Invasive Weeds of Humboldt County
introduction
INVASIVE WEEDS—WHY THE WORRY?

Should we worry about whether the plants growing around us are native to our area or not? Isn’t it all just “nature?” Before you dismiss this issue as unimportant, consider the following:
  • Invasive weeds in agricultural and natural areas cost our country $13 billion dollars per year
  • Invasive weeds are the second most important reason for the loss of biological diversity, after habitat destruction
  • The Bureau of Land Management, our nation’s largest public landowner, estimates that 2,300 acres per day of its land are being lost to invasive plants
If you find yourself alarmed by these facts, you are not alone. Local agencies, groups, and individuals have been quietly pouring money and resources for years into our local parks, open spaces, and natural areas to combat this pressing problem. Now, we are hoping to bring public awareness to this issue. The battle against invasive weeds cannot be won without public awareness and support. As a homeowner or gardener, your actions have a DIRECT effect on this problem, because many weeds escape from yards and gardens.

This brochure has been prepared to help you understand the problem of invasive weeds, identify them around your home and community, and take direct action to save our wildlands and protect our agricultural resources from these threats. The “A-list” plants are those that have proven most harmful, and which are the target of most eradication efforts. The “B-list” consists of species which have not yet and may never have quite the magnitude of impact of A-list species, but are or have the potential to become a major problem. Each plant description lists ways to remove and control these species.
WHAT EXACTLY IS AN INVASIVE WEED?

Most people are familiar with the concept of weeds in the context of their yard or gar-den. Weeds are simply undesirable plant species. This same principle holds true for our natural areas, which are home to a diverse array of native plants. The number and variety of these native species is described by the term “biological diversity.” Over the past 150 years, many non-native plants have been introduced to our region, both intentionally and accidentally. The vast majority of these plants coexist with native species, and are ecologi-cally “harmless.”

What makes a plant undesirable in the context of natural lands is first and foremost its ability to spread and crowd out native plants. This is why we distinguish invasive weeds from those that occur in small numbers and are innocuous. Invasive weeds are those that are able to reproduce in the wild, spread rapidly, and cause the decline or loss of our native plants. We don’t completely understand why some weeds become invasive and others don’t. But because invasive plants did not evolve locally, their populations are not held in check by natural predators or diseases, giving them a competitive edge over native plants. Invasive species proliferate and spread over large areas. Some are able to completely dis-place native plants, forming a homogeneous cover. Contrast this situation with the rich vari-ety of a native plant community such as we see in our local redwood forests, dunes, and wetlands.
WHAT YOU CAN DO
  1. Don’t Plant Invasive Weeds. Be selective when you choose plants for home landscaping. Some invasive plants are still sold in nurseries and garden shops, so beware! If you plant these in your yard, they may escape into nearby natural areas and become a problem by displacing native species. Not all non-native plants are invasive. There are many beautiful horticultural plants available for you to choose from without contributing to the invasive weeds problem. Also consider planting native species in your home garden. Natives offer a good choice for home landscaping because they are well-adapted to local conditions and often thrive with less care than required by many non-natives. Native plant gardening also enhances the value of your yard for local wildlife including birds and butterflies.
  2. Remove Invasive Weeds. Be on the lookout for invasive weeds and remove or report them whenever possible. You may have invasive plants already growing in your backyard. Birds and other animals may eat the seeds of these plants and then travel into nearby natural areas or range lands, resulting in the spread of noxious weeds. You can help stop these invasions by removing the source plants. Talk to your neighbors about the problem and share your concerns. Report sightings on public lands to the land manager. And if you do remove these plants from your own land be sure not to spread seed when disposing of them.
  3. Participate in Organized Weed Cleanup Activities. Look for opportuni-ties in your area to participate in local community workdays aimed at controlling invasive weeds. Many land managers sponsor volunteer events to help pull weeds on public lands. This is a good chance for you to learn to identify invasive species and to learn about the native plant communities that you will help save by freeing them of weeds.
  4. Help Prevent the Accidental Spread of Invasive Weeds. When you venture into natural areas, be aware that you could be introducing invasive weeds inadvertently. Check your shoes, socks, clothing, backpack, bicycle, or anything else that might be a carrier for weed seeds. Also avoid activities like carrying and waving stalks of pampas grass or other weeds. This may seem like fun, but can result in the spread of invasive plants!
  5. Educate Yourself and Spread the Word. Become better informed about how to identify invasive weeds, how to avoid spreading them, and how to help control them. Then share what you learn so that others can join in the WAR ON WEEDS!

Here are some local groups and agencies who can provide further information: 
    U.S. Fish and Wildlife Service      822-6378
    U.S. Bureau of Land Management      825-2300
    Redwood National and State Parks    822-7611 ext. 5282
    California Native Plant Society     826-4801
    Friends of the Dunes                444-1397
    City of Arcata                      822-8184
    City of Eureka                      441-4163
    U.C. Cooperative Extension          445-7351
    U.S. Forest Service (Six Rivers)    441-3162
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