Impacts of devegetation on the temporal evolution of soil saturated hydraulic conductivity in a vegetated sand dune area

作者：Wang Tiejun^*; Istanbulluoglu Erkan; Wedin David; Hanson Paul

来源：Environmental Earth Sciences, 2015, 73(11): 7651-7660.

DOI：10.1007/s12665-014-3936-8

• Saturated hydraulic conductivity
• Nebraska Sand Hills
• Devegetation
• Erosion processes
• Ecohydrology

Soil saturated hydraulic conductivity (K (S) ) is partly affected by vegetation activities, which can either increase K (S) by enhancing macropore flow or reduce K (S) by clogging pore space. Despite the complex interactions of K (S) with vegetation, the impact of devegetation on K (S) has not been adequately addressed, particularly in regions that are prone to drought-induced devegetation. In this study, the impacts of devegetation on K (S) 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 K (S) 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 K (S) was negligible, owing to that the existence of dead root systems prevented erosion processes. By comparison, the long-term impact of devegetation on K (S) emerged when devegetation-induced erosion processes exposed deeper soil layers with higher K (S) . Particularly, the dunetop locations that experienced higher erosion rates had larger temporal changes in K (S) . Thus, the impacts of devegetation on K (S) 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 K (S) , a newly developed ecohydrological model was also employed, and the simulation results showed that the impacts of changes in K (S) 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.

• 出版日期2015-6