Measuring the climate change mitigation potential of forests and TOF (tree outside forest) systems in Thrissur

Abstract

Inventorying of terrestrial carbon stock is important in understanding the role of forests and tree resources in the mitigation of climate change and its consequences. For this purpose, a total of 40 sample plots of 0.1ha area were inventoried. The sample plots included 4 plots within evergreen forests, 10 plots in moist deciduous forests and 26 plots in TOF (Trees Outside Forests) systems of Thrissur district in Kerala, Southern India. Five carbon pools, namely, above ground biomass, below ground biomass, deadwood, leaf litter and soil organic carbon were estimated. Chave’s generalised allometric model was used to estimate the above ground biomass. Below ground biomass component and deadwood carbon was calculated using IPCC default values. Litter carbon in forest systems were measured using gravimetric method while in TOF systems litter carbon was appropriated using UNFCCC guidelines. Soil organic carbon in every soil samples was measured using the Walkley black wet digestion method. A land use land cover map of Thrissur district for the same land use classes was also prepared using spectral signatures obtained from the GPS coordinates during field work. From the study, the mean carbon stock of evergreen forests, moist deciduous forests and TOF systems calculated were 623.68, 306.71, 150.15 tons/ha respectively. Above ground biomass was the major contributor in every land use type except in the case of plantations in TOF systems where soil organic carbon was the major contributor. The other major contributor included soil organic carbon, followed by below ground biomass while dead wood and litter carbon formed the least. The mitigation potential of forests and TOF systems in Thrissur district was calculated to be 19.22 million tons of CO2. The major contributor was the TOF systems which shows the immense potential of Kerala in mitigating the change in climate with its large population of trees outside forests.