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6.0 Results and Discussion
 6.1 | 6.2 | 6.3
 
6.1 Terrestrial Ecosystem 6.1 | 6.2 | 6.3

6.1.1 Land-Cover and Land-Use Analysis

Land-cover analysis using NDVI shows that 67% of the area is covered with vegetation and 33% area under non-vegetation (barren or nearly barren conditions, water bodies and builtup areas). Figure 4 depicts the NDVI for the sanctuary.

NIR = 2.458517 + 1.066769 (Red), r = 0.894265, CD = 79.97%

 

Figure 4. Land-cover map of svws

Land-use analysis was done using maximum likelihood classifier and percentage compositions of various categories of land-use are listed in Table 9; the same is depicted in Figure 5. The forest cover in the sanctuary is about 49.5% and 17.6% is water body at full level of the reservoir.

Table 9. Land-use analysis (%area) in SVWS.
Classification Area (%)
Built-up 8.62
Evergreen to semi-evergreen 35.63
Moist-deciduous 13.84
Plantation ( Areca/Acacia/Casuarina ) 15.27
Water body 17.64
Agriculture 2.66
Open land 6.35

 

 

Figure 5. Land-use map of Sharavathi Valley Wildlife Sanctuary.

6.1.2 Vegetation Studies

6.1.2.1 Lichens

Lichens are unique groups of plants exhibiting symbiotic association of fungi and algae, but represented as a single organism. Because of their sensitivity to microclimatic changes in environment, lichens aid as bioindicators. They require specific conditions in the environment and respond critically to any changes in it. Hence, they are widely used in air pollution, geochemical and geothermal emission, and biomonitoring studies. They play various roles as pioneers in successionaland climax ecosystems and could as well indicate the age and ecological continuity of a forest. Apart from this, they also can be used as tools in determining the age of an unknown rock surface (lichenometry) and soil formation (pedogenesis) during plant succession. Western Ghats harbour 800 species of lichens in which, 161 species are endemic to this region (Singh and Sinha, 1997). Our study shows the presence of 46 species of lichens in the SVWS (in semi-evergreen forest of Holebagilu , Honnemaradu Island , Karumane, Muppane and Siganduru) representing 5% from the Western Ghats of Karnataka. (Annexure I). However, lichen studies need to be carried out more intensively. Table 10 gives Simpson's and Shannon-Weiner's diversity indices. Holebagilu and Karumane are highly diverse, while Honnemaradu ( Island ) is least diverse in lichen composition.

Table 10. Simpson's (D) and Shannon-Weiner's (H') indices for the lichens of studied localities
Locality
D
H'
Honnemaradu ( Island )
1.26
1.397
Muppane
1.21
1.548
Karumane
1.14
1.675
Holebagilu
1.11
1.969
Siganduru
1.08
1.502

6.1.2.2 Other Vegetation

Vegetation types inside the sanctuary area including islands (in the reservoir) vary from grassland to evergreen forest. The vegetation type in the core zone and buffer zone varies from moist-deciduous to evergreen forest. But in few places, grasslands, especially on hill tops, are interspersed with evergreen forests. Scrub jungles to semi-evergreen forests are more prevalent in the tourist zone of the sanctuary.

The species richness suggests that semi-evergreen forests have more species due to the combined presence of both evergreen and deciduous species. The evergreen forest in the sanctuary area is more fragmented and disturbed and this is clearly depicted in the Shannon 's diversity index. The percentage evergreenness and endemic plants are more in the evergreen forest area.

The sanctuary has a variety of habitats that support rich flora of herbs, shrubs and climbers of which about 215 species have been recorded. Evergreen to semi-evergreen forests and grasslands of the Western Ghats have the largest congregations of endemic herbs. Some of the herbs are exclusive to specialised habitats like tree trunks and wet rocks. The increasing human impact and openings in forest canopy as well as over grazing are posing threats to many of these rare plants.

Evergreen to semi-evergreen forests are the major source of perennial waters. On the other hand in the deciduous tract, the streams mostly dry up in the summer months. Therefore conservation of evergreen forests and restoration of such forests are of paramount importance. Bulk of the water flow into reservoir comes from natural forests. Unfortunately, in some parts of the sanctuary area, monoculture plantations have been raised causing the drying up of streams and impoverishment of the ecosystems as a whole. Since the plantations do not yield any fodder or NTFP, the rural population is put to great hardship. Therefore such land-uses are not desirable in the sanctuary area.

The numerous streams and the banks of Sharavathi and Venkatapura rivers and their tributaries in the evergreen to semi-evergreen forest belt are lined with characteristic riparian vegetation of which the notable tree species are Calophyllum apetalum, Elaeocarpus tuberculatus, Mastixia arborea, Hydnocarpus laurifolia, Madhuca neriifolia, etc . Towards the drier forests, water bodies are lined with tree species such as Pongamia pinnata , Madhuca neriifolia, Hopea wightiana, Bambusa sp., etc. The riparian vegetation plays a crucial role in protecting the water bodies from siltation, creating shade conditions to maintain appropriate temperature regime for sustaining populations of endemic fishes, amphibians, phytoplankton, zooplankton and aquatic insects. Of late there has been numerous instances of misuse of the banks of streams and rivers in the catchment area causing severe upsets in the characteristic biota associated with them. Stream waters are often diverted to newly created horticultural farms, thereby, affecting the water flow into the reservoir. During field observations, it was noticed that the endemic vegetation patches were associated with perennial streams. Plant species lists are provided in Annexure II. The details of the sampling are given in Table 11.

Table 11. Details of different landscape elements sampled and their diversity indices, basal area, percentage evergreens and percentage endemics.
Vegetation type   Total transects Total quadrats Total area sampled (ha.) Total individuals Total species Estimated basal area/ha. Species richness Shannon 's diversity Simpson's diversity % Evergreens % Endemics
Evergreen 20 96 11.8 1818 128 35.3 17 3.94 0.96 95.8 56.7
Semi-evergreen 16 82 3.3 1916 138 31.1 18 4.03 0.97 77.1 40.9
Moist deciduous 3 18 0.7 318 58 19.8 10 3.44 0.95 43.6 19.7
Scrub 2 5 0.2 6 4 0.6 2 1.24 0.67 0.0 0.0

The estimated basal area per hectare is highest for evergreen forests and is decreasing from semi-evergreen to scrub. But higher Shannon diversity for semi-evergreen compared to evergreen, may be due to disturbances and canopy openings, which pave way for the addition of some pioneers and other secondary species. The percentage evergreens and percentage endemics decrease from evergreen towards moist deciduous (Table 11).

  Regeneration status

Regeneration status of trees in the evergreen forest patches inside the sanctuary area is detailed in Table 12. Among the regenerating deciduous trees viz., Lagerstroemia microcarpa, Terminalia alata and Vitex altissima , only L. microcarpa has representatives in all girth classes but no other species has enough individuals in the lower girth classes indicating that their numbers are declining in the evergreen forest patches. They must have appeared in the past when the forest canopy was opened due to human interferences in the form of clearfelling and burning for shifting cultivation, or in the gaps created by selective timber extraction.

In case of semi-evergreen forest the pioneer evergreen species like Olea dioica, Macaranga peltata, Aporosa lindleyana are more, indicating the return of evergreens. Evergreen forest areas in the core zone of the sanctuary are dominated by endemic tree species of the Western Ghats like, Poeciloneuron indicum , Palaquium ellipticum, etc. Such patches belong to the relic patches of primary forest. However, in the buffer zone these species are less in number compared to other ubiquitous species like, Prunus zeylonica , Knema attenuata , Aglaia Sp., etc.

Evergreen tree species with good regeneration are Aglaia Sp., Dimocarpus longan , Garcinia morella , Knema attenuata, and Olea dioica . Except Poeciloneuron indicum , all other late successional trees like Prunus zeylonica , Dipterocarpus indicus, Palaquium ellipticum are not represented by good number of individuals.

Table 12. Regeneration status of trees in the evergreen forests of SVWS.

