Whether it's wading through yellow starthistle while hunting upland game or finding only knapweed when looking for grass for a pack string on an elk hunt, most outdoor enthusiasts know the annoyance of noxious weeds.
While annoying to humans, weeds can be lethal to wildlife. Weeds can degrade plant composition and vegetation communities, replacing important forage and cover species on which wildlife rely. Forage on hundreds of thousands of acres of big game winter range has been replaced with knapweed or starthistle in Idaho. This reduces the availability of forage for deer and elk and reduces the number of big game animals these ranges can support. Many wildlife species also tend to avoid weed infestations, using instead areas where they may be more vulnerable to predators and hunters.
Experts estimate that state-designated noxious weeds have infested more than 8 million acres in Idaho. Among the worst rangeland weeds is rush skeletonweed, which in 1963 occupied about 40 acres in the Banks area. Today, it is found across 4 million acres and continues to spread. Yellow starthistle has increased from a few acres in 1955 to nearly 500,000 acres.
Medusahead rye and downy brome-commonly known as cheatgrass-have had profound effects on wildland ecosystems by altering fire frequencies and intensities in the sagebrush country of southern Idaho. At the Birds of Prey Wildlife Refuge near Kuna cheatgrass has replaced a significant portion of the native habitat, which has reduced ground squirrel and mice populations. Raptors that prey on these rodents have responded by leaving the refuge.
At North Dakota's Theodore Roosevelt National Park, leafy spurge has reduced available bison forage by 83 percent and deer and elk forage by 70 percent. In Montana, studies have shown that the forage capacity of elk range has been reduced 40 percent by spotted knapweed.
Across the country, the cost of invasive plants to the U.S. economy is more than $30 billion per year, researchers at Cornell University estimated recently. Based on information from private landowners and federal, state, and county governments, an estimated total direct cost statewide for all Idaho lands may be $300 million annually.
The indirect costs to Idaho residents from the effects of aquatic and terrestrial noxious weeds on plant diversity, wildlife habitat, watershed health, recreation, tourism, human life, and property are unknown, but result in an estimated total annual cost greatly exceeding the $300 million estimate.
Idaho is leading the way in fighting these invasive species through partnerships created by private property owners, conservation organizations, and local, county, state, tribal, and federal government entities. Millions of dollars in grants, cost-sharing, and other programs are spent around the state annually to limit the spread of noxious weeds.
The Idaho Department of Fish and Game has also recognized this growing weed problem, and is working to combat noxious weeds.
Fish and Game regional habitat biologists work closely with local Cooperative Weed Management Areas and the state habitat manager is chairman of the Idaho Weed Coordinating Committee. These partnerships make Fish and Game more effective at dealing with resource issues that cross property boundaries, watersheds, counties and regions of Idaho.
Fish and Game manages more than 375,000 acres in Idaho; nearly 200,000 acres are fee-title lands. Most of this land is associated with 32 wildlife management areas and 325 public fishing and boating access sites. Like all landowners in Idaho, Fish and Game is required by state law to control listed noxious weeds. Controlling noxious and invasive weeds is a high-priority program because it improves fish and wildlife habitat on lands Fish and Game manages and prevents the spread of noxious weeds to adjacent lands.
On the Craig Mountain Wildlife Management Area south of Lewiston, Fish and Game's goal for new invaders, such as whitetop, hawkweed, leafy spurge, and Dalmatian toadflax, is eradication. For established species such as yellow starthistle, Scotch thistle and knapweed, the goal is to stop the spread and contain the infestations and eradication of isolated patches.
Fish and Game uses mechanical, chemical and biological controls to fight weeds.
Mechanical methods include mowing, burning, chopping, disking and hand pulling. Biological control agents-insects-are released to control specific weeds, such as yellow starthistle and Dalmatian toadflax. Chemical treatment, however, is the most common option where feasible.
This year Fish and Game received a grant from the Rocky Mountain Elk Foundation to control whitetop on Craig Mountain. Whitetop is spreading into important big game wintering areas. Without control measures, the once healthy winter range would become a monoculture with little or no value for wildlife.
This grant allowed Fish and Game to treat 630 acres of whitetop by aerial application in early May. Treating this acreage from the ground would be impractical. It would take about five months, but chemical treatment of this species is effective only during a limited time. And the terrain is rugged.
Everyone can help stop the spread of weeds by following these suggestions:
- Be weed savvy and recognize there is a problem.
- Learn to identify weeds and report new weed locations to the county weed superintendent, Forest Service, Bureau of Land Management or Fish and Game.
- Control weeds on private land and assist others on theirs.
- Clean equipment. Check vehicles, animals and gear for weed seeds.
- Use weed-free hay and feed for livestock.
- Tread lightly. Minimize ground disturbance by staying on established travel routes and using low impact camping techniques.
2005 Fish and Game Accomplishments:
- Estimated acres mapped: 53,700
- Estimated acres treated: 16,000
- Estimated acres re-vegetated: 2,000
2005 Expenditures:
- Actual expenditures: $308,000
- Estimated cost-share: $140,000
- Estimated total project cost: $448,000
