Drivers of changes in ecosystem service values in Ganjiang upstream watershed

Land use change and land-cover can influence ecological functions and ecosystem services. Based on Xie's coefficient of ecosystem service value, land use change in Ganjing upstream watershed from the year 1990 to 2010 and the ecosystem service value caused by the land use change were quantitatively analyzed. Based on the statistical data and relevant research results, a gray correlation degree analysis was done between ecosystem services value (ESV) and its seven potential impact factors, i.e. Grain for Green program, population, gross domestic product (GDP), urbanization level, investment in fixed assets, the proportion of secondary industry and tertiary industry proportion. The boosted regression tree method was used to identify the driving factors for the changes of ESV during 1990-2010, 1990-1995, 1995-2000, 2000-2005 and 2005-2010 periods. The results showed that: (1) all seven indexes can affect the changes of ESV in Ganjiang upstream watershed during the study periods, (2) during 1990-2010 and from 2000 to 2005, the Grain for Green program is the most important factor influencing the ESV. The proportions of tertiary industry and GDP are the main factors influencing the ESV, whereas from 2000 to 2005 the main influential factor is GDP.