Exploring the role of normative benchmarks when gauging forthcoming effects of non-native species

The accelerating impacts of climate change compel conservation biology to rethink traditional approaches, including the rigid dichotomy between native and non-native species. Conservation efforts increasingly require adaptive, forward-looking strategies that acknowledge biotic novelty and prioritize ecosystem function and human well-being.

Non-native species, long viewed primarily as threats, may play vital roles in maintaining biodiversity and ecosystem services under future climatic regimes. Some are more likely to persist than native species, providing safeguards against extinctions and ensuring the continued provision of ecosystem functions such as pollination, carbon sequestration, or habitat structure. Novel ecosystems shaped by non-native species may also assist in species survival through processes such as hybridization or novel mutualisms.

In this presentation, I will address two related questions: (1) Can we identify distribution characteristics of non-native species that are desirable or undesirable? In other words, what might be the “ideal” distribution (presence and abundance) of non-native species in a rapidly changing world—both in absolute terms and relative to native species? (2) Empirically, what are the current distribution and abundance of non-native species at various spatial scales?

Most conservation strategies are silent about desired outcomes or implicitly use a “pristine” world as a benchmark. In addition, conservation biologists generally assume that the addition of non-native species to local ecosystems is undesirable because of the risk that some non-native species could become problematic or because they alter the “natural equilibrium.” Such benchmarks are increasingly obsolete in a rapidly changing world. I outline several alternative outcomes for the distribution of non-native species (relative to native species) and discuss their value in light of different worldviews or normative lenses (intrinsic, instrumental, relational values). I then quantify the relative abundance of non-native species at local and regional scales (numbers not available at the time of abstract submission) and discuss the empirical results in light of different theoretical and normative considerations.