Umbrella, flagship and keystone species are among the most widely employed surrogate species concepts. We explored whether these concepts are useful for understanding the consequences of landscape change. We assessed the literature on surrogate species in relation to landscape change and identified key foci and notable gaps within the existing evidence base. We outlined strengths and limitations of surrogate species as proxies for landscape change.
We found that few studies evaluated whether taxa claimed to be surrogate species were in fact robust proxies. This is particularly so for flagship species but is also common in work on umbrella species. We also found marked differences in how the terms and concepts of umbrella, flagship and keystone species were used, both between studies and between disciplines (e.g. forestry versus community ecology). Research into surrogates is often conducted independently of research on landscape change. This leaves a major gap in knowledge about how surrogates can inform decision-making in relation to ongoing threatening processes, including landscape change.
Based on results of our literature search and insights from large-scale, long-term empirical studies in south-eastern Australia, we identified a diverse mix of examples where the application of surrogate approaches has been successful, and where it has not. However, it is currently not possible to determine a priori where a given surrogate approach will work. Resolution of this problem requires considerable further work. Surrogates should be used in a critical way to help avoid mistakes in resource and biodiversity management.