April 4, 2010

Non-Native Plant Species Invading The U.S.

Brooklyn Botanic Garden researchers has released a 20-year study which offers a grim outlook on the future of some native flora in the United States, according to a recent Associated Press (AP) report.

The project has identified 50 native species that have disappeared from metropolitan New York in the last 100 years, as well as others that have become far less abundant because of factors like habitat destruction, pollution and competition from foreign interlopers.

In some areas, the landscape has become less biologically diverse.

"While you used to have a marsh of 50 or 60 species, you might now have an entire marsh of phragmites, the common reed," Moore said.

The study's focus was on counties 50 miles of New York City, however experts say other scientists have discovered similar results.

In the West, sagebrush has been taken over by cheatgrass, which has found its way to the U.S. by packing materials and ship ballast from the late 1800s.

Nature lovers that stroll through the wooded glades and think they are among trees that have stood since the Revolution are actually looking at Norway Maple native to Europe.

A Japan and China native plant known as Kudzu has infested the South after farmers in the 1930s through the 1950s used it to stop soil erosion.

Grand Teton National Park in Wyoming is now populated with Houndstongue and Yellow Toadflax, both Europe native plants.

Scientists say that the American landscape is slowly becoming less American.

"We are going to our national parks now and seeing Europe," Tom Stohlgren, a research ecologist for the U.S. Geological Survey, told AP's David Caruso. "We are homogenizing the globe at a very fast rate."

Experts say the trend has many causes, but the number one cause may turn out to be globalization.

European traders and settlers have been bringing Old World plants to the U.S. since colonization.  The process has accelerated with every advance in travel.

Foreign species now arrive so frequently aboard planes, trucks and cargo ships that the odds of the next Oriental Bittersweet arriving are exponentially greater.

"That's the scary part, and the $64,000 question," Stohlgren said. "What we have had is an explosion in trade and transportation, and we have yet to see the full effect of that."

"It took 170 million years for the continents to drift apart, but only 400 years to move them all back together," he said. "I describe this as Darwin on steroids, and we are going to see extremely fast changes because of it."

Peter Raven, president of the Missouri Botanical Garden in St. Louis, told Caruso in an interview that climate change and pollution may only worsen the problem, as they make the habitat of many native plants less hospital.

"Obviously the loss of wild areas and their reduction in size makes it harder for natives to persist. As global warming proceeds, it will get worse," he said.

The U.S. and the rest of the world are honed in on the problem.

The Nature Conservancy, which is a leading environmental group, has persuaded major home and garden retailers to stop selling invasive trees like the Norway maple and Lombardy poplar in certain areas.

It has also been working with researchers and government regulators on developing models that could predict when a nonnative plant might have the potential to become invasive.

Several states have established advisory committees on invasive species, and a few banned the sale of some plants.

The U.S. Coast Guard has been working on draft regulations for ballast water, which prevents ships from picking up invasive aquatic organisms on foreign coast and bringing them into North American waters.

Brooklyn Botanic Garden researcher's survey has found that wildflowers like the Scarlet Indian Paintbrush, pennywort, Sidebells wintergreen and the Sundial lupine have all seriously declined in the region.

Camphor weed, which is only found in the South, has now become comment throughout the metropolitan area.

"There is still a lot of native diversity out there, but this is an alarm," said Troy Weldy, director of ecological management for the Eastern New York chapter of the Nature Conservancy, and co-author of the New York Flora Atlas.

He said that species shift due to globalization "could turn out to be much more of a threat than climate change."


Image Caption: Kudzu has infested the South after farmers in the 1930s through the 1950s used it to stop soil erosion. Credit: Scott Ehardt/Wikipedia


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