Contrasting Responses of Vegetation Production to Rainfall Anomalies Across the Northeast China Transect

Abstract

AbstractIncreases in rainfall variability due to climate change influence gross primary production (GPP) in drylands, with important consequences for terrestrial carbon budget. However, it is not well understood if GPP responds in heterogeneous or even contrasting ways along the temperate bioclimate gradients. Here, based on satellite observations from 2001 to 2020, we identified rainfall anomalies as the magnitude of rainfall beyond its mean of one standard deviation, and examined differential responses of GPP to rainfall anomalies across Northeast China Transect (NECT). We found wet anomalies caused major GPP increase in western arid part of NECT, and the magnitude of increased GPP declined gradually toward the eastern humid region. As a result, GPP increased in desert steppe while decreased in mesic forest in response to wet anomalies. On the contrary, dry anomalies reduced GPP across the ecosystems except for mesic forest. The meadow steppe in the transition region between semi‐arid and sub‐humid regions, which lacks of drought‐tolerant species, showed greater GPP decline in response to dry anomalies than desert and typical steppe in the arid region. The heterogeneous responses of GPP to wet and dry anomalies resulted in contrasting asymmetries in diverse biomes, showing positive asymmetry in drier region, that is, greater magnitude of GPP increase in response to wet anomalies than GPP decrease in response to dry anomalies, and negative asymmetry in wetter region, with a transition between arid and semi‐arid regions. Our findings highlight that increased rainfall variability will enhance heterogeneous and even contrasting GPP changes along temperate bioclimate gradients.