The ratio of transpiration to evapotranspiration dominates ecosystem water use efficiency response to drought

IF 5.6 1区农林科学 Q1 AGRONOMY

Agricultural and Forest Meteorology Pub Date : 2025-01-30 DOI:10.1016/j.agrformet.2025.110423

Shanshan Yang, Jiahua Zhang, Jiaqi Han, Yun Bai, Lan Xun, Sha Zhang, Dan Cao, Jingwen Wang

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引用次数: 0

Abstract

Water use efficiency (WUE) is an important metric for quantifying the trade-off between ecosystem photosynthesis and transpiration, which can reflect how ecosystems respond to extreme climate events (e.g., drought). However, due to the different definitions of WUE indices and the complexity of drought with different dimensions, the responses of ecosystem WUE to drought still remain debated. Here, we use global flux observations to comprehensively examine whether different WUE indices (i.e., WUE_T=GPP/T, WUE_ET=GPP/ET, and uWUE= GPP*VPD^0.5/ET) have consistent responses to drought and how their responses are affected by drought intensity, duration and timing. The results show that WUE_T decreases, WUE_ET changes inapparently in direction of positive or negative, and uWUE increases during drought, although they have the same component GPP/T. The drought responses of ecosystem WUEs are significantly and nonlinearly influenced by drought intensity and duration, but insignificantly by drought timing. Increase in drought intensity leads to a higher reduction in WUE_T but greater increase in WUE_ET and uWUE. Short-term (< 2 months) and long-term droughts (> 6 months) have similar negative effects on WUE_T and WUE_ET, while medium to long-term droughts exert great positive impact on uWUE. The influences of drought intensity and duration are varied with drought timing. Further driver analyses reveal the unchanged GPP and increased T jointly lead to the decline in WUE_T during drought. Meanwhile, drought-driven rises in T/ET and VPD offset the reduced GPP/T, resulting in the inapparent change of WUE_ET and increase of uWUE, respectively. Overall, WUE_T response to drought is determined by T, while both WUE_ET and uWUE are controlled by T/ET. Our study highlights the necessary of disentangling the drought responses of different WUE indices with considering different drought dimensions, and investigating the T/ET variability during drought will provide deeper physiological understanding of ecosystem carbon-water coupling during drought.

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来源期刊

Agricultural and Forest Meteorology 农林科学-林学

CiteScore

10.30

自引率

9.70%

发文量

415

审稿时长

69 days

期刊介绍： Agricultural and Forest Meteorology is an international journal for the publication of original articles and reviews on the inter-relationship between meteorology, agriculture, forestry, and natural ecosystems. Emphasis is on basic and applied scientific research relevant to practical problems in the field of plant and soil sciences, ecology and biogeochemistry as affected by weather as well as climate variability and change. Theoretical models should be tested against experimental data. Articles must appeal to an international audience. Special issues devoted to single topics are also published. Typical topics include canopy micrometeorology (e.g. canopy radiation transfer, turbulence near the ground, evapotranspiration, energy balance, fluxes of trace gases), micrometeorological instrumentation (e.g., sensors for trace gases, flux measurement instruments, radiation measurement techniques), aerobiology (e.g. the dispersion of pollen, spores, insects and pesticides), biometeorology (e.g. the effect of weather and climate on plant distribution, crop yield, water-use efficiency, and plant phenology), forest-fire/weather interactions, and feedbacks from vegetation to weather and the climate system.