Diversity, composition and structure of understorey vegetation in the tropical forest of Achanakmaar Amarkantak Biosphere Reserve, India

The present study was conducted on the floristic composition, structure, diversity and biomass of understorey vegetation in the dry tropical forest of Achanakmaar Amarkantak Biosphere Reserve (AABR) of India using phyto-sociological analysis in each forest type by randomly laying ten sample plots of 1 × 1 m size. The herbs were enumerated for their girth and height in sampling plots. The structure, diversity and biomass of herb communities were analyzed at forest type level and the study found 2919 plant individuals belonging to 66 species, 62 genera and 31 families. The most important family as determined by the Family Importance Value (FIV) was Poaceae in herbs layer. In terms of Importance Value Index (IVI), the herb Arthraxon hispidus (Poaceae) was the most vital species in the herbaceous community. The present study revealed that the density of herbaceous community ranged from 0.40 to 244.80 herbs ha−1 in various forest types, Basal area was recorded highest in Sal mixed forest (0.00373 m2 ha−1) and lowest was found in Bamboo forest (0.00188 m2 ha−1). The number of species in different forests varied from 14 to 32. Similarly, the Shannon index values in different forest types varied from 2.18 to 3.64, Simpson index values ranged from 0.045 to 0.17, the values of species richness from 16.69 to 30.52 and species evenness ranged from 0.81 to 0.95 in herb vegetation of different forest types. Shannon index values recorded in Sal mixed forest and Bamboo forest were found to be minimum. In contrary, Bamboo forest recorded maximum dominance of species as compared to other forests. Interestingly, beta diversity values ranged from 3.12 to 7.36 and it was observed to be highest in Bamboo forest and lowest in Sal mixed forest. However, the total herbaceous biomass varied from 86.28 g m−2 to 321 g m−2. The study recommends adopting intensive conservation measures especially in the open mixed forest and immature Teak plantations. In addition to it, encouraging and improving sal regeneration in sal mixed forests will not only help in reducing the biotic pressure but also in restoring and conserving the fragile dry tropical forest ecosystems of India.