of plants are at a lower risk near threatened regionally. Moraceae is the dominant family.
Sreejith et al., 2016 studied the microhabitat diversity in a lateritic hillock of Madayipara in Northern Kerala. At least two field visits were made every month from December 2012-November 2013. Each location was marked with GPS, and plant specimens were collected and identified with the help of floras. A checklist of angiosperms has been prepared. The microhabitats were classified based on edaphic properties, water availability, and species composition. The similarity in species composition of these microhabitats was calculated using Sorensen’s Similarity index. Diversity indices like the Shannon-Wiener diversity index and Menhinick’s species richness index were calculated. A total of 263 angiosperm species were recorded of which 62 are endemic to Western Ghats. 9 microhabitats like Ephemeral flush vegetation, Exposed rock surfaces, Rock crevices/Fissures, Small ephemeral pools, Soil-filled depressions, Tree cover and Tree associated, Boulders, Crust edges or Cliffs and Soil-rich areas were identified in the study area and majority of them shows very narrow ecological niche. For their similarity in species composition, 36 combinations were possible when 9 communities were compared with each other, but only 2 found to have more than 50% similarity, indicating the diversity of habitats within the lateritic hillock.
Chandrashekara & Thasini, 2016 conducted a study on the non-crop edible plants and medicinal plants in the homegarden agroforestry system of Palakkad district in Kerala. The district has four agro-ecological zones: Palakkad plains, Midland laterite area, Foothills and High hills of Kerala. A total of 16 villages, four from each agroecological zone, were selected with a minimum distance of 15 km between nearby villages. From each village, 10 homegardens were randomly selected, resulting in 160 homegardens from the district. Only herbs, shrubs and climbers were considered for the study. Non-crop edible plants and medicinal plant species in a homegarden were identified with the help of the owners of respective home gardens. A new Index, named the Index of Species Occurrence, Usage and Management (ISOUM), was developed to study the differences in species distribution pattern, usage level and management in home gardens. The method used to calculate ISOUM was similar to the estimation of the species' importance value index in plant ecological studies. A total of 97 non-crop edible and medicinal plant species belonging to 40 families were recorded. Among these, 22 species were edible, 59 were medicinal, and the remaining 16 species were both edible and medicinal plants. Out of 97 species only 7 species (Aerva lanata, Amaranthus viridis, Cyanthillium cinereum, Cyperus rotundus, Mimosa pudica, Ocimum tenuiflorum and Scoparia dulcis), were seen in more than 30 homegardens. Among them Ocimum tenuiflorum was actively managed in more than 75% of the gardens. Based on index values, it is observed that Ocimum tenuiflorum, Aerva lanata and Scoparia dulcis are the first three important non-crop plant species.
Anoop et al., 2017 studied the floristic diversity of Thevarmala Sacred Grove in Kottayam district of Kerala, which is 400 m above MSL and covers 15 acres of land with a unique Western Ghats floristic composition. The natural vegetation of the sacred grove is a mixed deciduous type. Extensive floristic explorations were conducted during 2015-2016 in different seasons to assess the angiosperm plant diversity of Thevarmala sacred grove. Specimens were collected, and herbarium sheets were prepared. A total of 152 flowering plants belonging to 136 genera under 50 families were documented. Dicots dominate, with 129 species in 41 families, while monocots represent 23 species in 9 families. Shrubs dominate the area with 64 species (42 %), followed by herbs with 56 species (37 %) and trees with 32 species (21 %). Almost half of the shrubs are climbers. Among the herbs, 3 orchids, namely, Bulbophyllum sterile (Lam.) Suresh, Dendrobium barbatulum Lindl. and Pholidota imbricata Hook. are epiphytes. Of the total 152 species,18 are endemic to the Indian peninsula, and the majority of them are strictly confined to the Southern Western Ghats. 18 species found only in the Western Ghats-Sri Lanka biodiversity hotspot. Critically Endangered trees like Vateria indica L.were also reported. About half of the documented plants have recorded medicinal properties. Many plants are economically important as food (8 species), timber (6 species), and fodder (3 species) and as sources of fibres and resins (2 species).
Deepa et al., 2017 conducted a taxonomical and phytosociological study on Chithalikavu sacred grove in Thrissur district of Kerala. Field visits and plant collection were conducted during different seasons between April 2013 and September 2015. Field observations such as habit, habitat, local names, and medicinal uses available were noted by considering all angiosperms like trees, shrubs, herbs, and climbers for the study. Herbaria were prepared, and each species in fresh condition was critically studied with the help of floras. A phytosociological study by quadrate method was also conducted. Size and number of the quadrate were determined by species-area curve method. Two 20 m ×20 m size quadrates were randomly established in the site for tree species studies. Frequency, relative frequency, density, relative density, relative basal area and importance value index were estimated using standard formula. This resulted in collecting and identifying 57 species of angiosperms belonging to 54 genera and 35 families. Among them, 29.82 % were trees, 24.56 % were shrubs, 15.79 % were herbs, and 29.82 % were climbers. Almost all the plants have medicinal value. During this study, Euphorbiaceae was recorded as the dominant family of seven species. Only eight tree species were observed in the study area. Among them, Strychnos nux-vomica L. was the dominating species.
