Dynamics of solar-induced chlorophyll fluorescence (SIF) and its response to meteorological drought in the Yellow River Basin

Hao Wu; Pingping Zhou; Xiaoyan Song; Wenyi Sun; Yi Li; Songbai Song; Yongqiang Zhang

doi:10.1016/j.jenvman.2024.121023

Dynamics of solar-induced chlorophyll fluorescence (SIF) and its response to meteorological drought in the Yellow River Basin

J Environ Manage. 2024 May 10:360:121023. doi: 10.1016/j.jenvman.2024.121023. Online ahead of print.

Authors

Hao Wu¹, Pingping Zhou¹, Xiaoyan Song², Wenyi Sun³, Yi Li¹, Songbai Song¹, Yongqiang Zhang⁴

Affiliations

¹ Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas, Ministry of Education, Northwest A & F University, Yangling, 712100, Shaanxi, China.
² Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas, Ministry of Education, Northwest A & F University, Yangling, 712100, Shaanxi, China. Electronic address: xiaoyansong@nwsuaf.edu.cn.
³ Institute of Soil and Water Conservation, Northwest A&F University, Yangling 712100, Shaanxi, China.
⁴ Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China.

PMID: 38733837
DOI: 10.1016/j.jenvman.2024.121023

Abstract

Solar-induced chlorophyll fluorescence (SIF) has been used since its discovery to characterize vegetation photosynthesis and is an effective tool for monitoring vegetation dynamics. Its response to meteorological drought enhances our comprehension of the ecological consequences and adaptive mechanisms of plants facing water scarcity, informing more efficient resource management and efforts in mitigating climate change. This study investigates the spatial and temporal patterns of SIF and examines how vegetation SIF in the Yellow River Basin (YRB) responds to meteorological drought. The findings reveal a gradual southeast-to-northwest decline in SIF across the Yellow River Basin, with an overall increase-from 0.1083 W m^-2μm^-1sr^-1 in 2001 to 0.1468 W m^-2μm^-1sr^-1 in 2019. Approximately 96% of the YRB manifests an upward SIF trend, with 75% of these areas reaching statistical significance. The Standardized Precipitation Evapotranspiration Index (SPEI) at a time scale of 4 months (The SPEI-4), based on the Liang-Kleeman information flow method, is identified as the most suitable drought index, adeptly characterizing the causal relationship influencing SIF variations. As drought intensified, the SPEI-4 index markedly deviated from the baseline, resulting in a decrease in SIF values to their lowest value; subsequently, as drought lessened, it gravitated towards the baseline, and SIF values began to gradually increase, eventually recovering to near their annual maximum. The key finding is that the variability of SIF with SPEI is relatively pronounced in the early growing season, with forests demonstrating superior resilience compared to grasslands and croplands. The responsiveness of vegetation SIF to SPEI can facilitate the establishment of effective drought early warning systems and promote the rational planning of water resources, thereby mitigating the impacts of climate change.

Keywords: Causal link; Cumulative effect; Meteorological drought; Vegetation dynamics.