Habitat‐ and rainfall‐dependent biodiversity responses to cattle removal in an arid woodland–grassland environment

Abstract

Biodiversity conservation in rangeland environments is often addressed by removing livestock, but inconsistent responses by biota mean that the efficacy of this form of management is hotly debated. Reasons for this inconsistency include the usually short duration and small spatial scale of manipulations compared to the area of grazing properties, as well as divergent responses amongst biota. In low‐productivity arid environments, the pulse‐reserve dynamic also complicates the outcome of manipulations. Here, we tested and extended these ideas in a heterogeneous desert environment in central Australia that consists of small patches of open woodland (gidgee) in a grassland (spinifex) matrix. Taking advantage of a controlled property‐scale removal of cattle, and a rain event that stimulated productivity, we first quantified differences in the vegetation and small vertebrates of these two habitats, and then tracked the diversity, composition, and abundance of these biota for 6–19 months post‐rain. We predicted that the two habitats would differ in the structure, composition, and reproductive output of their constituent plant species. We predicted also that the effects of cattle removal would interact with these habitat differences, with the abundance, richness, and diversity of small mammals and reptiles differing across habitats and grazing treatments. As anticipated, plant species composition in woodland was distinct from that in grassland and varied over time. The effects of cattle removal were habitat specific: Plant composition responded to de‐stocking in woodland, but not in grassland; flowers were more abundant, and palatable plant cover also was greater following cessation of grazing pressure. The responses of small mammals but not reptiles showed some accord with our predictions, varying over time but inconsistently with treatment, and perhaps reflected high variability in capture success. We conclude that the timing and length of sampling are important when evaluating the responses of biota to livestock removal, as is the inclusion of all key habitats in the sampling regime.

Ecology and predator associations of the northern quoll (Dasyurus hallucatus) in the Pilbara

“…Riparian areas and shrublands ranked high in vegetation diversity, while rocky habitats ranked high in temporary and permanent cover (dens). This is consistent with observations that arid environments have patches of more productive areas embedded in a matrix of lower productivity (Frank et al 2014b). In my study area, shrublands, riparian, and rocky patches were embedded within spinifex grasslands.…”

Long‐term livestock exclusion facilitates native woody plant encroachment in a sandy semiarid rangeland

“…Livestock removal is often considered an essential tool for vegetation restoration and conservation in arid and semiarid rangelands (Frank et al. ). However, little is known about how livestock removal affects woody encroachment because isolating the effects of browsing on rangeland woody plant dynamics requires long‐term, controlled livestock exclusion experiments, which are rare in Eurasian rangelands (Wesche and Treiber ).…”

“…For example, Maher et al (2010) found that an absence of kangaroos in fenced plots in kwongan of southwestern Australia would result in the much more extensive and rapid encroachment of Allocasuarina huegeliana than it would in unfenced plots. Livestock removal is often considered an essential tool for vegetation restoration and conservation in arid and semiarid rangelands (Frank et al 2014). However, little is known about how livestock removal affects woody encroachment because isolating the effects of browsing on rangeland woody plant dynamics requires long-term, controlled livestock exclusion experiments, which are rare in Eurasian rangelands (Wesche and Treiber 2012).…”

The impact of grazing on seedling patterns in degraded sparse‐elm grassland

“…Other study showed that increasing grazing pressure changes chemical and physical properties of topsoil, enhancing soil degradation processes, and eventually affecting the structure of vegetation (Kölbl et al, ). Grazing can stimulate growth of some grazing‐tolerant plant species and contribute to changes in species diversity, and productivity (Augustine & McNaughton, ; Frank, Wardle, Dickman, & Greenville, ). This result supported the concept that grazing had a significant effect on the contribution of some functional groups shaping the structure of vegetation (Bermejo et al, ).…”