Ratheesh N. et al., 2017 studied the diversity of Mangroves in the Asramam area of Kollam District in Kerala. 48 acres in the Asramam adventure park and near the link road portion was studied in detail from March – June, 2016. The study was based on species-area estimation and quadrant analysis. Seven quadrates were selected randomly, and size of quadrate was fixed for 5 X 5 m. Quantitative characters such as frequency, density, abundance, relative frequency, relative density, relative dominance, Importance Value Index (IVI) were calculated. Diversity indices and species richness, Shannon– Weiner diversity, Simpson index, and equitability were measured by analyzing vegetation data. Six true mangroves species belonging to 4 plant families and several mangrove associates were recorded. Rhizophora apiculata showed highest abundance. Sonneratia caseolaris, a rare and threatened species, is present in large quantities along the Link Road area. Acrostichum aureum, a Pteridophyte species, shows fairly rich species diversity even in a highly degraded condition. Rhizophora apiculate shows the highest IVI and density values and high abundance. Relative frequency of Sonneratia caseolaris is high in all regions.
Sureshkumar et al., 2017 studied the medicinal plants used by the Adiyan community in Wayanad district of Kerala. The field survey was carried out from August 2015 to July 2016 among the Adiyan people in three villages of the Wayanad district, and ethnomedicinal information was obtained through interviews/discussions. A total of 30 informants were interviewed, aged between 20 and 89 years. A total of 71 plant species distributed in 60 genera from 38 families were used to treat 59 ailments, and the details were documented. The Lamiaceae family contributed the highest number of medicinal plants. The leaf was the most commonly used plant part. The different parts of the plant were made into different forms like powder, decoction, etc. 82% of herbal preparations were taken internally and 13% were used as a topical application, whereas 5% were used both internally and topically.
Synudeen Sahib, 2017 studied the biodiversity of Myristica swamp forests patches of Kulathupuzha and Anchal Forest Ranges and Shendurney Wildlife Sanctuary in Kerala. The floristic diversity indices were assessed by the quadrate method. A total of 246 angiosperms species belonging to 186 genera from 83 families were recorded. Myristica fatua var. magnifica and Gymnacranthera canarica of the Myristicaceae family are the dominant species. Myristica fatua is highly restricted to swampy areas only, hence it is considered as a flagship species. The dominant family is Fabaceae, with highest number of species. The flora shows a high degree of endemism. The vegetation is four storied with a continuous canopy. The species richness and floristic diversity of Myristica swamp is very low compared to other forest types and ecosystems of Western Ghats. This may be due to prevailing edaphic conditions and ecological requirements of swampy species. A major threat to the Myristica swamps was their conversion into rice fields.
K Praveenkumar, 2018 studied the floristic diversity of the sacred grove of Madathody Naga Kavu, Chalavara, Palakkad district of Kerala. The sacred grove was visited during different seasons, and two specimens of each species were collected and observations like plant habit, phenology, color, texture and smell of leaves, abundance, local names, local uses were noted. Species in fresh condition were critically studied using floras and identified by reference collections available at herbariums. 50 taxa of angiosperms coming under 49 genera and 25 families, including 19 herbs, 13 shrubs, 10 trees and 8 climbers were collected. Out of 50 species, 6 are endemic, 8 are exotic and 38 are medicinally important.
Sreelekshmi et al., 2018 studied the diversity, stand structure, and zonation pattern of mangroves in Kerala. 117 mangrove study sites were identified and investigated with the help of a Global Navigation Satellite System from 10 coastal districts of Kerala. The floristic survey and field sampling were conducted from March 2011 to April 2013. Quadrat method was used for the structural analysis of true mangrove flora. Each species in the quadrat was identified, counted, and analyzed. Structural variables such as stem density, relative density, abundance, and basal area were calculated using standard formula. Diversity indices, Shannon diversity, Margalef's species richness, Pielou's evenness and Simpson's dominance index were determined. The mangroves in Kerala comprised 18 species under 11 genera of eight families. Structural analysis revealed that the mean stem density was highest for Acanthus ilicifolius. Avicennia officinalis showed the highest mean basal area and highest IVI. For entire Kerala, the Shannon diversity index was 3.14 and the Simpson dominance index was 0.86. Mangrove vegetation is comparatively good in Kollam, Alappuzha, and Kannur districts and very sparse in Thiruvananthapuram district regarding diversity and richness. Among the ten districts, a maximum number of species were from Kollam district (15), followed by Alappuzha (14) and Ernakulam (13) districts. The least number of species was observed in Thiruvananthapuram district (3). All 18 mangrove species are evenly distributed throughout the coastal districts, occurring in heterogeneous mixtures. The study also shows the extinction of Bruguiera parviflora and sparse population of Ceriops tagal, Avicennia alba, and Sonneratia alba.
Praveenkumar, 2018 studied the floristic diversity of Puliyanamkunnu in Palakkad district of Kerala. Puliyanamkunnu is a moist deciduous forest element with 2 major roads, 23 ponds, 2 canals and 7 sacred groves. The study was conducted in the Puliyanamkunnu watershed area using field observations from different seasons. Two specimens each for different species were collected, and in fresh condition, species were studied critically with the help of standard floras. This resulted in the collection of 80 taxa of angiosperms, including 36 herbs, 18 trees, 14 Shrubs and 12 climbers. 12 species among them were endemics, and 10 were rare and red-listed. Sixty-nine species are used for medicinal purposes.
