Assessing the response of seasonal variation of NPP to climate using remote sensing data and GIS techniques in Xinjiang

Net primary productivity (NPP) is a key component of energy and matter transformation in the terrestrial ecosystem, and the responses of NPP to global change locally and regionally have been one of the most important aspects in climate–vegetation relationship studies. In order to isolate causal climatic factors, it is great meaningful to assess the response of seasonal variation of NPP to climate. In this paper, NPP in Xinjiang were estimated by NOAA/AVHRR NDVI data and GIS techniques. The impact of climatic factors (air temperature, precipitation and sunshine percentage) on seasonal variations of NPP was studied by time lag and serial correlation ageing analysis. The results showed that the NPP for different land cover types have a similar correlation with any one of the three climatic factors, and precipitation is the major climatic factor influencing the seasonal variation of NPP in Xinjiang. It was found that the positive correlation at 0-lag appeared between NPP and precipitation and the serial correlation ageing was 0 days in most areas of Xinjiang, which indicated that the response of NPP to precipitation was immediate. However, NPP of different land cover types showed significant positive correlation at 2-month lag Supported by the following projects: Preliminary study of NPP and its variation in Xinjiang (QSR2003010006); Climate Change Special Project of China Meteorological Administration (CCSF2006-37) ∗ Author for correspondence: Tel: +86(0)571 8697 1830; E-mail: [email protected]. with air temperature, and the impact of which could persist 1 month as a whole. No correlation was found between NPP and sunshine percentage.