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.