Grinson George et al., 2018 studied the structure and regeneration status of mangrove patches along the estuarine and coastal stretches of Kerala. All major mangroves in Kerala were studied by selecting 46 sites. The study was conducted from June 2014 to March 2015 by laying multiple line transects at each site. Quantitative data was collected using the quadrat method. A total of 13 mangrove tree species belonging to five families and eight genera were observed. Rhizophoraceae family has the highest number of species. From 10 districts in Kerala where mangroves show a presence, Ernakulam has the maximum number of species. 15,656 plants were counted, which comprised 31.31% saplings, 45.22% seedlings, and 23.47% trees. The genus Avicennia alone constituted 56% of the IVI which shows the dominance of the species in Kerala. Kozhikode has highest tree density and basal area. A comparison of diversity indices shows that mangroves in Kannur are the most diverse. The density of young plants is less than 50% of tree density, depicting the poor regeneration potential of mangroves in Kerala.
Neethu & Harilal , 2018 studied the diversity and distribution of mangroves in the coastal ecosystems of Kerala. Extensive literature survey and field visits were carried out. The mangrove patches were categorized into homogeneous and heterogeneous types. The assemblage of true mangrove species and their associates in a particular area, were grouped as homogeneous, while patches of true mangroves along with mangrove associates and other vegetation, were categorized as heterogeneous types. The regions were surveyed using a GPS. Plant specimens were collected, identified, and preserved. District-wise analysis and the extent and state of mangroves were studied. The survey estimated a total of 19.531 km2 mangroves in Kerala. Out of 10 districts studied, Kannur district has the highest mangrove cover. An increasing mangrove cover of about 2.821 km2 within the last 25 years is noted in Kerala. 15 true mangrove species falling under 9 genera and 6 families are observed. Even though there has been a technical increase in the number of mangroves, most mangrove-growing areas are under drastic pressure due to anthropogenic activities.
Nair, 2018 conducted a comprehensive study on the socio-economic and cultural aspects of sacred groves in Kerala, and their fifth report was about the sacred groves in Alappuzha district. The Geographical extent of the district was 1414 sq. km and holds 6 thaluks. The total number of sacred groves in the district was 2242, and it covers an area of 451.84 acres (182.93 ha.). Most of them have 0.3 to 0.8 canopy density. Trees are more in the groves, followed by climbers. The vegetation has clear tiers of trees, shrubs, herbs, besides the climbers, epiphytes, parasites, etc. The abundance of woody climbers is the most notable feature of the sacred groves in Alappuzha district. One time enumeration was carried out in 32 sacred groves based on the extant area, and it resulted in the enumeration of 324 species, of which 134 are trees, 112 climbers and 78 are shrubs. The most widely occurring species is Pothos scandens, which is seen in 31 sacred groves, followed by Artocarpus hirsutus in 28, Holigarna arnottiana in 27, Uvaria narum in 24 and Hydnocarpus pentandra in 23 sacred groves. No species are found in all sacred groves, whereas 122 species occur only in one sacred grove. Leguminosae is the dominating family with 34 species, followed by Rubiaceae with 22 species. Among the taluks, Mavelikkara has the highest species diversity. Encroachment, disputes on ownership, dumping waste, etc., are the major threats faced by the groves. The main recommendations by the researchers include conducting awareness programmes with suggestions to prevent the dumping of solid waste, fair grant distribution to deserving custodians, production of quality seedlings, and appropriate recognition to custodians for contribution to carbon sequestration.
Nair, 2018 conducted a comprehensive study on the socio-economic and cultural aspects of sacred groves in Kerala, and their sixth report was on the sacred groves in the Kannur district. The Geographical extent of the district was 2966 sq. km and includes 1096 sacred groves covering a total area of 263.82 Ha. The canopy density of most of the sacred groves is 0.3-0.8. Among these 74 sacred groves are more than one acre of area. The dominance of trees and climbers is noticed. An association of Myristia malabarica and Knema attenuata is seen where swampy areas prevail. A number of pteridophytes and bryophytes can also be seen in the groves. Species like Caryota urens, Artocarpus heterophyllus, etc., provide plenty of edible fruit and attract all birds and other fauna. Rare and important plants like Actinodaphne malabarica, Aglaia lawii can be seen in the groves. 25 sacred groves were inspected for plant identification, and a total of 343 species were enumerated in the study. It includes 144 trees, 103 climbers and 96 shrubs. The most widely occurring species are Pothos scandens, Holigarna arnottiana, and Caryota urens. Leguminosae is dominating among the 348 species. As Kannur district area is a flat terrain, the general floristic composition and physiognomy of vegetation of the sacred groves are typically like the lowland evergreen forests. Soil samples collected from 15 sacred groves were tested and the result shows that in most cases, organic carbon availability is generally medium. Ponds were present in almost all sacred groves. The sacred grooves harbour numerous birds, butterflies, bats, some primates, and small mammals. 78% of the total sacred groves in Kannur was owned by individuals, families, or family trusts, 14% by public or Janakeeya Committees, and 8% by Temple trusts or Devasam Boards. Encroachment to the groves, development activities, dumping of solid waste and presence of invasive species are major threats the sacred groves face. Awareness campaigns, production of quality seedlings of plants, etc., are the recommended measures to protect the groves.
