ASSESSING THE IMPACT OF URBANIZATION ON REGIONAL GROSS PRIMARY PRODUCTIVITY IN WUHAN URBAN AGGLOMERATION ENVIRONMENT. CHINA

摘要

The process of urbanization has rapidly changed the land use pattern and occupied a large amount of cropland and forest. Its influence on the global ecological environment is a hot topic of geog- raphy research. Studying the influence of urbaniza-tion process on regional gross primary productivity is essential to understand the carbon cycle of re- gional terrestrial ecosystem. At present, the centraregion of China is the fastest growing region in the process of urbanization in China. In this study, tak- ing Wuhan Urban Agglomeration as the research area, we aim to estimate the impact of urbanization on the variation of gross primary productivity (GPP) analyze land use change combined with the MODIS GPP/NPP data products to study the change of GPP in 2004-2016 by using Landsat TM and OLI image data to obtain land use information. The land use analysis shows that the urban sprawl is the most striking land use change, embodied by the conver- sion of cropland to urban, the conversion and supple- ment of cropland from forest, and the conversion of small part of the forest land into urban directly. Dur- ing 2004-2006, the mean of annual GPP of WuhanUrban Agglomeration decreased from 1129.23 gCm 2yearl to 981.98 gCm2year', and the total GPP de-creased by 7969.89 GgC, corresponding to a reduc- tion of 12911.22 GgC in the absorption of CO2 within a year. Among them, the existing cropland in 2004 accounts for 69.46% of the total decline, and the forest land accounts for 12.9%. The main reason for the decline of GPP in the whole region lies in the occupation of cropland by the urban land and the conversion of forest land into cropland. The migra- tion of non-urban population to urban areas has con- tributed to this decline.