Soil moisture dominates the variation of gross primary productivity during hot drought in drylands

Ruonan Qiu; Ge Han; Siwei Li; Feng Tian; Xin Ma; Wei Gong

doi:10.1016/j.scitotenv.2023.165686

Soil moisture dominates the variation of gross primary productivity during hot drought in drylands

Sci Total Environ. 2023 Nov 15:899:165686. doi: 10.1016/j.scitotenv.2023.165686. Epub 2023 Jul 21.

Authors

Ruonan Qiu¹, Ge Han², Siwei Li³, Feng Tian¹, Xin Ma⁴, Wei Gong⁵

Affiliations

¹ School of Remote Sensing and Information Engineering, Wuhan University, Wuhan 430079, China.
² School of Remote Sensing and Information Engineering, Wuhan University, Wuhan 430079, China; Perception and Effectiveness Assessment for Carbon-neutral Efforts, Engineering Research Center of Ministry of Education, Wuhan, China. Electronic address: udhan@whu.edu.cn.
³ School of Remote Sensing and Information Engineering, Wuhan University, Wuhan 430079, China. Electronic address: siwei.li@whu.edu.cn.
⁴ State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan, China.
⁵ Electronic Information School, Wuhan University, Wuhan 430079, China; Hubei Luojia Laboratory, Wuhan, China.

PMID: 37482354
DOI: 10.1016/j.scitotenv.2023.165686

Abstract

The frequency and severity of hot drought will increase in the future due to impact of climate change and human activities, threatening the sustainability of terrestrial ecosystems and human societies. Hot drought is a typical type of drought event, high vapor pressure deficit (VPD) and low soil moisture (SM) are its main characteristics of hot drought, with increasing water stress on vegetation and exacerbating hydrological drought and ecosystem risks. However, our understanding of the effects of high VPD and low SM on vegetation productivity is limited, because these two variables are strongly coupled and influenced by other climatic drivers. The southwestern United States experienced one of the most severe hot drought events on record in 2020. In this study, we used SM and gross primary productivity (GPP) datasets from Soil Moisture Active and Passive (SMAP), as well as VPD and other meteorological datasets from gridMET. We decoupled the effects of different meteorological factors on GPP at monthly and daily scales using partial correlation analysis, partial least squares regression, and binning methods. We found that SM anomalies contribute more to GPP anomalies than VPD anomalies at monthly and daily scales. Especially at the daily scale, as the decoupled SM anomalies increased, the GPP anomalies increased. However, there is no significant change in GPP anomalies as VPD increases. For all the vegetation types and arid zones, SM dominated the variation in GPP, followed by VPD or maximum temperature. At the flux tower scale, decoupled soil water content (SWC) also dominated changes in GPP, compared to VPD. In the next century, hot drought will occur frequently in dryland regions, where GPP is one of the highest uncertainties in terrestrial ecosystems. Our study has important implications for identifying the strong coupling of meteorological factors and their impact on vegetation under climate change.

Keywords: Decouple; Gross primary production; Hot drought; SMAP; Soil moisture; Vapor pressure deficit.