Potential invasives, or long-lost neighbors? Pros and cons of managed relocation of southern plants to New England
Written by Audrey Barker Plotkin, edited by Jenica Allen
Summary
Rapid climate change is outpacing plants’ dispersal abilities, prompting concerns about extinctions and proposals for managed relocation. But are we risking new harmful invasive plants if we move new species to New England? Bellemare et al. (2017) suggest that the risks may be lower than we fear, and that with care, New England can help endemic plants from the southeastern U.S. thrive in a changing climate. The plants of the eastern U.S. have repeatedly advanced north and retreated south during glaciations; New England’s flora most likely co-existed with southern flora in glacial refugia throughout the Pleistocene and therefore have a shared ecological history. Most of the plants in New England have broad climate tolerances and geographic ranges (one of their secrets to successfully migrating here after the last glacial maximum!), but some southern U.S. plants are endemics with very small ranges. These endemics are unlikely to have invasive traits, and with careful screening and planting in controlled environments, botanists, researchers, and plant-lovers can work together to protect the biodiversity of the eastern U.S.
Take home points
Most plant species native to New England have broad geographic ranges and migrated to the region after past glaciations, so are likely more resilient to immediate extinction risk from climate change, unlike hotspots of plant endemism in the southeastern U.S.
The risk of southeastern U.S. endemic plants becoming invasive in New England is low, because these species have likely co-existed with the current New England flora in the past, and typically have low dispersal ability compared to the current New England flora
What about hybridization? Again, these plants have likely encountered one another in the past so barriers to hybridization are likely already evolved (e.g., Anderson and Hill (2002) suggest that the late autumn flowering of the widespread Hamamelis virginiana L. might be niche partitioning with the late winter-early spring flowering H. vernalis Sargent, now an endemic southeastern species).
Management implications
Any managed relocation efforts planned in the future should include invasion risk screening based on plant traits and habitat affinity. Be especially cautious about aquatic plants.
A collaborative network of field botanists, land managers, conservationists, and academics in New England and the southeastern U.S. could test the viability and ecological effects of climate-threatened southeastern U.S. endemic plant species in New England.
Keywords
Range expansion; Review; Managed Relocation; Range Shifts; Plant; New England; Assisted Migration; Climate-smart Restoration