Abstract
BackgroundInfiltration is a key process in determining the water balance, but so far effects of earthworms, soil texture, plant species diversity and their interaction on infiltration capacity have not been studied.Methodology/Principal FindingsWe measured infiltration capacity in subplots with ambient and reduced earthworm density nested in plots of different plant species (1, 4, and 16 species) and plant functional group richness and composition (1 to 4 groups; legumes, grasses, small herbs, tall herbs). In summer, earthworm presence significantly increased infiltration, whereas in fall effects of grasses and legumes on infiltration were due to plant-mediated changes in earthworm biomass. Effects of grasses and legumes on infiltration even reversed effects of texture. We propose two pathways: (i) direct, probably by modifying the pore spectrum and (ii) indirect, by enhancing or suppressing earthworm biomass, which in turn influenced infiltration capacity due to change in burrowing activity of earthworms.Conclusions/SignificanceOverall, the results suggest that spatial and temporal variations in soil hydraulic properties can be explained by biotic processes, especially the presence of certain plant functional groups affecting earthworm biomass, while soil texture had no significant effect. Therefore biotic parameters should be taken into account in hydrological applications.
Highlights
The water balance of soils is determined by the interaction of water supply and water removal due to processes such as precipitation, infiltration, run-off, percolation and evapotranspiration
Effect of Soil Texture and Moisture on Infiltration The infiltration capacity in June and October did not differ between the four blocks (Table 2) encompassing the texture gradient
In order to assure that the latter result was not artefacts stemming from the non-orthogonal design of the observed plots, we tested for confounding correlations between the texture and the presence and absence of legumes
Summary
The water balance of soils is determined by the interaction of water supply and water removal due to processes such as precipitation, infiltration, run-off, percolation and evapotranspiration. It depends on total pore space, pore size distribution and tortuosity [1]. The smallest ones (micropores) are related to the grain size distribution and constitute the largest fraction of the total pore volume [2,3,4]. Larger pores (often referred to as meso- and macropores) make up a characteristic property of the soil structure [5], [6]. Soil structure is determined by aggregates of different sizes, divided into intraaggregate and inter-aggregate pore structures [7]. Intra-aggregate pores include micro- and mesopores, whereas inter-aggregate pores include meso- and macropores [8]. Infiltration is a key process in determining the water balance, but so far effects of earthworms, soil texture, plant species diversity and their interaction on infiltration capacity have not been studied
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