Nair, 2019 conducted a comprehensive study on the socio-economic and cultural aspects of sacred groves in Kerala, and their seventh report was on the sacred groves in Kottayam district. The Geographical extent of the district was 2208 sq. km. A total of 562 sacred groves, distributed to a total area of 35.20 Ha, are listed from the district. Most of the sacred groves have 0.5-0.9 canopy density, and the size of Sacred Groves varies from 3 cents-1100 cents (11 Acs.). 36 Sacred Groves have been studied about the flora present, and the species under different forms were listed. Rare and threatened species like Myristica malabarica, Gynecranthera farquhariana, and Syzygium travancoricum have been found in the groves. A total of 335 species were enumerated during the one-time enumeration study of 16 groves which include 133 trees, 80 climbers, 53 shrubs and 69 herbs. Among the 335 species, 116 occur only in one sacred grove. But species like Ophixinoides, Artocarpus hirsutus, Centrosema molle, Chassalia curviflora var. ophioxyloides, and Pothos scandens occur in all 16 groves. Caryota urens (flowers and fruits attract many birds and mammals) and Holygarna arnotiana (porcupine likes fruit) serve as keystone species. The fauna of the sacred groves include termites, bats, peacocks and civets. The major threats the sacred groves face include; intention to reduce the extent for self-motives, legal disputes on ownership, dumping of solid waste, and damage by invasive species.
Divya & Anitha, 2020 studied the community dependence on the natural resources of Parambikulam Tiger Reserve in Kerala. Four indigenous communities, namely Kadar, Muthuvar, Malasar and Malamalasar were inhabited in various six tribal colonies in the tiger reserve. The study is based on both primary and secondary data. Eleven Focus Group Discussions (FGDs) were conducted with the forest-dwelling community (one with each community), Forest Department (3), tribal coordinators (1), tribal watchers (1), and guides (1). From a total of 399 tribal households in all four tribal communities, 194 households were selected using stratified random sampling at 5 percent level of significance. From March 2018 to March 2019, a direct household survey was conducted. The Forest Dependence Index(FDI) helps to identify the dependence of the household on the resources available from forest. Logistic regression model with the help of SPSS software version 24 is used to develop the relationship between the socio-economic variables and forest dependency. The community was heterogeneous, with an average family size of 4 and a total population of 797 from 194 households. Primary sector dominance with wage employment was the main occupation. The dependence of the resident community on the Reserve ranges from the collection of food, fuelwood, poles, Non-Timber Forest Products (NTFP) to employment in forestry and allied activities, such as guards, watchers, and daily wage employees, providing an additional source of income to the local communities. The ecotourism enterprises involve honey processing, paper carry bag-making units for reducing plastic pollution, bamboo handicraft units where the products are sold through the Ecoshops, jams, and pickle units and bee wax balm production units for producing balm from the bee wax collected and the product is medicinally important for curing body aches and headaches. The FDI of the resident population depicts high economic dependency in terms of income generation from the collection of Non-Timber Forest Products (NTFP), fish (from the catchment areas), and the sale of the cultivars (pepper, arecanut, turmeric and ginger, of which the pepper is exported to Germany yielding a high price). The model developed for bringing out the relationship between the dependence and the socio-economic factors, predicted the result with 69.6 per cent accuracy, land holding size and market access showing expected result with p-values (α) less than or equal to 0.05.
Bindhu et al., 2020 conducted a preliminary study on the medicinal plants of Annallur Kole lands, Chalakudy, in Thrissur district of Kerala. Wetland plants were collected from Annallur Kole land during September-December 2019 to explore its diversity during post monsoon season. Field observations were recorded, specimens were collected and prepared herbarium. 44 species of medicinal herbs under 40 genera and 22 families were observed in the study area. Family Asteraceae was predominant with 8 genera. 3 ferns were noticed. The plant species were used for medicinal purposes like to cure gastrointestinal disorders, respiratory ailments, dermatological snags, urinogenital illnesses, cardiovascular problems, and neuro disorders. They were prepared in various forms, such as decoction, extraction, infusion, and paste preparation. Oral administration, inhalation, smoking, and massaging are the various methods of application in practice. Kole land plants in the region could provide income-generating opportunities to local communities. Almost all the medicinal plants found in Annallur Kole lands are commonly seen in Kerala.
Nair, 2020 conducted a comprehensive study on the socio-economic and cultural aspects of sacred groves in Kerala, and their eighth report was on the sacred groves in Idukki district. The Geographical extent of the district was 4358 sq. km., with four taluks namely Thodupuzha, Peermade, Idukki and Devikulam. Only 32 sacred groves were found in the district, which had around 3 ha. of vegetative cover. Most of them are between 3 cents - 10 cents. Devikulam taluk has a high concentration of sacred groves. The sacred groves in Marayur are very open, having rocky outcrops and scattered trees. Diversity in pants and richness in their number are comparatively low in the sacred groves of Idukki district. Amarankavu in Thodupuzha village, Paloor kavu in Mundakayam and Vazhuvelil kavu in peruvanthanam support thick vegetation with good diversity. In the rest of the sacred groves, the canopy is open or with too many climbers. The ground flora is very thin except in sacred groves of Thodupuzha. In Peermade and Thodupuzha taluks there is good collection of medicinally valued trees, herbs and orchids. One time enumeration of flora was carried out in 9 sacred groves in Thodupuzha and Peerumedu thaluks. A total of 210 species were enumerated from those 9 sacred groves, in which 99 are trees, 38 climbers, 34 shrubs and 39 were herbs. 116 species occur only in any one sacred grove. Amaramkavu in Thodupuzha village has the highest diversity. Of the 210 species studied, 33 are endemic, 37 are exotic, and 140 are indigenous. Faunal significance in the sacred groves was very low.
