Carbon stocks in selected dry and wet zone forests of Sri Lanka

Abstract

Understanding forest C sequestration of the tropical region is of paramount importance to reduce atmospheric CO2. Present study investigated C stocks of two selected wet (Udawattakele – Kandy) and dry zone (Sigiriya sanctuary) forests of Sri Lanka. Litter and soil samples were collected randomly in monthly intervals to cover an annual cycle. Plant biomass C stocks were calculated from standard biomass equations. Soil C was determined by chemical oxidation and loss on ignition (LOI) methods. Above ground biomass increment (AGBI) was predicted by a developed model.

The wet zone forest contained higher plant biomass C (249 t C/ha), annual biomass increment (4.85 t C/ha/yr), soil C stock (108 t C/ha) and litter fall C stock (5.73 t C/ha) than those of the dry zone forest of which the corresponding values were 77.0 t C/ha, 4.72 t C/ha, 93.6 t C/ha and 4.72 t C/ha, respectively. Higher amounts of fine root and floor litter C stocks (2.7 t C/ha and 2.36 t C/ha, respectively) were present in the dry zone forest than the wet zone forest (2.4 t C/ha and 2.01 t C/ha, respectively).

Total ecosystem C stock (361 t/ha) was higher in the wet zone forest than the dry zone forest (176 t/ha). In the dry zone forest, ca. 53% of the total C stock was in the soil, and ca. 44% was in the plant biomass, and corresponding values of the wet zone forest were 30% and 69%, respectively. Although these proportions were different, higher C stocks in the soil as well as plant biomass were stored in the wet zone forest contributing more towards C sequestration.