Katz, D. S., & Ibáñez, I. (2016). Biotic interactions with natural enemies do not affect potential range expansion of three invasive plants in response to climate change. Biological invasions, 18(11), 3351-3363. PDF.

Summary

Non-native species distributions are expected to shift with climate change, but range expansion into new habitats may be affected by the different communities of natural enemies that the invading species encounter. Using a seedling transplant approach, Katz et al quantified foliar disease and insect feeding damage for three invasive plant species (Berberis thunbergii, Celastrus orbiculatus, Elaeagnus umbellata) planted into southern Michigan forests where they are currently common, as well as areas near their northern range edges, where they are projected to increase in abundance. Over the four year study, insect feeding damage was greater for individuals of all three species at the range edge, where both B. thunbergii and E. umbellata also experienced more pathogen damage relative to plants within the interior range. However, neither insect herbivory nor pathogens were statistically significant in explaining survival patterns for the three species, with the exception of a minor effect of foliar disease on B. thunbergii. Results suggest that “differences in biotic interactions are unlikely to play a major role in range expansion.” Without more evidence from other systems, the authors caution about making generalizations about the impacts of natural enemies in moderating range expansion for other invasive species.

Take home points

  • Insect damage was greater for invasive species individuals at the range edge compared with the range interior.

  • Overall low levels of insect and pathogen attack, although different between the range edge and interior, did not significantly influence survival of the invasive plants.

  • Natural enemies are unlikely to suppress future range expansion of these plants, at least on a large scale.  

Management implications

Don’t rely on the resident communities of natural enemies to suppress invasions of non-native plants nor limit their range expansion!

Keywords

Range Expansion; Observational; Invasive Plant; Terrestrial Habitat; Risk Assessment