Density-dependent grazing impacts of introduced European rabbits and sympatric kangaroos on Australian native pastures

摘要: Little information is available on relationships between pest animal density and damage in natural ecosystems. Introduced European rabbits, Oryctolagus cuniculus, cause severe to Australian native vegetation but density–damage are largely unexplored. There no recognized simple methods estimate their impacts pastures, due part confusion with grazing impact of other herbivores. We tested quantitative sampling using multiple small quadrats detect site differences pasture cover, species richness dung pellet herbivores, from which rabbit relative abundance larger herbivores were estimated. Native cover declined exponentially increasing density, within the range 0–5 rabbits ha−1, while unpalatable exotic increased. By contrast, kangaroo was positively related palatable negatively weeds, had negative effect or that discernable against a background low moderate densities. Perennial forbs perennial grasses replaced invasive Wards weed as dominant ground at conclude that, regardless previous history, contemporary pressure invasion, severely degraded state pastures perpetuated by rabbits. The can be recorded manner suitable for identifying presence changes over time. This method seen particularly useful setting target densities below must managed maintain plant communities ecosystem function southern Australia. It may also demonstrate rabbits’ regions, including optimum biodiversity benefits range.