Thursday, June 5, 2008

Invasive Species ~ Thursday Thirteen #19

13 Non-native Invasive Species

In anticipation of the state-wide Let's Pull Together campaign, I thought I would list a number of invasive species that are contributing to the demise of our natural resources and costing billions of dollars to control.

1. Scotch Broom - Introduced to the Pacific Northwest by early settlers as an ornamental, it forms dense stands which crowd out native species and destroy wildlife habitat. Scotch Broom has plenty of help from people to move it to new sites. Its seed is a regular hitchhiker on vehicle tires, heavy equipment, and in infested gravel. Seedpods split suddenly at maturity and eject the seeds. Also, it is reported that ants aggressively collect the seed of Scotch broom, assisting in dispersal. Birds also assist with spread, but how well the seeds survive digestion varies with the species of bird.

2. Purple Loosestrife - An invasive wetland plant that is beautiful, but dangerous. Imported in the 1800s for ornamental and medicinal uses, Purple Loosestrife poses a serious threat to wetlands because of its prolific reproduction. Unfortunately, it is still sold as an ornamental plant in many states. Purple Loosestrife has gained a strong foothold in many North American wetlands, rivers and lakes, including many in Oregon.

3. Quagga & Zebra Mussels - One of the nastiest invaders, it isn't yet found in Oregon but it's arrival is feared by biologists. An adult female zebra mussel is one of the most reproductive organisms in the world. It may produce between 30,000 and 1 million eggs per year. These mollusks disrupt ecosystems, killing the local species primarily by out-competing them for food, damaging harbors, boats, and power plants. Water treatment plants were initially hit hardest because the water intakes brought the microscopic free-swimming larvae directly into the facilities. The U.S. Coast Guard estimates that economic losses and control efforts cost the United States about $5 billion each year.

4. Gypsy Moths - Introduced by an entomologist in Massachussets in the late 1860s. Oregon biologists are also concerned about Asian moths which have also been discovered traveling on ships and arriving at our ports. Eradication measures across Oregon have been successful in preventing the Gypsy Moth from developing a strong-hold in the state. They are 'hitchhikers' and the females lay their eggs on most anything (cars, lawn art, etc.) and are thereby transported to other areas unknowingly.

5. Himalayan Blackberry - Brought to Oregon in the late 1800s for the state's booming berry business. Although it didn't catch on as a berry crop, it has had lasting effects on our landscape and economy costing the state tens of millions of dollars a year. They are aggressive and dominate, excluding desirable plants and native animals. The difficulty in removing the significant root reserves, contributes to the reproductive success of this invasive blackberry.

6. English Ivy - Brought to Oregon to decorate gardens and hanging baskets. As ivy climbs a tree it chokes out the host and contributes to the loss of biodiversity.

7. Nutria - Brought to the United States in the 1800s for the fur market. They were introduced to Oregon in the 1930s just before the market crashed. Nutria are prolific feeders (eating the rushes, sedges, and bullrushes that filter the wetland water) and avid burrowers (contributing to erosion).

8. Oriental Weatherfish & Banded Killifish - Many introduced species are the result of illegally dumped aquarium fish. Both species can impact native species by direct predation or competition for food sources.

9. Feral Pigs - Feral Pigs carry diseases that spread to wildlife and domestic animals, destroy native plants, and damage agricultural crops.

10. Bullfrogs - Eating anything that moves and that will fit into their mouth, bullfrogs are voracious predators. Introduced into Oregon as a sport and food source in the early 20th century, they have been here so long, many people don't realize they are invasive.

11. European Beach Grass - Originally planted as a dune stabilizer along Oregon's beaches, European beachgrass is an aggressive colonizer of beach areas that forms a dense mat of grass and rhizomes, unlike any of the native dunemat species. The beachgrass captures sand, decreasing natural sand movement, and causing the dunes to increase in height. As the dunes increase in height and the normal ocean breeze diminishes behind the dunes, a new microclimate develops that is no longer suitable for dunemat species. Succession ensues toward more inland native coastal vegetation types and colonization by other exotic plant species, until the integrity of the entire native dunemat ecosystem is threatened.

Areas heavily infested with beachgrass are unsuitable as habitat for nesting snowy plovers. These marine birds require areas of open sand or low, native dunemat vegetation for nesting. The snowy plover is a federally listed, threatened species. Areas infested with beachgrass are also unsuitable as habitat for three sensitive plant species: beach layia (Layia carnosa) [also federally listed as endangered], Wolf's evening primrose (Oenothera wolfii) and pink sand verbena (Abronia umbellata ssp.brevifolia).

12. European Starlings - The nation-wide distribution of Starling are the descendants of about 100 birds introduced to New York's Central Park in 1890 by a society desiring to introduce all of the birds mentioned in the works of Shakespeare. Flocks of these birds destroy crops and eat cattle feed, costing agricultural farmers $800 million dollars yearly in preventative measures and damage control.

13. Western Pine Bark Beetle - These small beetles aggressively attack and kill Ponderosa Pine trees and other conifers of all ages and vigor, including apparently healthy trees. Group killing of trees is common in dense, overstocked stands of pure, even-aged, young sawtimber but also occurs among dense clumps of pine in stagnating mixed-conifer stands. One million or more trees containing more than 1 billion board feet of timber may be killed each year during an outbreak. Such extensive tree killing may deplete timber supplies, adversely affect levels and distributions of stocking, disrupt management planning and operations, and increase forest fire danger by adding to available fuels. Click here for images.

I encourage you to become familiar with the invasive animals and plants in your area and to do your part to prevent further distribution.

For more information, click upon the following link.

Invasive Species of Oregon

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  1. We have a big zebra mussel prob here. Totally stinky.

  2. The zebra mussels are a big thing here in WI too, and we have some plants and insects that are becoming an issue. We are also being asked to be very careful when we transport wood so as not to bring issues into our forests. Great environmental TT this week.
    Happy TT!
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