Optimising restoration and rehabilitation using environmental and spatial drivers of plant assemblages

Abstract

The extent, condition and connectedness of ecosystems has been significantly impacted by human activities globally, leading to a widespread appeal of and demand for ecological restoration. Maximising the ecological outcomes and cost effectiveness of restoration requires that plans be optimised by indexing the distribution, abundance and condition of habitat-forming species, and that target ecosystem conditions be developed in concert with restoration site attributes. This type of quantitative approach for creating malleable ecological targets which are informed by local environmental conditions is, however, uncommon. In this study, we surveyed the composition and coverage of understorey plants, and the composition and size of trees in coastal dunes at five transects at each of 20 sites (for n = 100) on the Sunshine Coast, central eastern Australia, and use this information to prioritise restoration sites and create optimised planting regimes for degraded sites. Each of the identified indicator species (six understorey and four tree species) had unique preferred conditions and was affected by multiple environmental and spatial variables at varying spatial scales, with most species affected by urbanisation. Species distribution models (SDMs) were used to identify target/reference ecosystems and optimal planting mixes for potential restoration sites given the site's environmental attributes. Our approach of integrating data on the distribution, abundance and condition of habitat-forming species into multiple SDMs can be used to optimise planting regimes at restoration sites and provides a framework for setting dynamic restoration targets across landscapes.