Summary:
Assessment of vegetation status is essential to implement appropriate management strategies towards reclamation of degraded land. Vegetation analyses provide insights to the possibility of natural regeneration or restoration and impact of mining activities. Vegetation sampling has been carried out in mining area at Bisgod of Yellapur taluk, Uttara Kannada district, Karnataka of Central Western Ghats. Vegetation sampling carried out through transect based quadrats showed the signs of succession of forests in the region. Highly disturbed landscapes due to mechanised mining are with poor natural regeneration compared to un-mechanised regions. The survey records a total of 151 species belonging to 63 families and 131 genera in the region. Habit-wise, trees (83 species) are in higher number, followed by shrubs (36 species), climbers (22 species), and herbs (10 species). Family-wise analyses show that Rubiaceae had the highest species number (11), followed by Leguminosae (9), and Anacardiaceae, Apocynaceae, Euphorbiaceae with 7 species. Shrub layer has higher species number, evergreeness and endemism showing a healthier recruitment of post mining status. The study reveals that the region with developed undergrowth and herb layers highlight the scope for regeneration. Planting native saplings in the region with soil amendments accelerate the reclamation of forests and maintenance of biodiversity.

Introduction:
Extraction of metal ores through opencast mining involves large scale destruction of natural forests, loss of productive top soil, siltation of water bodies. The natural recovery of forests in these regions takes long time (Sharma, and Wesley Sunderraj, 2005). Mining and quarrying have destroyed large tracts of forests land, evident from diversion of 1, 14, 304. 45 Ha in India between 1980 and 2008 (Mishra & Reddy. 2009, Department of Mines, GoI, 2008). Mining of mineral resources have severe environmental implications in the absence of planning and appropriate environment management strategies. Mining creates large amounts mine tailings, which are of concern due to the biotic and abiotic oxidation of minerals that release acidity and metals in the environment (Szczerski et al., 2013). Monitoring of such areas helps in the implementation of site specific remedial measures for environmental conservation.

Reforestation through planting and nurturing of native plants improves landscape’s physic-chemical structure (Young et al., 2013) and has been effective in reclamation to mitigate the spread of tailings and emissions in the environment. Re-vegetation protects the ground surface against wind erosion, diminishes the threat of water erosion and also provides obvious environmental benefits such as providing habitat for animal species, carbon capture, etc. (Koszelnik-Leszek et al., 2013). Permitting regeneration and plantation of local species of vegetation allows islands of vegetation to persist, where species and populations typical of specific habitats concentrate, increasing the biodiversity of post mined areas (Shu et al., 2003; Sena, 2014).

Degradation of land due to mining disrupts the regional biogeochemical cycles. Land reclamation of these soils requires appropriate choice of plant species, based on their ability to adapt to extreme and restrictive soil conditions (Leon et al., 2013). A systematic approach to improve degraded soils in mined regions is through reactivation of biogeochemical nutrient cycles (via litter production and decomposition), the establishment of active restoration models using new forestry plantations, agroforestry systems (Juan et al., 2014). The nutrient recycling is critical as lower nutrient conditions are associated with the mismanagement of top soil while mining. The litter provides substrate for leaf litter fungal assemblages that include ecological guilds such as saprotrophs, endophytes, parasitic and pathogenic fungi and a few mycorrhizal fungi. The litter decomposition is mediated by both biotic and abiotic processes, leaf litter fungal decomposers play an important biotic role in recycling ecosystem nutrients (Schneider et al. 2012). The establishment of vegetation cover improves ecosystem services such as: litter supply, nutrient cycling, water infiltration, control of erosion, and increasing of biodiversity (Murgueitio, et al., 2011). This occurs due to (i) nutrients cycling through plant’s root system, (ii) the protection of the soil surface against erosion, and (iii) maintenance of soil moisture and organic content via litter production, decomposition, etc. (Kumar, 2008).

The objective of the study is to understand the vegetation status in post mining period at Bisgod, Yellapur taluk, Karnataka. This involved an analysis of flora and structural characterization, diversity and regeneration. This provided insights to the secondary succession in degraded areas, which helps in evolving restoration strategies considering self-recovery potential.

Method

The vegetation status is assessed in Bisgod mining area, Yellapur taluk, Uttara Kannada district, Karnataka of Central Western Ghats. The region receives high rainfall of > 3500 mm annual). Vegetation in this region mainly comprises of tropical wet evergreen, semi-evergreen forest to moist deciduous as the rainfall is high. Scrub with savannas is found in more disturbed areas. The landscape elements also include a mosaic of natural forests with Acacia and teak plantations, rice fields and areca nut gardens.

