A clear trade‐off between leaf hydraulic efficiency and safety in an aridland shrub during regrowth

Abstract

It has been suggested that a trade‐off between hydraulic efficiency and safety is related to drought adaptation across species. However, whether leaf hydraulic efficiency is sacrificed for safety during woody resprout regrowth after crown removal is not well understood. We measured leaf water potential (ψleaf) at predawn (ψpd) and midday (ψmid), leaf maximum hydraulic conductance (Kleaf‐max), ψleaf at induction 50% loss of Kleaf‐max (Kleaf P50), leaf area‐specific whole‐plant hydraulic conductance (LSC), leaf vein structure and turgor loss point (πtlp) in 1‐ to 13‐year‐old resprouts of the aridland shrub (Caragana korshinskii). ψpd was similar, ψmid and Kleaf P50 became more negative, and Kleaf–max decreased in resprouts with the increasing age; thus, leaf hydraulic efficiency clearly traded off against safety. The difference between ψmid and Kleaf P50, leaf hydraulic safety margin, increased gradually with increasing resprout age. More negative ψmid and Kleaf P50 were closely related to decreasing LSC and more negative πtlp, respectively, and the decreasing Kleaf‐max arose from the lower minor vein density and the narrower midrib xylem vessels. Our results showed that a clear trade‐off between leaf hydraulic efficiency and safety helps C. korshinskii resprouts adapt to increasing water stress as they approach final size.

Hydraulic trade-off and coordination strategies mediated by leaf functional traits of desert shrubs

“…For example, H. ammodendron has a low efficiency (lower K max ) but strong resistance to embolism (i.e., more negative P 50 ), whereas A. bracteata exhibits the opposite trend, which is likely owing to their leaf and canopy structure characteristics (e.g., large crown size and leaf degeneration in H. ammodendron , but larger leaf area and leathery leaves in A. bracteata ) or differences in xylem anatomy, which merits further study. Our results are consistent with previous investigations that suggest strong trade-offs between hydraulic safety and efficiency within numerous single sites ( Martınez-Vilalta et al., 2002 ; Pratt et al., 2007 ) and among particular taxa ( Hacke et al., 2007 ; Yao et al., 2021 ). The relationships among traits at the global scale do not necessarily manifest similarly at specific sites or in a specific region—traits that appear closely coordinated at certain scales may have different sensitivities to scale-dependent drivers of variation ( Messier et al., 2017 ), which may be attributed to species evolving different life history traits (physiological and morphological traits) in different environments ( Xu et al., 2007 ; Gupta et al., 2020 ).…”

Trade-Off between Hydraulic Safety and Efficiency in Plant Xylem and Its Influencing Factors

“…Leaf vein density and conduit diameter are two characteristics of the xylem that are closely connected to leaf hydraulic efficiency [84]. Leaf water potential and hydraulic conductivity are negatively correlated, and hydraulic conductivity increases with leaf age [19]. Furthermore, leaf hydraulic safety is influenced by the characteristics of the tissues outside the xylem, such as the turgor loss point, and by the vein xylem's characteristics, such as vein structure [85].…”

“…Previous studies have shown that more efficient xylem comes at the cost of being more vulnerable to hydraulic failure [14,[17][18][19]. Nevertheless, whether there is a general tradeoff between hydraulic safety and efficiency remains controversial, and there is growing evidence that this trade-off might only exist in some cases or be weak [13].…”

Resistance and Resilience of Desert Riparian Communities to Extreme Droughts

“…This may have been because the greater the index of abundance, the greater the number of species, and the more complex water-use and water-sharing strategies that exist between species, the easier it is for species to survive. In the past, researchers have studied the factors that affect the resistance and resilience of individual species [2,5,7,8,12,13,16,19,[21][22][23][24]44], but few have studied the factors that affect the resistance and resilience of communities. Different communities have different characteristics of species composition, structure, and diversity.…”