The Nebulous Ecology of Native Invasions

Nackley, L. L., West, A. G., Skowno, A. L., & Bond, W. J. (2017). The Nebulous Ecology of Native Invasions. Trends in ecology & evolution. PDF.

Summary

In an era where few ecosystems resemble the past, and species are shifting out of habitats they historically colonized, invasion biologists and managers may need to reconsider the inclusion of native species when deciding what makes a species invasive. Grouping species by origin eases decision and policy making, but what origin based on political boundaries tell us about the impact of a species on its resident ecosystem is limited. Nackley et al. (2017) provide several examples of native species shifting ranges into new habitats resulting in impacts comparable to those of functionally similar exotic species. For example, in the U.S. native trees (e.g. Juniperus virginiana) are expanding into grasslands, reducing resource availability and changing fire regimes. Expansion of exotic species results in similar structural changes to grassland ecosystems. To refrain from biasing our understanding of invasion ecology, and possibly ignoring a species with high negative impact because of its origin, Nackley et al. (2017) recommend that researchers consider expanding studies to include native species, and managers base management and prioritization off of impact and conservation of high priority areas.

Take home points

  • Considering only exotic species to be invasive may no longer be a good strategy to combat invasions given that climate change causes species to shift their ranges into habitats they may not historically be adapted to. 

  • Making decisions based on empirical evidence and using more mechanistic models can help researchers and managers navigate some of the blurred lines in invasion biology (e.g. definitions, supporting dynamic ecosystems vs. historical landscapes, barrier of policy)

Management implications

  • Nackley et al. (2017) recommend prioritizing species based on quantified impacts, traits, and presence in high priority areas for conservation. They also recommend reconsidering natives in your definition of invasive. 

  •  Local policies regarding invasive species may improve our ability to handle the context-specific nature of invasions.

  • Comparing invaded and un-invaded sites can help frame decision-making based on the rate of change of an area.

Keywords

Range Expansion; Impact Study; Review