Coordination of stem and leaf traits define different strategies to regulate water loss and tolerance ranges to aridity

Abstract

Summary Adaptation to drought involves complex interactions of traits that vary within and among species. To date, few data are available to quantify within‐species variation in functional traits and they are rarely integrated into mechanistic models to improve predictions of species response to climate change. We quantified intraspecific variation in functional traits of two Hakea species growing along an aridity gradient in southeastern Australia. Measured traits were later used to parameterise the model SurEau to simulate a transplantation experiment to identify the limits of drought tolerance. Embolism resistance varied between species but not across populations. Instead, populations adjusted to drier conditions via contrasting sets of trait trade‐offs that facilitated homeostasis of plant water status. The species from relatively mesic climate, Hakea dactyloides, relied on tight stomatal control whereas the species from xeric climate, Hakea leucoptera dramatically increased Huber value and leaf mass per area, while leaf area index (LAI) and epidermal conductance (gmin) decreased. With trait variability, SurEau predicts the plasticity of LAI and gmin buffers the impact of increasing aridity on population persistence. Knowledge of within‐species variability in multiple drought tolerance traits will be crucial to accurately predict species distributional limits.

Unlocking Drought-Induced Tree Mortality: Physiological Mechanisms to Modeling

“…Process-based models can overcome these weaknesses by representing biological processes in detail. Current experimental evidence points to the crucial role of plant hydraulic traits in explaining the pattern of drought-induced tree mortality ( Anderegg et al, 2016 ; Zhu et al, 2018 ; Chen et al, 2019 , 2021a ; Powers et al, 2020 ; Nolan et al, 2021 ), which subsequently motivated the development and integration of plant hydraulic modules into LSMs ( De Kauwe et al, 2020 ; Eller et al, 2020 ; Sabot et al, 2020 ; López et al, 2021 ). Nonetheless, physiological processes driving hydraulic dysfunction are incompletely integrated into these models, mainly because of knowledge gaps surrounding the physiological mechanisms of drought response, as well as inadequate empirical datasets enabling adequate model parameterization ( Meir et al, 2015 ; Hartmann et al, 2018 ).…”

SurEau: a mechanistic model of plant water relations under extreme drought

“…From 2017 onwards, we developed a new dynamic version of this model, based on a plant segmentation in different organs and implemented in the C programming language. This model has already been used in a number of recent studies (Martin-StPaul et al 2017Scoffoni et al 2018;Duursma et al 2019;Cochard 2020a;Brodribb et al 2019;Brodribb et al 2020;Dayer et al 2020;Lamarque et al 2020;Lopez et al 2021), but never formally described as here.…”

Fruit orchards under climate change conditions: adaptation strategies and management

“…Many crops had to shed the leaves partially when facing a water deficit for a long time, regularly shedding of older leaves start first to reduce water loss, then followed by young leaves when drought remain for a longer period. 20,21…”

“…Canopy architecture plays a significant role in adapting trees to stress conditions, so, Dwarf cultivars with dense crowns are more tolerant to drought as a result of reducing dehydration compare to wide-crown varieties. 21 Compactness canopy reducing leaf size, also, change crown shape which reduces transpiration and saves energy by prevents high light density from reaching the inner leaves and decrease the penetration of the solar radiation to improve the microclimate in the tree, therefore, Dwarf cultivars with compacting crowns could tolerant drought more than open crown varieties by delaying dehydration.…”