Nair, 2020 conducted a comprehensive study on the socio-economic and cultural aspects of sacred groves in Kerala, and their ninth report was on the sacred groves in Palakkad district. The Geographical extent of the district was 4480 sq. km, having a forest area of 1761 sq.km. A total of 184 sacred groves were found in the district, which had a 63 % extent or below 5 cents. Pattambi taluk in the district contains the maximum number of sacred groves. The largest sacred grove in the district is Parakatt kavu in Alathur taluk (25 Acres in extent). The district consists of both deciduous and evergreen vegetation. Unlike in other districts, common plants such as Artocarpus hirsute, Bombax ceiba, Terminalia bellirica , Saraca asoka, etc. are scarce in the sacred groves of Palakkad district. Larger sacred groves exhibit a high diversity of trees, climbers, and herbs. One time enumeration was carried out in 18 sacred groves and a total of 332 species were enumerated. In the 332 species, 106 were trees, 71 climbers, 56 shrubs, and 99 were herbs. Species like Cassia fistula, Ichnocarpus frutescens, and Dioscorea sp. were found in 16 sacred groves studied. As many as 171 species occur only in any one sacred grove. There are a greater number of tree species, but the frequency is poor. The density of vegetation is poor as the area of most of the sacred groves is less. A number of plants have medicinal value. The open canopy density in the district receives direct sunlight, long periods of dry season, and wind blowing along the Palakkad gap promotes more plants of medicinal value.
Thomas et al., 2020 studied the angiosperm diversity of agroecosystems by conducting a case study from Kooroppada Gramapanchayath in Kottayam district of Kerala. Floristic analysis was carried out by collecting samples from 9 sites of the panchayath. Plants were identified using standard floras and enumerated according to APG III. Quantitative data was collected by the quadrat method based on the species-area curve method. The biodiversity assessment shows 402 known angiosperm species in 101 families in different areas. Family Fabaceae dominates with 37 members. The vegetation profile includes 125 herbs, 98 shrubs, 49 climbers, and 118 trees. The highest distribution frequencies are shown by Ageratum conyzoides, Glycosmis pentaphylla and Hevea brasiliensis in herbs, shrubs and climbers and trees categories respectively. Oldenlandia corymbosa, Psychotria flavida and Hevea brasiliensis showed the highest density values among the herbs, shrubs and climbers and trees categories respectively. The abundance value was highest in herbs by Bambusa vulgaris and Bulbophyllum sterile, in shrubs and climbers by Psychotria flavida and in among trees by Hevea brasiliensis.
George & Christopher, 2020 studied the structure, diversity, and utilization of plant species in tribal home gardens of Attappady valley, Palakkad district of Kerala. From a total of 189 hamlets in Attappady, 8 hamlets were selected from 3 tribal communities (Irula-4, Muduga-2 and Kurumba-2), which have different rainfall zones, represent proportionately the tribal communities, have accessibility with at least jeepable road and actively participate in agricultural practices. Data were collected from 104 randomly selected home gardens from each of the eight sample hamlets. Species diversity and similarity was calculated. A cluster analysis considering the occurrence of species was performed. A total of 182 plant species belonging to 160 genera and 67 families were recorded of which 43% were herbs, 26% were shrubs, 19% were trees, and 12% were climbers. The diversity and richness of tribal homegardens in Attappady is relatively high (182 species from 104 home gardens) when compared with the various studies conducted in Kerala State. Rainfall and proximity to non-tribal hamlets influence the floristic composition in the area. A high similarity of plant species is observed between Muduga and Kurumba. A total of 56 plant species were common distribution across the gardens of all three communities. 39% of species were edible plants, 25% were used for medicinal purpose, 24% species have ornamental value, 5% were used in ritual events and 7% contributed for construction, timber, firewood, shade tree, fence, and saleable products.
Halliru Bilyaminu et al., 2021 conducted an ecological study on the southern secondary moist deciduous forest of Shendurney Wildlife Sanctuary in Kollam district of Kerala. The data was collected from 2019 to 2020 following a primary survey. Structural analysis was carried out, and sample plots were collected using a stratified random sampling method. Structural attributes and phytosociological observations were enumerated. 58 species with DBH ≥ 10 cm were recorded. Out of these 7 species are endemic to the Western Ghats, 2 are endangered, another 2 belong to the near-threatened category, and 4 are vulnerable to extinction. Terminalia paniculata is the dominant species and the species with maximum species importance value. The Euphorbiaceae family has a maximum family index value. The distribution of the trees showed a completely L-shaped distribution with decreasing density with increasing girth size. The tree species density was 876.97 individuals per hectare. The abundance-frequency ratio depicts that species show both contagious and uniform distribution patterns.
Nair, 2021 conducted a comprehensive study on the socio-economic and cultural aspects of sacred groves in Kerala, and their tenth report was on the sacred groves in Kasargod district. The Geographical extent of the district was 1061 sq. km, with a forest area of 857 sq. km. A total of 392 sacred groves were present in the district, of which 13 % are of and below 5 cents in extent, and 64 sacred groves are of and above one acre extend, which shows that comparatively, Kasargod district has more large sacred groves in the state. Evergreen and semi-evergreen types of vegetation can be seen in the district. Adukathukavu, Edayilakkadu kavu, Kammadam kavu and Paaliyerikavu are some examples of large sacred groves with thick vegetation and high diversity of trees, shrubs, climbers, and herbs. Indigenous species as well as endemic species such as Hopea parviflora, Hopea ponga, Myristica malabarica, Knema attenuate, Diospyros malabarica, Percia malabarica can be seen plenty. Myristica swamps are common, and orchid diversity is prominent in the district. Vegetation contains more number of trees with dense growth.