Species
Family
Tree type
Girth classes (cm)
30-59 60-89 90-119 120-149 150-179 180-209 210-239 240-269 270-299 >300
Lagerstroemia microcarapa* Lythraceae
D
3
3
6
3
3
2
2
2
2
Terminalia alata Combrataceae
D
2
1
Vitex altissima Verbenaceae
D
3
3
2
1
Callicarpa tomentosa Verbinaceae
E
4
4
Macaranga peltata Euphorbiaceae
E
1
1
Actinodaphne hookeri* Lauraceae
E
19
7
Aglaia ananmallayana* Meliaceae
E
12
6
2
6
Aglaia sp 1.(red bark, small leaf) Meliaceae
E
6
6
1
Aglaia sp 2.(red bark, big leaf) Meliaceae
E
4
2
3
3
1
Aglaia Sp. Meliaceae
E
40
19
9
4
3
1
1
Antidesma menasu* Euphorbiaceae
E
9
1
Aporosa lindleyana Euphorbiaceae
E
11
4
Artocarpus hirsutus* Moraceae
E
11
6
4
2
Beilschmiedia fagifolia* lauraceae
E
6
4
1
2
3
1
Bischofia javanica Euphorbiaceae
E
1
2
2
2
7
1
3
1
1
Calophyllum tomentosum Clusiaceae
E
3
7
3
2
4
1
2
1
Canarium strictum* Burseraceae
E
1
2
1
1
1
Cinnamomum macrocarpum Lauraceae
E
8
1
2
1
Dimocarpus longan Sapindaceae
E
51
31
13
7
5
Diospyros sylvatica* Ebenaceae
E
8
4
4
2
1
Diospyros candolleana* Ebenaceae
E
27
9
1
Diospyros crumenata Ebenaceae
E
5
7
1
Diospyros paniculata Ebenaceae
E
19
8
2
1
Dipterocarpus indicus Dipterocarpaceae
E
7
1
2
1
2
1
Elaeocarpus serratus Elaeocarpaceae
E
9
7
Elaeocarpus tuberculatus Elaeocarpaceae
E
1
1
2
4
1
3
3
Euonymus indicus* Celastraceae
E
6
3
Ficus nervosa Moraceae
E
2
1
1
2
2
Flacourtia montana * Flacourtiaceae
E
6
4
1
3
1
Garcinia gummi-gutta Cluciaceae
E
5
6
5
1
Garcinia morella Cluciaceae
E
54
15
2
1
Garcinia talbotii* Cluciaceae
E
2
1
1
1
1
Holigarna arnottiana* Anacardiaceae
E
13
7
3
1
1
Holigarna grahamii* Anacardiaceae
E
19
8
2
6
2
1
1
Hopea ponga* Dipterocarpaceae
E
15
2
5
4
Ixora arborea* Rubiaceae
E
13
2
Knema attenuata* Myristicaceae
E
99
40
12
6
1
1
Lauraceae member Lauraceae
E
17
2
5
1
Phoebe cathia Lauraceae
E
8
1
1
Mastixia arborea* Cornaceae
E
4
5
1
2
2
Mimusops elengi Sapotaceae
E
9
4
1
Myristica dactyloides Myristicaceae
E
8
9
2
1
Myristica malbarica* Myristicaceae
E
4
2
2
1
Nothopegia colebrookeana* Anacardiaceae
E
20
Olea dioica Oleaceae
E
60
50
49
42
18
6
1
1
1
Palaquium ellipticum* Sapotaceae
E
2
3
1
1
Persea macrantha Lauraceae
E
1
3
2
3
1
3
1
Poeciloneuron indicum Cluciaceae
E
44
17
10
5
3
1
Polyalthia fragrans* Anonaceae
E
11
4
Prunus zeylonica Olacaceae
E
1
2
Symplocos racemosa* Symplocaceae
E
20
15
4
3
2
Syzygium cumini Myrtaceae
E
3
2
1
Syzygium gardneri* Myrtaceae
E
14
11
8
3
2
2
3
2
1
Syzygium laeta* Myrtaceae
E
4
3
Syzygium macrocephala* Myrtaceae
E
15
Syzygium Sp. Myrtaceae
E
10
2
1
3
1
2
1
2
Note: E – Evergreen; D – Deciduous * Western Ghats endemics

The semi-evergreen forests are a mixture of evergreen and deciduous species but dominated by evergreens (Table 13). The common deciduous species found in this type of forests are usually the pioneers or gap loving plants like Macaranga peltata and Ervatamia heyneana. Other deciduous species are Lagerstroemia microcarpa , Careya arborea , Terminalia paniculata and Vitex altissima . This highlights that deterioration of the habitat leads to more number of deciduous individuals coming up in that region.

If such semi-evergreen forest patches get protection, it will pave the way for the re-establishment of the shade loving (heliphilous) evergreen forest tree species. Common evergreen species in the landscape presently are Aglaia anamallayana , Aporosa lindleyana , Elaeocarpus serratus , Holigarna arnottiana , Knema attenuata , Olea dioica and Symplocos racemosa .

he moist deciduous forests (Table 14) are dominated by the deciduous tree species. The species like Careya arborea , Dillenia pentagyn a and Terminalia paniculata have been represented by good number of individuals in the younger girth classes indicating the continuation of such species in the given environment. Among the evergreen evergreen species Aporosa lindleyana and Olea dioica have fairly good regeneration. These are the pioneer-evergreens, which can thrive better in the partial shade.

Table 13. Regeneration status of trees in the semi-evergreen forests of SVWS.

Species
Family
Tree type Girth classes (cm)
30-59 60-89 90-119 120-149 150-179 180-209 210-239 240-269 270-299 >300
Buchanania lanzan Anacardiaceae
D
2
7
Careya arborea Lecythidaceae
D
21
2
1
Dillenia pentagyana Dillenaceae
D
12
2
1
Diospyros montana Ebenaceae
D
7
3
1
3
1
Ervatamia heyneana* Apocynaceae
D
21
1
1
Glochidion zeylanicum Euphorbiaceae
D
7
3
1
1
Lagerstroemia microcarapa* Lythraceae
D
10
8
6
9
9
9
4
3
2
1
Pterospermum sp . Sterculiaceae
D
9
1
1
1
Randia dumentorum Rubiaceae
D
9
1
Steriospermum personatum Bignoniaceae
D
1
1
1
1
2
1
1
Terminalia paniculata Combrataceae
D
23
17
10
3
1
1
Terminalia alata Combrataceae
D
11
16
2
1
1
Vitex altissima Verbenaceae
D
19
8
1
Xantolis tomentosa Sapotaceae
D
5
5
8
3
Macaranga peltata Euphorbiaceae
E
17
6
1
Acronychia laurifolia Rutaceae
E
7
1
1
Actinodaphne hookeri* Lauraceae
E
23
11
4
Aglaia ananmallayana* Meliaceae
E
37
12
3
1
3
Aglaia sp . Meliaceae
E
11
6
3
1
Aporosa lindleyana Euphorbiaceae
E
51
12
4
1
Artocarpus hirsutus* Moraceae
E
7
4
3
1
1
1
Bischofia javanica Euphorbiaceae
E
1
1
1
Canarium strictum* Burseraceae
E
2
1
2
1
Cinnamomum macrocarpum Lauraceae
E
17
9
9
4
Dimocarpus longan Sapindaceae
E
17
9
4
1
Diospyros candolleana* Ebenaceae
E
28
4
2
1
Diospyros crumenata Ebenaceae
E
13
2
2
1
Diospyros buxifolia Ebenaceae
E
14
5
1
1
Dipterocarpus indicus Dipterocarpaceae
E
1
1
Elaeocarpus serratus Elaeocarpaceae
E
35
14
4
Elaeocarpus tuberculatus Elaeocarpaceae
E
1
1
1
Flacourtia montana * Flacourtiaceae
E
19
8
5
1
Garcinia morella Cluciaceae
E
25
4
Gordonia obtusa* Theaceae
E
6
3
2
1
Holigarna arnottiana* Anacardiaceae
E
22
17
11
5
1
1
Holigarna beddomei* Anacardiaceae
E
2
1
1
1
1
Hopea ponga* Dipterocarpaceae
E
20
5
Ixora arborea* Rubiaceae
E
38
2
1
Knema attenuata* Myristicaceae
E
63
24
13
1
Lauraceae member Lauraceae
E
25
5
2
Mangifera indica* Anacardiaceae
E
12
3
3
1
1
1
Memecylon umbellatum Melastomataceae
E
25
2
1
Mimusops elengi Sapotaceae
E
36
10
3
2
2
Myristica dactyloides Myristicaceae
E
6
1
Myristica malbarica* Myristicaceae
E
3
1
Nothopegia colebrookeana* Anacardiaceae
E
12
2
Olea dioica Oleaceae
E
122
59
45
22
4
3
Palaquium ellipticum* Sapotaceae
E
3
2
3
1
1
Persea macrantha Lauraceae
E
3
2
3
2
1
1
Poeciloneuron indicum Cluciaceae
E
2
1
4
3
1
1
Pterospermum acerifolium Sterculiaceae
E
3
5
4
2
3
1
Scheflera sp (tree) Araliaceae
E
1
2
Prunus zeylonica Oleaceae
E
1
1
Symplocos racemosa* Symplocaceae
E
43
16
6
4
Syzygium cumini Myrtaceae
E
3
3
1
2
2
1
1
Syzygium sp . Myrtaceae
E
15
1
10
2
2
Note: E – Evergreen; D – Deciduous * Western Ghats endemics

Table 14. Regeneration status in the moist deciduous forests of SVWS.

