Spatial-temporal change in vegetation Net Primary Productivity and its response to climate and human activities in Qinghai Plateau in the past 16 years
Based on MOD13Q1-250-m resolution- 16-day synthesis NDVI data for the Qinghai Plateau from 2000 to 2015, by using the improved CASA model, we estimated the vegetation net primary productivity (NPP) of the Qinghai Plateau, analyzed the characteristics and regularities of NPP spatial-temporal variation, evaluated the correlation between NPP and meteorological factors, and explored the ecological effect of ecological protection project in different regions. The results indicate the following:① The average annual NPP in the Qinghai Plateau is 242.50 g C m~(-2) a~(-1),which is high in the east and south and increases from northwest to southeast.② During 2000-2015, the annual amount of NPP increased stably from 53.24 to 96.56 Tg C, with an annual growth rate of 1.32 Tg C/a.③ The warm and humid climate is the main factor affecting the increase in vegetation NPP,and precipitation and temperature are significant factors in the inter-annual fluctuation of NPP in the Qinghai Plateau. Additionally, in different areas, the factors controlling NPP growth differed.④The implementation of different ecological protection projects has a varying influence on spatial-temporal patterns and inter-annual trends in regional NPP. Among them, the annual increasing trend in NPP in the Sanjiangyuan region was the most obvious, followed by the Qinghai Lake area, Eastern region, and Qaidam region.