Sebastian et al., 2021 studied the species diversity and abundance patterns of epiphytic orchids in Aralam Wildlife Sanctuary in Kerala. Field sampling was done, and linear line transects were developed in four habitats like: Wet evergreen (low-mid elevation), Moist deciduous, Semi-evergreen, and Montane wet evergreen (high elevation) habitats. Characteristics of habitat, host tree, and the substrate of orchids were recorded. Statistical analysis of data from 40 transects was performed using the statistical software R (version 3.5.0) and PAST 3.19. Orchids were ranked based on their abundance, and rarefied diversity indices were estimated. Bulbophyllum fischeri and B. fuscopurpureum were found growing both as epiphyte and terrestrial forms. 29% of total orchids (62 orchids) and 38% of epiphytic orchids (39 orchids) from the area were endemic to the Western Ghats. Species accumulation curves suggest that species are yet to be sampled from Aralam Wildlife Sanctuary. All four habitat types possessed distinct epiphytic orchid diversity. Wet evergreen was the most diverse habitat for epiphytic orchids.
Pradheep et al., 2021 conducted a study about the update status of agriculturally important crops in Kerala. All the cultivated taxa (except medicinal, aromatic, ornamental and forestry species) were considered for analysis. Field observations, literature survey, information from social media, visits to crop-based institutes and botanical gardens, interaction with crop experts, herbarium consultation, and live material studies were the methods employed for the study. Analysis shows that 306 crop taxa (290 crop species) belonging to 179 genera under 61 families are being cultivated in various regions across the state. Top genera representing greater than 5 cultivated species include Solanum, Citrus, Dioscorea, Garcinia, Annona, Syzygium, Artocarpus and Vigna. The top families with more crop species, are Fabaceae, Poaceae, Cucurbitaceae, Solanaceae, Myrtaceae, Rutaceae and Malvaceae. The analysis was critically compared with the early estimate in 2011 by Nayar NM and it shows 104% higher estimate of crop species (142 vs. 290) stemming from the present work.
Archana & Gayatri, 2021 studied the floristic diversity of Chirakkal chira and Rajarajeshwara chira in Kannur district, which are the largest temple ponds in the district. The samples were collected in a polythene bag in November 2018 and screened for algae and fungi under a compound research microscope. Angiosperms and pteridophyte flora were studied from the site, and herbarium was prepared. A total of 27 algae were identified, of which 16 belong to Chlorophyceae. 10 genera of fungi belonging to Ascomycetes and Deuteromycetes were identified. Bryophytes were absent in both sites. 4 pteridophytes and 20 angiosperms were observed from the sites. Asteraceae was the dominant family in the angiosperms. Chirakkal chira supported a vast diversity of flora than Rajarajeshwara chira.
Divya et al., 2021 studied the diversity, classification, and ethnobotanical uses of wild edible fruit plants in the Kallar and Ponmudi region of Agasthyamala Biosphere Reserve in Kerala. A detailed literature survey was conducted and a check list of wild edible fruit plants was prepared. 12 plant exploration trips were conducted to different localities of the region in all seasons during the period 2017-2019. A herbarium were prepared, and passport data sheets for each accession with first-hand information were prepared from the field. Wild edible fruit plants of 30 indigenous species from 13 angiosperm families were enumerated. There were 9 endemic, 4 threatened and 7 least concern species. Family Myrtaceae was the mostly used plant family having 8 fruit species. 11 indigenous wild fruit plants are used by the Kani tribe of the locality, 7 species are seasonal in harvest, 4 indigenous wild species were not much exploited and 8 species were exclusively wild, lesser known, endangered endemic fruit plants. Most of the species’ flowering and fruiting period was from January to June.
Sreelekshmi et al., 2021 studied the mangrove forests along Kerala's coastline, focusing on its current status and future prospects. The northern zone of Kerala has a higher area of mangroves (11.91 km2), and Kannur district holds a high area among other districts in Kerala. Mangroves hold 18 species of which Avicennia officinalis and Rhizophora mucronata are the dominant species. Reclamation of land for inhabitation and agriculture, utilization of mangrove resources as a source of income are the two major reasons for mangrove degradation in Kerala. Most of the mangrove wetlands in Kerala were polluted through agricultural runoff and the discharge of untreated sewage, trace elements, plastics, and other degradable and non-degradable materials. The mangrove flora has remained stunted or degraded in many pockets in the coastal area due to the increase in the pollution load. Mangrove patches in Chettuva (Thrissur district), Kumarakom (Kottayam district), Munroe Island, Asramam (Kollam district) and Veli (Thiruvananthapuram district) are tourism spots, which create a huge threat to the pristine mangrove ecosystems of the region. The vertical rise of the water column due to sea-level rise will result in water logging and the destruction of mangroves and associated fauna. Institutional efforts in conservation through legal and financial support have to be considered to improve the extent of mangroves. Awareness should be created among the local communities about the importance of this unique ecosystem. Effective governance, adaptation, mitigation options for climate change, better planning for rehabilitating degraded mangroves, etc. are necessary to conserve, protect and restore mangrove ecosystems.
