Impacts Of Devegetation On The Temporal Evolution Of Soil Saturated Hydraulic Conductivity In A Vegetated Sand Dune Area
Published 2014 · Geology
Soil saturated hydraulic conductivity (KS) is partly affected by vegetation activities, which can either increase KS by enhancing macropore flow or reduce KS by clogging pore space. Despite the complex interactions of KS with vegetation, the impact of devegetation on KS has not been adequately addressed, particularly in regions that are prone to drought-induced devegetation. In this study, the impacts of devegetation on KS in a native grassland-stabilized sand dune area were investigated by artificially controlling surface vegetation at an experimental site in the Nebraska Sand Hills. The experimental results revealed that the temporal evolution of KS at the site was mainly affected by the erosion processes triggered by devegetation. Over a short-term (about 1 year), the impact of devegetation on KS was negligible, owing to that the existence of dead root systems prevented erosion processes. By comparison, the long-term impact of devegetation on KS emerged when devegetation-induced erosion processes exposed deeper soil layers with higher KS. Particularly, the dunetop locations that experienced higher erosion rates had larger temporal changes in KS. Thus, the impacts of devegetation on KS mainly depended on two factors (i.e., time and topographic locations) that were related to erosion processes in this native grassland-stabilized sand dune area. To further investigate the ecohydrological implications of the temporal change in KS, a newly developed ecohydrological model was also employed, and the simulation results showed that the impacts of changes in KS on water balance components and biomass production were non-negligible and highly nonlinear. In spite of previous studies, the findings presented here demonstrate the close tie between near-surface hydrology and land surface evolution processes controlled by vegetation in sand dune areas, and highlight the importance of coupling eco-hydro-geomorphic interactions in the context of climate change.