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Using sap flow to measure whole-tree hydraulic conductance loss in response to drought
- Eller, C. B., Bittencourt, P. R. L., Oliveira, R. S.
- Acta horticulturae 2018 no.1222 pp. 75-84
- Drimys, drought, drying, models, plant response, sap, sap flow, vegetation, xylem
- Xylem vulnerability to cavitation is an important physiological trait that strongly influences how plants respond to drought. There are several techniques available to measure branch-level xylem vulnerability to cavitation, however these are often time and resource consuming and might not always reflect the hydraulic bottlenecks on the soil-canopy continuum. These characteristics restrict the availability of tissue specific hydraulic traits and its use in large-scale modelling. In this study we propose a sap flow-based approach to estimate hydraulic parameters that describe the whole-tree conductance loss in response to drought. The hydraulic parameters estimated by our whole-tree approach are close to the branch-level parameters measured with the traditional bench drying technique. Consequently, the hydraulic parameters derived from both approaches produce similar model predictions of plant responses to soil and atmospheric drought. This indicates a coordinated loss of conductance among the different tissues that compose the soil-canopy hydraulic continuum of the studied species (Drimys brasiliensis). Our approach provides an alternative and easier way to characterize whole-plant hydraulic response to drought and could be useful to produce plant and ecosystem-level hydraulic parameters to be used in large-scale vegetation models.