A framework to predict the effects of livestock grazing and grazing exclusion on conservation values in natural ecosystems in Australia

Abstract

Grazing by domestic livestock has greatly degraded many Australian ecosystems and its legacy will be long-lasting in many areas. Although livestock are usually removed from conservation reserves because they are perceived to be incompatible with the conservation of natural ecosystems, they have been retained in several reserves in south-eastern Australia as a management tool to achieve conservation outcomes. These cases highlight the fact that no framework currently exists to address the question, under what circumstances (and in what ecosystems) is livestock grazing—or the removal of grazing—likely to have positive, negative, neutral or uncertain impacts on the diversity and composition of native plants? This paper provides a conceptual framework to predict the effects of livestock grazing and grazing exclusion on the conservation values of native vegetation across natural ecosystems in Australia. It should prove equally relevant to other ecosystems around the world which have evolved without heavy grazing by large herbivores. The framework is based on disturbance- and grazing-ecology literature from Australia and elsewhere, and incorporates the following six main factors: (1) impacts of livestock grazing on soil and ecosystem processes, (2) historical exposure to grazing, (3) site productivity, (4) relative palatability of dominant species, (5) species-specific factors influencing plant recruitment and (6) spatial scale and landscape context. These factors are integrated into a decision tree to describe the potential impacts of livestock on native vegetation in a particular area. Livestock grazing is likely to have detrimental impacts on conservation values in many ecological contexts, especially in relatively intact, uninvaded ecosystems on unproductive soils. By contrast, it may be a useful management tool to achieve conservation objectives where it either (1) controls the biomass of existing potentially dominant, grazing-sensitive plants (native or exotic), (2) prevents encroachment by undesirable, grazing-sensitive, potential dominants, (3) provides disturbance niches required by rare or significant plant species, (4) maintains fauna habitat structure or (5) enhances the diversity of species and vegetation structures across the landscape, especially when most of the landscape is ungrazed. In many cases, other disturbance regimes (especially burning) may achieve similar outcomes; however, other disturbances will not necessarily be more effective than grazing per se, especially in degraded or invaded areas. The framework provides a coarse-level filter to inform management decisions and to allow the findings from individual studies to be placed in a larger ecological context. Although the framework is intended to improve decisions about conservation management, it is clear that much more research is needed to assess the role of grazing exclusion in previously grazed ecosystems, and that modifications to current grazing regimes require testing, perhaps by using adaptive management principles, to ensure optimal outcomes for biodiversity conservation.

The importance of grasslands for animal production and other functions: a review on management and methodological progress in the tropics

“…High biodiversity is threatened by anthropogenic factors including livestock grazing, land clearance, introduction of exotic species, soil cultivation, fertilizer application and altered fire management (Lunt et al, 2007;Prober and Smith, 2009). Livestock, as the largest user of grasslands, increases pressure on ecosystems, natural resources and biodiversity (Lunt et al, 2007;FAO, 2009).…”

“…Livestock, as the largest user of grasslands, increases pressure on ecosystems, natural resources and biodiversity (Lunt et al, 2007;FAO, 2009). Extensive grazing animal systems generally use a wide range of plant resources for livestock feed and impose variable pressure on habitats.…”

Ecosystem structure, function and composition in rangelands are negatively affected by livestock grazing

“…The economies of many people, particularly from rural areas, depend on the provision of goods and services such as milk, meat, wool, and hide derived from livestock. The economic importance of grazing and the reports of positive or neutral effects of grazing on species richness in specific studies (e.g., Socher et al 2013, Fensham et al 2014, Kimuyu et al 2014 has led some to suggest that introducing or reintroducing commercial herds of livestock to intermittently grazed or ungrazed areas (e.g., alpine high country of Australia; Williams et al 2006) might have benefits for biodiversity and ecosystem functioning (Lunt et al 2007, Williamson et al 2014). …”

“…The most obvious functional effect is a direct reduction in net primary productivity through herbivory (Milchunas et al 1988), resulting in reduced decomposition and changes in the amount and distribution of litter and dung. Grazing also compacts soils, increases erosion, and alters soil hydrological processes (Lunt et al 2007). Together these direct and indirect effects of livestock grazing can have pronounced legacy effects on soils and landscapes that diminish their capacity to maintain key ecological processes, such as decomposition and nutrient flows (Lunt et al 2007).…”

Application of an integrated multidisciplinary economic welfare approach to improved wellbeing through Aboriginal caring for country

“…European settlement and the dispossession of Aboriginal people from country led to changes in land management practices, the introduction of exotic species, and ecological alterations (Gale and Haworth 2005;Lunt et al 2007;Edwards et al 2008). The resulting decrease in the mosaic of burnt/unburnt areas led to an increase in the occurrence, intensity and extent of wild fires over the drier, hotter months, and the release of biologically sequestered greenhouse gases due to the loss of woody plants (Edwards et al 2008).…”