Studies on forest vegetation were carried out using belt transects. Each transect with a length of 180m had alternating 5 quadrats with 20 m inter-distance (between quadrats). Trees (> 30 cm GBH) were studied in each quadrat of 20 x 20 m. Members of the shrub layer (GBH <30 cm and height more than 1 m) were enumerated in two shrub quadrats (5x5m) placed diagonally inside each tree quadrat. Inside each shrub quadrat two herb plots (height < 1 m) were laid diagonally (1 x 1m). Total of 3 transects with 15 quadrats were laid in different regions of mining area.  Associated features such as presence of epiphytes, climbers, parasites, human disturbances etc. were recorded. Opportunistic survey was also carried out to list species that are not encountered in the transect areas. The data from the transects were pooled into three classes locality wise with herb layer (<1m height), shrub layer (≥ 1m and < 30 cm GBH) and tree layer (≥ 30cm GBH) and analysed accordingly layer wise  (mostly tree and shrub layer) to get the present status of vegetation and regeneration aspects.

Table 1(a): Study area details

RESULTS AND DISCUSSION

Composition and structure of Flora: A total of 151 species of 63 families and 131 genera were recorded in the study area (Table 1 (a)) and habit-wise trees dominate (83 species), followed by shrubs (36 species), climbers (22 species), and herbs (10 species) (Figure 1).  Family-wise Rubiaceae had the highest species number (11), followed by Leguminosae (9), and Anacardiaceae, Apocynaceae, Euphorbiaceae with 7 species each (Figure 2).

Figure 1: Habit wise species distribution in the mined area.

Figure 2: Family richness in the study area

Forest structure: Tree layer
Due to higher rainfall in these locations, forests type are predominantly evergreen to semi-evergreen forests. Disturbed patches due to anthropogenic activities consist of disturbed semi-evergreen to moist deciduous forests. Forests in Balekodlu-Keral-Dehalli transect (in mined regions) have attained their average biomass of 48.31 m2/ha (per hectare basal area comparable natural forests in nearby regions). Nagerkhan-Angod area has lowest basal area (30.79 m2/ha.) indicating higher disturbance or insufficient recovery (Table 1 (b)). Acacia plantations are with poor natural regeneration (Figure 3), and poor canopy opening (Figure 4). Planting mixed species varieties in these localities would enrich the ecosystem. The organic matter and nutrient return rate via litter depends on factors that influence decomposition process at the ecosystem level. Plant species selected for reclamation of mined regions should preferably have symbiotic associations with soil microorganisms (i.e., mycorrhizal fungi and N2 fixing bacteria).   

Table 1 (b): Total individuals, total species, average height, tree population per hectare and per hectare basal area in the tree layer of Bisgod transects.

Figure 3: absence of regeneration in dense Acacia auriculiformis plantation

Figure 4: Very less regeneration in mined pit area

Forest diversity and endemism
Generally undisturbed forests are higher in evergreeness, endemism and diversity. However in the studied forest area owing to the past and present disturbance such as mining, forest extractions such as fuel wood collection, logging etc., forest is both less in endemism and evergreeness. Endemism percentage is as low as 13.33 in Nagarkhan-Angod area (Table2). Forest with low endemism is dominated by Olea dioica, Schleichera oleosa, Aporosa lindleyana,etc. However, in the absence any further human impacts such forests gradually pass through progressive succession stages towards higher biomass, diversity and endemism.
Table 2: Species richness, Shannon diversity, Simpson dominance, Simpson diversity, Pielou’s evenness index, percentage Western Ghats endemics, and percentage evergreeness in the study area.

Important value index
In these localities, important value index (IVI) was higher for midlevel succession evergreen species such as Olea dioca and Aporosa lindleyana and deciduousspeciessuch as Schleichera oleosa Terminalia bellirica, Vitex altissima etc. These species indicate progressive forest succession towards better forests from earlier impacts on mining activities. The presence of mid-succession evergreens and associated deciduous trees in higher IVI indicates the prospects of return of evergreen if the region is not subjected to further disturbance. The presence of evergreens in all the transects is an indication of absence of fire which otherwise hardly give chance to evergreen species such as Olea dioica, Aporosa lindleyana, Cinnamomum malabatrum, Aglaia roxburghii, Ixora brachiata, Alseodaphne semecarpifolia etc.

