Seminar: Exploring the Roles of Non-Native Species Under Rapid Environmnetal Change

Non-native species, long viewed primarily as threats to biodiversity, 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. I then quantify the relative abundance of non-native plant species within Switzerland and discuss the empirical results in light of different theoretical and normative considerations.

Dr. Martin A. Schlaepfer is a conservation biologist and Senior Lecturer at the University of Geneva’s Institute for Environmental Sciences. He is trained a field ecologist and early work explored the effects of habitat fragmentation and invasive species on biodiversity. Increasingly his work focuses on how societal values shape conservation priorities and scientific practices. Schlaepfer also co-founded GE-21, a Geneva-based network promoting biodiversity and ecosystem services through research, collaboration, and practical conservation initiatives.