Choose Local: Dung Addition from Native Herbivores Can Produce Substantial Positive Effects on the Growth of Native Grasses Compared to Livestock Dung

Abstract

AbstractLivestock grazing and dung deposition can increase soil nutrients, contributing to the dominance of exotic species. Recent research suggests that native herbivore grazing has positive effects on native vegetation and soil health. However, little is known about the effects of native herbivore dung on plant growth and its potential implications for the restoration of degraded grasslands. This study examined the effects of dung addition from a native herbivore, kangaroo (Macropus giganteus), and ruminant livestock, sheep (Ovis aries), on biomass production and nutrient uptake of the native perennial wallaby grass (Rytidosperma auriculatum) and the annual exotic wild oat (Avena barbata), two of the most abundant grasses from the temperate grasslands of southern Australia. We conducted a glasshouse experiment, adding each type of dung to each plant species grown without competition in pots containing soil with a nutrient composition similar to that of old fields. Kangaroo dung produced higher wallaby grass aboveground biomass than other treatments and less wild oat aboveground biomass than the control. Kangaroo dung affected nutrient uptake but not nutrient concentration. Sheep dung had no effect. We demonstrated that native herbivores and livestock dung can have different effects on the biomass of native and invasive grasses. The higher nutrient uptake in wallaby grass appeared to be a consequence of the higher biomass production, suggesting that the effects produced by kangaroo dung could be related to its chemical and biological characteristics rather than its nutrient composition. Incorporating native herbivores’ dung or facilitating their presence can improve restoration outcomes in degraded grasslands.