|Eldridge, David -|
|Koen, Terry -|
|Killgore, Aaron -|
|Huang, Niki -|
|Whitford, Walter -|
Submitted to: Geomorphology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 3, 2011
Publication Date: January 1, 2012
Citation: Eldridge, D.J., Koen, T.B., Killgore, A., Huang, N., Whitford, W.G. 2012. Animal foraging as a mechanism for sediment movement and soil nutrient development: Evidence from the semi-arid Australian woodlands and the Chihuahuan Desert. Geomorphology. 157-158:131-141. Interpretive Summary: Desert environments occur on all continents and comprise about one-third of the world's land surface. This study compared effects of small animals on erosion and the fertility of soils in Australia and New Mexico desert. Animal effects are important to understand in deserts because both the impact of animals, such as burrowing, and the stability and fertility of desert soils both occur at or near the surface of the soil. In general, the effects of animals such as kangaroo rates in New Mexico and bettongs in Australia are similar in that they disturb soil surfaces and impact soil fertility. More specifically, though, animal impacts are site-specific and actual effects depend upon this specific desert and the specific animal.
Technical Abstract: An emerging area of interest in geomorphology over the past two decades has been the effects of biota on ecosystem processes. We examined the roles of a range of vertebrates on soil disturbance in two markedly different environments, the semi-arid woodland of eastern Australia and a Chihuahuan Desert grassland–shrubland in the south-western United States. Foraging pits of soil-disturbing vertebrates varied markedly from small 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). Vertebrates moved 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, foraging was 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.