Hot and happy? The future of invasive plant abundance in the eastern U.S.

Evans AE., Jarnevich C., Beaury EM., Teich N., Engelstad P., LaRoe J., Bradley BA. Shifting hotspots: Climate change projected to drive contractions and expansions of invasive plant abundance habitats. (2024). Diversity and Distributions,  30,  41–54. https://doi.org/10.1111/ddi.13787

Written by Annette Evans, reviewed by Bethany Bradley

Summary

Climate change is expected to exacerbate the spread and impacts of invasive species with hundreds of new invasive plant species projected to establish in the eastern United States (Allen & Bradley 2016). With limited resources, identifying which range shifting species to prioritize for monitoring and management can be challenging. One strategy is to prioritize species that are most likely to reach high abundance as these species are likely to have the greatest impact on ecosystems (Bradley et al. 2019). However, most current spatial models rely on species occurrence data (modeling habitat for where a species could occur), which often fail to accurately predict locations of species abundances.

In this study, Evans et al. (2024) used species distribution models based on abundance data for 144 invasive plant species already established in the U.S. to predict current and future hotspots where climatic conditions are suitable for abundant populations. Current abundance hotspots (areas with climate suitable for more than 30 abundant invasive plant species) are located in the Great Lakes region, mid-Atlantic region and northern coastal Florida and Georgia. Given a 2C climate change scenario, these hotspots will shift an average of 213 km north, with some areas becoming suitable for abundant infestations of up to 21 new invasive plant taxa.    

The extent of future abundance habitat varied widely across the species included in the study. The authors found that future climatic conditions are projected to increase the extent of abundance habitat for one third of the plant species included in the study. In contrast, for 62% of modeled taxa, future climate conditions are projected to be less suitable for abundant populations, leading to a projected overall decline in abundance habitat. The resulting species range maps and state-specific watch lists produced from this work can inform proactive regulation, monitoring, and management of invasive plants most likely to cause future ecological impacts.

Take home points

  • Climate change is projected to facilitate both expansion and contraction of habitat suitable for abundant populations of invasive plants. 

  • Abundance hotspots are projected to shift towards the northeastern U.S., where some areas will become suitable for up to 21 new invasive plant species.

  • Species specific range maps (both current and future range) are available as geotiffs at https://scholarworks.umass.edu/data/157/

  • Future abundance habitat projections for all 144 plant species included in this study are also available on EDDmapS via the species search engine (https://www.eddmaps.org/distribution/). Choose the ‘county’ option to see current and future projections of occurrence and abundance.

Management implications

  • State lists of invasive plants with future abundance habitat are available in the supplementary materials and online (see Appendix 4).

  • Species-specific maps of abundance habitat can inform early detection and rapid response by identifying areas where invasive plants are expanding. 

  • Areas where invasive plant abundances are projected to contract with climate change could be candidate sites for restoration.

  • Many invasive plants will remain abundant in locations where abundant populations are currently established thus current management strategies will need to be on-going for these taxa and locations.

Related papers: Allen & Bradley, 2016

Keywords Range shift, Climate change, Abundance habitat, Invasive plants, Hotspots, Species distribution model