Exotic herbivores dominate Australian high‐elevation grasslands

• Published in: Conservation science and practice 2022-02, Vol.4 (2), p.n/a
• Main Authors: Hartley, Renée, Blanchard, Wade, Schroder, Mellesa, Lindenmayer, David B., Sato, Chloe, Scheele, Ben C.
• Format: Article
• Language: English
• Subjects: Biodiversity; Density; Ecosystem degradation; Ecosystems; Elevation; Endemism; Environmental protection; Foliage; Forbs; Geographical distribution; Grasslands; grazing; Ground cover; herbaceous; Herbivores; Herbivory; Introduced species; Invasive species; Investigations; landscape elements; Livestock; mountain; National parks; nonindigenous; Nonnative species; non‐native; plant–herbivore interactions; Soil compaction; subalpine; Vegetation; vegetation structure; Weeds; Wildlife conservation
• ISSN: 2578-4854; 2578-4854
• DOI: 10.1111/csp2.601

Invasive species are major drivers of ecosystem degradation globally. How invasive herbivore impacts differ from native herbivore impacts remains understudied. We examined the relationships between herbivore sign and vegetation height, foliage density, cover of forbs, weeds, bare ground, and soil compaction across environmental and herbivore activity gradients in the mainland Australian Alps. We detected native and exotic herbivore sign at 32.8% and 94.0% of sites, respectively. Total herbivore activity was primarily attributed to exotic herbivores and was associated with elevation and grassland type. Greater horse (exotic) activity was associated with lower vegetation height, lower foliage density, higher forb cover, and higher soil compaction. Greater rabbit and hare (exotic) activity was associated with lower vegetation height, lower foliage density, and a higher cover of bare ground. Greater total herbivore activity was associated with greater weed cover. Neither deer (exotic) nor kangaroo and wallaby (native) activity was related to response variables. We demonstrate that exotic herbivores dominate mammalian herbivory in these grasslands, which evolved without analogous hooved species. Given the restricted distribution and high endemism of these ecosystems, and associations between exotic herbivores and characteristics of degraded grasslands, we recommend landscape‐scale exotic herbivore management, focusing on maintaining ground cover and vegetation structure. Horses in subalpine grasslands of the Australian Alps. Our study determined the mean vegetation height of the area pictured to be 8 cm, which contrasts with the description of the same area circa 1839 “… mostly covered with kangaroo grass that reached stirrup height …”