Table 2.
A non-exhaustive list of plant hydraulic traits within each axis (leaf, stem, and root) of the whole-plant hydraulic strategy, the scales at which they are typically measured and reported, and the variables that exert the most influence over each trait.
| Trait description | Measurement scale | Potential influencing variables |
|---|---|---|
| Leaf level | ||
| Maximum stomatal conductance | Leaf, canopy | PAR, VPD, temperature, CO2 concentration, regulation strategy |
| Slope of stomatal response to leaf water potential | Leaf, canopy | VPD, CO2 concentration, regulation strategy |
| Cuticular conductance | Leaf, canopy | Leaf form, cuticle thickness |
| Stem level | ||
| Maximum xylem conductance | Stem, branch | Xylem architecture, aquaporin activity, seasonality, plant age, growth history |
| Xylem vulnerability curve | Stem, branch | Xylem architecture, aquaporin activity, seasonality, plant age, growth history |
| Fraction of active xylem | Stem, branch | Xylem architecture, seasonality, plant age, growth history |
| Saturated xylem water content | Stem, branch | Xylem architecture, wood density |
| Wood density | Stem, branch | Xylem architecture |
| Root level | ||
| Maximum depth | Root, tree | Plant age, soil type, soil moisture/groundwater availability, nutrient environment |
| Vertical distribution of root density | Tree, stand | Plant age, soil type, soil moisture/groundwater availability, nutrient environment |
| Maximum root xylem conductance | Root | Xylem architecture, aquaporin activity, seasonality, plant age, growth history |
| Mycorrhizal activity | Root, tree | Nutrient environment, hyphal density, soil moisture, soil temperature |