Archana & Surabhi, 2022 studied the ethnobotanical relevance of flora in the Kollam and Thiruvananthapuram districts of Kerala. Varkala in Thiruvananthapuram district and Eravipuram in Kollam district are chosen as study areas. The climatic conditions of the study area are similar to the biodiversity hotspot Agasthyarkoodam; therefore, a wide range of endemic species can be found across these two districts. Survey was carried out mainly in both study areas' wetlands, river banks and rural regions. Field trips involve interviews with experienced people and Ayurvedic doctors. Plant species names and local names of the plant, family, and their uses against various diseases are documented. The tribal medicines are prepared from various plant parts such as seeds, flowers, bark, leaves, roots, and stems. Fresh herbs are rich in its nutritive and therapeutic constituents such as volatile oils, tannins, terpenoids, saponins, flavonoids, alkaloids, and anthraquinones. They are used as traditional remedies to various illnesses like diarrhoea, dysentery, dyspnoea, piles, tuberculosis, etc. Most of these formulations are devised by the Kani tribal community.
Faizal et al., 2022 studied the status of plant bioresources utilised in herbal industries and the need for conservation in Kerala state. Raw data about 25 licensed herbal manufacturing units with a turnover of more than one crore rupees were shortlisted from baseline data of pharmaceutical companies from 14 districts of Kerala. This data was sorted, tabulated, and compiled in district-wise by including the part used, quantity and IUCN status, and local/regional conservation status. About 562 species of plants are currently in trade for herbal preparations by herbal-cosmetic and nutraceutical industries. 10% of plants are used above 10 tonnes. 40% of the plant species are consumed below 100 kilograms. The root is the most important for herbal preparation among the plant parts. To meet the demand for root, 142 species are harvested destructively. 116 species are used wholly, and seeds of about 87 species are used for formulations. The industries also use heartwood and metabolites. The 90% of the plants fall either in the Least Concerned (LC) or Not Evaluated (NE) or Data Deficient (DD) category of conservation status. Of the remaining, 8% (45) are in the threatened list at global (IUCN) or regional level (Western Ghats). Ten species are with Near Threatened (NT) status. The most consumed medicinal and aromatic plants includes nutraceuticals like Moringa oleifera, Curcuma longa, Eclipta prostrata, Sida rhombifolia, Aegle marmelos, and Justicia adhatoda.
Nair, 2022 conducted a comprehensive study on the socio-economic and cultural aspects of sacred groves in Kerala, and their eleventh report was on the sacred groves in Pathanamthitta district. The Geographical extent of the district was 2652 sq. km, with a forest area of 1385.27 sq. km. There are 721 sacred groves in this district, covering an area of 144.55 Acres. 16 sacred groves are of and below 5 cents, and 13 are of and above one acre in extent. Adoor taluk in the district contains the highest number of sacred groves (238 ), in which 9 are very large ones (>1 acre). The vegetation in the sacred groves consist of evergreen, semi evergreen and deciduous, most of which come under evergreen category. Undisturbed groves have good vegetation, and several stories of trees and shrubs can be seen with plenty of highly buttressed trees such as, Ficus.sp, Vateria indica, Hydnocarpus etc. One time, enumeration was carried out in 13 sacred groves in Adoor and Thiruvalla thaluks. 256 species were enumerated of which 97 are trees, 68 climbers, 49 shrubs and 47 are herbs. In all the 13 sacred groves studied, Chassalia curviflora var. ophioxyloides, Pothos scandens and Xanthophyllum arnottianum were found in all of them. Cetrosema molle and Ichnocarpus frutescens were found in 12 sacred groves. 87 species occur only in one sacred grove. With more number of trees, thick vegetation density can be seen in some sacred groves while in others climbers dominate and their density is poor. Species like Artocarpus hirsutus, Adanenthera pavonina, Holigarna arnotiana and Hydnocarpus pentandra show generally good regeneration and are common in almost all sacred groves. Medicinal plants like Curculigo orchiodes and Costus speciosus were noticed in the sacred groves.
Nair, 2022 conducted a comprehensive study on the socio-economic and cultural aspects of sacred groves in Kerala, and their twelfth report was on the sacred groves in Malappuram district. The Geographical extent of the district was 3549 sq. km, with a forest area of 758.8 sq. km. There are 1120 sacred groves in the district. 738 of them fall under 5-10 cents category, and 22 sacred groves have above one acre extend. Evergreen, semi-evergreen and deciduous vegetation types can be seen in the sacred groves in which most are evergreen type. Undisturbed sacred groves have luxuriant vegetation, while disturbed sacred groves have low density of vegetation and a preponderance of climber species. Some climbers are large, have long age and are seen on trees such as Lophopetalum. Coastal zones of sacred groves have random occurrences of trees like Diospyros perigrina, Aphanamixis polystachia, Samadera indica and shrubs like Rauvolfia tetraphylla. Rare palm Corypha umbaculifera is seen in Kayalot Kavu. Antiaris toxicaria have good regeneration. One time enumeration was carried out in 22 sacred groves resulting in the enumeration of 382 species in which 120 are trees, 92 climbers, 77 shrubs and 93 were herbs. A rare tree Syzygium chavaran is seen in Mukkuthala Temple Kavu of Ponnani taluk. Most of the sacred groves have Ficus species, and more than five species of Ficus can be seen in them. In sacred groves where climbers are predominant, fruit-bearing trees are fewer and birds attracted to these groves are few. Vateria indica, Alstonia scholaris and Aphanamixis polystachya severe as keystone species in the groves. Medicinally important species and invasive species were also noticed in the sacred groves.
