DOI: 10.5061/dryad.qbzkh18t0
title: Responses to water limitation are independent of light for saplings of a seasonally dry tropical forest

description: Seasonally dry tropical forests (SDTFs) experience large spatial and
 temporal variation in water and light, and how heterogeneity in
 availability of these limiting resources affect species water use,
 physiology, and growth is still not well understood. We examined plant
 water uptake in saplings of four co-occurring SDTF species, including
 evergreen and deciduous plant functional types. We asked how water uptake
 responded to experimentally imposed water and light limitations, and how
 these responses were related to leaf-level physiology and plant growth.
 Water uptake varied dramatically among species with a five-fold difference
 in maximum whole-plant transpiration (WPT). While species differed in how
 WPT, leaf physiology and growth responded to shade, there were no
 differences among species, or between evergreen and deciduous functional
 types, in responses to limited water. Importantly, responses to shade were
 independent of water availability in all four species. Changes in WPT in
 response to limited light and water were largely congruent with changes in
 leaf physiology and growth. However, the magnitude of change in leaf
 physiology was largely driven by light, while changes in WPT and growth by
 water availability, suggesting that whole-plant water uptake may be a
 better indicator of plant growth responses in these species. Overall these
 results suggest that responses to light and water limitations may be
 independent of each other, and this would allow species in SDTFs to
 explore a wider range of combinations of light and water responses to
 adapt to heterogeneous light and water niches.
description: # Responses to water limitation are independent of light for saplings of a
 seasonally dry tropical forest
 [https://doi.org/10.5061/dryad.qbzkh18t0](https://doi.org/10.5061/dryad.qbzkh18t0) ## Description of the data and file structure A controlled common-garden experiment was conducted to impose a shade and low-water treatment in a factorial design on the saplings of four dominant tree species of the Northern Western Ghats of India, to examine their responses with respect to water use, leaf-level physiology, biomass allocation and growth. The treatment was imposed for a period of 50 days during the summer from May to June, 2015. Six replicate saplings were used for each of the four treatments (Sun x High water, Sun x Low water, Shade x High water, Shade x Low water), resulting in 96 total saplings (6 replicates x 4 treatments x 4 species). Whole plant water uptake was estimated by the gravimetric (pot-weighing) method through the course of the experiment. Leaf-level physiology was measured towards the end of the treatment period with an Infra-red gas analyser (LICOR-6400). Leaf, stem and root dry weights were measured at the end of the experiment to estimate biomass fractions. Relative growth rate was calculated for leaf area and stem diameter. The data collected during the course of the experiment is compiled here.  ### Files and variables #### File: sunny2024\_traits.xlsx **Description:**  Response in water use, leaf-level physiology, biomass allocation and growth to the light and water treatments in saplings of the four study species ##### Variables * light: The light levels used during the experiment i.e., Sun (98% of the sunlight) and Shade (13% of sunlight) * water: The water levels used during the experiment i.e., High (80 % of the saturated pot water content)  and Low (40 % of the saturated pot water content) * species: *Memecylon umbellatum*, *Syzygium cuminii*, *Terminalia chebula* and *Diospyros montana* * whole_plant_transpiration: Individual-level whole-plant transpiration (WPT) in ml per day * whole_plant_transpiration_per_leaf_area: Leaf area normalized whole-plant transpiration (WPT) in ml per m2 per day * photosynthesis: measured in micromoles per m2 per sec * conductance: measured in mol per m2 per sec * transpiration: measured in millimol per m2 per sec * leaf_mass_fraction: Mass fraction for leaf presented as a fraction of the total dry biomass on a dry weight basis * stem_mass_fraction: Mass fraction for stem presented as a fraction of the total dry biomass on a dry weight basis * root_mass_fraction: Mass fraction for root presented as a fraction of the total dry biomass on a dry weight basis * RGR_total_leaf_area calculated as ln(LAFINAL) - ln(LAINITIAL)/40, where LAFINAL and LAINITIAL correspond to the final and initial total leaf area, respectively, measured in cm2 cm-2 day-1 * RGR_stem_diameter calculated as ln(DFINAL) - ln(DINITIAL)/36, where DFINAL and DINITIAL correspond to the final and initial stem diameter, respectively, measured in mm mm-1 day-1 #### File: sunny2024\_water\_uptake.xlsx **Description:** Whole-plant transpiration over the course of the experiment in response to limited light and water availability in saplings of four tropical species ##### Variables * light: The light levels used during the experiment i.e., Sun (98% of the sunlight) and Shade Sh (13% of sunlight) * water: The water levels used during the experiment i.e., Control Con (80 % of the saturated pot water content)  and Low (40 % of the saturated pot water content) * species: *Memecylon umbellatum*, *Syzygium cuminii*, *Terminalia chebula* and *Diospyros montana* * The whole plant transpiration reported here is in the units mL per day. The measurements were done for the days 11, 14, 16, 19, 21, 24, 27, 30, 33, 37, 40, 43, 46 and 49. Missing data: n/a