Modelling the spatial distribution of aboveground biomass based on vegetation index in a tropical forest in Bawangling, Hainan Island, South China.

Abstract

Aims The biomass of tropical forests plays an important role in the global carbon cycle; however,the distribution of tropical forest biomass based on vegetation index is seldom explored. Our objectives were to evaluate relationships between biomass and vegetation indices and to determine the spatial distribution of the aboveground biomass of tropical forest in Bawangling,Hainan Island,South China. Methods Using measurements of forest biomass from 135 sample plots distributed over the study area,we correlated four vegetation indices (normalized difference vegetation index (NDVI),moisture vegetation index using Landsat's 5 (MVI5),moisture vegetation index using Landsat's band 7 (MVI7) and ratio vegetation index (RVI)) with aboveground biomass (total biomass,climax species biomass and pioneer species biomass) using the Pearson correlation method. We also developed models describing the relationships between forest aboveground biomass and vegetation indices using stepwise linear regression analysis. Three maps of biomass components were produced using the developed models,and residual maps were used to test the validity of the models. Important findings MVI7 and MVI5 are most effective for total biomass and climax species biomass,whereas NDVI and RVI seem to be good indices of pioneer species biomass. The strongly predictive percent areas for total species,climax species and pioneer species biomass models were 69.24,73.98 and 88.08,respectively. Simulated biomasses of total species and climax species were distributed in the center,north and southwest parts of the study area; however,simulated biomass of pioneer species was scattered.