Does drought alter hydrological functions in forest soils? An infiltration experiment

Abstract

Abstract. The water cycle is expected to change in future and severely affect precipitation patterns across central Europe and in other parts of the world, leading to more frequent and severe droughts. Usually, it is assumed that system properties, like soil properties, remain stable and will not be affected by drought events. To study if this assumption is appropriate, we address the effects of drought on the infiltration behavior of forest soils using dye tracer experiments on six sites in three regions across Germany, which were forced into drought conditions. The sites cover clayey, loamy and sandy textured soils. In each region, we compared a deciduous and a coniferous forest stand to address differences between the main tree species. The results of the dye tracer experiments show clear evidence for changes in infiltration behavior at the sites. The infiltration changed at the clayey plots from regular and homogeneous flow to fast preferential flow. Similar behavior was observed at the loamy plots, where large areas in the upper layers remained dry, displaying signs of strong water repellency. This was confirmed by WDPT tests, which revealed, in all except one plot, moderate to severe water repellency. Water repellency was also accountable for the change of regular infiltration to fingered flow in the sandy soils. The results of this study suggest that the "drought-history" or generally the climatic conditions in the past of a soil are more important than the actual antecedent soil moisture status regarding hydrophobicity and infiltration behavior; and also, that drought effects on infiltration need to be considered in hydrological models to obtain realistic predictions concerning water quality and quantity in runoff and groundwater recharge.

Influence of soil and climate on root zone storage capacity

“…Vico et al, 2015], even on the sandy soil. This follows the line of argument set by Gimbel et al [2015], who concluded that medium-term to long-term climatic conditions of an area were more important than short-term antecedent soil moisture for the system behavior under drought conditions. Kleidon and Heimann [1998] showed that root depth is strongly related to climate, especially to the difference in precipitation and potential evaporation.…”

“…This follows the line of argument set by Gimbel et al . [], who concluded that medium‐term to long‐term climatic conditions of an area were more important than short‐term antecedent soil moisture for the system behavior under drought conditions.…”

Phosphorus fractions in preferential flow pathways and soil matrix in hillslope soils in the Thuringian Forest (Central Germany)

“…Based on the SPW classification and the share of each SPW class per depth, five types of flow processes were derived: for (1) homogeneous and (2) heterogeneous matrix flow, and macropore flow with (3) low, (4) mixed, and (5) high interaction with the soil matrix. Here, the macropore flow types explicitly differ in the width of stained objects with long and narrow shapes for type (3) and broader objects in types (4) and (5), which also have increasing interaction ( i.e ., lateral water flow) into the adjacent soil matrix ( Weiler and Flühler , ; Gimbel et al, ).…”

Differences in preferential flow with antecedent moisture conditions and soil texture: Implications for subsurface P transport

“…Dye staining is an established method to visualize subsurface water and study the relative importance—in terms of spatial extent—of different flowpaths (Forrer, Kasteel, Flury, & Flühler, ; Weiler & Flühler, ). This method is common in agricultural landscapes (Ali, Macrae, Walker, Laing, & Lobb, ; Bachmair, Weiler, & Nützmann, ; Chyba, Kroulík, Lev, & Kumhála, ; Kasteel, Garnier, Vachier, & Coquet, ; Yao, Cheng, Sun, Zhang, & Zhang, ) and other landscapes including grasslands (Bachmair et al, ; Weiler & Naef, ) and forests (Bachmair et al, ; Gimbel, Puhlmann, & Weiler, ). Dye staining has also been used to compare dominant flowpaths under different regional and climatic factors, including soil texture (Bachmair et al, ; Gimbel et al, ), soil moisture conditions (Yao et al, ), rainfall amounts (Bachmair et al, ), and rainfall rates (Weiler & Naef, ).…”

“…This method is common in agricultural landscapes (Ali, Macrae, Walker, Laing, & Lobb, 2018;Bachmair, Weiler, & Nützmann, 2009;Chyba, Kroulík, Lev, & Kumhála, 2013;Kasteel, Garnier, Vachier, & Coquet, 2007;Yao, Cheng, Sun, Zhang, & Zhang, 2017) and other landscapes including grasslands (Bachmair et al, 2009;Weiler & Naef, 2003) and forests (Bachmair et al, 2009;Gimbel, Puhlmann, & Weiler, 2015). Dye staining has also been used to compare dominant flowpaths under different regional and climatic factors, including soil texture (Bachmair et al, 2009;Gimbel et al, 2015), soil moisture conditions (Yao et al, 2017), rainfall amounts (Bachmair et al, 2009), and rainfall rates (Weiler & Naef, 2003). Within agricultural landscapes, this method has been used to study flowpaths under different management practices including tillage (Chyba et al, 2013;Kasteel et al, 2007;Wuest, 2009) and manure application (Ali et al, 2018).…”