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EAFES Special Symposium EX02-3

Temporal Variability of Aboveground Net Primary Productivity of Temperate Steppe Along a Precipitation Gradient in North China

GUO Qun (CAS) et al

Most of analyses on precipitation-aboveground net primary productivity (ANPP) relationship focused on the spatial variations of ANPP in the past, however, little was known about the temporal variations in ANPP along precipitation gradient. In this study, we used ANPP and rainfall data from remote sensing and field survey 1) to describe the temporal variations of ANPP across temperate grassland in Inner Mongolia, China; and 2) to address how sensitivity of ANPP to both annual precipitation (AP) and precipitation seasonal distribution (PSD) changed along the precipitation gradient (sensitivity defined as the slope of ANPP and precipitation). Our results demonstrated that the temporal variability of ANPP was lower at both the dry and wet end, and peaked at a precipitation of ca.200mm. The sensitivity of ANPP to AP was increased exponentially with increasing rainfall for the total temperate grassland, but few site of meadow steppe was shown to be significant. PSD at only 6% sample sites were significantly correlated with ANPP. Among the sites of statistical significance, there was a threshold at a precipitation of ca.300mm, before which ANPP was positively related to PSD, but opposite pattern was found in the rest portion. Our results implied that greatest ANPP temporal variations occur at moderate precipitation. AP is likely to account for more ANPP temporal variations than PSD.