Two-thirds of all forest inventory plots in the Northeast and Midwestern United States contain at least one non-native plant species, a new U.S. Forest Service study found. The study across two dozen states from North Dakota to Maine can help land managers pinpoint areas on the landscape where invasive plants might take root.
"We found two-thirds of more than 1,300 plots from our annual forest inventory had at least one introduced species, but this also means that one-third of the plots had no introduced species," said Beth Schulz, a research ecologist at the Pacific Northwest Research Station who led the study, which is published in the current issue of the journal Environmental Monitoring and Assessment. "By describing forest stands with few or no introduced species, we help managers focus on areas where early detection and rapid response can be most effective to slow the spread of introduced and potentially invasive plant species."
Nonnative, or introduced, plants are those species growing in areas where they are not normally found. Whether they were intentionally released or escaped cultivation, nonnative plants ultimately can become invasive, displacing native species, degrading habitat, and altering critical ecosystem functions.
Schulz and her colleague Andrew Gray, a research forester at the station, analyzed data gathered by the Northern Research Station's Forest Inventory and Analysis (FIA) Program, which collects and reports statistics on the condition of forests in a 24-state region as part of its regular surveys. The data set, collected from 2001 to 2008, includes a sample of all trees, shrubs, vines, herbs, grasses, fern and fern-like plants conducted on a subset of the region's FIA plots.
Among the study's findings:
The study's results can help focus research on individual species more widely distributed than previously thought or with yet-unexplored potential to become problematic.
The Pacific Northwest Research Station—headquartered in Portland, Ore.—generates and communicates scientific knowledge that helps people make informed choices about natural resources and the environment. The station has 11 laboratories and centers located in Alaska, Oregon, and Washington and about 390 employees.
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