Climate and functional traits jointly mediate tree water‐use strategies

Abstract

Tree water use is central to plant function and ecosystem fluxes. However, it is still unknown how organ-level water-relations traits are coordinated to determine whole-tree water-use strategies in response to drought, and whether this coordination depends on climate.Here we used a global sap flow database (SAPFLUXNET) to study the response of water use, in terms of whole-tree canopy conductance (G), to vapour pressure deficit (VPD) and to soil water content (SWC) for 142 tree species. We investigated the individual and coordinated effect of six water-relations traits (vulnerability to embolism, Huber value, hydraulic conductivity, turgor-loss point, rooting depth and leaf size) on water-use parameters, also accounting for the effect of tree height and climate (mean annual precipitation, MAP).Reference G and its sensitivity to VPD were tightly coordinated with water-relations traits rather than with MAP. Species with efficient xylem transport had higher canopy conductance but also higher sensitivity to VPD. Moreover, we found that angiosperms had higher reference G and higher sensitivity to VPD than did gymnosperms.Our results highlight the need to consider trait integration and reveal the complications and challenges of defining a single, whole-plant resource use spectrum ranging from 'acquisitive' to 'conservative'.

Wood density and hydraulic traits influence species’ growth response to drought across biomes

“…Climate change will pose higher pressure on forests through increasing temperatures and higher frequency and intensity of droughts, exerting higher drought limitations on growth whilst reducing low‐temperature limitations (Babst et al, 2019; Pompa‐Gárcia et al, 2021). Such changes may influence species distributions, promoting retractions and drought‐induced mortality at dry edges (Anderegg et al, 2019) and growth—temperature decoupling and expansion at cold treelines (Camarero et al, 2021), with potential influences on carbon stocks and ecosystem fluxes (Eller et al, 2020; Flo et al, 2021; Martin et al, 2018; Sabot et al, 2019). Our results indicating that cross‐species interannual growth variability associated with drought is related to WD and hydraulic traits support the importance of such traits on regulating carbon fluxes, which is particularly relevant under the expected increase of drought pressures on forests.…”

Revealing a significant isotopic offset between plant water and its sources using a global meta-analysis

“…Here, we calculated LC-excess and SW-excess values from a compilation of 112 studies reporting the dual water isotopic composition of plant (stem) and source waters and analysed their relationship with environmental and climatic conditions (air temperature and soil moisture content). In addition, we also assessed the influence of ecologically relevant factors, including mycorrhizal habit and plant functional traits, mediating nutrient and water-use strategies (Chen et al, 2016b;Flo et al, 2021), as well as the comparison 120 between taxonomic groups (angiosperms vs. gymnosperms) with known distinct hydraulic architecture and functioning (Johnson et al, 2012). Our aim was to quantify potential isotopic offsets between plant and source water and their relationship with biotic and abiotic drivers.…”

Genetic variation in leaf traits and gas exchange responses to vapour pressure deficit in contrasting conifer species

“…Previous studies have shown that species with higher g sref tend to show a greater stomatal sensitivity to VPD (Flo et al., 2021; Oren et al., 1999). The results of our FVT models indicated that a similar pattern could exist among genotypes within a species, although this may not hold true for all species (Figure 2).…”