Correlation analysis between Enhance Vegetation Index and Wood Volume in Thua Thien Hue Province, Vietnam

Abstract

REDD+in developing countries needs to estimate forest carbon stocks and above ground biomass. Remote sensing has been widely used for monitoring of vegetated area using the satellite-derived vegetation index since vegetation indices are thought to have high correlation with above ground biomass or vigor of vegetation. However, these satellite-derived vegetation indices are still doubtful whether they are available for REDD+in any types of forests such as forests with different species. We studied the relationship between wood volume data obtained by field survey and the time series of MODIS EVI data to check whether the above ground biomass in different forests with different species could be accurately estimated from satellite remotely sensed data. This paper presents the different correlation for different forests. Our analysis illustrated the correlation between annual wood volume and annual average EVI using a simple linear regression. The regression equation for Forest 1 was Y＝249.02x+37.474; R²＝0.82; N＝22 and for Forest 2 was Y＝668.3x-258.61; R²＝0.80; N＝15, and R²＝0.0285; N＝15 for forest 3 which mixed more than 7 species, respectively. These different correlations are strongly correlated with composition of species in different forests. The forests with a few tree species had high correlations, while the forest mixed with many species of trees had low correlation. The composition of tree species in forests is an important characteristic for estimating above ground biomass of forests using remote sensing data.