Grazing management of Australian native woody regeneration as an effective nature-based climate-change solution

Rangelands are playing a major role in delivering ~50% of the Australian land-sector abatement across some 42 million ha. Carbon credits are an incentive for the regeneration of native woody vegetation through grazing management that remove past suppression activities preventing the establishment of forest cover.1 Although there are divergent views on the use of grazing management as a credible land management activity and carbon market mechanism, guidelines to support effective woody regeneration outcomes are lacking. We review the literature, adopting a case-study approach for the semi-arid rangelands in south-eastern Australia, asking ‘What is the capacity for grazing management to influence patterns of woody recruitment and growth’? The role of grazing in the context of woody plant encroachment and life stages of regeneration for mulga (Acacia aneura) were examined. We identify climate as the primary driver setting the potential for carbon accumulation and outline the capacity of grazing management to directly and indirectly affect temporal patterns of accretion, to influence initial site condition, germination and establishment, growth and mortality. Grazing management will determine the direction and pattern of carbon accumulation by influencing (i) the size of the seed pool available to commence the regeneration process and buffer the effects of preceding fire on seed production; (ii) the functionality of the landscape, suitability of seedbed conditions and resource retention; (iii) the successful establishment of woody seedlings through herbivory or trampling; (iv) the growth rate of young plants and time required to reach reproductive maturity or forest canopy height; and (v) fuel availability and the capacity to manage fire. On the basis of this information, we develop broad grazing management principles and guidelines. The question is therefore not about whether specific grazing management is essential to allow regeneration to occur, but the extent to which grazing management can allow the potential set by climate to be realised.