As climate continues to warm, study finds several barriers to northward tree migration

March 15, 2019 by Elyse Catalina, University of Maine
A low canopy tree species, staghorn sumac, grows in an invasive shrub thicket that otherwise lacks regeneration in New Jersey. Credit: Kathryn Miller

Extensive land development, invasive species and too many deer may make it difficult for tree migration to keep pace with climate change in the Northeast, according to newly published research.

The study, led by Kathryn Miller, a plant ecologist with the National Park Service Inventory and Monitoring Division, and Brian McGill, a University of Maine professor of ecological modeling, analyzed U.S. Forest Service data covering 18 states from Tennessee to Maine.

The researchers found a large swath of land in the mid-Atlantic states that was severely lacking in . Even where present, species regenerating on the were different than those making up the forest canopy.

Earlier studies have raised concern about regional regeneration, but this is the first to document the sheer extent and severity of the problem, according to Miller, who recently earned a Ph.D. from the UMaine School of Biology and Ecology.

Coining the term "regeneration debt" to describe this phenomenon, the researchers found the region simultaneously faces challenges of increasing invasive plants, deer overabundance and heavy land development by humans.

The zone of regeneration debt raises questions about the future of forests in the immediate region, but also far into the northeastern U.S., according to the researchers.

"I monitor health in eastern national parks, many of which have the same issues of overabundant deer, regeneration failure and mismatch, and numerous invasive plants," Miller says. "At some point, I started to connect the dots geographically and began to wonder if these problems are restricted to our parks or if they were a symptom of a larger regional problem. Recognizing that this is part of a larger regional issue was both a relief that it wasn't only us, and distressing at just how widespread the problem is."

Miller and McGill say combining this research with a 2018 study they conducted raises even more concerns. The earlier study simulated a century of seed dispersal for 15 across the eastern U.S. while taking into account current land development patterns.

"Our dispersal simulations revealed an area in the mid-Atlantic region with such extensive human land use that tree dispersal was effectively blocked from moving northward. The species most affected by this dispersal barrier are the same oak, hickory and pine species we found to be experiencing severe regeneration debt," Miller says. "Without intervention, we can expect long-term declines in in the region, and it will become a significant barrier against climate-driven tree migration. In fact, this may already be occurring, as migration studies have yet to detect a strong signal of northern expansion for these tree ."

The new study, "Compounding human stressors cause major debt in over half of eastern US forests," was published online in the Journal of Applied Ecology.

Explore further: Tropical forests naturally regrow quickly, but without species variety

More information: Kathryn. M. Miller et al. Compounding human stressors cause major regeneration debt in over half of eastern US forests, Journal of Applied Ecology (2019). DOI: 10.1111/1365-2664.13375

Related Stories

How can forests regenerate without birds?

April 30, 2018

Human activity continues to shape environmental systems around the world creating novel ecosystems that are increasingly prevalent in what some scientists call the Anthropocene (the age of humans). The island of Guam is well ...

Deer prefer native plants leaving lasting damage on forests

October 6, 2017

When rampant white-tailed deer graze in forests, they prefer to eat native plants over certain unpalatable invasive plants, such as garlic mustard and Japanese stiltgrass. These eating habits lower native plant diversity ...

Natural regeneration may help protect tropical forests

November 21, 2016

A new article summarizes the findings of 16 studies that illustrate how natural regeneration of forests, a low-cost alternative to tree planting, can contribute significantly to forest landscape restoration in tropical regions.

Recommended for you

Study reveals properties of a Type Ib supernova in NGC 4080

March 25, 2019

A recent study conducted by astronomers has revealed important observational properties of a Type Ib supernova designated MASTER OT J120451.50+265946.6, which exploded in the galaxy NGC 4080. The research, presented in a ...

Catalyst advance removes pollutants at low temperatures

March 25, 2019

Researchers at Washington State University, University of New Mexico, Eindhoven University of Technology, and Pacific Northwest National Laboratory have developed a catalyst that can both withstand high temperatures and convert ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.