Abstract:
Future carbon storage in tropical forests will be influenced strongly by
species composition. Huge knowledge gap has arisen on how floristic
richness correlates or contributes to soil carbon storage. This study examines
correlations among floristic parameters, soil carbon and relevant
environmental variables. We collected soil data (carbon fractions, total C,
total N, soil pH, and fine root biomass) from at the Sigiriya forest sanctuary,
and Popham Arboretum in the dry zone and Udawattakelle forest sanctuary
in the wet zone. The data were pooled and biomass/carbon stocks (e.g.
above-ground biomass stock, above-stock, and below-ground C stocks) were calculated using standard equations.
The correlation analysis between biomass/C stock and soil parameters was
performed using principle factor analysis (PFA) and multiple regression of
SAS version 6.12. PFA resulted in five clusters. One cluster was formed by
soil C, soil N, and Mackintosh Distance (U) with high correlation (R2 = 082).
Multiple regression model showed that there is a positive relationship
between the biomass stocks and species richness, while Mackintosh evenness
has a negative relationship with total carbon of the soils. Basal area of the
forests was recognized as a neutral parameter, because it acts as both
positively and negatively. These results indicated that the above
floristic composition parameters acted as determinants of total soil carbon
stock. Thus, changing floristic composition to maximize storage of soil
carbon will provide opportunity to enhance soil carbon sequestration.
