Abstract
Clarifying spatial variations in aboveground net primary productivity (ANPP) and precipitation-use efficiency (PUE) of grasslands is critical for effective prediction of the response of terrestrial ecosystem carbon and water cycle to future climate change. Though the combination use of remote sensing products and in situ ANPP measurements, we quantified the effects of climatic [mean annual precipitation (MAP) and precipitation seasonal distribution (PSD)], biotic [leaf area index (LAI)] and abiotic [slope gradient, aspect, soil water storage (SWS) and other soil physical properties] factors on the spatial variations in ANPP and PUE across different grassland types (i.e., meadow steppe, typical steppe and desert steppe) in the Loess Plateau. Based on the study, ANPP increased exponentially with MAP for the entire temperate grassland; suggesting that PUE increased with increasing MAP. Also PSD had a significant effect on ANPP and PUE; where more even PSD favored higher ANPP and PUE. Then MAP, more than PSD, explained spatial variations in typical steppe and desert steppe. However, PSD was the dominant driving factor of spatial variations in ANPP of meadow steppe. This suggested that in terms of spatial variations in ANPP of meadow steppe, change in PSD due to climate change was more important than that in total annual precipitation. LAI explained 78% of spatial PUE in the entire Loess Plateau temperate grassland. As such, LAI was the primary driving factor of spatial variations in PUE. Although the effect of SWS on ANPP and PUE was significant, it was nonetheless less than that of precipitation and vegetation. We therefore concluded that changes in vegetation structure and consequently in LAI and/or altered pattern of seasonal distribution of rainfall due to global climate change could significantly influence ecosystem carbon and water cycle in temperate grasslands.
Highlights
Precipitation is the key factor in controlling primary production of most of the world’s grassland ecosystems, especially in arid and semiarid regions [1,2,3]
Contrary to mean annual precipitation (MAP), precipitation-use efficiency (PUE) decreased with increasing coefficient of variation of the monthly precipitation (CVmp)
We noted exponential correlation between MAP and Aboveground net primary productivity (ANPP) for the Loess Plateau temperate grassland, suggested that PUE increased with increasing MAP
Summary
Precipitation is the key factor in controlling primary production of most of the world’s grassland ecosystems, especially in arid and semiarid regions [1,2,3]. Aboveground net primary productivity (ANPP), a key integrative measure of ecosystem function, is reported to be greatly affected by changes in mean annual precipitation (MAP) and/or precipitation seasonal distribution (PSD) [6,7,8,9,10,11]. Some studies have reported simple linear relation between MAP and ANPP [12,13,14,15] and others have noted exponential relation [10,16,17] for the same temperate grasslands in China
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