Forest type and leaf habit mediate thermal and drought tolerance across a tropical elevational gradient

Understanding how local climate patterns select for thermal and drought tolerance traits is needed to predict differential responses to climate change across complex ecosystems. Here, we used high throughput methods to measure traits that confer heat and drought tolerance across a tropical climatic variability gradient, and examined how forest type and leaf habit mediate these traits. Using standardized methods, we estimated thermotolerance thresholds (Tcrit, T50, T95), drought tolerance traits (water potential at turgor loss point [𝝭TLP] and osmotic potential [𝞹osm]), and morphological traits (wood density and leaf mass per area [LMA]) for 92 woody plant species across six sites along a tropical dry-to-wet gradient in Área de Conservación Guanacaste, Costa Rica. Among evergreen species, T95 showed a weak decline with elevation, LMA was positively associated with both T50 and T95, and drought tolerance increased at lower elevations and with greater wood density. T95 was higher on a..., Thermal indices
We used standardized methods to quantify thermal tolerances of plants. Individual sunlit branches were collected from the field in the morning on the day of measurement. Discs of healthy, mature leaves were collected from each individual. Following established protocols, leaf discs were exposed to eleven sous-vide water baths at different temperatures (room temperature (~23), 24, 28, 32, 36, 40, 44, 48, 52, 56, 60 °C) where they remained for 15 minutes under dim light. Following treatment, the discs were removed from the water baths and placed into humid petri dishes to recover for 24 hours, then dark-adapted for 20 minutes. Fv/Fm was measured using an LI-600 fluorometer (LI-COR Biosciences). Following Perez & Feeley (2020), we modeled the relationship between Fv/Fm and heat treatment temperature using the nls function from the stats package in R 4.4.2 (R Core Team 2024). From this relationship, we estimated three key thermal tolerance metrics: Tcrit, T50, and T95. T..., # Data from: Forest type and leaf habit mediate thermal and drought tolerance across a tropical elevational gradient

Dataset DOI: [10.5061/dryad.k98sf7mn0](https://doi.org/10.5061/dryad.k98sf7mn0)

## Description of the data and file structure

We estimated thermotolerance thresholds (Tcrit, T50, T95), drought tolerance traits (water potential at turgor loss point [𝝭TLP] and osmotic potential [𝞹osm]), and morphological traits (wood density and leaf mass per area [LMA]) for 92 woody plant species across six sites along a tropical dry-to-wet gradient in Área de Conservación Guanacaste, Costa Rica.

### Files and variables

#### File: species_traits_OutliersRemoved.csv

**Description:** Trait measurements for 92 tropical plant species, including thermal indices, drought indices, wood density, and leaf mass per area (LMA).

##### Variables

* forest type: Sites were classified into three forest types: dry, ecotone, and wet based on elevation, tree species composition, and Holdridge Life Zo..., ,