DOI: 10.5061/dryad.844rs7d
title: Data from: Effects of dry-season irrigation on leaf physiology and biomass allocation in tropical lianas and trees

description: Lianas are more abundant in seasonal forests than in wetter forests and
 are thought to perform better than trees when light is abundant and water
 is limited. We tested the hypothesis that lianas perform better than trees
 during seasonal drought using a common garden experiment with 12
 taxonomically diverse species (6 liana and 6 tree species) in 12
 replicated plots. We irrigated six of the plots during the dry season for
 four years, while the remaining 6 control plots received only ambient
 rainfall. In year 5, we measured stem diameters for all individuals and
 harvested above- and belowground biomass for a subset of individuals to
 quantify absolute growth and biomass allocation to roots, stems, and
 leaves, as well as total root length and maximum rooting depth. We also
 measured photosynthesis, intrinsic water use efficiency (iWUE), pre-dawn
 and midday water potential, and a set of functional and hydraulic traits.
 During the peak of the dry season, lianas in control plots had 54% higher
 predawn leaf water potentials (ΨPD), and 45% higher photosynthetic rates
 than trees in control plots. By contrast, during the peak of the wet
 season, these physiological differences between lianas and trees become
 less pronounced and, in some cases, even disappeared. Trees had higher SLA
 than lianas; however, no other functional trait differed between growth
 forms. Trees responded to the irrigation treatment with 15% larger
 diameters and 119% greater biomass than trees in control plots. Liana
 growth, however, did not respond to irrigation; liana diameter and biomass
 were similar in control and irrigation plots, suggesting that lianas were
 far less limited by soil moisture than were trees. Contrary to previous
 hypotheses, lianas did not have deeper roots than trees; however, lianas
 had longer roots per stem diameter than did trees. Our results support the
 hypothesis that lianas perform better and experience less physiological
 stress than trees during seasonal drought, suggesting clear differences
 between growth forms in response to altered rainfall regimes. Ultimately,
 better dry-season performance may explain why liana abundance peaks in
 seasonal forests compared to trees, which peak in abundance in less
 seasonal, wetter forests.
description: Leaf nutrient
 contentPercent leaf carbon,
 nitrogen, stable isotope13C, and stable isotope 15NLeafNutrientContent.csvLeaf water potential photosynthesis conductance soil moisturePredawn and midday leaf water potential, photosynthetic rates, stomatal conductance, and percent soil moistureLeafWaterPotentialPhotosynthesisConductanceSoilMoisture.csvSLASpecific leaf areaStem root wood densityStem root wood density of harvested individualsStemRootWoodDensity.csvStem diameterStem diameter in mm measured at 20 cm and 130 cm from the base of the plant.StemDiameter.csvBiomass of harvested individualsTotal leaf, stem, and belowground biomass, diameter in mm measured at 20 cm from the base of the plant (StemDiameterAt20cm_mm), the sum of the length of all main stems (SumStemLength_cm), maximum rooting depth (MaxRootDepth_cm ), the sum of the diameter of all roots measured at the base of the roots (SumRootBaseDiameter_mm), and the sum of the length of all roots (SumRootLength_cm).Biomass.csvLeaf turgor loss point, relative water content and capacitanceLeaf turgor loss point (TLP_MPa), percent leaf relative water content at TLP (RWCTLP_%), leaf capacitance at TLP (CTLP_MPa-1), and absolute capacitance at full turgor (ACFT_g m-2 MPa-1).TurgorLossPointAndCapacitance.csv