Correlation analysis between the biomass of oasis ecosystem and the vegetation index at Fukang

The information of biomass and productivity of an ecosystem is an essential to evaluate the ecosystem and its environment. This sort of data is usually retrieved from satellite data. However, the accuracy of the retrieval and the algorithms for the retrieval vary with the environment and the type of the ecosystem. In this study, the relationship between the biomass of oasis ecosystems at Fukang, Xinjiang, China and the normalized vegetation index (NDVI) was established in order to derive biomass data of the ecosystem from satellite data. The NDVI data were from the MODIS data with a resolution of 250 meters. Biomass measurements were taken in August, 2003 at 53 sampling sites. Linear and nonlinear regression analyses were performed on this data set. In general, the nonlinear models perform better than the linear models although all of them can successfully generate biomass data with the input of NDVI. Among those nonlinear models, the model Y = -593.3NDVI³+ 7509.7NDVI² - 1268.9NDVI + 191 performs the best in terms of the retrieval accuracy, where Y represents the biomass.