Science Story

Native Trees Naturally Fight Invasive Plants in Some Eastern Forests

Eastern Forest Environmental Threat Assessment Center
February 24th, 2016 at 4:30PM

A non-invaded hardwood forest in the Southern Appalachians In this modern society, non-stop movement of people and goods means that invasive species will continue to move and spread, too. Recent research indicates that invasive plants can be found in nearly half of the forests of the eastern United States, raising concerns about the sustainability of these ecosystems and the benefits and services they provide. The good news is that some eastern forests seem to have a natural ability to resist invasion. To understand why, a team of U.S. Forest Service and university researchers looked for clues within “big data” from the Forest Inventory and Analysis (FIA) program.

With these big data—information collected from more than 42,000 FIA research plots surveyed across the East—the researchers used innovative statistical models to study the associations between native trees and invasive plants. “At the landscape scale, we found that more native tree biomass and greater evolutionary diversity meant that invasive plants were less likely to be established or to become dominant if they were established,” says Kevin Potter, a North Carolina State University scientist working with the Eastern Forest Environmental Threat Assessment Center and an author of the study, recently published in the journal Landscape Ecology. Evolutionary diversity, which refers to species’ genetic relationships (much like a family tree), appears to play a more significant role in limiting the dominance of invasive species than preventing their establishment.

Greater evidence of invasion resistance emerged in patterns seen in some forests of the Upper Midwest and in and around the Appalachian Mountains. “These regions may exhibit ecosystem characteristics that allow native biomass and evolutionary diversity to more effectively prevent invader establishment and dominance,” says Potter. More research is needed to understand the ecosystem processes and spatial variables at play in these areas.

An eastern hardwood forest invaded by English ivy and other non-native plants The researchers’ use of big data across such a large spatial scale and their application of sophisticated evolution-based measures of biodiversity uncover trends that bring new thinking to the issue of forest invasions and the importance of native trees. And with this new thinking comes further inquiry, according to Basil Iannone, a researcher with Purdue University and the study’s lead author. "These findings raise important new questions about how we quantify biodiversity, about the mechanisms by which different metrics of biodiversity impact invasion and other ecological processes, and about how these mechanisms vary across large geographic areas. Answering these questions will provide valuable insights into how to best manage forests and other ecosystems," says Iannone.