Long-term effects of restoration on soil hydraulic properties in revegetation-stabilized desert ecosystems

Improving structure of soils found at 0-5 cm depth, and increasing the thickness of biological soil crusts are both associated with sand dune revegetation-stabilization in arid northwestern China. Since 1956, research on sand dune stabilization has included the use of straw chequer-boards to facilitate development of soil structure. One method to gauge the degree of stabilization is to compare undisturbed soil hydraulic properties, including water retention [h(theta)] and hydraulic conductivity [K(h)] functions, with properties from stabilized sites of different ages. This study examined properties at five experimental sites of different ages since revegetation (51, 42, 34, 20 and 0 years). Saturated hydraulic conductivity (K(s)) was determined in-situ from all five sites, and the h(theta) curve was determined from samples collected from three sites. A significant negative correlation existed between K(s) and the clay, silt and organic matter contents. Differences in most van Genuchten parameters for h(theta) were observed between the revegetated plots and the migrating sand dune area. Results of this long-term study show that changes in soil hydraulic properties and improvement in soil structure were associated with migrating dune stabilization.