Mammalian bioturbation amplifies rates of both hillslope sediment erosion and accumulation along the Chilean climate gradient
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Published:2023-08-14
Issue:15
Volume:20
Page:3367-3394
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ISSN:1726-4189
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Container-title:Biogeosciences
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language:en
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Short-container-title:Biogeosciences
Author:
Grigusova Paulina, Larsen AnnegretORCID, Brandl Roland, del Río Camilo, Farwig Nina, Kraus Diana, Paulino LeandroORCID, Pliscoff Patricio, Bendix Jörg
Abstract
Abstract. 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.
Funder
Deutsche Forschungsgemeinschaft
Publisher
Copernicus GmbH
Subject
Earth-Surface Processes,Ecology, Evolution, Behavior and Systematics
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