Species
Family
Tree type Girth classes (cm)
30-59 60-89 90-119 120-149 150-179 180-209 210-239
Buchanania lanzan Anacardiaceae
D
21
2
Careya arborea Lecythidaceae
D
5
2
Dillenia pentagyana Dillenaceae
D
14
5
1
1
Diospyros montana Ebenaceae
D
6
4
2
1
Ervatamia heyneana* Apocynaceae
D
2
Grewia tiliifolia Tiliaceae
D
2
2
Lagerstroemia microcarapa* Lythraceae
D
3
3
2
3
1
3
1
Pterocarpus marsupium Fabaceae
D
2
2
Schleichera oleosa Sapindaceae
D
9
2
1
Terminalia chebula Combrataceae
D
5
1
Terminalia paniculata Combrataceae
D
10
10
2
2
Terminalia alata Combrataceae
D
6
2
Vitex altissima Verbenaceae
D
4
2
Xantolis tomentosa Sapotaceae
D
4
4
1
Aporosa lindleyana Euphorbiaceae
E
12
2
1
2
Cinnamomum macrocarpum Lauraceae
E
4
1
Diospyros candolleana* Ebenaceae
E
3
2
Elaeocarpus serratus Elaeocarpaceae
E
7
3
Holigarna arnottiana* Anacardiaceae
E
2
3
Ixora arborea* Rubiaceae
E
7
Olea dioica Oleaceae
E
24
9
2
1
1
Pterospermum acerifolium Sterculiaceae
E
5
Symplocos racemosa* Symplocaceae
E
13
2
Syzygium Sp. Myrtaceae
E
2
1
2
Note: E – Evergreen; D – Deciduous * Western Ghats endemics

In the evergreen forests, the major species with higher IVI value are Olea dioica (34.39), Knema attenuate (18.38), Dimocarpus longan (13.59), Aglaia Sp. (11.69), Lagerstroemia microcarpa (9.44) and Poeciloneuron indicum (8.71).

Most of the evergreen forest patches occurring in the SVWS are secondary. In the process of natural restoration of evergreen forests, the long lived pioneer evergreen like Olea dioica get established first along with short lived pioneer trees like Macranga peltata . The openings in the canopy due to human interference or natural fall of trees are also occupied by these pioneers.

Some of the relic primary evergreen forest patches, dominated by Poeciloneuron indicum are still occurring in the Karani area, which is dominated by Poeciloneuron indicum . IVI (Table 15) for Poeciloneuron indicum is contributed by Karani locality only.

Table 15. IVI for evergreen forests.
Name
Family
IVI
Olea dioica Oleaceae 34.39
Knema attenuata* Myristicaceae 18.38
Dimocarpus longan Sapindaceae 13.59
Aglaia sp . Meliaceae 11.69
Lagerstroemia microcarapa* Lythraceae 9.44
Poeciloneuron indicum Clusiaceae 8.71
Garcinia morella Clusiaceae 8.56
Bischofia javanica Euphorbiaceae 7.67
Syzygium gardneri* Myrtaceae 7.38
Holigarna grahamii* Anacardiaceae 7.33
Diospyros candolleana* Ebenaceae 5.97
Persea macrantha Lauraceae 5.79
Symplocos racemosa* Symplocaceae 5.77
Calophyllum tomentosum Clusiaceae 5.67
Syzygium sp . Myrtaceae 5.43
Elaeocarpus tuberculatus Elaeocarpaceae 5.31
Aglaia ananmallayana* Meliaceae 4.67
Diospyros paniculata Ebenaceae 4.10
Lauraceae member Lauraceae 3.83
Beilschmiedia fagifolia* Lauraceae 3.81
Artocarpus hirsutus* Moraceae 3.77
Diospyros assimilis* Ebenaceae 3.77
Hopea ponga* Dipterocarpaceae 3.76
Ficus nervosa Moraceae 3.45
Actinodaphne hookeri* Lauraceae 3.41
Holigarna arnottiana* Anacardiaceae 2.97
Flacourtia montana * Flacourtiaceae 2.95
Syzygium laeta* Myrtaceae 2.95
Garcinia gummi-gutta Cluciaceae 2.91
Myristica dactyloides Myristicaceae 2.77
Mastixia arborea* Cornaceae 2.74
Dipterocarpus indicus Dipterocarpaceae 2.72
Nothopegia colebrookeana* Anacardiaceae 2.65
Casearia sp . Flacourtiaceae 2.55
Syzygium macrocephala* Myrtaceae 2.45
Syzygium cumini Myrtaceae 2.43
Ixora arborea* Rubiaceae 2.32
Mimusops elengi Sapotaceae 2.29
Litsea sp . Lauraceae 2.27
Aglaia sp2 . Meliaceae 2.25
Cinnamomum macrocarpum Lauraceae 2.20
Elaeocarpus serratus Elaeocarpaceae 2.15
Mangifera indica* Anacardiaceae 2.07
Vitex altissima Verbenaceae 2.01
Canarium strictum* Burseraceae 1.95
Aglaia sp1 . Meliaceae 1.95
Aporosa lindleyana Euphorbiaceae 1.94
Diospyros crumenata Ebenaceae 1.87
Polyalthia fragrans* Anonaceae 1.72
Diospyros sp . Ebenaceae 1.72
Pterospermum diversifolium Sterculiaceae 1.68
Caryota urens* Arecaceae 1.61
Lophopetalum wightianum Celastraceae 1.54
Euonymus indicus* Celastraceae 1.53
Antidesma menasu* Euphorbiaceae 1.53
Myristica malbarica* Myristicaceae 1.52
Palaquium ellipticum* Sapotaceae 1.45
Diospyros buxifolia Ebenaceae 1.41
Garcinia talbotii* Clusiaceae 1.33
Diospyros pruriens* Ebenaceae 1.32
Phoebe cathia Lauraceae 1.28
Artocarpus gomezianus Moraceae 1.16
Dimorphocalyx lawianus Euphorbiaceae 1.12
Canthium dicoccum* Rubiaceae 1.03
Pterospermum acerifolium Sterculiaceae 0.98
Hydnocarpus laurifolia* Flacourtiaceae 0.97
Ailanthus malabarica Simaroubiaceae 0.92
Callicarpa tomentosa Verbenaceae 0.91
Lepisanthes decipiens Sapindaceae 0.90
Mallotus philippensis Euphorbiaceae 0.89
Linociera malabarica Oleaceae 0.84
Memecylon umbellatum Melastomataceae 0.84
Holigarna ferruginea* Anacardiaceae 0.79
Cinnamomum zeylanicum Lauraceae 0.76
Cassine glauca Celastraceae 0.71
Blachia denudata Euphorbiaceae 0.66
Diospyros nigrescens* Ebenaceae 0.65
Diospyros oocarpa Ebenaceae 0.64
Arenga wightii* Arecaceae 0.63
Terminalia alata Combretaceae 0.62
Glochidion sp . Euphorbiaceae 0.57
Prunus zeylonica Olacaceae 0.55
Atlantia wightii Rutaceae 0.53
Cinnamomum sp . Lauraceae 0.51
Ficus sp . Moraceae 0.47
Gordonia obtusa Theaceae 0.42
Terminalia paniculata Combretaceae 0.41
Steriospermum personatum Bignoniaceae 0.38
Meliaceae member Meliaceae 0.37
Chrysophyllum roxburghii Sapotaceae 0.36
Calophyllum wightianum Clusiaceae 0.35
Vangueria spinosa Rubiaceae 0.35
Holigarna beddomei* Anacardiaceae 0.34
Scheflera sp (tree) Araliaceae 0.31
Litsea lavigata* Lauraceae 0.30
Diospyros montana Ebenaceae 0.29
Terminalia bellirica Combretaceae 0.27
Dysoxylum sp . Meliaceae 0.26
Macaranga peltata Euphorbiaceae 0.26
Careya arborea Lecythidaceae 0.25
Adina cordifolia Rubiaceae 0.24
Amoora lawii Meliaceae 0.21
Harpullia imbricata Sapindaceae 0.20
Xantolis tomentosa Sapotaceae 0.20
Artocarpus heterophylla Moraceae 0.19
Glochidion zeylanicum Euphorbiaceae 0.19
Rubiaceae member Rubiaceae 0.19
Bauhinia sp . Fabaceae 0.18
Cassia fistula Fabaceae 0.17
Celtis cinnamomea Ulmaceae 0.17
Ervatamia heyneana* Apocynaceae 0.17
Neolitsea scrobiculata Lauraceae 0.17
Tetrameles nudiflora Datiscaceae 0.17
Cleidion javanicum Euphorbiaceae 0.17
Mitrephora heyneana* Annonaceae 0.17
Polyalthia sp . Annonaceae 0.17
Unidentified members   2.87
* Endemic to Western Ghats

The semi-evergreen forests have Olea dioica (32.37) and Lagerstroemia microcarpa (18.58) as first and second dominant tree species with respect to IVI. In case of the former, many individuals occur in the first five girth classes, whereas in the latter, the individuals are distributed among all girth classes. Other species dominating the semi-evergreen forests are Knema attenuata , Symplocos racemosa , Holigarna arnottiana and Aglaia anamallayana , which are all evergreens (Table 16).

