Grassland productivity in arid Central Asia depends on the greening rate rather than the growing season length

Jianhao Li; Wanqiang Han; Jianghua Zheng; Xiaojing Yu; Ruikang Tian; Liang Liu; Jingyun Guan

doi:10.1016/j.scitotenv.2024.173155

Grassland productivity in arid Central Asia depends on the greening rate rather than the growing season length

Sci Total Environ. 2024 May 11:933:173155. doi: 10.1016/j.scitotenv.2024.173155. Online ahead of print.

Authors

Jianhao Li¹, Wanqiang Han¹, Jianghua Zheng², Xiaojing Yu¹, Ruikang Tian¹, Liang Liu¹, Jingyun Guan³

Affiliations

¹ College of Geography and Remote Sensing Sciences, Xinjiang University, Urumqi 830046, China.
² College of Geography and Remote Sensing Sciences, Xinjiang University, Urumqi 830046, China; Xinjiang Key Laboratory of Oasis Ecology, Xinjiang University, Urumqi 830046, China. Electronic address: zheng.jianghua@xju.edu.cn.
³ College of Tourism, Xinjiang University of Finance & Economics, Urumqi 830012, China.

PMID: 38735323
DOI: 10.1016/j.scitotenv.2024.173155

Abstract

Climate change has induced substantial impact on the gross primary productivity (GPP) of terrestrial ecosystems by affecting vegetation phenology. Nevertheless, it remains unclear which among the mean rates of grass greening (RG), yellowing (RY), and the length of growing season (LOS) exhibit stronger explanatory power for GPP variations, and how RG and RY affect GPP variations under warming scenarios. Here, we explored the relationship between RG, RY, LOS, and GPP in arid Central Asia (ACA) from 1982 to 2019, elucidating the response mechanisms of RG, RY, and GPP to the mean temperature (TMP), vapor pressure deficit (VPD), precipitation (PRE), and soil moisture (SM). The results showed that the multi-year average length of greening (LG) in ACA was 22.7 days shorter than that of yellowing (LY) and the multi-year average GPP during LG (GPP_lg) was 38.28 g C m^-2 d ^-1 more than that of during LY (GPP_ly). RG and RY were positively correlated with GPP_lg and GPP_ly, although the degree of correlation between RG and GPP_lg was higher than that between RY and GPP_ly. Increases in RG and RY contributed to an increase in GPP_lg (55.44 % of annual GPP) and GPP_ly (35.44 % of annual GPP). The correlation between RG and GPP_lg was the strongest (0.49), followed by RY and GPP_ly (0.33), and LOS and GPP was the weakest (0.21). TMP, VPD, PRE, and SM primarily affected GPP by influencing RG and RY, rather than direct effects. The positive effects of TMP during LG (TMP_lg), PRE during LG (PRE_lg), and SM during LG (SM_lg) facilitated increases in RG and GPP_lg, and higher VPD during LY (VPD_ly) and lower PRE during LY (PRE_ly) accelerated increases in RY. Our study elucidated the impact of vegetation growth rate on GPP, thus providing an alternate method of quantifying the relationship between vegetation phenology and GPP.

Keywords: Arid Central Asia; Grassland phenology; Greening rate; Gross primary productivity; Length of growing season.