Carbon Sequestration Potential of Privately Managed Swietenia macrophylla Plantations in the Wet and Intermediate Zones of Sri Lanka

Abstract

Global warming is the most widespread problem of the new millennium. Carbon dioxide(CO2) is the most important greenhouse gas released as a result of human activities. As aconsequence, global average temperature is projected to increase by 1.4 to 5.8 0C over theperiod of 1990 to 2100. Forest tree plantations play an important role in reducing thisatmospheric carbon dioxide through carbon sequestration through photosynthesis and storingthe carbon within their biomass. The objective of the present study was to investigate thecarbon sequestration potential of different aged Swietenia macrophylla (Mahogany)established by a private tree planting company (Touchwood plantations in the Wet andIntermediate zones of Sri Lanka).

The ages ranged from 6 to 14 years and the total extent was 936.48 ha and the total numberof trees was 443,516. The available literature on the dbh and height of the trees in all theplantations were taken. In each selected age class representative trees were taken for detailedsampling for aboveground and belowground biomass measurements as well as abovegroundcomponent biomass. Using the wet:dry ratios from destructive sampling the dry weights ofall the tree components were estimated. Using the equation WC = W * 0.5 (WC =weight ofcarbon, W= weight of biomass) the carbon content lodged in the components of the biomasswas calculated. Using the equation WCO2 = WC *3.67 the carbon dioxide content in biomasswas calculated. Total litter fall was assessed by litter traps and the rate of litter decompositionwas estimated.

According to the results the total carbon sequestration potential of the 12 years agedplantations was 187.89 mt/ha followed by 11 years aged plantations (146.83 mt/ha), 10 yearsaged plantations (90.52 mt/ha), 9 years aged plantations (42.22 mt/ha), 8 years agedplantations (38.50 mt/ha), 7 years aged plantations (17.11 mt/ha), 6 years aged plantationsrecorded the lowest (9.05 mt/ha). When considering the tree component contribution towardsthe total carbon stock the highest contribution comes from the stem followed by the root,branches and the lowest from the leaves. The total ecosystem carbon sequestration includingthe contribution from litter fall and release to the atmosphere are also included in thepresentation.