Ecological Studies on Four Rainforests in Karnataka, India: I. Environment, Structure, Floristics and Biomass

Abstract

(1) The environment, structure and floristics of four evergreen rainforest sites at 575-800 m altitude in Karnataka, southern India, are described. (2) The mean annual rainfall on the four sites ranges from 5310 to 7670 mm. Most of the rainfall occurs from June to September and there is an intense dry period from December to April. All the sites occur on oxisols overlying hornblendic rocks. (3) The forests at three of the sites are species-rich with an important contribution from the Dipterocarpaceae but one site is unusual and has an almost monospecific dominance by Poeciloneuron indicum (Guttiferae). (4) The total aboveground tree biomass was 420-649 t ha-1. The root fraction was 13.9-20.2 t ha-1. (5) Girth increment data over 35 years were available for one site and these were used with biomass estimates to calculate the approximate mean annual increase of above-ground and root (.gtoreq. 5-cm girth) biomass in the four sites. These were 6.4-11.1 t ha-1 for aboveground material and 0.2-0.4 t ha-1 for roots. (6) For small trees (.ltoreq. 5 cm dbh) and herbs, biomass was estimated by destructive sampling in one plot. The combined above-ground biomass of these fractions was 7.2 t ha-1.