Code to support 'Canopy rejuvenation mitigates Amazon photosynthetic vulnerability to rising atmospheric dryness'

This repository contains the code and example data used to perform the analyses described in the following paper: 'Canopy rejuvenation mitigates Amazon photosynthetic vulnerability to rising atmospheric dryness' Rising atmospheric vapor pressure deficit (VPD) can constraint leaf-level photosynthesis by reducing stomatal aperture, yet can trigger canopy-level effects by stimulating plants to produce younger, more photosynthetically efficient leaves in Amazon rainforest. Here, we examine the opposing effects between leaf-level stomatal constraint and canopy-level rejuvenation using a satellite-based model. We show that incorporating canopy rejuvenation markedly improves the simulation of spatiotemporal variability in vegetation productivity, revealing that most of the Amazon rainforest exhibit a positive response of vegetation productivity to rising VPD. Canopy rejuvenation largely delayed the VPD threshold at which vegetation productivity becomes constrained. These results indicate that canopy rejuvenation makes Amazon rainforest productivity less vulnerable to rising atmospheric dryness than previously thought.本存储库包含用于开展下述论文所述分析的代码与示例数据：《冠层更新缓解亚马逊雨林光合过程对大气干燥加剧的脆弱性》。大气水汽压亏缺（vapor pressure deficit, VPD）可通过降低气孔开度限制叶片尺度的光合作用，却也能通过刺激亚马逊雨林植物生成更年轻、光合效率更优的叶片，引发冠层尺度的正向效应。本研究借助基于卫星的模型，探究叶片尺度气孔限制与冠层更新之间的拮抗效应。研究表明，纳入冠层更新过程可显著改善植被生产力时空变异性的模拟效果，结果显示绝大多数亚马逊雨林的植被生产力对加剧的VPD呈现正向响应。冠层更新大幅推迟了植被生产力受到抑制的VPD阈值。上述结果表明，冠层更新使得亚马逊雨林的生产力相较于此前学界的认知，更不易受大气干燥加剧的影响。