DOI: 10.5061/dryad.tb2rbp0ch
title: High-resolution, long-term, continuous leaf temperature measurements in an Indian tropical forest

description: Increasing temperatures in the tropics will reduce performance of trees
 and agroforestry species and may lead to lasting damage and leaf death.
 One criterion to determine future forest resilience is to evaluate damage
 caused by temperature on Photosystem-II (PSII), a particularly sensitive
 component of photosynthesis. The temperature at which 50% of PSII function
 is lost (T50) is a widely used measure of irreversible damage to leaves.
 To assess vulnerability to high temperatures, studies have measured T50 or
 leaf temperatures, but rarely both. Further, because extant leaf
 temperature records are short, duration of exposure above thresholds like
 T50 has not been considered. Finally, these studies do not directly assess
 the effect of threshold exceedance on leaves. To understand how often, and
 how long, leaf temperatures exceed critical thresholds, we measured leaf
 temperatures of forest and agroforestry species in a tropical forest in
 the Western Ghats of India where air temperatures are high. We quantified
 species-specific physiological thresholds and assessed leaf damage after
 high temperature exposure. We found that leaf temperatures already exceed
 T50. However, continuous exposure durations above critical thresholds are
 very skewed with most events lasting for much less than 30 minutes. As T50
 was measured after a 30-minute exposure, our results suggest that
 threshold exceedances and exposure durations for lasting damage are
 currently not reached and will rarely be reached if maximum air
 temperatures increase by 4°C. Consistent with this, we found only minor
 indications of heat damage in the forest species. However, there were
 indications of heat-induced reduction in PSII function and damage in the
 agroforestry leaves which have lower T50. Our findings suggest that, for
 forest species, while high temperature thresholds may be surpassed,
 durations of exposure above thresholds remain short, and therefore, are
 unlikely to lead to irreversible damage and leaf death, even under 4°C
 warming.
description: # High-resolution, long-term, continuous leaf temperature measurements,
 temperature thresholds and Fv/Fm measurements
 [https://doi.org/10.5061/dryad.tb2rbp0ch](https://doi.org/10.5061/dryad.tb2rbp0ch) ## Description of the data and file structure #### High-resolution, long-term, continuous leaf temperatures, thermal thresholds and Fv/Fm measurements The dataset accompanies the manuscript titled "**Leaf temperatures in an Indian tropical forest exceed physiological limits but durations of exposures are currently not sufficient to cause lasting damage**" Data were collected in Sirsi, Karnataka during the summer season of 2023. Detailed methods and experimental design is provided in the manuscript.  ### Files and variables #### File: Long\_term\_forestry\_leaf\_temperatures.xlsx **Description:** These are the leaf and air temperatures measured on multiple leaves of four forest species continuously during the summer of 2023 using thermistors attached on leaves. There's a separate sheet in the excel file detailing the columns of the dataset and further details.  #### File: Spot\_leaf\_temperature\_measurements\_of\_forest\_and\_agroforestry\_species.xlsx **Description:** These are the leaf temperatures measured using a handheld thermal camera during times of peak sun over a few weeks of the hottest period. The measurements were taken on leaves of multiple individuals of 13 agroforestry species and 4 forest species. There's a separate sheet in the excel file detailing the columns of the dataset and further details. #### File: FvFm\_of\_forest\_and\_agroforestry\_species.xlsx **Description:** These are the Fv/Fm measurements done soon after summer. Measurements were taken on leaves of 4 forest species and 7 agroforestry species. Further details of the measurements are given in the manuscript. There's a separate sheet in the excel file detailing the columns of the dataset and further details.  ## Code/software The data can be viewed/analysed in any spreadsheet software (MS Excel, LibreOffice Calc, etc.), or using programming languages like R, Python etc. Codes for the estimation of durations of exposure are available on request.