Comment on esurf-2021-104

doi:10.5194/esurf-2021-104-rc2

Abstract

Abstract. Burrowing animals influence surface microtopography and hillslope sediment redistribution, but changes often remain undetected due to a lack of automated high-resolution field monitoring techniques. In this study, we present a new approach to quantify microtopographic variations and surface changes caused by burrowing animals and rainfall-driven erosional processes applied to remote field plots in arid and Mediterranean climate regions in Chile. We compared the mass balance of redistributed sediment between burrow and burrow-embedded area, quantified the cumulative sediment redistribution caused by animals and rainfall, and upscaled the results to a hillslope scale. The newly developed instrument, a time-of-flight camera, showed a very good detection accuracy. The animal-caused cumulative sediment excavation was 14.6âcm3âcmâ2âyrâ1 in the Mediterranean climate zone and 16.4âcm3âcmâ2âyrâ1 in the arid climate zone. The rainfall-related cumulative sediment erosion within burrows was higher (10.4âcm3âcmâ2âyrâ1) in the Mediterranean climate zone than the arid climate zone (1.4âcm3âcmâ2âyrâ1). Daily sediment redistribution during rainfall within burrow areas was up to 350â%(40â%) higher in the Mediterranean (arid) zone compared to burrow-embedded areas and much higher than previously reported in studies that were not based on continuous microtopographic monitoring. A total of 38â% of the sediment eroding from burrows accumulated within the burrow entrance, while 62â% was incorporated into hillslope sediment flux, which exceeds previous estimations 2-fold. On average, animals burrowed between 1.2â2.3 times a month, and the burrowing intensity increased after rainfall. This revealed a newly detected feedback mechanism between rainfall, erosion, and animal burrowing activity, likely leading to an underestimation of animal-triggered hillslope sediment flux in wetter climates. Our findings hence show that the rate of sediment redistribution due to animal burrowing is dependent on climate and that animal burrowing plays a larger than previously expected role in hillslope sediment redistribution. Subsequently, animal burrowing activity should be incorporated into soil erosion and landscape evolution models that rely on soil processes but do not yet include animal-induced surface processes on microtopographical scales in their algorithms.

Highlights

Animal burrowing activity affects surface microtopography (Reichman and Seabloom, 2002; Kinlaw and Grasmueck, 2012), surface roughness (Yair, 1995; Jones et al, 2010; Hancock and Lowry, 2021) and soil physical properties (Ridd, 1996; Yair, 1995; Hall et al, 1999; Reichman and Seabloom, 2002; Hancock andLowry, 2021; Coombes, 2016; Larsen et al, 2021)
That the ratio between the sediment redistribution caused by rainfall in the areas affected and not affected by burrowing animals varies between the climate zones
Lower than cumulative sediment redistribution only within the mound and the burrow roof (Fig. 9 and A4). These results suggest that 28% of the eroded sediment from animal mounds and burrow roofs is re-accumulated within the burrow entrance during rainfall-runoff events, and the remaining 62% is incorporated into overall hillslope sediment flux

Summary

Introduction

Animal burrowing activity affects surface microtopography (Reichman and Seabloom, 2002; Kinlaw and Grasmueck, 2012), surface roughness (Yair, 1995; Jones et al, 2010; Hancock and Lowry, 2021) and soil physical properties (Ridd, 1996; Yair, 1995; Hall et al, 1999; Reichman and Seabloom, 2002; Hancock andLowry, 2021; Coombes, 2016; Larsen et al, 2021). The complex interaction of sediment excavation and accumulation and erosion processes at the burrow and hillslope scales are not yet included in the modelling, as for this, a suitable method capable of measuring all occurred redistribution processes is needed. The reason for this knowledge gap is that previous studies have not provided data on low magnitude but frequently occurring sediment redistribution due to the specific limitations of their approaches. T., Shao, M.’a., Jia, Y., Jia, X., and Huang, L.: Small-scale observation on the effects of the burrowing activities of mole crickets on soil erosion and hydrologic processes, Agriculture, Ecosystems &. M., and Gan, M.: Small‐scale observation on the effects of burrowing activities of ants on soil hydraulic processes, Eur J Soil Sci, 70, 236–244, doi:10.1111/ejss.12748, 2019c

Results

Discussion

Conclusion