Manipulations of albedo and mortality of upper canopy leaves in a tropical forest diverge from Earth System model results

How tropical forest leaves respond to climate change has important implications for the global carbon cycle and biodiversity.  Climate change could impact the energy balance properties of tropical forest canopies through 1) long-term trait changes and 2) abrupt disruptions/damage to leaf/photosynthetic machinery.  We assessed the radiative and evaporative impacts of two recently proposed impacts of climate change on tropical forest canopies: 1) long-term leaf darkening and 2) leaf death through high temperature extremes.  We darkened leaves to absorb 138 Wm-2 more energy in the upper canopy of a seasonally-dry tropical moist forest in Panama.  20% of this energy went towards heating leaves by ~4°C, 3% went towards warming the air, and 77% went towards evaporative cooling.  This leaf warming led to the appearance of necrosis across 9±5 % of the leaf area on certain species.   In contrast, brightening leaves decreased energy absorbed by an average o..., Site location –We used a 60-m tall canopy crane managed by the Smithsonian Tropical Research Institute (STRI) in Parque Natural Metropolitano (8.994410, -79.543000) near Panama City, Panama, to access canopy top leaves (Fig 1).  We focused on five distinct canopy level trees of five species. The species we used were: Anacardium excelsum (Bertero & Balb. ex Kunth) Skeels (Anacardiaceae), Castilla elastica Cerv. (Moraceae), Aiouea montana (Sw.) R.Rohde (Lauraceae), Spondias mombin L. (Anacardiaceae) and Luehea seemannii Triana & Planch. (Malvaceae).  A meteorological station installed at 25 m height on the tower of the crane shows that this area has a mean annual temperature of 26.2°C (average day/night: 28.0/24.5°C), and receives ~1900 mm rain per year, with a 4-month dry season from late December to late April (Paton, 2020).  We accessed living canopy top leaves on March 22, 25, 26 and 27 of 2024, which is towards the end of the dry season.  Land surface temp..., , # Manipulations of albedo and mortality of upper canopy leaves in a tropical forest diverge from Earth System model results

[https://doi.org/10.5061/dryad.kprr4xhds](https://doi.org/10.5061/dryad.kprr4xhds)

## Description of the data and file structure

**Leaf Manipulations**

*Albedo* - We added a thin coat of Viva Doria Virgin Activated Charcoal Powder from hardwood tree to darken 3–5 leaves per branch, and white kaolin clay powder (Al2Si2O5(OH)4) to brighten 3–5 leaves per branch, each on several (3–5) branches per tree.  We put the powders in a small plastic bag and dipped the leaf (still attached to the tree) in the bag trying to evenly coat the top of the leaf with a thin layer without getting powder on the bottom.

*Dead leaves* – We heat-killed leaves by dipping attached leaves into boiled water (~100°C), submerging most of the leaf, while keeping the petiole dry and unaffected by the heat treatment.  We would dip ~20–30 canopy top leaves over a period of ~15 minutes for singl..., , **Changes after Oct 8, 2024:** Minor changes to the code based on peer review comments.

**Changes after Oct 16, 2025:** I had uploaded the wrong code in the prior version.  This is the correct version.

热带森林叶片对气候变化的响应，对全球碳循环与生物多样性具有重要意义。气候变化可通过两种途径影响热带林冠的能量平衡特性：1）长期性状改变；2）对叶片/光合机制的突发性干扰与损伤。本研究评估了近期提出的两类气候变化对热带林冠的影响在辐射与蒸发方面的效应：1）长期叶片变暗；2）极端高温导致的叶片死亡。我们在巴拿马一处季节性干旱热带湿润林的上层林冠中，通过处理使叶片多吸收138 Wm⁻²的能量。其中约20%的能量用于将叶片加热约4℃，3%用于加热周围空气，77%用于蒸发冷却。该叶片升温导致部分物种的叶片表面出现9±5%的坏死区域。与之相反，增白处理则降低了平均吸收的能量……，试验场地——我们使用由史密森尼热带研究所（Smithsonian Tropical Research Institute, STRI）管理的60米高林冠起重机，位于巴拿马巴拿马城附近的大都会自然公园（Parque Natural Metropolitano，坐标8.994410, -79.543000），以获取林冠顶部叶片（图1）。本研究聚焦于5个物种的5株不同林冠层级树木，所用物种分别为：高大腰果木（Anacardium excelsum (Bertero & Balb. ex Kunth) Skeels，漆树科）、弹性卡斯蒂利亚树（Castilla elastica Cerv.，桑科）、山地琼楠（Aiouea montana (Sw.) R.Rohde，樟科）、黄酸枣（Spondias mombin L.，漆树科）以及西曼氏桐（Luehea seemannii Triana & Planch.，锦葵科）。起重机塔架25米高度处安装的气象站数据显示，该区域年平均气温为26.2℃（日间/夜间平均气温分别为28.0℃/24.5℃），年降水量约1900 mm，每年12月末至4月末为为期4个月的旱季（Paton, 2020）。我们于2024年3月22、25、26及27日采集活体林冠顶部叶片，此时正值旱季末期。地表温度……
# 热带森林上层林冠叶片反照率与死亡率操控试验结果与地球系统模型结论存在差异

[https://doi.org/10.5061/dryad.kprr4xhds](https://doi.org/10.5061/dryad.kprr4xhds)

## 数据与文件结构说明

**叶片操控处理**
*反照率（Albedo）调控*——我们使用硬木来源的Viva Doria天然活性炭粉末（Viva Doria Virgin Activated Charcoal Powder），在每根枝条上为3~5片叶片涂抹薄层以加深叶片颜色；同时使用白色高岭土粉末（kaolin clay powder，Al₂Si₂O₅(OH)₄）为每根枝条上的3~5片叶片涂抹以增白叶片，每棵树设置3~5根枝条进行此类处理。我们将粉末置于小型塑料袋中，将仍附着于植株的叶片浸入袋中，力求在叶片上表面均匀涂抹一层薄粉，同时避免粉末沾染叶片下表面。
*枯叶处理*——我们通过将附着于植株的叶片浸入沸水（约100℃）中进行热灭活，浸没叶片大部分区域，同时保持叶柄干燥、不受热处理影响。单次处理需在约15分钟内完成20~30片林冠顶部叶片的操作……，**2024年10月8日后的修改**：根据同行评审意见对代码进行小幅调整。
**2025年10月16日后的修改**：此前版本上传了错误的代码，本版本为正确版本。