Table 16. IVI for semi-evergreen forests .
Name
Family
IVI
Olea dioica Oleaceae 32.37
Lagerstroemia microcarapa* Lythraceae 18.58
Knema attenuata* Myristicaceae 12.70
Symplocos racemosa* Symplocaceae 9.40
Holigarna arnottiana* Anacardiaceae 9.12
Terminalia paniculata Combrataceae 8.40
Aporosa lindleyana Euphorbiaceae 8.18
Aglaia anamallayana* Meliaceae 8.01
Mimusops elengi Sapotaceae 7.74
Elaeocarpus serratus Elaeocarpaceae 6.73
Cinnamomum macrocarpum Lauraceae 6.41
Syzygium sp . Myrtaceae 6.24
Actinodaphne hookeri* Lauraceae 5.53
Flacourtia montana * Flacourtiaceae 5.43
Ixora arborea* Rubiaceae 5.31
Diospyros candolleana* Ebenaceae 4.93
Mangifera indica* Anacardiaceae 4.77
Dimocarpus longan Sapindaceae 4.41
Garcinia morella Clusiaceae 4.39
Xantolis tomentosa Sapotaceae 4.06
Terminalia alata Combretaceae 3.98
Lauraceae member Lauraceae 3.97
Pterospermum acerifolium Sterculiaceae 3.84
Syzygium cumini Myrtaceae 3.78
Persea macrantha Lauraceae 3.58
Macaranga peltata Euphorbiaceae 3.36
Holigarna grahamii* Anacardiaceae 3.35
Diospyros montana Ebenaceae 3.27
Artocarpus hirsutus* Moraceae 3.24
Vitex altissima Verbenaceae 3.15
Memecylon umbellatum Melastomataceae 3.14
Aglaia sp . Meliaceae 3.10
Ervatamia heyneana* Apocynaceae 3.06
Diospyros buxifolia Ebenaceae 2.87
Steriospermum personatum Bignoniaceae 2.55
Dillenia pentagyana Dilleniaceae 2.54
Careya arborea Lecythidaceae 2.47
Diospyros crumenata Ebenaceae 2.45
Hopea ponga* Dipterocarpaceae 2.37
Poeciloneuron indicum Cluciaceae 2.27
Pterospermum sp . Sterculiaceae 2.09
Glochidion zeylanicum Euphorbiaceae 1.93
Canthium dicoccum* Rubiaceae 1.85
Bischofia javanica Euphorbiaceae 1.79
Nothopegia colebrookeana* Anacardiaceae 1.65
Lophopetalum wightianum Celastraceae 1.56
Gordonia obtusa Theaceae 1.47
Acronychia laurifolia Rutaceae 1.43
Litsea sp. Lauraceae 1.42
Terminalia bellirica Combretaceae 1.40
Palaquium ellipticum* Sapotaceae 1.36
Diospyros sp. Ebenaceae 1.35
Holigarna beddomei* Anacardiaceae 1.32
Canarium strictum* Burseraceae 1.31
Casearia sp. Flacourtiaceae 1.28
Randia dumentorum Rubiaceae 1.27
Buchanania lanzan Anacardiaceae 1.26
Celtis cinnamomea Ulmaceae 1.24
Nothapodytes foetida* Icacinaceae 1.18
Sterculia guttata Sterculiaceae 1.11
Myristica dactyloides Myristicaceae 1.10
Schleichera oleosa Sapindaceae 1.09
Linociera malabarica Oleaceae 1.06
Garcinia gummi-gutta Clusiaceae 1.03
Mallotus philippensis Euphorbiaceae 1.01
Diospyros assimilis* Ebenaceae 0.99
Holigarna ferruginea* Anacardiaceae 0.96
Odina wodier Anacardiaceae 0.91
Phoebe cathia Lauraceae 0.90
Beilschmiedia fagifolia* Lauraceae 0.89
Hydnocarpus laurifolia* Flacourtiaceae 0.87
Elaeocarpus tuberculatus Elaeocarpaceae 0.71
Vepris bilocularis* Rutaceae 0.72
Scheflera sp (tree) Araliaceae 0.71
Cinnamomum zeylanicum Lauraceae 0.70
Meliaceae member Meliaceae 0.69
Emblica officinalis Euphorbiaceae 0.68
Murraya paniculata Rutaceae 0.65
Glochidion sp . Euphorbiaceae 0.65
Bignoniaceae member Bignoniaceae 0.61
Ficus sp . Moraceae 0.61
Myristica malbarica* Myristicaceae 0.59
Litsea lavigata* Lauraceae 0.58
Lagerstroemia parviflora Lythraceae 0.58
Amoora lawii Meliaceae 0.54
Grewia Sp. Tiliaceae 0.47
Ficus nervosa Moraceae 0.46
Chrysophyllum roxburghii Sapotaceae 0.46
Alstonia scholaris Apocynaceae 0.45
Prunus zeylonica Olacaceae 0.45
Diospyros paniculata Ebenaceae 0.41
Cassine glauca Celastraceae 0.40
Callicarpa tomentosa Verbinaceae 0.39
Cassia fistula Fabaceae 0.37
Syzygium gardneri* Myrtaceae 0.36
Artocarpus gomezianus Moraceae 0.30
Mastixia arborea* Cornaceae 0.30
Cinnamomum malabathricum? Lauraceae 0.29
Pterospermum diversifolium Sterculiaceae 0.26
Caryota urens* Arecaceae 0.26
Antidesma menasu* Euphorbiaceae 0.24
Dipterocarpus indicus Dipterocarpaceae 0.24
Syzygium caryophyllatum Myrtaceae 0.24
Gnidia glauca Thymelaeaceae 0.24
Aglaia sp1 Meliaceae 0.23
Zanthoxylum rhetsa Rutaceae 0.23
Rutaceae member Rutaceae 0.23
Vangueria spinosa Rubiaceae 0.23
Ailanthus malabarica Simaroubiaceae 0.22
Grewia tiliifolia Tiliaceae 0.21
Calophyllum tomentosum Clusiaceae 0.20
Alseodaphne semicarpifolia Lauraceae 0.18
Wendlandia thyrsoidea Rutaceae 0.18
Unidentified members   2.25
* Western Ghats endemics

The moist deciduous forests are dominated by deciduous species Terminalia paniculata and Lagerstroemia microcarpa , and equally dominated by the evergreen species Olea dioica. Other species with higher IVI are Dillenia pentagyna and Buchanania lanzan having more individuals in the younger girth classes (Table 17).

