China's southeast coastal areas have undergone rapid expansion over the past few decades due to increasing population and economic growth. Although there are many studies focusing on the urban growth in this part of China, there is very little work that examines the carbon consequences of such growth. This research is concerned with the gross primary production change associated with urbanization process.In this study, MODIS Gross Primary Productivity (GPP) product, along with population, built-up area, and GDP data for 16 regions in the Yangtze River Delta were used to establish an empirical model which examined and quantified the relationship of urbanization and GPP change from 2003 to 2008. Also, Landsat remote sensing data calibrated with biophysical parameters were used to assess GPP using the light use efficiency (LUE) method for the Hangzhou city from 2001 to 2010. Additionally, the method of using vegetation phenology curves and climate indicators to forecast or backcast EVI was assessed. The empirical model results indicate that there is a significant positive association of a one-percent increase in built-up area ratio and a 15.4-percent decrease in annual total GPP for the Yangtze River Delta and capitals have a higher GPP given other things being equal. The primary cause of decreasing GPP is urban expansion, which encroached on large areas of surrounding cropland. Moreover, the estimation of GPP using phenology curves contains great uncertainty. The factors that strongly affect vegetation growth should be identified for a better estimation.
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