L-band vegetation optical depth as an indicator of plant water potential in a temperate deciduous forest stand

Abstract. Vegetation optical depth (VOD) retrieved from microwave radiometry correlates with the total amount of water in vegetation, based on theoretical and empirical evidence. Because vegetation varies relative content (as well as biomass), this correlation further suggests a possible relationship between VOD plant potential, quantity that drives hydraulic behavior. Previous studies have found evidence for scale satellite pixels tens kilometers across, but these comparisons suffer significant scaling error. Here we used small-scale remote sensing to test link remotely sensed potential. We placed an L-band radiometer tower above canopy looking down at red oak forest stand during 2019 growing season central Massachusetts, United States. measured stem xylem leaf potentials trees within single-channel algorithm continuous measurements soil moisture. exhibited diurnal cycle similar peak approximately 05:00 eastern daylight time (UTC?4). was also positively correlated both dielectric constant over season. The presence moisture leaves did not affect observed our VOD–water-potential estimate stand-level values radiative transfer parameter parameter, which compared published literature. Our findings support use temperate forests.