Aboveground tree carbon stocks of Lowland evergreen mixed vegetation at Gannoruwa

Abstract

Conservation of global forests is being considered as one of the sustainable ways of mitigating global warming, because forests are widely perceived to act as major sinks for atmospheric carbon. Estimation of carbon stocks of tropical forests are important for management, planning and for REDD initiatives.Therefore, this study was initiated to estimate existing carbon stocks of a Lowland evergreen mixed forest at Gannoruwa and how it has changed overtime.

The sampling points were selected using an unsupervised classified Landsat TM satellite image and topograhpic maps, considering the elevation level and the vegetation type. A GPS (Global Position System) was used to detect the correct location of sampling points and sampling plot size was set as 30m×30m. The dbh and height of each individual in the sampling plot which is greater than 5cm dbh was measured.

The dbh and height values were applied to a pre-derived regression equation and the above ground biomass was calculated. The equation was Y=exp {-3.3012+0.9439 ln(D2H)},(r2=0.9) where, Y is aboveground biomass, D is dbh and H is height. Assuming the carbon stock as 50% of the biomass, the above ground carbon stock was calculated. It was 146.4 mt/ha of carbon and the total aboveground tree carbon stock was 39.1×103 tons. The estimated basal area of the forest has declined compared to 25 year old recorded data and it reflects the carbon reduction of the forest due to anthropogenic activities.