Increasing precipitation during first half of growing season enhances ecosystem water use efficiency in a semiarid grassland

Jiayang Zhang; Zhongling Yang; Daiyu Qiao; Lei Su

doi:10.3389/fpls.2023.1119101

Increasing precipitation during first half of growing season enhances ecosystem water use efficiency in a semiarid grassland

Front Plant Sci. 2023 Feb 2:14:1119101. doi: 10.3389/fpls.2023.1119101. eCollection 2023.

Authors

Jiayang Zhang^{1

2}, Zhongling Yang¹, Daiyu Qiao¹, Lei Su¹

Affiliations

¹ International Joint Research Laboratory for Global Change Ecology, Laboratory of Biodiversity Conservation and Ecological Restoration, School of Life Sciences, Henan University, Kaifeng, Henan, China.
² School of Life Sciences & Basic Medicine, Xinxiang University, Xinxiang, China.

Abstract

Precipitation amount and seasonality can profoundly impact ecosystem carbon (C) and water fluxes. Water use efficiency (WUE), which measures the amount of C assimilation relative to the amount of water loss, is an important metric linking ecosystem C and water cycles. However, how increasing precipitation at different points in the growing season affects ecosystem WUE remains unclear. A manipulative experiment simulating increasing first half (FP+) and/or second half (SP+) of growing-season precipitation was conducted for 4 years (2015-2018) in a temperate steppe in the Mongolian Plateau. Gross ecosystem productivity (GEP) and evapotranspiration (ET) were measured to figure out ecosystem WUE (WUE = GEP/ET). Across the four years, FP+ showed no considerable impact on ecosystem WUE or its two components, GEP and ET, whereas SP+ stimulated GEP but showed little impact on ET, causing a positive response of WUE to FP+. The increased WUE was mainly due to higher soil water content that maintained high aboveground plant growth and community cover while ET was stable during the second half of growing season. These results illustrate that second half of growing-season precipitation is more important in regulating ecosystem productivity in semiarid grasslands and highlight how precipitation seasonality affects ecosystem productivity in the temperate steppe ecosystem.

Keywords: evapotranspiration; gross ecosystem productivity; precipitation amount; precipitation seasonality; water use efficiency.

Grants and funding

The field equipment installation and data collection were completed with support from the National Natural Science Foundation of China (Nos. 41807158 and 31570429) and major public welfare projects in Henan Province (No. 201300311300).