부산대학교 도서관

Knowledge of plant hydraulic traits is critical for simulating terrestrial water storage, ecosystem water use, and tree responses to drought. The isotopic composition of tree xylem water (δXYLEM) has proven to be useful for understanding rooting strategies and for tracing terrestrial water flowpaths. Despite the broad collection of δXYLEM observations, few studies have estimated other plant traits from these data. We demonstrate the sensitivity of process‐based isotope‐enabled ecohydrological model (EcH2O‐iso) simulations of rooting depth distributions (KROOT), maximum stomatal conductance (gsMAX), optimal growth temperatures (TOPT), canopy light interception (KBEERS), stomatal sensitivity to vapor pressure deficits (gs‐VPD), and tree water storage capacity (TreeV) to δXYLEM observations. We sampled the δXYLEM of 30 Eastern hemlock (Tsuga canadensis) trees across 7 months, spanning a range of topographic positions and diameters. We calibrated the model 30 times with δXYLEM from each sampled tree. Calibrated values for gsMAX, KBEERS, and KROOT were validated with independent datasets of latent heat flux, canopy light interception, and xylem observations from independent hemlock stands. The calibrated values of several vegetation traits were significantly correlated with the diameters and topographic positions of the trees sampled in the field. These results indicate that δXYLEM reflects the characteristics and locations of the individual trees that are sampled, and therefore care must be taken in upscaling calibrated or measured plant traits for individual trees to larger horizontal scales. This research demonstrates that isotope‐enabled hydrological‐, land surface‐, and Earth systems‐models can leverage widely available water isotopic data to accurately estimate plant hydraulic traits. Plain Language Summary: Plants exert significant control over the amount of water stored in both soils and groundwater. For this reason, an accurate representation of plant water use is needed to simulate water and solute transport in large‐scale hydrologic and land surface models. In these models, plant water use is frequently estimated by series of equations that rely on many unknown parameters that control characteristics such as rooting depths and how much light the canopy intercepts. Estimating the correct values for these parameters is a challenging task, particularly for distinct plant species in mixed species communities. Our research shows that observations of stable isotopes (2H, 18O) in plant xylem water can be used in model calibration to estimate several plant water‐use traits, allowing for more accurate representations of both plants and the water cycle. Key Points: Accurate estimation of vegetation parameters is critical for simulation of the hydrologic cycle in land surface modelsXylem water isotopic observations are used to calibrate plant hydraulic parameters for a forested stand of Eastern hemlockIntegrated model‐field research can guide field sampling strategies to obtain the most representative xylem isotopic data [ABSTRACT FROM AUTHOR]