A demographic framework for the adaptive management of the endangered arid-zone tree species Acacia peuce

Slow-growing desert tree species pose unique conservation challenges; their demography is driven by rare stochastic climatic events, remoteness of populations makes monitoring difficult and, consequently, their management is often information-limited. In particular, the paucity of information on vital rates at a relevant temporal scale makes analyses of demography and population viability difficult. Our objective was to undertake a demographic analysis of the threatened arid-zone tree species (Acacia peuce F.Muell.) that is a model system in terms of being (1) a slow-growing desert tree species whose recruitment is limited to stochastic and rare extreme rainfall events, and (2) a species of conservation significance growing in a remote location where remoteness imposes limitations on conservation monitoring. Complementary analyses using pattern- and process-derived matrix population models, based on a dataset derived from a 30-year monitoring effort, verified that the smallest of the A. peuce populations would continue to grow under current environmental conditions. Population growth in this species is most influenced by the survival or adult and sapling stages. Stochastic demographic simulations revealed that climate change is likely to significantly elevate the risk of population decline, particularly in fragment stands. The long-term viability of A. peuce hinges on sustaining the survival rates of adult and sapling stages by managing stresses to individuals in these stages, and through minimising anthropogenic disturbance to populations during rare, stochastic and extreme rainfall events that trigger recruitment. Extending the current non-binding agreement enabling the use of fences to exclude cattle, and improved interpretative signage to raise awareness of anthropogenic impacts on this species will significantly aid conservation of this species. The integration of modelling, monitoring, and management within a demographic framework can facilitate efficient and effective conservation of slow-growing arid-zone tree species, despite the challenges imposed by remoteness.