The stomatal response to vapor pressure deficit drives the apparent temperature response of photosynthesis in tropical forests

IF 8.3 1区生物学 Q1 PLANT SCIENCES New Phytologist Pub Date : 2024-05-12 DOI:10.1111/nph.19806

Martijn Slot, Sami W. Rifai, Chinedu E. Eze, Klaus Winter

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Abstract

As temperature rises, net carbon uptake in tropical forests decreases, but the underlying mechanisms are not well understood. High temperatures can limit photosynthesis directly, for example by reducing biochemical capacity, or indirectly through rising vapor pressure deficit (VPD) causing stomatal closure.
To explore the independent effects of temperature and VPD on photosynthesis we analyzed photosynthesis data from the upper canopies of two tropical forests in Panama with Generalized Additive Models.
Stomatal conductance and photosynthesis consistently decreased with increasing VPD, and statistically accounting for VPD increased the optimum temperature of photosynthesis (T_opt) of trees from a VPD-confounded apparent T_opt of c. 30–31°C to a VPD-independent T_opt of c. 33–36°C, while for lianas no VPD-independent T_opt was reached within the measured temperature range. Trees and lianas exhibited similar temperature and VPD responses in both forests, despite 1500 mm difference in mean annual rainfall.
Over ecologically relevant temperature ranges, photosynthesis in tropical forests is largely limited by indirect effects of warming, through changes in VPD, not by direct warming effects of photosynthetic biochemistry. Failing to account for VPD when determining T_opt misattributes the underlying causal mechanism and thereby hinders the advancement of mechanistic understanding of global warming effects on tropical forest carbon dynamics.

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气孔对蒸汽压力不足的反应推动了热带森林光合作用的表观温度反应。

随着气温的升高，热带森林的净碳吸收量会减少，但人们对其深层机理并不十分清楚。高温可以直接限制光合作用，例如通过降低生化能力，或通过增加蒸气压差（VPD）导致气孔关闭来间接限制光合作用。为了探索温度和蒸气压差对光合作用的独立影响，我们使用广义相加模型分析了巴拿马两片热带雨林树冠上部的光合作用数据。气孔导度和光合作用始终随着 VPD 的升高而降低，而根据 VPD 的统计结果，乔木的光合作用最适温度（Topt）从与 VPD 有关的约 30-31°C 的表观 Topt 提高到了与 VPD 无关的约 33-36°C 的 Topt，而藤本植物在测量的温度范围内没有达到与 VPD 无关的 Topt。尽管两个森林的年平均降雨量相差 1500 毫米，但树木和藤本植物对温度和 VPD 的反应相似。在与生态相关的温度范围内，热带森林的光合作用主要受限于变暖的间接影响，即 VPD 的变化，而非光合生物化学的直接变暖效应。在确定 Topt 时，如果不考虑 VPD，就会错误地归因于潜在的因果机制，从而阻碍从机理上理解全球变暖对热带森林碳动态的影响。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

New Phytologist 生物-植物科学

自引率

5.30%

发文量

728

期刊介绍： New Phytologist is an international electronic journal published 24 times a year. It is owned by the New Phytologist Foundation, a non-profit-making charitable organization dedicated to promoting plant science. The journal publishes excellent, novel, rigorous, and timely research and scholarship in plant science and its applications. The articles cover topics in five sections: Physiology & Development, Environment, Interaction, Evolution, and Transformative Plant Biotechnology. These sections encompass intracellular processes, global environmental change, and encourage cross-disciplinary approaches. The journal recognizes the use of techniques from molecular and cell biology, functional genomics, modeling, and system-based approaches in plant science. Abstracting and Indexing Information for New Phytologist includes Academic Search, AgBiotech News & Information, Agroforestry Abstracts, Biochemistry & Biophysics Citation Index, Botanical Pesticides, CAB Abstracts®, Environment Index, Global Health, and Plant Breeding Abstracts, and others.