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

Abstract

Increases 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.

Asymmetric response of gross primary productivity to precipitation changes over China’s karst areas

“…Similarly, relatively drier conditions will promote an increase in GPP over Southwest China (e.g., Chongqing and Sichuan provinces, characterized by a negative precipitation asymmetry), showing positive GPP asymmetry. Similar results could be found in the humid regions of Northeast China Transect (Zhao et al, 2022).…”

“…Our results showed that the grasslands represent the highest positive AI, indicating that the grassland areas dominate the positive asymmetry over China’s karst areas during the 2003 to 2018 period. These findings support the positive asymmetry observed in grasslands of China, using satellite observations (Chang et al, 2023; John et al, 2013; Zhao et al, 2022), as well as long-term multiple grassland sites (Bai et al, 2008; Yang et al, 2008). Grasslands have high growth potential without under water stress (Al-Yaari et al, 2020; Chang et al, 2023), leading to a disproportionate GPP increase during the wet years.…”

“…However, the opposite spatial pattern was found in parts of Southwest China's karst areas, namely, a positive precipitation asymmetry and a negative GPP asymmetry could be found in these regions. This is because the Southwest China karst areas are humid regions (Dong et al, 2023), vegetation in these regions is usually more limited by solar radiation and growing season temperature than by precipitation (Zhao et al, 2022). During the wet years, the lower solar radiation and growing season temperature linked to the prolonged rainy season can constrain the vegetation photosynthesis and productivity over the humid regions (Walther et al, 2019).…”

Earlier Precipitation Enhances Dryland Annual Primary Production

“…Most temperate steppes distributed in drier region than alpine steppes and rainfed croplands. Sensitivities of LUE to soil water availability were stronger in drier region than that in more humid region, and the same for NDVI (Walther et al., 2019; Zhao et al., 2022), which determined APAR. In addition, advanced precipitation promotes production through increased growth of annual plant species in temperate steppe, and therefore enhancing annual production (Guo et al., 2012; Zhang et al., 2004).…”

The strengthened impact of water availability at interannual and decadal time scales on vegetation GPP

“…The relationship between WA and GPP has been a focal point in numerous studies. These studies have consistently highlighted a positive correlation between WA and GPP in arid regions while noting a negative or weak correlation in humid regions (Al-Yaari et al, 2020;Zhao et al, 2022). However, many of these studies have been confined to examining this relationship at a single scale, overlooking potentially valuable insights offered by other temporal dimensions (Chen et al, 2021;Chen, Wilson, et al, 2019;Du et al, 2015;Vicente-Serrano et al, 2013).…”