Higher sediment redistribution rates related to burrowing animals than previously assumed as revealed by time-of-flight-based monitoring

[摘要] Burrowing animals influence surface microtopography and hillslope sedimentredistribution, but changes often remain undetected due to a lack ofautomated high-resolution field monitoring techniques. In this study, wepresent a new approach to quantify microtopographic variations and surfacechanges caused by burrowing animals and rainfall-driven erosional processesapplied to remote field plots in arid and Mediterranean climate regions in Chile. We comparedthe mass balance of redistributed sediment between burrow and burrow-embedded area, quantified the cumulative sediment redistribution caused byanimals and rainfall, and upscaled the results to a hillslope scale. Thenewly developed instrument, a time-of-flight camera, showed a very gooddetection accuracy. The animal-caused cumulative sediment excavation was14.6 cm 3  cm −2  yr −1 in the Mediterranean climate zone and 16.4 cm 3  cm −2  yr −1 in the arid climate zone. Therainfall-related cumulative sediment erosion within burrows was higher (10.4 cm 3  cm −2  yr −1 ) in the Mediterranean climate zone than the aridclimate zone (1.4 cm 3  cm −2  yr −1 ). Daily sedimentredistribution during rainfall within burrow areas was up to 350 % ( 40 %) higher in the Mediterranean (arid) zone compared to burrow-embeddedareas and much higher than previously reported in studies that were notbased on continuous microtopographic monitoring. A total of 38 % of the sedimenteroding from burrows accumulated within the burrow entrance, while 62 % wasincorporated into hillslope sediment flux, which exceeds previousestimations 2-fold. On average, animals burrowed between 1.2–2.3 times amonth, and the burrowing intensity increased after rainfall. This revealed anewly detected feedback mechanism between rainfall, erosion, and animalburrowing activity, likely leading to an underestimation of animal-triggeredhillslope sediment flux in wetter climates. Our findings hence show that therate of sediment redistribution due to animal burrowing is dependent on climate and that animal burrowing plays a larger than previously expectedrole in hillslope sediment redistribution. Subsequently, animal burrowingactivity should be incorporated into soil erosion and landscape evolutionmodels that rely on soil processes but do not yet include animal-inducedsurface processes on microtopographical scales in their algorithms.

[学科分类] 土壤学