Browsing by Author "Bendix, Joerg"

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    A Case Study on Fog/Low Stratus Occurrence at Las Lomitas, Atacama Desert (Chile) as a Water Source for Biological Soil Crusts
    (2018) Lehnert, Lukas W.; Thies, Boris; Trachte, Katja; Achilles, Sebastian; Osses, Pablo; Baumann, Karen; Schmidt, Jakob; Samolov, Elena; Jung, Patrick; Leinweber, Peter; Karsten, Ulf; Buedel, Burkhard; Bendix, Joerg
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    Area-Wide Prediction of Vertebrate and Invertebrate Hole Density and Depth across a Climate Gradient in Chile Based on UAV and Machine Learning
    (MDPI, 2021) Grigusova, Paulina; Larsen, Annegret; Achilles, Sebastian; Klug, Alexander; Fischer, Robin; Kraus, Diana; Uebernickel, Kirstin; Paulino, Leandro; Pliscoff, Patricio; Brandl, Roland; Farwig, Nina; Bendix, Joerg
    Burrowing animals are important ecosystem engineers affecting soil properties, as their burrowing activity leads to the redistribution of nutrients and soil carbon sequestration. The magnitude of these effects depends on the spatial density and depth of such burrows, but a method to derive this type of spatially explicit data is still lacking. In this study, we test the potential of using consumer-oriented UAV RGB imagery to determine the density and depth of holes created by burrowing animals at four study sites along a climate gradient in Chile, by combining UAV data with empirical field plot observations and machine learning techniques. To enhance the limited spectral information in RGB imagery, we derived spatial layers representing vegetation type and height and used landscape textures and diversity to predict hole parameters. Across-site models for hole density generally performed better than those for depth, where the best-performing model was for the invertebrate hole density (R-2 = 0.62). The best models at individual study sites were obtained for hole density in the arid climate zone (R-2 = 0.75 and 0.68 for invertebrates and vertebrates, respectively). Hole depth models only showed good to fair performance. Regarding predictor importance, the models heavily relied on vegetation height, texture metrics, and diversity indices.
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    Biological soil crusts along a climatic gradient in Chile: Richness and imprints of phototrophic microorganisms in phosphorus biogeochemical cycling
    (2018) Baumann, Karen; Jung, Patrick; Samolov, Elena; Lehnert, Lukas W.; Buedel, Burkhard; Karsten, Ulf; Bendix, Joerg; Achilles, Sebastian; Schermer, Michael; Matus, Francisco; Oses, Romulo; Osses, Pablo; Morshedizad, Mohsen; Oehlschlaeger, Claudia
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    Mammalian bioturbation amplifies rates of both hillslope sediment erosion and accumulation along the Chilean climate gradient
    (Copernicus Gesellschaft MBH, 2023) Grigusova, Paulina; Larsen, Annegret; Brandl, Roland; Río López, Camilo del; Farwig, Nina; Kraus, Diana; Paulino, Leandro; Pliscoff, Patricio; Bendix, Joerg
    Animal burrowing activity affects soil texture, bulk density, soil water content, and redistribution of nutrients. All of these parameters in turn influence sediment redistribution, which shapes the earth's surface. Hence it is important to include bioturbation into hillslope sediment transport models. However, the inclusion of burrowing animals into hillslope-wide models has thus far been limited and has largely omitted vertebrate bioturbators, which can be major agents of bioturbation, especially in drier areas.Here, we included vertebrate bioturbator burrows into a semi-empirical Morgan-Morgan-Finney soil erosion model to allow a general approach to the assessment of the impacts of bioturbation on sediment redistribution within four sites along the Chilean climate gradient. For this, we predicted the distribution of burrows by applying machine learning techniques in combination with remotely sensed data in the hillslope catchment. Then, we adjusted the spatial model parameters at predicted burrow locations based on field and laboratory measurements. We validated the model using field sediment fences. We estimated the impact of bioturbator burrows on surface processes. Lastly, we analyzed how the impact of bioturbation on sediment redistribution depends on the burrow structure, climate, topography, and adjacent vegetation.Including bioturbation greatly increased model performance and demonstrates the overall importance of vertebrate bioturbators in enhancing both sediment erosion and accumulation along hillslopes, though this impact is clearly staggered according to climatic conditions. Burrowing vertebrates increased sediment accumulation by 137.8 % +/- 16.4 % in the arid zone (3.53 kg ha(-1) yr(-1) vs. 48.79 kg ha(-1) yr(-1)), sediment erosion by 6.5 % +/- 0.7 % in the semi-arid zone (129.16 kg ha(-1) yr(-1) vs. 122.05 kg ha(-1) yr(-1)), and sediment erosion by 15.6 % +/- 0.3 % in the Mediterranean zone (4602.69 kg ha(-1) yr(-1) vs. 3980.96 kg ha(-1) yr(-1)). Bioturbating animals seem to play only a negligible role in the humid zone. Within all climate zones, bioturbation did not uniformly increase erosion or accumulation within the whole hillslope catchment. This depended on adjusting environmental parameters. Bioturbation increased erosion with increasing slope, sink connectivity, and topography ruggedness and decreasing vegetation cover and soil wetness. Bioturbation increased sediment accumulation with increasing surface roughness, soil wetness, and vegetation cover.