Water Storage Discharge and Refilling in the Main Stems of Canopy Tree Species Investigated Using Frequency Domain Reflectometry and Point Electronic Dendrometers

OLIVA CARRASCO L; BUCCI SJ; SCHOLZ FG; CAMPANELLO PI; MADANES N; CRISTIANO P; HAO GH; ZHANG Y; WEELER LT; HOLBROOK MN; GOLDSTEIN G

Workshop; 9th Workshop on Sap Flow; 2013

Trunks of large trees play an important role in whole-plant water balance but technical difficulties have limited most hydraulic research to small stems, leaves and roots. To investigate the dynamics of water economy processes in tree trunks diurnal changes in volumetric water content (VWC) and radius length were monitored continuously using frequency domain moisture sensors and electronic dendrometers respectively, in 10 canopy tree species of a subtropical seasonal forest in Northern Argentina. In addition, species-specific water storage capacitance of the active xylem was assessed using pressure volume relationships determined with a psychometric method. In nearly all the species, trunk VWC and radius length decreased during the daytime when the air saturation deficit increased, suggesting that the trunk water storage was drawn by canopy transpiration, while the increase of VWC during the nighttime suggests stem water storage recharge. Species with higher water storage capacitance exhibited lower wood density, and higher average VWC.