Autor:innen:
Dr. Vincent Felde | Leibniz Universität Hannover | Germany
Dr. Lennart Hinz | Leibniz Universität Hannover | Germany
Lucas Freudenthal | Leibniz Universität Hannover | Germany
Dr. Susanne K. Woche | Leibniz Universität Hannover
Dr. Emilio Rodriguez-Caballero | University of Almeria | Spain
Prof. Dr. Shubin Lan | Northeast Normal University
Dr. Jalil Kakeh | University of Tehran
Michelle Szyja | University of Kaiserslautern
Prof. Dr. Roberto de Philippis | University of Florence
Prof. Dr. Eduard Reithmeier | Leibniz Universität Hannover
Prof. Dr. Stephan Peth | Leibniz Universität Hannover
Biological soil crusts (biocrusts) are topsoil microbial communities that are estimated to cover > 10 % of the global land surface. They play key roles in ecosystem functioning by increasing soil stability and reducing erosion. In drylands, one of their most important functions is the regulation of hydrological processes, such as water infiltration and water redistribution via run-off, which is strongly related to their surface properties. Depending on many factors such as texture and organismal composition, biocrusts exhibit strong differences in microtopography, which affects, among others, the connectivity of pathways for surface run-off and ultimately controls infiltration and soil erosion. While the connection between biocrust development and microtopography has been well documented, little is known about the dynamics of biocrust surface properties, especially in relation to hydrophobicity. To investigate the link between wettability and surface swelling after wetting, we scanned different biocrust successional stages from study sites around the world before and after a simulated wetting event. High-resolution 3D data of the biocrust surfaces was obtained with a structured-light 3D scanner (80 µm resolution). Since especially in hydrophobic soils, swelling of the surface may only occur once the hydrophobicity was overcome, we repeated the scans 10 times in 3 min intervals. Point measurements of contact angles (sessile drop method) were interpolated via Kriging to relate them with changes in biocrust microtopography. In all samples, the main surface changes occurred directly after wetting, i.e. during the first 3-6 minutes and differences between wettability and changes in surface microtopography were strongly related to crust type and study site, but no clear connection between wettability and surface swelling could be identified. Implications for water redistribution and erosion control are discussed.