Basic ecological theory can inform habitat restoration for woodland birds

Abstract

Summary 1. Extensive clearing of native vegetation for agriculture has severely impacted upon Australia’s biodiversity. Environmental tree planting, forestry and restoration of existing remnant patches provide ways for improving the matrix habitat value between larger conservation areas. However, improved guidelines are required to inform land managers on appropriate ways to design these areas when resources for habitat improvement are limited. 2. We developed a simple habitat suitability model for woodland birds from two basic observations of ecology: (i) the species–area relationship and (ii) the relationship between bird species richness and vegetation structural diversity. The model provides a suite of species–area relationships for habitats of different structural diversity. Data from across Australia were used in developing the model to ensure its generality. 3. A single species–area relationship for patches from 2 ha to 16 million ha was estimated for high‐quality habitat patches using data from across mainland Australia. When this was combined with information on habitat complexity, the resultant species richness model was able to adequately describe the variation in woodland bird species richness within patches of various sizes (1–500 ha) in an independent data set from the Australian Capital Territory. 4. The results from the model suggest that for small patches of high quality, increases in patch size or quality reap benefits whereas the marginal return in species richness for increasing patch size is almost negligible for low quality patches above 10 ha or high quality patches of 20 ha. For small patches of low quality, there is little benefit in increasing patch area and so quality should be improved. These results agree with recommendations obtained using various other techniques. 5. Synthesis and applications. Investigation of the relationships embedded in the model provided similar recommendations for habitat restoration as determined by more detailed methods. The success of a simple combination of ecological principles linking area, structure and species richness supports the notion that existing basic theory can provide a sufficient basis for informing habitat restoration.