Environmental associations and effects of disturbances by common wombats in alpine Tasmania

Abstract

The common wombat (Vombatus ursinus) is the largest extant fossorial mammal in Tasmania. Fossorial mammals have substantial edaphic and geomorphic effects, which, in turn can affect vegetation. We asked whether wombat disturbances were associated with particular environments in an alpine environment in Tasmania, and whether, and to what degree, they altered topography, soil or vegetation. Soil analyses, vegetation surveys and topographic transects were used to test for the effects of wombat activity. We contrasted toilets and controls. We compared adjacent burrows, mounds and paths. We also mapped burrows and animal trails. Wombat burrowing created distinct topography and was linked to feeding areas by path systems. There was no difference in bulk density, pH or phosphorus among burrow mounds, paths and undisturbed areas. Burrow mounds, usually used as toilets, were higher in nitrogen (mg L−1) (9. 8 ± 6.3) than either paths (2.3 ± 2.0) or controls (1.08 mg L−1 ± 1.5). Herbs were favoured by wombat disturbance, having a mean percentage cover of 27.8 ± 4.1 on burrow mounds compared to 14 ± 2.69 on controls, and a mean percentage cover of 51.6 ± 7.8 in toilets compared to 25.6 ± 4.8 in control plots. In contrast, shrubs have greater percentage cover in controls than on mounds (47.2 ± 12.0 cf. 12.7 ± 5.0) and toilets (37.3 ± 10 cf. 17.8 ± 6.5). Overall, wombat activity and modification of the alpine environment were concentrated in grassy vegetation above the winter water table, although paths, burrows and toilets extended into less grassy alpine communities. Our results imply that common wombats have a major role in engineering topography and soils with subsequent effects on vegetation, directly affecting at least 1.2% of the study area. Their reduction, or loss, is likely to lead to substantial changes in patterns of geodiversity and biodiversity.

Informal camping on the margin of wild country: Early indicators of degradation and potential for some positive nature conservation outcomes

“…All the grazing animals recorded from the sites preferred eating the herbs and short grasses that characterised the campsites to the tall shrubs and rushes that characterised the control area (Figure 4) (Heaton et al, 2022). However, wombats place their scats in toilets in areas not covered by their food plants, including the bare areas outside their burrows (Guy & Kirkpatrick, 2021). Food availability from fish cleaning and other rubbish and the high availability of potential prey appeared to have attracted Tasmanian Devils (Figure 5).…”

“…The Central Plateau provides a wide variety of habitats for animal species. The most common native herbivore species are the Bennett's Wallaby ( Notamacropus rufogriseus ) (Desmanret 1817) and the Common Wombat ( Vombatus ursinus ) (Shaw 1800) (Guy & Kirkpatrick, 2021). The endangered Tasmanian endemic carnivorous marsupial, the Tasmanian Devil ( Sarcophilus harrisi ) (Boitard) and the non‐native Rabbit ( Oryctolagus cuniculus ) (Linnaeus) are also common (Bridle et al, 2001).…”

Recreational fishers contribute to path formation in subalpine vegetation

“…The lack of predictability of the scat variables in our models for path width and depth indicates further that human trampling may be the main contributor to parallel path formation, as does the greater scat numbers on orthogonal paths than parallel paths. However, this difference might partly result from defecation in the heathier areas used for daytime shelter (Carter & Goldizen 2003;While & Mcarthur 2005) that are concentrated away from the shores of the lakes, as are Wombat burrows (Guy & Kirkpatrick 2021).…”

“…(Cyperaceae) and alpine sedgeland dominated by Pineapple Grass (Astelia alpina R. Br) (Liliaceae) (Pharo & Kirkpatrick 1994;Kirkpatrick et al 2019). In the study area, there are several native marsupial herbivores, mainly Bennett's Wallaby (Notamacropus rufogriseus) and the Common Wombat (Vombatus ursinus) (Guy & Kirkpatrick, 2021), while in the broader region, a Tasmanian endemic carnivorous marsupial, the Tasmanian Devil (Sarcophilus harrisi) (Boitard) and the non-native, European Rabbits (Oryctolagus cuniculus) (Linnaeus) are also found (Bridle et al 2001).…”

Strange bedfellows: Mammal burrow disturbances may provide thermoregulatory microsites for fossorial reptiles in densely vegetated dunes

“…Disturbance occurs at multiple spatial scales, with processes like fire generating heterogeneity at a landscape level, while at a local level burrowing animals are an important source of patch diversity (Kinlaw, 1999; Moretti et al, 2006). The diggings and burrows of mammals are important ecosystem processes responsible for nutrient redistribution (Huntly & Inouye, 1988) and concentration (Guy & Kirkpatrick, 2021). Moreover, burrows also provide thermoregulatory and hydroregulatory benefits for both burrow creators and interspecific burrow users (Thornett et al, 2017).…”