Spatiotemporal variations and its influencing factors of grassland net primary productivity in Inner Mongolia, China during the period 2000–2014

Abstract

The quantification of changes in long-term trends in grassland net primary productivity (NPP) and its large-scale driving forces are important for understanding terrestrial ecosystem changes in arid and semi-arid regions. Based on the MODIS-NPP dataset, this study investigated patterns in the spatiotemporal variations in NPP and its possible influencing factors in Inner Mongolia during 2000–2014 using the linear trend analysis method, correlation analysis, and an F test. The results show that grassland NPP had an annual rate of increase of 4.53 g C/(m2·a) with a significant increasing trend (p < 0.01). Spatial analysis results indicate that the average grassland NPP presented a gradual increasing trend from southwest to northeast, with an area of longitudinal zonality being identified. Grassland NPP presented a significant increase (p < 0.05) in more than 31.93% of the region. Grassland NPP and growing season precipitation (GSP) had a significant negative correlation in 54.78% of the study area. Grassland NPP and the growing season average land surface temperature (GSALST) had a significant negative correlation for 65.93% of the study area; growing season average temperature (GSAT) had no significant effect on the grassland NPP. For different grassland types, GSP had the greatest impact on alpine meadows (r = 0.73), and GSALST had the greatest impact on alpine steppes and alpine meadows (r = −0.81). Related ecological restoration projects such as fenced rangeland and planted grass played a positive impact on annual NPP in the study area.