Does grazing reduce survival of indigenous perennial grasses of the semi‐arid woodlands of western New South Wales?

Abstract

Abstract Exclosures were used to examine the impact of grazing upon the mortality patterns of populations of six indigenous grass species. The experiment compared unfenced areas with areas from which either sheep only or sheep, rabbits and kangaroos were excluded. There were large interspecific differences in mortality patterns, with Stipa nitida and Aristida browniana having relatively high mortality rates and Eragrostis eriopoda having relatively low mortality rates. Grazing‐induced mortality was observed in treatment areas that were grazed by sheep, rabbits and kangaroos and in areas grazed only by rabbits and kangaroos. The short‐lived S. nitida appears less likely to suffer grazing‐induced mortality than species of intermediate longevity such as Monachather paradoxa. These observations help explain the decline in endemic perennial grasses that has taken place in the vegetation of western New South Wales since European settlement. Management of these rangelands to encourage these grasses must consider total grazing pressure and not simply the impact of livestock.