Dry-season length affects the annual ecosystem carbon balance of a temperate semi-arid shrubland

Yanmei Mu; Xin Jia; Ziqi Ye; Tianshan Zha; Xulin Guo; T Andrew Black; Yuqing Zhang; Shaorong Hao; Cong Han; Shengjie Gao; Shugao Qin; Peng Liu; Yun Tian

doi:10.1016/j.scitotenv.2024.170532

Dry-season length affects the annual ecosystem carbon balance of a temperate semi-arid shrubland

Sci Total Environ. 2024 Mar 20:917:170532. doi: 10.1016/j.scitotenv.2024.170532. Epub 2024 Jan 29.

Authors

Yanmei Mu¹, Xin Jia², Ziqi Ye³, Tianshan Zha⁴, Xulin Guo⁵, T Andrew Black⁶, Yuqing Zhang⁴, Shaorong Hao¹, Cong Han¹, Shengjie Gao¹, Shugao Qin⁷, Peng Liu⁴, Yun Tian⁸

Affiliations

¹ Yanchi Research Station, School of Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China.
² Yanchi Research Station, School of Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China; State Key Laboratory of Efficient Production of Forest Resources, Beijing Forestry University, Beijing 100083, China; Key Laboratory for Soil and Water Conservation, National Forestry and Grassland Administration, Beijing Forestry University, Beijing 100083, China. Electronic address: xinjia@bjfu.edu.cn.
³ School of Natural Sciences, Laurentian University, Sudbury, ON P3E 2C6, Canada.
⁴ Yanchi Research Station, School of Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China; State Key Laboratory of Efficient Production of Forest Resources, Beijing Forestry University, Beijing 100083, China; Key Laboratory for Soil and Water Conservation, National Forestry and Grassland Administration, Beijing Forestry University, Beijing 100083, China.
⁵ Department of Geography and Planning, University of Saskatchewan, Saskatoon, SK S7N 5C8, Canada.
⁶ Biometeorology and Soil Physics Group, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
⁷ Yanchi Research Station, School of Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China; Key Laboratory for Soil and Water Conservation, National Forestry and Grassland Administration, Beijing Forestry University, Beijing 100083, China.
⁸ Yanchi Research Station, School of Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China; State Key Laboratory of Efficient Production of Forest Resources, Beijing Forestry University, Beijing 100083, China.

PMID: 38296104
DOI: 10.1016/j.scitotenv.2024.170532

Abstract

Semi-arid ecosystems have been shown to dominate over tropical forests in determining the trend and interannual variability of land carbon (C) sink. However, the magnitude and variability of ecosystem C balance remain largely uncertain for temperate semi-arid shrublands at the decadal scale. Using eddy-covariance and micro-meteorological measurements, we quantified the interannual variation in net ecosystem production (NEP) and its components, gross primary production (GPP) and ecosystem respiration (Reco, i.e., the sum of autotrophic and heterotrophic respiration), in a semi-arid shrubland of the Mu Us Desert, northern China during 2012-2022. This shrubland was an overall weak C sink over the 11 years (NEP = 12 ± 46 g C m^-2 yr^-1, mean ± SD). Annual NEP ranged from -66 to 77 g C m^-2 yr^-1, with the ecosystem frequently switching between being an annual C sink and a C source. GPP was twice as sensitive as Reco to prolonged dry seasons, leading to a close negative relationship between annual NEP and dry-season length (R² = 0.80, P < 0.01). Annual GPP (R² = 0.51, P = 0.01) and NEP (R² = 0.58, P < 0.01) were positively correlated with annual rainfall. Negative annual NEP (the ecosystem being a C source) tended to occur when the dry season exceeded 50 d yr^-1 or rainfall dropped below 280 mm yr^-1. Increases in dry-season length strengthened the effects of low soil moisture relative to high vapor pressure deficit in constraining NEP. Both GPP and NEP were more closely correlated with C uptake amplitude (annual maximum daily values) than with C uptake period. These findings indicate that dry-season extension under climate change may reduce the long-term C sequestration in semi-arid shrublands. Plant species adapted to prolonged dry seasons should be used in ecosystem restoration in the studied area to enhance ecosystem functions.

Keywords: Ecosystem respiration; Eddy-covariance; Gross primary production; Interannual variation; Net ecosystem production.