February 25, 2003

Alien Invaders Threaten Idaho's Lands

The aliens in question aren't little green men from outer space, but "little green plants" not native to Idaho. Each day, non-native plants spread across over 4,600 acres in the western United States! This week has been designated National Invasive Weeds Awareness Week to increase awareness of the threats from these alien invasions–and inform citizen weedbusters what they can do to help stop the spread.

Aliens threaten pocketbooks and more
Why should we care about the invasive spread of non-native plants? In Idaho alone, damages from noxious weeds cost an estimated $300 million annually. These damages include reduced productivity on agricultural and rangelands, as well as reduced property values.

But alien weeds don't affect just the pocketbook, they also threaten our native wildlife. Wildlife need a variety of different plants for food and cover. Unfortunately, when non-native plants invade an area, they usually out-compete natives, leaving behind uniform stands of non-native plants that support fewer wildlife species.

Alien weeds can also threaten recreation areas. Hiking through a field of cheatgrass, with it's sock-sticking barbed seeds, is little fun. Hiking through a thick patch of Canada thistle or yellow starthistle can be downright impossible. Weeds affect water recreation as well. Rivers can be clogged by purple loosestrife, and Eurasian watermilfoil in lakes can entangle motor boats–and even swimmers.

Alien invaders at Deer Flat National Wildlife Refuge
One of the biggest challenges to the health of Idaho's public lands, including Deer Flat National Wildlife Refuge, is the spread of alien weeds. Two aliens being battled at Deer Flat, and elsewhere in Idaho, are purple loosestrife and Russian olive. Both were intentionally introduced to the U.S.

Purple loosestrife has beautiful flowers, grows well in moist soil and wetlands, and was planted for landscaping around ponds. Unfortunately, it didn't stay where it was planted, and has replaced native plants on as many as 400,000 acres of Federal wetlands, marshes, and meadows. Because purple loosestrife does not provide good food or cover, wildlife has been displaced as well.

Several marshy areas near Lake Lowell have been invaded by purple loosestrife. To battle the invasion, refuge staff have released insects that eat only purple loosestrife. These insects have successfully reduced purple loosestrife invasions at many other sites in Idaho and elsewhere.

Russian olive trees have been planted as wind breaks and to reduce erosion. Unfortunately, like other alien invaders, they escaped cultivation and spread rapidly. Although Russian olives do have some wildlife value, diverse native forests provide better food and cover.

Russian olives grow just about everywhere at Deer Flat. To increase habitat and wildlife diversity, the refuge has embarked on a long-term project to remove Russian olives and replant with more wildlife-friendly vegetation. As part of this effort, volunteers from Syringa House in Nampa recently planted cottonwoods in an area currently dominated by Russian olives. Once they become established, these cottonwoods will provide food and cover for wildlife, and the alien Russian olives will be removed.

Stopping the spread of aliens
Idaho's citizens can join in the battle against non-native plants by getting to know what the aliens look like. A photographic guide to the state's 35 noxious weeds is available online and at County Extension Offices. Citizen weedbusters can then help stop new weed invasions on their own property–and notify the land managers when they spot weed invasions on public lands.

People who don't recognize the aliens can still help prevent their spread by taking two simple steps. First, don't pick the flowers! Many of Idaho's worst invasive weeds have quite pretty flowers. Unfortunately, when people pick these flowers to bring them home, they can accidentally spread seeds to new areas.

Second, stop the hitchhikers! Outdoor recreationists can accidentally spread weeds from infested areas to weed-free areas by carrying hitchhiker seeds, like burs and foxtails, on their clothing, camping gear, pack animals, and even vehicles. To help prevent the spread of aliens, weedbusters should avoid traveling through weed-infested areas and stay only on established roads and trails. Also, before traveling to a new area, be sure to remove weed seeds from animals, vehicles, and gear–including socks and shoelaces.

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