Noxious Weeds

Of the 3,000 native species of plants in Colorado, 500 or 17% have already been displaced by noxious weeds.

Noxious weeds, what are they?
Noxious weeds are non-native plant species that have been introduced into an environment with few, if any, natural biological controls, thus giving them a distinct competitive advantage in dominating and crowding out native plant species. They have the ability to dominate plant communities to the extent plant diversity and ecosystem integrity are threatened. Noxious weeds are aggressive, spread rapidly, possess a unique ability to reproduce profusely, and resist control. Noxious weeds also threaten valuable wildlife habitat and natural resources, cause economic hardships to agriculture producers, and are a nuisance for recreational activities.

How Noxious Weeds Spread
Noxious weeds become established in soils disturbed by a variety of activities including but not limited to: construction, motorized vehicles, road maintenance, recreation, improper livestock grazing and natural disturbances such as fire. Noxious weed seeds are transported to new sites in numerous ways such as wind, water, tires, people, as well as wild and domestic animals.

Environmental Impacts From Noxious Weeds
Biodiversity and ecosystem stability are threatened by noxious weeds. A common characteristic of all noxious weeds is their aggressive, competitive behavior. Typically, they steal precious moisture, nutrients, and sunlight from the surrounding plants. Noxious weeds also alter soil properties, the composition of plant communities, and change the structure of animal communities.

Many animal species that co-evolved with native plant communities for habitat cannot readily adapt to rapid changes in theses plan communities caused by noxious weeds.

Some wetland weeds rob waterfowl and mammals of their food sources, nesting areas, and access to water which they need for protection from predators.

Noxious weeds such as cheatgrass can change the frequency of fire in sagebrush communities from approximately 50-75 years to 3-5 years. This suppresses the establishment of new sagebrush plants and other native species but provides ideal growing conditions for cheatgrass, an annual grass.

Some noxious weed species impact water availability and water quality. Tamarisk or salt cedar now dominates plant communities in many southwestern riparian areas. This deep rooted tree depletes water tables and displaces native cottonwoods and willows which provide native habitat.

Noxious weeds negatively impact livestock forage, crop production and reduce crop yields. Increased demand upon both agricultural and natural lands necessitates increased awareness of noxious weeds.

A Threat To Our Native Vegetation
Native plant species are being displaced by the invasion of noxious weeds. Areas that once displayed a rich diversity of native plants are now dominated by single or multiple noxious weed species such as cheatgrass, knapweeds, leafy spurge, yellow toadflax and others.

Once established, noxious weeds have a tremendous capacity to invade adjacent undisturbed native plant communities. This is particularly true in drier regions at lower elevations. These areas most closely resemble the conditions in Eurasia where many noxious weeds evolved.

Noxious Weeds Impact Our Enjoyment of the Land
Colorado, like the rest of the West, is blessed with a great diversity of plant communities. The variety of vegetation on the landscapes in our state are key reasons why we choose to live and recreate here. Noxious weeds negatively impact recreational activities in parks, refuges, forests, lake shores, grasslands, and other natural areas.

Invasive Ornamental Plants
Most plants used for landscaping purposes lack the ability to proliferate outside of the cultivated environment of the home garden. Some plants, however, were imported to the United States for their aggressive growth habits, drought tolerance, or re-seeding capabilities. These plants are known as Invasive Ornamentals. The vary traits which make these plants desirable for a garden or landscape, also enable them to thrive outside cultivated areas and become fierce competitors with our native vegetation. Fortunately, there are plant choices available to the home gardener which provide similar colors and growth habits as Invasive Ornamentals, but not the problems associated with them. Invasive Ornamental plants have become a serious threat to the delicate balance of our native ecosystems. Wildflowers such as Colorado Blue Columbine, our state flower, can’t compete with Invasive Ornamental plants for nutrients, sunlight, and water. Invasive Ornamental plants have become a serious threat tot the delicate balance of our native ecosystems.

Integrated Weed Management Is The Solution
Integrated weed management (IWM) is a strategy using a comprehensive, interdisciplinary approach to weed management. By viewing a problem in its entirety, it is easier to design a management plan that is safe, cost effective and gets results without damage to natural controls and the environment. The purpose of integrated weed management is to achieve healthy and productive natural and agricultural ecosystems through a balanced program. This program would include but not be limited to education, prevention measures, good stewardship and the following control methods: culture, physical, biological, and chemical.

We Can All Help Maintain Our Natural Resources
As land users and managers, we must manage our natural resources to maintain plant diversity as well as enhancing the productivity of our agricultural lands. We must also take responsibility for our own land and manage noxious weeds. This can be achieved through greater efforts in education, awareness, and prevention.

Colorado Can Learn From Others
Tremendous economic and ecologic impacts from noxious weeds have already been realized in several western states from weed infestations that have diminished the productivity and value of millions of acres. Coloradoans have a unique opportunity to prevent new infestations while aggressively managing existing problems to reduce and/or prevent the loss of thousands of acres in Colorado.

Colorado Noxious Weed Act
Coloradoans now exercise increased influence in protecting the natural resources we enjoy and depend upon. The Colorado Noxious Weed Act revised in 2003, enables county and city governments to implement management programs aimed at undesirable plants to reclaim infested acres and protect weed-free land.

Weed-Free Forage Program
The Colorado Weed-Free Forage Certification Act was passed into law in 1993. This Act provides standards for a voluntary program that gives growers the opportunity to produce and market forage (alfalfa, native grass hay, straw, mulch, etc.) certified as noxious weed-free. The Bureau of Land Management, United States Forest Service and some National Parks require the use of certified weed-free forage on public lands as well as the Colorado Department of Transportation, Colorado State Land Board and Colorado Division of Wildlife.

Information obtained from the Colorado Weed Management Association