Root water uptake and transport: using physiological processes in global predictions
Authors: Jackson, RB, JS Sperry, TE Dawson
Plant water loss, regulated by stomata and driven by atmospheric demand, cannot exceed maximum steady-state supply through roots. Just as an electric circuit breaks when carrying excess current, the soil-plant continuum breaks if forced to transport water beyond its capacity. New research suggests that roots may be the weakest link along this hydraulic flow path. We examine recent molecular, biophysical, and ecological research in water uptake and transport. Using hydraulic properties of plants and the soil, we generate predictions for rooting depth and water uptake that can be tested from individual sites to the globe and suggest how new physiological tools may contribute to larger-scale studies of hydraulic lift, the water balance, and biosphere-atmosphere interactions.