TREE SPECIES DIVERSITY, SPECIES REGENERATION AND BIOLOGICAL PRODUCTIVITYTI TREE SPECIES DIVERSITY, SPECIES REGENERATION AND BIOLOGICAL PRODUCTIVITY OF SEEDED ACACIA CATECHU WILLD. IN REHABILITATED LIMESTONE MINES IN THE NORTH WEST INDIAN HIMALAYAS

摘要

Degraded sites like mine spoils on hillslopes are characterized by poor soil physico-chemical environments and instability. Reclamation of such areas using low cost bioengineering and vegetative methods were carried out in an abandoned limestone mine in the lower western Indian Himalayas and the impact of these measures on vegetation diversity, secondary succession and growth of seeded Acacia catechu Willd. after two decades of protection are reported in this paper. Results reveal that introduction of fast growing leguminous species affected species diversity and hampered the regeneration and growth of native vegetation, due to the dense shade of the over-storey component. Species diversity (H') levels increased with the opening of the canopy at different elevations, with the highest diversity (1.624) being recorded on the hilltop with Acacia catechu and Wedlandia exserta dominating the area. Enumeration of various species in the growth stages indicated a large population in the pole stage followed by tree and sapling stage indicating scattered regeneration mostly by 1-2 species. Tree associations in the lower, middle and upper reaches were of Leucaena leucocephala-A. catechu, A. catechu-Boehemeria rugulosa and A. catechu-W. exserta, respectively. Seeded A. catechu plants now in the tree stage have attained an average height of 5.5 m and dbh of 10.44 cm with an average wood volume of 0.027 m3 in a period of 16-21 years. At current prices of heartwood (US $435 per m(3)) of A. catechu which is used in the manufacture of 'kattha', the investments made two decades ago (US$ 13043) in the rehabilitation of the limestone mine are fairly justified