Table 3: Location wise tree species and their Important Value Index (IVI)

Regeneration in Shrub layer
Compared to tree layer, shrub layer has higher species number, evergreeness and endemism which highlights a healthier recruitment (Table 4 and 5). Shannon diversity was highest in Hosmane-Angod area (3.2).  Recruitment of endemic species is higher in Balekodlu-Keral-Dehalli (49.48) compared to tree layer (24.7).  Hence regeneration in forests surrounding the non-mecanised pit is good. Compared to this, in machinery mined pit tree saplings are very less due to heavily compacted hard soil and absence of any leaf litter.  These are sparsely covered by climbers such as Calycopteris floribunda, and tree saplings of Terminalia paniculata, Diospyros montana, Syzygium cumini, Lea indica, etc. However in more densely planted Acacia auriculiformis areas, there are no tree or climber saplings and seedlings.  In manually mined areas without machinery, good regeneration of most forest tree species was observed including evergreen species as seen in Hosmane-Angod area.
This analysis highlights the return of evergreen forest with endemic species of Western Ghats in the non-mechanised mining area in Bisgod (Table 6). The growing stock needs protection from cattle grazing and illicit extraction of forest produce, especially timber, firewood, etc. 

Table 4: Species number and individuals per transect and shrub population per hectare in studied localities

                                                    
Table 5: Shrub layer Species richness, Shannon diversity, Simpson dominance, Simpson diversity, Pielou’s eveness index, percentage Western Ghats endemics, and percentage evergreeness in the study area.

Table 6: Tree species with good regeneration in the study area

References

1. Juan D., León and Nelson Osorio, W., 2014. Role of Litter Turnover in Soil Quality in Tropical Degraded Lands of Colombia, The Scientific World Journal, 11 pages, doi:10.1155/2014/693981.
2. Koszelnik-Leszek, A., Podlaska, M., & Tomaszewska, K. (2013). Diversity of vascular flora of waste dumps and dumping grounds in Lower Silesia. Archives of Environmental Protection, 39(2), 81-105.
3. Kumar, B.M., 2008. Litter dynamics in plantation and agroforestry systems of the tropics-a review of observations and methods, in Ecological Basis of Agroforestry, D. R. Batish, R. V. Kohli, S. Jose, and H. P. Singh, Eds., pp. 181–216, CRC Press, Boca Raton, Fla, USA.
4. Leon, D., Castellanos, J., Casamitjana, M., Osorio, N.W., and Loaiza, J.C., 2013. Alluvial gold-mining degraded soils reclamation using Acacia mangium plantations: an evaluation from biogeochemistry, in Plantations Biodiversity, Carbon Sequestration and Restoration, R. Hai, Ed., pp. 155–176, Nova Science, New York, Ny, USA.
5. Mishra. P.P & M. Gopinath Reddy. 2009. Mining in Forest Areas - Problems, Causes and Concerns: A Review. RULNR-CESS Working Paper Series No. 1. Research unit for livelihoods and natural resources, Centre for economic and social studies. Hyderabad.
6. Murgueitio, E., Calle, Z., Uribe, F., Calle, A., and Solorio, B., 2011. Native trees and shrubs for the productive rehabilitation of tropical cattle ranching lands, Forest Ecology and Management, 261 (10), 1654–1663.
7. Ricardo R.R., Sebastia o Venaˆncio Martinsb., Luiz Carlos de Barrosc. 2004. Tropical Rain Forest regeneration in an area degraded by mining in Mato Grosso State, Brazil. Forest Ecology and Management 190. 323–333.
8. Sena, K.L., 2014. Influence of Spoil Type on Afforestation Success and Hydro chemical Function on a Surface Coal Mine in Eastern Kentucky, uknowledge.uky.edu.
9. Shu, W.S., Ye, Z.H., Zhang, Z.O., Lan, C.Y., Wong, M.H., 2005. Natural colonization of plants on five lead/zinc mine tailings in Southern China. Restor. Ecol., 13, 49.
10. Sharma, D., and Wesley Sunderraj. S. F., 2005. Species selection for improving disturbed habitats in Western India. CURRENT SCIENCE, 88 (3).
11. Szczerski, C., Naguit, C., Markham, J., Goh, T. B., & Renault, S. (2013). Short-and long-term effects of modified humic substances on soil evolution and plant growth in gold mine tailings. Water, Air, & Soil Pollution, 224(3), 1-14.
12. Young, I. W., Naguit, C., Halwas, S. J., Renault, S., & Markham, J. H. (2013). Natural revegetation of a boreal gold mine tailings pond. Restoration Ecology, 21(4), 498-505.