Coal mining impact on vegetation of the Nokrek Biosphere Reserve, Meghalaya, India

Abstract

Extensive coal mining activity in the buffer zone of the Nokrek Biosphere Reserve (NBR) in Meghalaya, India, has led to habitat degradation and a landscape dotted with mine spoils. The present study analyses the impact of coal mining on different aspects of vegetation of the NBR. For this purpose, three coal mining sites, viz. Budugiri, Buduwathegiri and Faramgiri, were randomly selected from the 18 sites present within the biosphere reserve. It was found that the total number of species was much less in mined areas than un-mined areas. Tree and shrub populations showed a drastic reduction in their species composition due to coal mining. The density of trees, shrubs and herbs in mined areas was significantly lower than in un-mined areas at all three sites. The basal area of trees follows the same trend as density. The dominance of plant species was shared by many species both at un-mined and mined sites. Fifteen species of trees, four shrubs and 28 herb species were found in mined sites, while 27 tree species, four shrub species and 16 herb species were found only in the un-mined sites. The dominance–diversity curves for the mined sites resemble the broken-stick series model, which indicates less species occurring in these areas and also represents a stressed environment with conditions unfavourable for plant growth. Shannon's diversity index for tree species was low in the mined sites, which indicates adverse impacts from mining. The diversity index for herbs increased with mining, suggesting that the mining operation enhanced the colonisation of certain species in the newly created habitats. Trees of the medium girth class dominated both the mined and un-mined areas at all three sites. The density of trees, irrespective of their girth classes, was lower in the mined areas than the un-mined areas. There was not much variation in the distribution pattern of the species as most tree species showed contagious distribution patterns both in the un-mined and mined areas.