Researchers predict climate change will encourage invasive species

By Melanie Muller

Climate change will allow for a new wave of invasive species, according to an assessment performed by an international group of researchers who recommended that the United States Department of Agriculture introduce policies to guard against this impending environmental predicament.

Interviewed in a news release for the University of Massachusetts, Bethany Bradley of The Environmental Conservation Department, who led the effort, described the analysis she and her team had completed. She stated that as global average temperatures continue to rise, there will likely be increased demand for foreign heat and drought resistant import plants. Imports are by far the greatest cause of introduction of invasive species, according to Bradley. In turn, these newly imported plants will have an increased ability to survive in the warming conditions.

Even as this demand for imported plants rises, globalization and an increased number of trading partners in southeast Asia and the Middle East will be increasingly able to fill it. Bradley compared the potential tenacity of the new import to kudzu. The kudzu plant, a vine originally imported from Japan, came to dominate areas of southeast United States. It swathed entire trees, gullies and even houses in its green tendrils, killing the plants beneath by depriving them of sunlight.

The USDA has indicated that temperatures across climate areas in the U.S. have risen in the last two decades, changing previously colder areas to warmer climate zones according to their growing hardiness ranking system.

Until recently, new categories of non-edible imported plants, unlike fruits and vegetables, were not screened as potential pests by the USDA.. The USDA, however, having recognized that “plants for planting can carry a wide variety of pests that are more likely to become established in the United States” than those in fruits or vegetables, and that  “the plant itself also could be a pest,” has proposed a new category for possible imported plants. Plants in this category would have to undergo pest risk analysis prior to being authorized.

In her interview Bradley supported such a review process, suggesting that it was urgent the USDA impose the process. She also noted that similar rules had been used successfully in Australia for several years.

According to Bradley, 60 percent of invasive species are introduced as foreign imports, so the U.S.DA’s new regulations could have a great impact on preventing invasive species from getting their roots, leaves and tendrils entrenched in American ecosystems and overwhelming native plants.  Bradley’s group’s analysis was published in the Feb. 1 issue of Frontiers in Ecology and the Environment, and is now available in an early online version.

Melanie Muller can be reached at [email protected]