Animal foraging as a mechanism for sediment movement and soil nutrient development: Evidence from the semi-arid Australian woodlands and the Chihuahuan Desert

Authors

David J. Eldridge, University of NSWFollow
Terry B. Koen, Department of Environment, Climate Change and WaterFollow
Aaron Killgore, New Mexico State UniversityFollow
Niki Huang, University of NSW
Walter G. Whitford, USDA-ARS Jornada Experimental Range

Date of this Version

2012

Citation

Geomorphology 157-158 (2012) 131–141; doi:10.1016/j.geomorph.2011.04.041

Abstract

An emerging area of interest in geomorphology over the past two decades has been the effects of biota on ecosystemprocesses.We examinedthe roles of a rangeof vertebrates onsoildisturbance in twomarkedlydifferent environments, the semi-arid woodland of eastern Australia and a Chihuahuan Desert grassland–shrubland in the south-westernUnited States. Foraging pits of soil-disturbingvertebrates variedmarkedly fromsmall scratchings of heteromyid (mainly Dipodomys spp.) rodents (1.8×10⁻⁴m³) to deep (1.0×10⁻² m³) excavations of the burrowing bettong (Bettongia leuseur) and greater bilby (Macrotis lagotis). Vertebratesmoved substantial volumes of soil in both environments, and activity was highly temporally and spatially variable. At large spatial scales, soil disturbance by echidnas (Tachyglossus aculeatus) and Gould's sand goannas (Varanus gouldii) was substantially greater in communities dominated by shrubs, and where domestic livestock had been excluded. Heteromyid rodents tended to excavate more foraging pits in coarse-textured vegetation communities (both grasslands and shrublands). In both environments, foragingwas concentrated close to perennial plants such as grass tussocks and tree canopies rather than in the interspaces. Foraging pits of Chihuahuan desert animals tended to be higher in labile carbon and support greater levels of infiltration, though this was plant community-dependent. Overall our results indicate that animal foraging is an important geomorphic mechanism capable of mobilizing substantial volumes of soil in arid and semi-arid environments and with potential effects on soil function.