Table 17. IVI for moist-deciduous forests
Name
Family
IVI
Terminalia paniculata Combretaceae 28.20
Lagerstroemia microcarapa* Lythraceae 26.67
Olea dioica Oleaceae 25.14
Dillenia pentagyana Dilleniaceae 16.32
Buchanania lanzan Anacardiaceae 14.64
Aporosa lindleyana Euphorbiaceae 14.37
Diospyros montana Ebenaceae 12.25
Symplocos racemosa* Symplocaceae 9.56
Schleichera oleosa Sapindaceae 9.21
Careya arborea Lecythidaceae 7.88
Elaeocarpus serratus Elaeocarpaceae 7.48
Xantolis tomentosa Sapotaceae 7.39
Terminalia alata Combretaceae 6.83
Ixora arborea* Rubiaceae 6.02
Holigarna arnottiana* Anacardiaceae 5.65
Syzygium sp. Myrtaceae 5.19
Diospyros candolleana* Ebenaceae 5.03
Terminalia bellirica Combretaceae 4.89
Terminalia chebula Combretaceae 4.76
Mimusops elengi Sapotaceae 4.76
Persea macrantha Lauraceae 4.68
Cinnamomum macrocarpum Lauraceae 4.67
Grewia tiliifolia Tiliaceae 4.67
Pterospermum acerifolium Sterculiaceae 4.34
Pterocarpus marsupium Fabaceae 3.74
Vitex altissima Verbenaceae 3.52
Diospyros crumenata Ebenaceae 3.37
Alseodaphne semicarpifolia Lauraceae 2.80
Unidentified members   3.36
Odina wodier Anacardiaceae 2.55
Memecylon umbellatum Melastomataceae 2.39
Mangifera indica* Anacardiaceae 2.31
Lagerstroemia parviflora Lythraceae 2.10
Randia dumentorum Rubiaceae 2.08
Ervatamia heyneana* Apocynaceae 2.07
Sterculia guttata Sterculiaceae 1.95
Diospyros malanoxylon Ebenaceae 1.59
Lauraceae member Lauraceae 1.49
Syzygium cumini Myrtaceae 1.41
Syzygium caryophyllatum Myrtaceae 1.39
Macaranga peltata Euphorbiaceae 1.35
Glochidion zeylanicum Euphorbiaceae 1.34
Glochidion sp . Euphorbiaceae 1.17
Canthium dicoccum* Rubiaceae 1.17
Nothopegia colebrookeana* Anacardiaceae 1.16
Xylia xylocarpa Fabaceae 1.16
Madhuca latifolia Sapotaceae 1.13
Beilschmiedia fagifolia* Lauraceae 1.11
Aglaia ananmallayana* Meliaceae 1.11
Sapindaceae member Sapindaceae 1.10
Holigarna ferruginea* Anacardiaceae 1.10
Hopea ponga* Dipterocarpaceae 1.10
Wendlandia thyrsoidea Rutaceae 1.10
Meliaceae member Meliaceae 1.05
Vangueria spinosa Rubiaceae 1.05
Alstonia scholaris Apocynaceae 1.04
Mallotus Sp. Euphorbiaceae 1.02
Diospyros buxifolia Ebenaceae 1.01
Linociera malabarica Oleaceae 1.01
* Western Ghats endemics
6.1.3 Faunal Distribution  

Faunal studies indicate the diverse groups of organisms found in the sanctuary. The data gathered both by sampling and opportunistic surveys are listed in Table 18.

Table 18. Species diversity across various faunal groups in the SVWS.
Fauna
Species
Ants
84
Coleopterans
166
Butterflies
173
Molluscs
21
Amphibians
24
Fishes
60
Birds
122
Reptiles
23
Mammals (including Bats)
43

6.1.3.1 Ants

Ants show tremendous diversity, and numerical and biomass dominance in almost every habitat throughout the world. At present there are about 9000 species of ants described from world-over representing 296 genera and 16 subfamilies (Agosti et al., 2000). The Indian subcontinent records ant species under 8 subfamilies representing 600 species and 92 genera (Bingham, 1903; Veeresh and Ali, 1991). Ants belonging to 7 subfamilies represented by 125 species and 44 genera are known to occur in Karnataka.

Towards the latter part, truly arboreal taxa as Oecophylla and Polyrhachis, Harpegnathos, Pachycondyla, and Leptogenys were present, suggesting the presence of dense evergreen and semi-evergreen forests. Also the only record of Polyrhachis mayri was made from the region. Human influence at the sampling sites is confirmed by the presence of Tapinoma . But, the human intrusions in the environment are not in huge proportions as evident from the presence of overlapping canopy areas and thick leaf litter.

6.1.3.2 Coleopterans

  Coleoptera is the largest order in the animal kingdom comprises of beetles and weevils with more than 130 families and over 350,000 species known worldwide. Beetles play a pivotal role in nutrient recycling via degradation of leaf-litter, wood and dung disposal. This order comprises a specialised group called Weevils with about 60,000 species around the world. They contribute to plant pollination and seed dispersal and also maintain the plant community, composition and structure via phytophagy. They are prey materials for insectivorous animals and some of them are predators, serving as bio-control agents.

A total of 166 species representing 29 families were recorded from the sanctuary with Carabidae, Scarabaeidae and Chrysomelidae families predominating in the observation (Annexure IV).

 6.1.3.3 Butterflies

Butterfly diversity and community composition are dependent on plants, as their caterpillars are highly specific to host plants, on which they feed and metamorphose into the adults. Therefore, richness of hostplant diversity contributes to butterfly diversity. They undergo metamorphosis, which contributes to local diversity. Ecologically they have dual role than monomorphic organisms as they have two different life styles.

The Western Ghats comprises 330 species belonging to 166 genera and five families. It includes the largest butterfly, the Southern Birdwing (Troides minos) with a wingspan of about 140-190mm to the smallest, the Grass Jewel (Freyeria trochylus) and Tiny Grass Blue ( Zizula hylax ) with wingspan only 15-22 mm and 16-24 mm respectively. Nymphalidae and Lycaenidae are the major families that contribute to the entire Western Ghats butterfly species diversity. SVWS comprises five butterfly families with 173 species (Annexure V). The family composition and the conservation status of the butterflies in Western Ghats are cited in Table 19.

Most of the Swallotails (Family; Papilionidae) show habitat preferences and hence can be used as indicators of ecosystem health. For instance, Spot Sword tail is found only in the thick evergreen forest and its larval host plants are Thottea siliquos, etc., are found in the core and buffer zone of the sanctuary. The swallowtails are also found puddling near the streams.

The Brush-footed butterflies of the family Nymphalidae are represented by 65 species in the sanctuary. They are well distributed in the sanctuary area and some are habitat specific in nature. The Map Butterfly, Blue Nawab and Malabar Tree Nymph are found only in the moist and shady places. Blue Nawab is an endangered species encountered in Banukuli locality. Indian Sunbeam is found in moist places within the sanctuary area. Family Hesperiidae, popularly known as the family of “Skippers” comprises of tiny butterflies found throughout the sanctuary. Spotted Small Flat is endemic species found only in few localitie.

Table 19. Butterfly family composition in SVWS.

Family

India

Western Ghats

Inside the sanctuary
Total species Endangered Western Ghats Endemics Shared Endemics ( Western Ghats and Sri Lanka )
Papilionidae
107
19
19
2
5
3
Pieridae
109
33
23
2
Nymphalidae
520
96
65
2
3
6
Lycaenidae
450
101
38
1
Hesperiidae
320
81
28
1

6.1.3.4 Molluscs

Molluscs are one of the most diverse groups of invertebrates - both in form and habitat. They have figured prominently in palaeobiological and biological studies, and have served as study organisms in numerous evolutionary, biomechanical, ecological, physiological, and behavioural studies. Many species of freshwater mussels and snails are threatened or endangered throughout the world. Twenty-one species belonging to 7 families were recorded from different localities. The list of species collected has been given in Annexure VI. The plight of freshwater mussels is a prime example of the decline of aquatic habitats and the species that inhabit them. If trends are not reversed and stream degradation and loss of habitat continues many of the interesting and beautiful molluscs will be lost forever.

6.1.3.5 Reptiles

157 species of reptiles including a crocodile Crocodulus palustris is known from the Western Ghats . Out of 157 species 97 are endemics and majority of them are snakes. Twenty-three species of reptiles were recorded in the present study (Annexure VII). Three endemic species, viz., skink, malabar pit viper and bamboo pit viper were also recorded. Tortoises are commonly found in the reservoir. Crocodile ( Crocodulus palustris) was recorded from reservoir at Madenur and Muppane area during the study. Two juveniles were caught in the nets of the fishermen at Holebagilu. There was an instance of livestock death due to crocodile at Muppane. King cobra is found in shady places and in the riparian vegetation dominated by Ochlandra sp. Malabar pit viper is found in between the buttresses of the huge trees of species like, Ficus nervosa , Syzigium gardneri and on the medium height shrubs. Hump nosed pit viper is found concealing in the litter cover.

6.1.3.6 Avifauna

Birds are a unique group of vertebrates and can indicate the quality of habitat or environment. In the ecosystem studies, birds play a pivotal role as predators of lower organisms and prey to higher vertebrates. The bird diversity of an area not only indicates its health but also stability. A total of 122 bird species were sighted in the sanctuary area during the study period (refer Annexure VIII). Inside the sanctuary, few localities are very important in bird diversity like, Muppane, Kanur and Govardhanagiri state forest. Muppane nature camp is an important area for bird watching as it is surrounded by heterogenous habitats from Scrub jungle to Semi-evergreen forest and also reservoir. The presence of some of the endemic and endangered species like, Malabar Grey Hornbill, and Great Indian Hornbill found in these areas signifies the presence of primary forest remnants. During the study, a flock of great Indian hornbill with 14 individuals were found in the Govardhanagiri forest. Apart from that, in some of the islands, malabar grey and Malabar Pied Hornbill are encountered which in turn shows the presence of endemic tree species, like, Myristica malabarica , Knema attenuata . In some of the forest enclosures the presence of green pigeons, hornbills and parakeets signifies also the presence of their foraging plant species.

