How woody plants adjust above‐ and below‐ground traits in response to sustained drought

Abstract

Summary Future increases in drought severity and frequency are predicted to have substantial impacts on plant function and survival. However, there is considerable uncertainty concerning what drought adjustment is and whether plants can adjust to sustained drought. This review focuses on woody plants and synthesises the evidence for drought adjustment in a selection of key above‐ground and below‐ground plant traits. We assess whether evaluating the drought adjustment of single traits, or selections of traits that operate on the same plant functional axis (e.g. photosynthetic traits) is sufficient, or whether a multi‐trait approach, integrating across multiple axes, is required. We conclude that studies on drought adjustments in woody plants might overestimate the capacity for adjustment to drier environments if spatial studies along gradients are used, without complementary experimental approaches. We provide evidence that drought adjustment is common in above‐ground and below‐ground traits; however, whether this is adaptive and sufficient to respond to future droughts remains uncertain for most species. To address this uncertainty, we must move towards studying trait integration within and across multiple axes of plant function (e.g. above‐ground and below‐ground) to gain a holistic view of drought adjustments at the whole‐plant scale and how these influence plant survival.

Anatomical distribution of starch in the stemwood influences carbon dynamics and suggests storage‐growth trade‐offs in some tropical trees

“…It is important to note that radial growth is not the only form of growth in trees, and other forms of growth may be adjusted or prioritized. Nevertheless, reducing radial growth rates during periods of low productivity may make trees more tolerant to a wider range of environmental conditions (Rowland et al, 2023).…”

Accounting for trait variability and coordination in predictions of drought‐induced range shifts in woody plants

“…Phenotypic plasticity, on the contrary, can be very fast in plants (Nicotra et al, 2010). Our understanding of the factors determining (and limiting) phenotypic plasticity withinspecies ranges is increasing (Stotz et al, 2021;Sol e-Medina et al, 2022), including trait adjustments in response to drought (Rowland et al, 2023). Plastic adjustments typically reduce the likelihood or anticipated magnitude of range shifts relative to a constant-traits scenario (Hoffmann & Sgr o, 2011;Razgour et al, 2019), although cases of maladaptive plasticity have been recorded (Zettlemoyer & Peterson, 2021).…”

Vapour pressure deficit modulates hydraulic function and structure of tropical rainforests under nonlimiting soil water supply

“…Previous research indicates that RC and CB have different whole-tree-and site-level hydraulic conductance (Binks et al, 2021), confirming the different selection pressures of the hydraulic environment at each site. However, hydraulic conductance has been shown to be a labile trait in several studies (Schuldt et al, 2011;Tng et al, 2018), while P50 is known to be taxonomically conservative (Rowland et al, 2023). It is possible that P50 and HSM principally respond to soil water availability, while whole-tree hydraulic conductance is more sensitive to evaporative demand: perhaps as a result of turgor-driven differences in growth (Kroeger et al, 2011), vessel size (Hacke et al, 2001;R.L.…”