Vegetation impact on the hydrology of an aeolian sandy soil in a continental climate

Plant cover and surface crusts can influence soil hydrology considerably after long periods of hot weather and drought when water repellency (WR) is greatest. This was studied on an aeolian sandy soil that frequently experiences long dry and hot weather, followed by intense precipitation. The different vegetation covers examined were (1) predominantly grass species ('grassland soil'); (2) a 30-year-old Scots pine forest ('forest soil'); (3) mainly moss species ('glade soil') and (4) subsoil at 50-cm depth of treatment (3) to remove the influence of vegetation or soil crusts ('pure sand'). Vegetation cover influenced hydrological and pedological properties of the sandy soil. Both the water drop penetration time WDPT and WR index R decreased in the order: forest soil > glade soil approximate to grassland soil > pure sand. This was reflected in water sorptivity S(w) (-2 cm) and hydraulic conductivity k (-2 cm), which had the opposite trend: forest soil <glade soil approximate to grassland soil <pure sand. WDPT and R were up to 3 orders of magnitude greater, whereas S(w) (-2 cm) and k (-2 cm) were up to 3 orders of magnitude less, in some vegetated soils compared to pure sand. Water repellency, however, had a smaller impact on saturated hydraulic conductivity, K(s). It increased in the order: grassland soil <glade soil approximate to forest soil <pure sand. Under tension infiltration, the inverse proportionality between the capillary suction and hydrophobic coating of soil particles probably restricted transport. Preferential flow through macropores may have reduced this impact for K(s) Copyright (C) 2010 John Wiley & Sons, Ltd.