Invasive plants are increasingly altering the structure and function of our natural environment, and now researchers have determined how far-reaching the problem has become.
According to a study conducted by U.S. Forest Service and university scientists and published in the journal NeoBiota, at least one invasive species is present in 39 percent of forested plots sampled nationwide for invasive plants by the Forest Service Forest Inventory and Analysis (FIA) program. Results are provided for all U.S. regions and reveal that a significant portion of the more than 741 million acres of forested land in the United States has been invaded.
Eastern forests have higher invasion-intensity — that is, a higher percentage of FIA sample sites containing invasive plants of concern in the region or individual states within — than western forests (46 percent vs. 11 percent). Hawaii’s forests have the highest invasion-intensity (70 percent), while forests in Alaska (6 percent) and the Intermountain region (6 percent) have the lowest invasion-intensity. The researchers created a U.S. map of invasion-intensity to illustrate the extent of the problem and help inform management actions across the landscape.