Land-use intensity and biodiversity effects on infiltration capacity and hydraulic conductivity of grassland soils in southern Germany

Evidence from experimental and established grasslands indicates that plant biodiversity can modify the water cycle. One suspected mechanism behind this is a higher infiltration capacity (nu(B)) and hydraulic conductivity (K) of the soil on species-rich grasslands. However, in established and agriculturally managed grasslands, biodiversity effects cannot be studied independent of land-use effects. Therefore, we investigated in established grassland systems how land-use intensity and associated biodiversity of plants and soil animals affect nu(B) and K at and close to saturation. On 50 grassland plots along a land-use intensity gradient in the Biodiversity Exploratory Schwabische Alb, Germany, we measured nu(B) with a hood infiltrometer at several matrix potentials and calculated the saturated and unsaturated K. We statistically analysed the relationship between nu(B) or K and land-use information (e.g., fertilising intensity), abiotic (e.g., soil texture) and biotic data (e.g., plant species richness, earthworm abundance). Land-use intensity decreased and plant species richness increased nu(B) and K, while the direction of the effects of soil animals was inconsistent. The effect of land-use intensity on nu(B) and K was mainly attributable to its negative effect on plant species richness. Our results demonstrate that plant species richness was a better predictor of nu(B) and K at and close to saturation than land-use intensity or soil physical properties in the established grassland systems of the Schwabische Alb