Sensitivity of a data-driven soil water balance model to estimate summer evapotranspiration along a forest chronosequence

Abstract

The hydrology of ecosystem succession gives rise to new challenges for the analysis and modelling of water balance components. Recent large-scale alterations of forest cover across the globe suggest that a significant portion of new biophysical environments will influence the long-term dynamics and limits of water fluxes compared to pre-succession conditions. This study assesses the estimation of summer evapotranspiration along three FLUXNET sites at Campbell River, British Columbia, Canada using a data-driven soil water balance model validated by Eddy Covariance measurements. It explores the sensitivity of the model to different forest succession states, a wide range of computational time steps, rooting depths, and canopy interception capacity values. Uncertainty in the measured EC fluxes resulting in an energy imbalance was consistent with previous studies and does not affect the validation of the model. The agreement between observations and model estimates proves that the usefulness of the method to predict summer AET over mid- and long-term periods is independent of stand age. However, an optimal combination of the parameters rooting depth, time step and interception capacity threshold is needed to avoid an underestimation of AET as seen in past studies. The study suggests that summer AET could be estimated and monitored in many more places than those equipped with Eddy Covariance or sap-flow measurements to advance the understanding of water balance changes in different successional ecosystems

Dominant controls of transpiration along a hillslope transect inferred from ecohydrological measurements and thermodynamic limits

“…A higher atmospheric demand increases evaporation from intercepted water and from the soil, which reduces the amount of precipitation entering the soil. Second, the hillslope inclination could have enhanced lateral runoff at the steeper south-facing sites, which reduces the soil water holding capacity (Bronstert and Plate, 1997). These topographical factors of soil moisture availability are also apparent in the tree species composition of our sites.…”

Quantification of soil water balance components based on continuous soil moisture measurement and the Richards equation in an irrigated agricultural field of a desert oasis

“…Soil moisture measurements were used to estimate the infiltration for unsaturated porous mediums by numerical solutions as early as the 1950s (Hanks and Bowers, 1962;Gardner and Mayhugh, 1958). With the advent of automated soil moisture monitors (Topp et al, 1980), ET estimation was implemented using continuous soil moisture data with simple water balance approaches (Young et al, 1997), but the computations are usually interrupted during rainfall or irrigation periods, as there is no means of accounting for drainage or recharge, due to inadequate turbulent flux measurements (Breña Naranjo et al, 2011). It has only been during recent years that some researchers, including Zuo and Zhang (2002), Schelde et al (2011), and Guderle and Hildebrandt (2015), have started exploring the potential of using highly resolved soil moisture measurements to determine ET, by accounting for vertical flow, demonstrating that such measurements can work when the appropriate approach is used.…”

Soil organic carbon dynamics of black locust plantations in the middle Loess Plateau area of China

“…In recent decades, human disturbances, such as deforestation, urbanization and afforestation, have caused extensive changes in land use and cover globally. The large-scale changes in terrestrial ecosystems have caused great concern about the temporal dynamics of energy and mass flows during ecosystem succession or recovery (Breña Naranjo et al, 2011). To date, soil carbon dynamics following disturbances have not been well documented, especially for the later phases of succession (Foote and Grogan, 2010).…”