Tree hydraulic traits are coordinated and strongly linked to climate‐of‐origin across a rainfall gradient

Abstract

Plant hydraulic traits capture the impacts of drought stress on plant function, yet vegetation models lack sufficient information regarding trait coordination and variation with climate-of-origin across species. Here, we investigated key hydraulic and carbon economy traits of 12 woody species in Australia from a broad climatic gradient, with the aim of identifying the coordination among these traits and the role of climate in shaping cross-species trait variation. The influence of environmental variation was minimized by a common garden approach, allowing us to factor out the influence of environment on phenotypic variation across species. We found that hydraulic traits (leaf turgor loss point, stomatal sensitivity to drought [P ], xylem vulnerability to cavitation [P ], and branch capacitance [C ]) were highly coordinated across species and strongly related to rainfall and aridity in the species native distributional range. In addition, trade-offs between drought tolerance and plant growth rate were observed across species. Collectively, these results provide critical insight into the coordination among hydraulic traits in modulating drought adaptation and will significantly advance our ability to predict drought vulnerability in these dominant trees species.

Desiccation time during drought is highly predictable across species of Eucalyptus from contrasting climates

“…It is also consistent with large differences between the hydraulic vulnerability of leaves and stems recorded for this and other arid‐zone species in our sample group (Li et al ., ), suggesting that leaves may act as hydraulic fuses in delaying the onset of cavitation in more carbon‐expensive stems (Tyree & Ewers, ; Johnson et al ., ). Interestingly, the onset of leaf shedding tended to occur earlier in species from more mesic environments with lower levels of leaf and stem cavitation resistance (Li et al ., , ). This suggests a possible causal link between embolism and leaf shedding (Hochberg et al ., ), although there is still some uncertainty regarding the consistency of the shedding response with leaf water status under strongly contrasting conditions.…”

“…Contrary to expectations, plants with higher capacitance did not achieve longer plant desiccation times. In fact, we observed a trend of increasing desiccation time with decreasing capacitance, which is consistent with previous findings (Gleason et al ., ) and points to the trade‐off between cavitation resistance and capacitance already shown in these species (Li et al ., ). Nevertheless, it is reasonable to suggest that capacitance may exert a stronger influence on plant desiccation time, both in mature trees where the contribution of stem‐specific hydraulic capacitance may be higher (Scholz et al ., ) and in species with strong drought‐avoidance strategies (Wolfe, ; Blackman et al ., ).…”

“…Stem hydraulic vulnerability to drought‐induced embolism was characterized for each species in a previous study (Li et al ., ) using the bench dehydration technique on plant material grown under approximately the same environmental conditions. The critical level of hydraulic dysfunction Ψ crit in stems was defined as the water potential associated with an 88% reduction in stem hydraulic conductivity (see Table S1).…”

More than iso/anisohydry: Hydroscapes integrate plant water use and drought tolerance traits in 10 eucalypt species from contrasting climates

“…Moreover, embolism thresholds have been shown to be responsible for organ and whole‐plant death (Blackman, Brodribb, & Jordan, ; Brodribb & Cochard, ; Li et al, ; Urli et al, ). These hydraulic traits characterizing plant vulnerability to embolism are often well correlated with climatic factors across species, therefore informing the evolutionary drivers shaping the adaptation of drought response strategies (Blackman et al, ; Bourne, Creek, Peters, Ellsworth, & Choat, ; Choat et al, ; Li, Blackman, Choat, et al, ; Skelton et al, ; Trueba et al, ). In addition, significant differences between leaf and stem vulnerability provide evidence for hydraulic vulnerability segmentation (HSM HS ), a strategy that minimizes water loss during drought via leaf shedding (Pivovaroff, Sack, & Santiago, ; Zhang, Zhang, & Cao, ; Zhu, Liu, Xu, Cao, & Ye, ).…”

Hydraulics of woody plants

“…Plantation‐grown pine trees showed greater branch dieback and hydraulic constraints on growth than trees growing in natural forest (Liu et al, ). Surprisingly though, hydraulic traits of 12 woody species were more strongly related to rainfall and aridity patterns in their native distribution range than their actual growth environment (Li et al, ).…”