COS 199-1 - CANCELLED - Drought avoidance-tolerance spectrum in woody plants across habitats along water availability gradient

Background/Question/Methods

Water storage in plants is an important player in plant water balance and dynamics. It could help meet plant water demands (especially during hot/dry weather) and buffer the effect of sudden changes in environmental conditions. This could also underpin how hydraulic traits are coordinated in plants across habitats with different water availability. We used sapwood capacitance (C_S) as a measure of plant’s internal water storage capacity as it is the amount of stored water released per unit sapwood volume for a unit change in xylem water potential. We compiled a dataset including C_S and 7 hydraulic traits for 149 species across 15 sites around the globe to explore (1) how C_S influences the xylem safety (P₅₀) - efficiency (K_S) tradeoff across species and (2) how hydraulic traits coordinate with C_S and (3) whether C_S-hydraulic trait-trait associations are driven by water availability gradient.

Results/Conclusions

We found that C_S could represent an important drought avoidance strategy especially in species from wet habitats. Tall plants with high leaf-to-sapwood area ratio, low sapwood density, high K_S, less-negative P<sub>50 and less-negative stem water potentials at predawn and midday generally have high C_S values. This could represent a single axis of associated plant hydraulic strategies along a drought avoidance-tolerance spectrum driven by water availability gradient. Such hydraulic coordination with underlying tradeoffs has important implications for plant responses to emerging climate crisis and improving our predictions of plant hydraulic failure and mortality.