The definition of "weed" is always debatable. Traditional definitions include "plants out of place" or "plants that by their presence conflict with management objectives for the site." The definition included here also tries to incorporate the concepts of public land health and sustainability. A weed is defined as "a non native plant that disrupts or has the potential to disrupt or alter the natural ecosystem function, composition and diversity of the site it occupies. It 's presence deteriorates the health of the site , it makes efficient use of natural resources difficult and it may interfere with management objectives for that site. It is an invasive species that requires a concerted effort (manpower and resources) to remove from its current location, if it can be removed at all." This definition is adapted from Noss and Cooperider (1994) and Beck (personal communication).
"Noxious" weeds refer to those plant species which have been legally designated as unwanted or undesirable. This includes national, state and county or local designations. According to the Federal Noxious Weed Law, native plant species are not designated "noxious". Native plant species that may be of a management concern, such as poisonous plants or desert shrub and sub-shrub species are not considered priorities for noxious weed work or funding and are not included on the following list.
All weeds are not of equal importance for management. The focus of this list is on exotic species that are highly invasive in natural systems. Those species that are of a concern in agricultural situations, but do not pose a threat to rangelands, forestlands and wetlands have not been included. Many annual forbs have not been included. Exotic species typically used in range restoration which are known to be invasive have not been included. Invasive annual grasses which disrupt natural ecosystem function have been included.
The concept for weed management areas (WMAs) comes from the Guidelines for Coordinated Weed Management of Noxious Weeds in the Greater Yellowstone Area, a document put together by managers in three states to control undesirable plants that were spreading in 20 million acres that includes National Forests, National Parks, federal reservations, state lands and parks, National Wildlife Refuges, Bureau of Land Management lands, Bureau of Reclamation lands and private lands. In a typical Weed Management Area, partners come together and delineate boundaries of an area on the ground and work to get all land owners in that area to contribute to the management of a designated weed species. Often the area delineated does not follow jurisdictional boundaries, but it based on the location of a weed infestation or an area where it is high priority to detect and control weeds. The partners work together to plan and budget weed management both in the long term and seasonally.
BLM Colorado supports forming WMAs because they are the most effective and cost efficient way to manage weeds. They are a high priority for BLM funding at both the state and national level. Both, The Colorado Noxious Weed Management Fund and the National Fish and Wildlife Foundation's Pulling Together Initiative target weed management area partnerships for matching funds.