Global meta‐analysis of soil‐disturbing vertebrates reveals strong effects on ecosystem patterns and processes

Abstract

Aim Organisms that disturb the soil while foraging or creating shelter (ecosystem engineers) can have profound effects on ecosystems. Soil ejecta from these disturbances can enhance surface nutrients and the resulting depressions accrue organic matter and develop into biological hotspots. Here, we describe a global meta‐analysis of studies that assessed the impacts of vertebrate soil disturbance on both biotic and abiotic components of ecosystems. Location Global land surface. Time period 1941–2016. Major taxa studied Vertebrates. Methods After conducting a systematic literature search, we quantitatively synthesized the findings of 149 published studies that compared disturbed and undisturbed surfaces. Our meta‐analysis included 64 engineer species, primarily comprised of rodents and a subset of other mammals. Results We found that vertebrate soil disturbance significantly enhanced soil nitrogen (by 77%) and phosphorus (35%), and the productivity (32%) and recruitment (32%) of vascular plants. Disturbances had a greater cover of bare soil (126%) than undisturbed controls, and higher abundances of secondary vertebrates (1,233%), that use pre‐constructed burrows as shelter and foraging grounds. Soil disturbance significantly reduced water run‐off (63%) and the abundance of biocrusts (82%). Soil disturbance effects generally intensified with increasing aridity, and the magnitude of soil disturbance effects was not moderated by the area of the disturbance. Disturbances older than 12 months were more distinct from the surrounding matrix than fresh disturbances. The phylogeny of engineers was unrelated to their ecosystem effects, indicating that the same functionality could readily evolve in different taxa. Main conclusions In general, disturbances become localized patches of elevated functioning, providing strong evidence that vertebrate engineers, especially those in drylands, are an important source of environmental heterogeneity.

Rainfall‐dependent impacts of threatened ecosystem engineers on organic matter cycling

“…In arid areas, digging mammals increased SOM substantially, but they had little impact in mesic systems. Our findings therefore support suggestions from previous studies that the impact of ecosystem engineers on ecosystem functions depends on resource limitations (Coggan et al, ; Crain & Bertness, ), with the greatest benefits in the most resource‐limited environments (Brooker & Callaghan, ; Bruno, Stachowicz, & Bertness, ; Mallen‐Cooper et al, ). The high response ratio of SOM in arid and semi‐arid systems suggests that nutrient loss by wind erosion (Larney, Bullock, Janzen, Ellert, & Olson, ; Li, Okin, Alvarez, Okin, Alvarez, & Epstein, ) might be avoided in the presence of digging mammals.…”

“…Decomposition and nutrient cycling maintain productivity in natural ecosystems (Vitousek, ). Vertebrates, including digging and burrowing mammals, play an important role in nutrient cycling globally (Canals, Herman, & Firestone, ; Davidson & Lightfoot, ), particularly in arid environments (Mallen‐Cooper, Nakagawa, & Eldridge, ; Whitford, ). Ecosystem engineers include digging and burrowing animals, which may affect organic matter decomposition directly or indirectly, and because decomposition is a crucial step in nutrient cycling (Swift, Heal, & Anderson, ), it is important to understand and conserve the function of these species.…”

“…Vertebrates, including digging mammals, play an important role in nutrient cycling globally (Canals et al, ; Davidson & Lightfoot, ), but might be particularly important in arid environments (Mallen‐Cooper et al, ; Whitford, ). Water availability affects terrestrial ecosystems through a range of mechanisms (Jenny, ), and nutrient cycles in the soil are largely driven by precipitation (Austin et al, ).…”

Brown bear digging for cicada nymphs: a novel interaction in a forest ecosystem

“…Bioturbation by digging mammals is a well-studied example of ecosystem engineering that alters habitat structure for other species and soil nutrient dynamics (Tardiff and Stanford 1998, Meysman et al 2006, Mallen-Cooper et al 2019. We observed the area of a dug patch was often over 100 m 2 , and there were at least several dozen of the patches.…”

Effects of digging by a native and introduced ecosystem engineer on soil physical and chemical properties in temperate grassy woodland

“…In contrast, some studies have found a reduction in certain nutrients in pits, perhaps as a result of leaching due to increased water infiltration (Garkaklis, Bradley & Wooller, 2003; Eldridge & Mensinga, 2007), and others have found no effect (Groot Bruinderink & Hazebroek, 1996). A recent global meta-analysis of the effects of digging animals on soil found they significantly increased soil N and P, but there was no overall effect for C or pH (Mallen-Cooper, Nakagawa & Eldridge, 2019).…”