Monday, October 15, 2007

Blog Action Day 2007

For many years now, I have been intrigued by alien invasions. Not little green men from outer space or scary monstrous beings but silent invasions of plants and animals here on earth. In the late 1990s, I had an unique opportunity to work for the local soil and water conservation district. In this role, one of my responsibilites was to write and distributie a county-wide newsletter informing landowners of sustainable land-use practices and share topics related to the environment. This is one of those articles.

Controlling Noxious Weeds

Generally, the term weed is used to describe any plant that is unwanted and grows or spreads aggressively. The term exotic weed describes an invasive, unwanted, non-native plant. Terms such as invasive weed or noxious weed are used somewhat interchangeably to refer to weeds that infest large areas or cause economic and ecological damage to an area. The term "noxious" weed has legal ramifications in some states that maintain official lists of noxious weeds. What is considered a weed in one area may not be a weed in another.

Upsetting the Balance
Native plants evolved over millions of years to fill unique ecological niches. What we know as weeds today (non-native, ecologically damaging plants) did not exist in the wilderness then. These plants developed in and are native to other countries. Like our native plants, they are kept in check in their native environment by insects or diseases and by competition with other species. In order to survive in their native ecosystems, many plants develop characteristics that make them especially hardy.

Early European settlers in North America inadvertently brought weed seeds with them, perhaps in the hay they brought for their animals or in the dirt they used as ballast for their ships, or even in their clothes or bedding. Some activities, such as clearing the land, opened up niches that created places for weeds to grow. Settlers also purposely brought plants from their "home country" to seed areas, make dye for clothing, and use as ornamental plants.

Without their natural enemies, some non-native plants became invasive, reducing the diversity and quantity of native plants. Weeds are continuing to spread rapidly in many areas across the country. Weeds spread to an estimated 4,000 acres (over 6 square miles) each day on public lands managed by the Bureau of Land Management (BLM) and the Forest Service. But weeds know no boundaries. They also are spreading on private and park lands.

Looks Can be Deceiving
Weeds take over important habitat areas for wildlife, devastating shelter and forage while reducing the diversity and quantity of native plants. When weeds do not hold and protect the soil the way native plants do, erosion increases, causing sediment in streams, which can hurt fish populations and water quality. Weeds are often less resistant to wildfire than are native plants. Weeds also reduce land values, causing damaging economic impacts to local communities. For example, weeds have a profound effect on ranching and agricultural operations because they can reduce production of forage and crops.

Controlling Weeds
Controlling weeds poses a special dilemma because, once a weed infestation is identified, it is often already so large that containment is difficult and expensive. Biological control (using organisms such as introduced insects or diseases to suppress populations) is effective in slowing the spread of weeds but generally cannot eradicate the infestation. Manually pulling weeds or using machines to dig them up is effective with smaller infestations if done carefully to avoid spreading seeds. Herbicides can be effective in controlling weeds and stopping their spread especially when infestations are detected early. Land managers generally take an integrated approach, using a combination of these methods.

A special emphasis is placed on early detection of infestations and prevention of new infestations. Educated citizens who can report these new, small infestations will make a major difference in the national effort to control the spread of invasive weeds.

For more information about noxious weeds or invasive species in general, contact your local agency or one of the following state & federal agencies.

Army Corps of Engineers
Farm Service Agency
National Association of Conservation Districts
Natural Resources Conservation Service
Oregon Association of Conservation Districts
Oregon Department of Agriculture
Oregon Department of Environmental Quality
Oregon Department of Fish and Wildlife
Oregon Department of Forestry
Oregon Division of State Lands
Oregon State University Coos County Extension Service
Oregon Watershed Enhancement Board
US Department of Agriculture

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1 comment:

  1. Interesting post. I think in California IVY is outlawed because it is so evasive.


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