Tree diversity and community composition in sacred forests are superior than the other community forests in a human-dominated landscape of Meghalaya

Abstract

Tree diversity and community composition in six sacred forests (SF) of Meghalaya were compared with those of six adjacent community forests (CF) to understand how protection provided to sacred forests by the communities impacts their diversity and community characteristics. The SFs harboured a greater number of tree species (187) compared to the CFs (56). Tree density in the SFs ranged from 750 trees ha−1 (MKSF) to 1470 trees ha−1 (MTSF) while in CFs, it was 875 trees ha−1 (ILCF) to 1236 trees ha1 (NBCF). Among the SFs, the highest basal area was recorded in MNSF (56.89 m2 ha−1) and least in NBSF (40.75 m2 ha−1), while among the CFs tree basal area ranged from 23.7 m2 ha−1 in MKCF to 36.0 m2 ha−1 in MNCF. The canopy cover in SFs ranged from 73.3 to 86.2% while in CFs it ranged from 54.3 to 70.8%. Species rank abundance distribution (RAD) curve or dominance-diversity curve showed high equitability and low dominance in all the six SFs while the RAD curve showed high dominance and low equitability in all the six CFs. The dominance-diversity curve in the SFs followed a log-normal distribution whereas the CFs exhibited a broken stick distribution pattern. Among the CFs, Pinus kesiya was the dominant tree species in five out of six study sites. The dominant species were different for different SFs, which were Microtropis discolour (ILSF), Citrus latipes (MNSF), Castanopsis tribuloides (MTSF), Castanopsis armata (NBSF), Myrica esculenta (NKSF) and Taxus wallichiana (MKSF). SFs were characterized by high diversity and low dominance as seen in old-growth forests. Shannon’s diversity index (H′) in the SFs ranged from 2.06 to 4.28 indicating high tree diversity, while in CFs it was 0.76–2.61 reflecting relatively lower diversity. Simpson’s dominance index for trees was higher in CFs (0.09–0.73) than the SFs (0.02–0.26).