6.1.3.7 Mammals

Mammals are the group of animals that have reached a pinnacle during the evolution of life. In wildlife conservation, prioritisation is mainly given to mammals, because of their direct relevance to human beings. Their presence in the wild is an indication of the health of that habitat. The study area harbours many mammalian species as listed in Annexure IX . Of the 43 mammals recorded from the sanctuary, Tiger and Lion-tailed Macaque are endangered, and leopard is vulnerable. Annexure IX also lists the bats (flying mammals) found in this region. The endemic and endangered lion tailed macaque is sighted in the Karani area. Reports indicate their presence in Kogar, Gurta, Kodachadri and Sharavathi valley area. Now its population is on the decline due to the destruction and fragmentation of habitat and hunting for its skin and meat.

Tigers ( Panthera tigris tigris) inhabit mostly in the evergreen and moist deciduous forests. According to forest department 7 leopard and 2 tigers were found in the sanctuary and its immediate surroundings (Figure 6). In the sanctuary area tiger was sighted near Shashichowka, Kogar, Karumane and Karani. Linganamakki catchment area has records of 4 leopards and 6 tigers.

 

Figure 6 . Tiger and leopard distribution in SVWS.

Sloth bear, a vulnerable species, is found in the rocky caves. They mainly feed on honey and jackfruit. Sloth bear is distributed in the few localities and all these areas come in the core and buffer zone of the sanctuary (Figure 7). Kattinkar, Sulmane, Karani, Meghane, Henni, Kanur and Halur are the few localities recognised for their distribution. They are sighted on the hilltops during the fruiting months of Phoenix sylvestris and Zizuphus rugosa . In Sulmane area they throng in good numbers during the fruiting period of Artocarpus integrifolius . Bear-human conflict is prevalent in this region, which is evident from the cases like death and injury in localities like, Henni, Kanur and Kattinkar.

 

Figure 7. Sloth bear distribution in SVWS.

aur inhabits deciduous, semi-evergreen and evergreen hilly forest areas and low land bamboo jungles. It is a vulnerable species. In the hilly tracts they prefer the open areas and tall grassy blanks. Sometimes they are found in the agricultural lands nearer to the dense forest areas. In drier seasons they are found near to the human settlements and near to the roads. Presently their population is well established in Karani, Kogar and

Madenur (12 individuals), Shashichowka and Hallibylechowka (30-40) forest enclosures (Figure 8).

 

Figure 8. Gaur distribution in the SVWS.

The ungulates comprise sambar, spotted deer, mouse deer, barking deer and wild boar and their distribution is cited in the Figure 9. Sambar (Cervus unicolor) inhabits deciduous, evergreen hilly forest areas and low land bamboo jungles. It is included in Schedule III of Indian Wildlife (Protection) Act, 1972. In the hilly tracts they prefer the open areas and tall grassy blanks. Sometimes they are found in the agricultural lands nearer to the dense forest areas. They are much less gregarious than chital and are often seen alone, especially the stags. During the field survey 12-15 individuals were seen at Halgod near Kattinkar, and two individuals at Muppane. Sambar is also found in the areas like Karani and Meghane. In the forest enclosures like Muppane, Shashichowka and Hallibylechowka, their number is increasing in recent years. They often invade crops and are being hunted to minimise the destruction.

Chital or Spotted Deer ( Axis axis ) is found in the open forest areas, moist deciduous forest, grasslands and scrub jungles. In Madenur and Muppane enclosures, their estimated population is 20-40. They are also found in Chikkamathur, Shashichowka and Bellanne. Illegal hunting is noticed in Muppane, Bilkandur and Arodi region. Indian Wildlife {Protection} Act, 1972 includes the Chital as the Schedule III animal.

Mouse Deer has become very scarce in many of the areas of its range of occurrence. The decline in its population is largely due to over hunting, as the animal is timid in nature, falls easy prey to hunters. They are associated with large tree buttresses, hollow trunks and burrows near Karumane, Aralagodu, Muppane, Kogar, Kanur and Karani.

Barking deer or muntjac ( Muntiacus muntjak ) is a rare species, occasionally seen in the sanctuary either solitary or in pairs in localities like, Banukuli and Vatemadike. Due to hunting pressure, barking deer's are on decline.

Indian wild boar ( Sus scrofa cristatus ) is most common in this region. The wild boars are the favourite food of the large carnivores. In many areas, however, shrinkage of the riverine forest has affected their population. It is included in Schedule III of the Indian Wild Life (Protection) Act.

 

Figure 9. Ungulates distribution in SVWS.

Common giant flying squirrel ( Petaurista petaurista ) and Indian giant squirrel ( Ratufa indica ) are seen in most parts of the sanctuary. Indian giant squirrel is found in the localities with the foraging plant species like, Cassine glauca , Bischofia javanica, etc.  

6.2 Aquatic Ecosystem Terrestrial Ecosystem 6.1 | 6.2 | 6.3

Aquatic ecosystems contribute to a large proportion of the planet's biotic productivity as about 30% of the world's primary productivity comes from plants living in the ocean. These ecosystems also include riverbanks, wetlands located at lakeshores, the ocean shoreline, and any habitat where the soil or vegetation is submerged for some duration. These ecosystems have been subjected to various levels of stresses, due to unplanned developmental activities in the last century. Anthropogenic activities involving changes in land-use ultimately affects the receiving water in that drainage. Activities include unplanned agricultural practices, unscientific usage of inorganic fertiliser, pesticides and herbicides applied to crops, silt washed away because of vegetation removal, or even due to atmospheric deposition, or disposal of solid and liquid wastes. The Linganamakki reservoir (in eastern part) and Talakalale reservoir (northern side) form a part of the lacustrine ecosystem in SVWS, while many first and second order streams of river Sharavathi and Venkatapura forms the lotic ecosystem in the sanctuary.

  6.2.1 Phytoplankton

Phytoplankton are the microscopic suspended algae that occur in different forms such as unicellular, colonial or filamentous, which are mainly photosynthetic in nature. They are one of the most rapid detectors of environmental change and are regarded as the primary producers in aquatic food chain. The family, genus and species composition of phytoplankton are listed in Table 20. Species list is given in Annexure X

Table 20. Familywise composition of phytoplankton.
Family composition I-collection II-collection III -collection
Desmidials
50
51
48
Bacillariophyceae
12
25
22
Cyanophyceae
4
6
6
Chlorococcales
3
9
8
Dinophyceae
2
2
4
Chrysophyceae
1
4
Total no. of genera
44
64
61
Total no. of species
71
94
92

Qualitative dominance of the phytoplankton was in the order of Desmidials > Bacillariophyceae > Cyanophyceae >Chlorococcales > Dinophyceae in the first sampling. In this collection population of Desmidial member Staurastrum multispiniceps was highest (58,944/L) in Muppane of the reservoir. While, in the second sampling, qualitative dominance was in the order of Desmidials > Bacillariophyceae > Chlorococcales > Cyanophyceae > Dinophyceae >Chrysophyceae. Similarly in the third collection, it was in the order of Desmidials > Bacillariophyceae > Chlorococcales > Cyanophyceae > Dinophyceae = Chrysophyceae. Table 21 reveals diversity and diversity indices calculated in various sampling localities.

Table 21. Diversity indices calculated in various sampling localities.  
Parameter
Collection
Muppane
Talakalale
Reservoir Centre
Yenne holé
Madenur
Total individual
1
10339
2770
3414
820
-
2
49
96
33
437
74
3
232
59
88
585
175
Total species
1
21
13
14
23
-
2
15
18
18
19
24
3
21
17
15
20
19
Species richness
1
2.16
1.51
1.59
3.27
-
2
3.59
3.72
4.86
2.96
5.34
3
3.67
3.92
3.12
2.98
3.48
Shannon-diversity
1
1.96
1.85
2.24
2.69
-
2
2.43
2.11
2.75
1.97
2.85
3
1.57
2.45
2.21
1.57
2.21
Simpson-dominance
1
0.2
0.22
0.12
0.09
-
2
0.11
0.23
0.07
0.24
0.07
3
0.4
0.12
0.14
0.38
0.15
Simpson-diversity
1
0.79
0.77
0.87
0.9
-
2
0.88
0.76
0.92
0.75
0.92
3
0.59
0.87
0.85
0.61
0.84

Abrupt variations in total number of individuals indicate that the growth and distribution patterns of phytoplankton are not uniform. High total number of individuals during I-collection compared to other two can be attributed to the rains during the month of September just prior to I-collection during October, which might have added nutrients to the waters along with run-off water from the catchment.

