Biomass estimation in some dry zone forests in Sri Lanka from Forest Inventory Data

Abstract

Tropical forests are a major sink for carbon dioxide produced globally. Estimation of above-groundbiomass of these forests is an essential aspect of studies of carbon stocks and the effects of carbon sequestration on the global carbon balance. Long term monitoring plots across several tropical dryevergreen forests in India, in the recent past, shows they are highly carbon dense ranging from 73.06Mg ha-1 to 173.1 Mg ha1. In Sri Lankan forests, biomass estimates are confined to the wet zone forestsand plantations.To assess the carbon dynamics in Sri Lankan dry zone forests, as a pilot study, above-ground biomass infive dry zone forests were estimated using past forest inventory data from 1961. Our objective was todevelop an above-ground carbon database for dry zone forests, which can be used to determine the carbon dynamics in those forests. The data of published stand and stock tables from the five dry zoneforests, Hurulu, Kumbukkan, Kantalai, Pallekelle and Madhu, were converted to above ground biomassusing published allometric models. Estimated above-ground biomass ranged from a minimum of 75.7Mg ha-1 in the Kumbukkan forest to a maximum of 129.6 Mg ha-1 in the Kantalai forest. The total abovegroundcarbon stocks ranged from 37.8 Mg ha-1 in the Kumbukkan forest to a maximum of 64.8 Mg ha-1 inthe Kantalai forest. The average above-ground biomass for dry zone forests was 92.62 Mg ha-1. Whencompared with the wet zone estimates (eg.Sinharaja 336.8 Mg ha-1) the dry zone forests have lowerabove-ground biomass due to high disturbances, low tree density and other factors such as slow growthpattern of most of the tree species. However, present above-ground biomass estimates are not availablefor dry zone forests and estimates from this study can be considered as the above-ground carbon stock1960’s. These estimates shall be presented to assess the carbon dynamics in dry zone forests of SriLanka.