Net primary productivity (NPP) of oasis changes in trends in Xinjiang and responses to climate change analysis in 1981-2000

Using the Xinjiang NPP data simulated by GLOPEM from 1981 to 2000, combining with the corresponding meteorological data, vegetation data and LUCC, the space-time changes of NPP and climate factors in 1981-2000 were analyzed. The correlation between climate factors and NPP was also analyzed. Finally, the responses of the NPP changes to climate changes were studied. The results showed that, (1) in the period of 1981 to 2000, the year-average NPP increased remarkably and the temperature and the precipitation also increased. NPP increased in spring, summer and autumn, but there was space-time variance between inter-annual changes of NPP and the changes of climate factors. (2) Inter-annual changes of NPP and precipitation and temperature were positively correlated, the growth of NPP is less than that of temperature and precipitation. The year that NPP peaked was not correspondent with the year that the temperature and precipitation peaked, yet the growth rate of NPP lag behind of that of temperature and precipitation slightly. There were also differences of NPP changes tendency among different vegetations. (3) From the view of vegetation types, during 1990s, the correlation coefficients between NPP and climatic factors increased more or less than 1980s. Moreover, the coefficients of the higher vegetation cover types were generally greater than that of the lower vegetation cover types.