In order to apply biological means of determining the trophic status, Shannon and Weiner's species diversity values were calculated. The degrees of pollution is categorised based on the ranges of Shannon and Wiener's species diversity as ‘slight' (species diversity range of 3.0-4.5), ‘light' (2.0-3.0), ‘moderate' (1.0- 2.0) and ‘heavy' (0.0-1.0).

From Table 21 it is clear that in general, species diversity values are in the range of moderate or light pollution level. From Shannon 's diversity indices it is clear that the waters of sanctuary area are of oligotrophic nature.

A total of 109 species are collected from the SVWS; 28 species of diatoms, 58 species of desmidials, 12 species of chlorococales, 7 species of cynophyceae, 3 species of chrysophyceae and a species of dinophyceae represent total number. The biological examination of the stream and reservoir ecosystems showed a rich and diverse phytoplankton population. Desmids predominated in reservoir waters while diatoms in streams.

  6.2.2 Zooplankton

Zooplankton are the primary consumers of an aquatic ecosystem, which feed on phytoplankton. Rotifera, Cladocera and Copepoda are the major groups among freshwater zooplankton. A detailed knowledge about zooplankton composition and their seasonal fluctuations is essential for proper management of water bodies. In India , Baird (1860) initiated systematic studies on freshwater zooplankton. Michael and Sharma (1982) reported 93 cladoceran taxa belonging to 8 families from inland waters of India . Segers et al., (1994) reported about 300 species of rotifers from Indian inland waters but the information about Rotifers from lotic water system is still far from complete. Cladocerans are the favourite prey of most of the fishes. To study the zooplankton diversity in aquatic systems of the SVWS water samples were collected at Muppane, Talakalale, Reservoir center and Yenneholé.

Majority of rotifers inhabits freshwater but some genera also occur in brackish water and marine environment. Most species are free-living while some are epizoic or parasitic. Generally the size of the rotifera range from 400 µm to 0.2 mm. Six species belonging to two families are recorded in the present study. Number of species belonging to rotifers, cladocerons and copepoda are given in Table 22.

Table 22. Zooplankton of SVWS
Groups
Family
Muppane
Talakalale
Reservoir Centre
Yenneholé
Rotifera Brachionidae
1
0
1
1
Lecanidae
1
2
1
3
Cladocera Sididae
1
0
0
0
Daphnidae
1
1
0
0
Moinidae
1
0
1
0
Macrothricidae
0
0
0
1
Chydoridae
1
0
0
1
Copepoda Cyclopidae
0
0
0
1
Diaptomidae
1
1
1
0

Cladocerans are ubiquitous in distribution, i.e., they are found in the Arctic to Antarctic, in temperate and tropical latitudes. Recently they were also reported from ground water (Dumont, 1987; Negrea 1983). The size ranges from 0.2 mm to 18 mm. Like other Zooplankton cladocerans are excellent food for zooplanktivorous fish. Six species belonging to five families are recorded in the present study (Table 22).

Copepods are the very ancient arthropods. In inland waters copepods are well known, up to family level, but numerous species are yet to be discovered. Of the three groups of zooplankton, Copepoda was least represented in terms of diversity with only three species (Table 22).

In the present study, 15 species of zooplankton were recorded from four localities along the River Sharavathi, showing a typical tropical assemblage. Refer Annexure XI for localitywise species list. Large zooplankton species were absent in this river system, probably due to high predatory pressure.

  6.2.3 Ichthyofauna

The Western Ghats records 288 species belonging to 12 orders, 41 families and 109 genera, of which 118 species are endemic and 51 are unique (Dahanukar et al., 2004). This diverse fish fauna composition aptly demonstrates the hotspots status of the Western Ghats . A major portion of the Linganamakki reservoir falls under the SVWS. The ichthyological studies gain importance, as it helps to adopt appropriate conservation strategies for sustainable management of the aquatic ecosystem. Several rivers in the Western Ghats are being exploited for fisheries and there is hardly any information available on its effect on such a pristine resource stock of the region. This necessitates a detailed investigation on fish and fisheries.

We have recored from SVWS 60 species of fishes (Annexure XII). Considering the IUCN status of these species, there are about 16.6% (10 species) endangered, 18.3% (11 species) vulnerable, 16.6% (10 species) data deficient, 33.2% (20 species) are with lower risk and the status of 3 species is unknown. There is about 16 endemic fish species in the reservoir. Compared to the Western Ghats this value is relatively low, which could be attributed to the formation of the reservoir that has lead to the flourishing of generalist species and diminishing of sensitive endemic species. Also, the introduction of the exotic species into the reservoir has increased the species richness while decreasing the endemism. About 16.6% (10 species) are restricted to peninsular India and 41.6% (25 species) have their distribution all over India .

Large-scale fishery began in this reservoir with the commissioning of the dam. This commercialisation of inland fishery that took place over a few decades has led to transformation of the subsistence fishing into commercial fishing in the wildlife sanctuary area of the Linganamakki reservoir. The introduction of exotic and alien species in to the Linganamakki reservoir has been practiced since 1965. Fingerlings of Catla catla, Labeo rohita, Cirhina mrigala, Cyprinus carpio and Oreochromis mossambica are introduced haphazardly into the reservoir on yearly basis.

The commercial fish catch of the reservoir is dominated by species belonging to Cyprinidae (54%). The other major families are Bagridae (23%) and the Siluridae (15%). When biomass is considered, the fast growing Indo-gangetic carps, popularly known as Indian major carps, occupy a prominent place namely Catla catla (21%), Labeo rohita (8.4%) and Cirhina mrigala (6.32%). These fishes are introduced to fulfill the commercial fish requirement along with the exotic species ( Cyprinus carpio 21%). The native fishes with significant biomass are Gonoproktopterus kolus (11.5%) , Ompok bimaculatus (10%) and Wallago attu (9%).

Data on fish catch of the selected five localities (Table 23) show that at the center of the reservoir (Holebagilu), the yield variation is very high compared to other regions. During monsoon season, the central region yields the introduced species in bulk. In the peripheral localities (Muppane, Konjavalli, Melmanji and Kogar) variation in catch during two seasons is less.  

Table 23. Fish-catch observed at different locations during the year 2003-04
Locality
Catch per unit effort (Kg/boat/day)
Non-monsoon
Monsoon
Holebagilu
1.34
39.4
Muppane
7.93
16.5
Konjavalli
6.2
16.5
Melmanji
6.8
24.2
Kogar
8.2
28.5

The fish biomass composition (Table 24) in the central region is dominated by introduced species (Holebagilu - 55.8%) during monsoon season. Among the indigenous population, Ompok bimaculatus has shown significant biomass in these localities. Whereas in other localities without any introduced species, their catch includes indigenous commercial fishes like Gonoproktopterus kolus, Wallago attu, Mastacembelus armatus and Ompok bimaculatus . Apart from G. kolus , the market value for all indigenous fishes is higher than the introduced species.  

Table 24. Percentage catch composition of various species during monsoon season
Species name
Holebagilu
Muppane
Konjavalli
Melmanji
Kogar
Catla catla
25.4
0.0
0.0
0.0
0.0
Cyprinus carpio
12.7
0.0
0.0
0.0
0.0
Labeo rohita
10.1
0.0
0.0
0.0
0.0
Cirhina mrigala
7.6
0.0
0.0
0.0
0.0
Cirhinus fulungee
0.0
12.7
5.4
2.5
3.2
Gonoproktopterus kolus
0.0
39.0
43.4
38.9
43.2
Mastacembelus armatus
8.1
9.7
12.1
4.9
8.4
Mystus bleekeri
0.0
0.3
0.0
0.0
0.0
Mystus cavacius
9.1
7.2
1.4
0.6
0.5
Mystus malabaricus
1.7
2.7
1.4
0.6
2.1
Ompok bimaculatus
24.0
23.9
15.9
8.1
37.1
Ompok pabo
0.0
1.3
2.6
0.9
1.5
Osteocheilichthys nashii
0.0
0.9
0.0
0.0
0.0
Pseudeutropius atherinoides
0.0
0.2
0.3
0.1
0.2
Puntius filamentosus
0.0
1.1
1.4
1.5
3.8
Tor khudree
0.0
0.9
0.0
0.0
0.0
Tor mussullah
0.0
0.0
0.9
0.6
0.0
Wallago attu
0.0
0.0
15.1
41.2
0.0
Xenentodon cancilla
1.2
0.0
0.0
0.0
0.0

During summer season, catch is mainly represented by Mystus cavecius, M. malabaricus and Mastacembelus armatus in almost all the localities (Table 25). This shows the absence of any introduced species in these localities. At the peripheral localities Gonoproktopterus kolus shows significant catch whereas its catch is negligible at the central region.

