Unravelling hydraulic capacitance dynamics in <i>Platanus</i> x <i>acerifolia</i>: insights from combined analysis of shrinkage, mass loss, and conductivity data

Understanding water transport and storage dynamics in trees is crucial for improving mechanistic tree models, especially in the face of environmental stressors like drought. Despite extensive research, gaps persist in comprehending how trees respond to drought stress. This study focuses on hydraulic capacitance dynamics in Platanus × acerifolia trees, examining different phases including capillary, elastic, and embolism-associated water storage. Capillary storage involves water held between cells, elastic storage occurs in living tissues, and embolism-associated storage refers to water released from xylem conduits when embolisms are formed. By visualizing shrinkage, percentage loss of conductivity (PLC), and mass decrease data as a function of function of both time and water potential, we aim to elucidate how trees manage these water resources. Our results demonstrate that elastic tissues continue releasing water beyond the onset of embolism formation. Contribution of elastic storage to hydraulic capacitance during the embolism phase is, however, relatively low because of its small dimension compared to the entire xylem network. Moreover, the high hydraulic capacitance associated with embolism formation seems considerably constant. Our findings hold promise for using a constant hydraulic capacitance value for each of the three storage compartments in mechanistic tree modeling.