Nair, 2022 conducted a comprehensive study on the socio-economic and cultural aspects of sacred groves in Kerala, and their thirteenth report was on the sacred groves in Ernakulam district. There are 708 sacred groves in the district,of which 39% are of and below 5 cents and 9 sacred groves are above one-acre extent. Among the 708 sacred groves, 20 sacred groves have been studied in detail. Most of the sacred groves contain 12 to 24 tree species, 10 to 22 shrubs, and 25 to 34 climbers. Rare and threatened species like Myristica malabarica, Gynecranthera farquhariana, Syzygium travancoricum have been noticed in these sacred groves, and families like Euphorbiaceae, Lauraceae, Fabaceae, Rubiaceae, and Apocynaceae are very well represented. Vateria indica, Holigarna arnottiana, Calophyllam calaba, and Hopea ponga are the most common dominant species in the groves that shows an affinity towards each other. The sacred groves hold valuable presence of a variety of species like Raphidophora pertusa (large climber), Naringi crenulata (small evergreen tree), Morinda umbulata (rare medicinal plant), Acampe praemorsa (Orchid) and Bulbophyllum neilgherrense (Orchid). The vegetation pattern in these groves is different from others because the number of tree species is higher than other habit forms. 6 species of Ficus can be seen in the groves that serve as keystone species in the ecosystem.
Nair, 2022 conducted a comprehensive study on the socio-economic and cultural aspects of sacred groves in Kerala, and their fourteenth report was on the sacred groves in Wayanad district. The Geographical extent of the district is 2132 sq. km with a forest area of 886 sq.km. A total of 137 sacred groves were present in the Wayanad district, in which very small sacred groves were almost absent, and 14% are large in extent. Both evergreen and semi-evergreen types of vegetation can be seen in these sacred groves. Luxuriant vegetation and high diversity are seen in less disturbed and largely sacred groves. Some endemic species are seen plenty in the sacred groves, which include species such as Hopea parviflora, Hopea ponga, Myristica malabarica, Knema attenuate, Diospyros malabarica and Percia malabarica. Promising growth of bamboos can be seen in some sacred groves of Wayanad, which was rarely seen among the sacred groves of other districts except of Thrissur. Good regeneration was observed in the sacred groves because many important trees in the groves were either shade demanding or shade tolerant. One time enumeration was conducted in nine sacred groves, and plants found in these groves were listed. As most of the sacred groves lie in hilly tracts of the district, the general floristic composition and vegetation physiognomy of sacred groves in Wayanad are typically like hilly evergreen forests. More than eight species of Ficus can be seen in the groves, which serve as keystone species by attracting birds and providing habitat for insects.
Lekshmi et al., 2022 studied the floral diversity in Villumala in Kulathupuzha region of Kollam district in Kerala. The study was conducted from January to April 2019. Field trips were conducted to Villumala, raw materials were collected, plant species were identified with the help of floras and medicinal uses of species were obtained from people. A total of 34 species were documented in which all of them have potential medicinal importance. The various uses of species include fodder, food, basket making, spice production etc. Out of 34 species Cassia alata and Aporosa cardiosperma have antimicrobial property and Connarus monocarpus is used for eye diseases, Centella asiatica and Ocimum sanctum are used in fever, cold, flue etc. The floral wealth is depleting due to deforestation, overgrazing, habitat destruction, and improper agricultural practices.
Ameesha & Saradha, 2023 documented the floristic diversity of medicinal plants in Ponparakunnu hills of Kozhikode district in Kerala and the biological activities of Eclipta prostrata L. and Eupatorium triplinerve Vahl species in Asteraceae family. Field survey was carried out during October- December 2022. Based on personal knowledge and with the help of local people, information about medicinal plants were collected and classified on the basis of habit of the plant. Leaves of Eclipta prostrata and Eupatorium triplinerve were collected, washed, air dried, powdered, and ethyl acetate extract and ethanolic extract were prepared to study the antibacterial and antioxidant activity of the plant. 30 species of medicinal plants belonging to 18 families were recorded, showing Asteraceae as the dominant family in the area. Of the total 30 species, 16 were herbs, 7 were shrubs, 6 were trees, and 1 species was climber. The phytochemical analysis in the leaf extracts of Eclipta prostrata and Eupatorium triplinerve revealed the presence of carbohydrates, protein, phenol, tannin, flavonoids, saponins, glycosides, steroids, terpenoids, and alkaloids in the species and show prominent antioxidant and antibacterial activity of the species.
Krishnan Remya & S Nelson Jiji, 2023 conducted a floristic study in ten randomly selected paddy fields of Thiruvananthapuram district of Kerala. Field surveys were conducted, and quadrat method were used for sampling. Field identification was carried out by dividing the field into field proper, bunds, and ditch sections. Monthly observations were carried out at each site, and the details of the species, genera, families, economic importance and IUCN status were recorded. A total of 44 plant species belonging to 41 genera of 22 families were observed. Poaceae was the dominant family. 21 species were dicots, 19 were monocots, and 4 were Pteridophytes. 32 species are used for medicinal purposes.
Venkatesan et al., 2023 studied the conservation status and diversity of medicinal plants used in the Indian system of medicine, focusing on the Munnar Forest Division, Kerala. The study was conducted in November 2015 by collecting information about the medicinal plants in the Munnar forest division through conversations with traditional healers and comparing the data with previous literature. 31 rare wild medicinal plant species used in Ayurveda, Siddha, Unani and also folk medicine were identified. They were used to treat various diseases such as dry cough, menstrual disorders, piles, viral fever, kidney stone, joint pain, jaundice, skin diseases, contraceptive purposes, etc. The plant species were of different habits like trees (14), herbs (9), shrubs (5), and Climbing shrub (3) and statuses of plants show 23 rare, 3 Endangered, 2 Critically endangered, each one of Threatened, Vulnerable and Least Concern species in the study area.
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