Department of Earth and Environment, School of Geography, University of Leeds, Leeds, UK.
Departamento de Ciências Biológicas, Laboratório de Ecologia Vegetal, Universidade do Estado de Mato Grosso, Nova Xavantina, Mato Grosso, Brasil.
Plant Cell Environ. 2023 Jan;46(1):185-198. doi: 10.1111/pce.14465. Epub 2022 Oct 20.
The continued functioning of tropical forests under climate change depends on their resilience to drought and heat. However, there is little understanding of how tropical forests will respond to combinations of these stresses, and no field studies to date have explicitly evaluated whether sustained drought alters sensitivity to temperature. We measured the temperature response of net photosynthesis, foliar respiration and the maximum quantum efficiency of photosystem II (F /F ) of eight hyper-dominant Amazonian tree species at the world's longest-running tropical forest drought experiment, to investigate the effect of drought on forest thermal sensitivity. Despite a 0.6°C-2°C increase in canopy air temperatures following long-term drought, no change in overall thermal sensitivity of net photosynthesis or respiration was observed. However, photosystem II tolerance to extreme-heat damage (T ) was reduced from 50.0 ± 0.3°C to 48.5 ± 0.3°C under drought. Our results suggest that long-term reductions in precipitation, as projected across much of Amazonia by climate models, are unlikely to greatly alter the response of tropical forests to rising mean temperatures but may increase the risk of leaf thermal damage during heatwaves.
在气候变化下，热带森林能否继续发挥功能取决于其对干旱和高温的适应能力。然而，我们对于热带森林将如何应对这些压力的组合还知之甚少，迄今为止也没有野外研究明确评估持续干旱是否会改变对温度的敏感性。我们在世界上运行时间最长的热带森林干旱实验中，测量了八种超优势亚马逊树种的净光合作用、叶片呼吸和光合作用系统 II 的最大量子效率（F / F ）对温度的响应，以研究干旱对森林热敏感性的影响。尽管长期干旱后树冠空气温度升高了 0.6°C-2°C，但净光合作用或呼吸的整体热敏感性没有变化。然而，光合作用系统 II 对极端高温破坏的耐受能力（T ）从干旱下的 50.0±0.3°C 降低到 48.5±0.3°C。我们的研究结果表明，气候模型预测的亚马逊地区大部分地区的降水量长期减少不太可能大大改变热带森林对气温升高的反应，但可能会增加热浪期间叶片热损伤的风险。
