Tree Diversity and Structure of Andaman Giant Evergreen Forests, India

Abstract

We investigated tree diversity in 'giant evergreen forest' of Andaman and Nicobar Islands, which falls within the Indo-Burma hot spot of biodiversity in the world. A one hectare square plot was established in sites Kalapahad (KP) and Macarthy Valley (MV) of Middle Andamans, in which all trees ≥30 cm girth at breast height (gbh) were enumerated. Tree diversity totaled 105 species that belonged to 63 genera and 49 families. Site MV harboured ~10% greater species richness than KP. Species diversity indices did not vary much between the two sites. In the two sites, there were 1311 individuals of trees (579 ha^(-1) in KP and 732 in MV). The stand basal area was nearly equal in both the sites (KP- 45.59 m^2 ha^(-1); MV- 47.93 m^2 ha^(-1)). Thirteen tree species (12.38%) were strict endemics to Andamans. Ten species recorded are rare to the flora of these islands. The two sites are distinctly dominated by two different plant families; Dipterocarpaceae in KP and Myristicaceae in MV. Most of the species were common to central and lower region of Myanmar and Indian mainland. The forest stand structure exhibited a typical reverse-J shape, but site MV had double the density of stems in the lower tree size class than that of KP. The voluminous dipterocarps contributed more to the total above-ground live biomass. The need to preserve these species- and endemics-rich, fragile island forests, prioritized for biodiversity conservation, is emphasized.