COMPOSITION, STRUCTURE AND FLORAL DIVERSITY OF FOREST COMMUNITIES OF ACHANAKMAR- AMARKANTAK BIOSPHERE RESERVE :A COMPARISON AND CONSERVATION IMPLICATION

The core region of Achanakmar- Amarkantak Biosphere Reserve falls in Chhattisgarh State (India) and lies between lat.22 0 15’ to 20 0 58’ N and long. 81 0 25’N to 82 0 5’E. Shorea robusta Gaertn F. (sal) is the dominant species occurring in this region.The present study deals with the comparative account of composition and diversity of pure Shorea robusta forest and degraded mixed moist forest of Achanakmar- Amarkantak Biosphere Reserve.Based on the repeated reconnaissance of the area, three representative sites of size 1 hac. in pure sal forest was selected for two growth strata stages eg.upper story(trees )under story(,saplings and seedlings ). The forest vegetation was analyzed using 10 randomly placed quadrate(each 10 *10m) within the representative sites. The vegetation data were quantitavely analyzed for frequency, density, abundance and Importance value index and various indices of alpha and beta diversity .The pure Shorea robusta forest showed high density and basal cover of trees (1233stem ha-1,basal cover 36.36 m2ha-1)and under story vegetation (density1575 stem ha-1 ,basal cover 1.85 m2ha-1). The degraded mixed moist deciduous forest sites represents the degraded stage having low density of trees and basal cover(633 stem ha-1,basal cover 32.82 m2ha-1)and under story vegetation (density 918 stem ha-1 ,basal cover 0.37 m2ha-1). The total number of species was high in pure Shorea robusta forest as compared to degraded mixed moist deciduous forest.Similarly plant diversity was also high in pure Shorea robusta (sal) forest for trees and understory(2.82;2.92 Shanon index;4.76;2.32 richness index ,0.99;1.01 equitability ,0.21;0.22 concentration of dominance,5.78;8.82 beta diversity)respcectively than on degraded mixed moist deciduous forests for trees and understory(1.99;2.44 Shanon index;3.48 ;1.43richness index , 0.78;1.04 equitability index,0.39;0.26 concentration of dominance,8.20;11.93; beta diversity)respcectively..The climatic condition of the region supported the regeneration of Shorea robusta (sal) and its associates in the climax formation over a long successional