Table 25. Percentage catch composition of various species during non-monsoon season
Species name
Holebagilu
Muppane
Konjavalli
Melmanji
Kogar
Native  
Gonoproktopterus kolus
0.0
28.4
28.9
13.3
11.0
Cirhina fulungee
5.6
8.5
8.4
2.2
4.6
Garra gotyla stenorhynchus
0.0
1.5
0.6
0.0
0.0
Mastacembelus armatus
0.0
25.2
19.3
17.8
19.5
Mystus cavecius
16.8
3.8
6.0
8.9
14.6
Mystus malabaricus
22.4
5.7
7.2
7.8
10.1
Ompok bimaculatus
32.8
8.3
14.1
39.1
29.5
Ompok pabo
0.0
13.9
10.6
9.8
10.7
Oreochromis mossambica
0.0
1.0
2.4
1.1
0.0
Puntius arulius
0.1
0.0
0.0
0.0
0.0
Puntius filamentosus
17.9
0.0
0.0
0.0
0.0
Tor khudree
0.0
3.8
2.4
0.0
0.0
Xenentodon cancilla
4.5
0.0
0.0
0.0
0.0

The fish catch composition shows variations between different sites as the composition in the peripheral regions of the sanctuary like Holebagilu is of introduced species while Yenneholé tributary is of native species. Fishery in the sanctuary is being practiced illegally and continued overharvesting proves to be unsustainable. Yenneholé tributary has witnessed a self-preserving fishery within the biological limits of its resource's productivity, through a limited seasonal uptake, while ensuring future harvests. On the other hand, Holebagilu region, which supplies the fish requirements of the nearby urban centers has large number of fishermen and wider access and has led to illegal fishing activities.

The fortunes of the fishermen at the central parts of the reservoir like Holebagilu and the Hasaramakki seem to have touched bottom during recent years. During the winter and the summer seasons, the catch kg/per person/day is around one, which fetches about 25 rupees. During monsoon season, they get the introduced species. The competition for food and space between the exotic and indigenous has also led to the decline in the latter.

Variable fishing pressure

Monsoon is the peak fishing period with 3.4 times fish catch per person per day compared to non-monsoon period and accounts for 86.7% of the total fish-catch. Increased fishing pressure is noticed with migratory fishermen (accounting to 63% of the total) from various parts of peninsular India and the density of fishermen increases to 2.75 times the native fisher folk. During the initial monsoon season, the reservoir attains the minimum water spread area. It is observed that most of the fishermen get concentrated in the central regions like Holebagilu leading to overexploitation of fish resource.

Muppane, Konjavalli, Melmanji and Kogar represent the peripheral localities of the western region. The biomass composition of this region shows that in these localities, the catch is formed by the native species. These are the flood plains where majority of the fish species breed during monsoon season. Huge quantities of fish catch in these localities during monsoon season poses severe threat to their population. It is evident that the catch per unit effort increases at the periphery than the other localities.

Fish translocation from other basins

Details on the pattern of introduction clearly reveal that no scientific approach has been adopted before determining the quantity of introduction. Seeds have been introduced depending on the availability. This unscientific approach has resulted in an artificial system of fishing wherein the indigenous fishing population has to rely on an external source to increase the fishing stock. The low catches during non-monsoon season affect the permanent fishermen of the region who are completely dependent on fish resources for livelihood. The biomass composition of this region also reveals that other than catfishes, no other native species has succeeded to form a stable population. Thus the fishermen are dependent on an artificial system in the form of introduction and harvest. It is implicative that the original fauna has been changed and hardy fish species has taken advantage of the vacant niches. Thus translocation of fishes from other basins has led to changes in the species composition.

  6.2.4 Amphibians

Amphibians are the best ecological indicators among vertebrates for the unique features like duplex life style, moist permeable skin and ectothermic nature (Lips and Donnelly, 2002). They are the indicators of habitat fragmentation, as they negatively respond to both qualitative and quantitative changes in the habitat (Gururaja, 2002), ecosystem stress (Welsh and Ollivier, 1998), impact of anthropogenic activities like dam construction, and sedimentation in streams due to road construction (Hecnar and McCloskey, 1996; Lambert, 1997a and b, Welsh and Ollivier, 1998).

Twenty-four species of amphibians with 178 individuals were recorded in SVWS accounting to 19% of the Western Ghats . Of the 24 species, 16 are endemic (71%) to the Western Ghats . Based on the IUCN criteria for conservation priority, 1 species endangered ( Nyctibatrachus aliciae ), 2 vulnerable, 2 threatened, 14 with least concern and 5 data deficient. Species list is provided in Annexure XIII.

These species belong to four families, namely bufonidae, microhylidae, ranidae and ichthyophiidae. Ranidae members predominate in the richness, abundance and endemism (20, 168, and 15). Based on the species abundance (Figure 10), the top six species include Euphlyctis cyanophlyctis (43) followed by Philautus cf . leucorhinus (24), Nyctibatrachus aliciae (21), Indirana semipalmata (16), Micrixalus saxicola (11) and Rana temporalis (10).

 
 

  Figure 10. Amphibian species abundance in SVWS.

The species richness is comparable to earlier studies in the Western Ghats (Vasudevan et al., 2001; Gururaja, 2002; Krishnamurthy, 2003). Presence of endemics (16 species), endangered species Nyctibatrachus aliciae and vulnerable species Micrixalus saxicola and Nyctibatrachus major indicates the ecological importance of the region.

6.3 Humans – Socio-Economic-Energy Studies 6.1 | 6.2 | 6.3
Cooking and water heating are the two major end uses that require huge amount of firewood in the region. It is estimated that the average per capita firewood consumption is 1.17 tonnes/year, based on sample survey covering 25% of the villages and 20% of the households. The villagewise cooking and water heating energy consumption values are given in Table 26. Estimation of the total fuelwood requirement of the region amounts to 10,435 tonnes for the year 1991 and it increased to 15,328 during 2001.

6.3.1 Forest biomass availability

Spatial extent of SVWS is about 431 sq.km, with 110 sq.km under semi-evergreen to evergreen forests, 49 sq.km under deciduous forests, 66 sq.km under plantations and 90 sq.km under wastelands. Considering the average secondary productivities of each type of forest (3.6 t/h/y for evergreen, 12.5 t/h/y for deciduous, 5 t/h/y for plantations and 0.6 t/h/y for scrub and waste lands), the annual availability of forest biomass as a source of fuelwood is about 189.23x10 3 tonnes.

Population increase at 3.9% per year has resulted in increased fuel wood demand. Apart from gathering dried and fallen twigs and leaves, local people also cut young saplings, green twigs, and even whole tree. Several plant species preferred by wild animals are being cut for fuel wood as well as for mulching and fodder. Table 26, lists the villagewise fuelwood consumption.

Table 26. Villagewise per-capita fuelwood consumption (Kg/person/day)
Village Name
Cooking
Water Heating
Monsoon
Winter
Summer
Ambargodlu
1.5
1.5
1.2
1.2
Chikkamathur
1.7
1.5
1.3
1.3
Mattikoppa
1.5
1.4
1.2
1.2
Hunalamadike
1.8
2.8
1.7
1.7
Valagere
1.6
1.8
1.4
1.3
Kalasavalli
1.7
1.8
1.4
1.4
Araballi
1.4
1.8
1.4
1.4
Honnemardu
1.8
1.7
1.4
1.4
Baliggere
2.0
2.0
1.3
1.3
Bannumane
1.6
1.4
1.2
1.2
Aravadi
1.7
1.7
1.2
1.2
Brahmana Ilakalale
1.6
1.5
1.2
1.2

At present the domestic energy consumption is well within the total biomass availability from the region. However, with increasing population poses a serious threat to the sustainability of forest resources.

The average livestock holding is in the order of 3.33 buffaloes, 2.27 bullocks and 4.5 cattle per household. Most of the households opt for open grazing in forests that hampers natural regeneration. The estimated total number of livestock in the sanctuary area is 17655. Animal residue (dung) can be used for biogas production, which might minimise the fuelwood pressure on forests. Quantification shows an order of 7,627 cu.m to 11,122 cu.m per day of biogas generation potential in the region (assuming that a kilogram of fresh animal residue provides 0.03 – 0.042 m 3 of gas), which is sufficient to meet the cooking energy needs of 27,572 – 21,801 persons. However the energy transition from fuelwood to biogas requires policy initiatives as most collect firewood at zero cost due to proximity of forests.

Village forest farms in the selected village would reduce the pressure of cattle on natural forests. Promotion of stall-feeding and conversion of degraded common lands to community fodder farm would bring down the pressure on forests. Village self help groups to be involved in creation and maintenance of village fodder farms in selected villages