Non-native Invasive Plant Species - Problem and Solution
Non-native invasive plants are everywhere, and threaten the sustainability of our forest ecosystems; regionally, nationally and globally. Prior to 2000, non-native invasive plants had already infested over 100 million acres across the United States; increasing an additional 3 million acres each year.
What Is A Non-Native Invasive Plant? – Federal Definition
A non-native invasive plant is a species not native to the ecosystem under consideration, and its introduction causes or is likely to cause economic or environmental harm.
Non-native invasive plants, exotic plants, and weeds are terms often used interchangeably, but there are differences between them.
- Exotic plants are non-native species introduced to a new area by humans. Unlike non-native invasive species, these plants cause little to no economic or environmental damage, and do not out-compete or displace native vegetation.
- Weeds are undesirable plants, native or non-native, invading a given area, such as a lawn or garden. A good example of a weed is the common dandelion (Taraxacum officinale), a non-native species common throughout the United States.
Why Are Non-Native Invasive Species So Successful?
Once established, non-native invasive species can out-compete native vegetation, including Threatened, Endangered and Sensitive plants for valuable water, light, nutrients and space. Non-native invasive species success is derived from their ability to:
- flourish in habitats where population control mechanisms (i.e. defoliators or pathogens) are absent;
- thrive on disturbed soils;
- produce large quantities of seed;
- disperse seeds over great distances by a variety of mechanisms (wind, birds, mammals; even humans);
- develop aggressive root systems able to spread quickly over a large space; and
- produce chemicals on one or more parts of the plant that inhibit the growth of nearby plants, or make them unpalatable (even poisonous) to grazing animals.
Non-Native Invasive Plant Pathways
Non-native invasive plant pathways are the means by which invasive plants are moved from one location to another.
Transport of non-native invasive plants can be accidental or intentional, and can occur along natural or transportation-related pathways.
Examples of non-native invasive plant pathways include:
- Natural – wind, currents, etc.
- Transportation – aircraft, ships, trains, vehicles, foot travel, pets, etc.
- Rights-of-way – roads, railroads, utility, canals, trails, etc.
- Ecosystem disturbances – clear-cuts, development, dams, stream channelization, etc.
Non-Native Invasive Species Impacts
Non-native invasive species have serious economic and environmental impacts throughout the United States. Studies by Pimental et al (2000) show $138 billion in annual economic and other losses due to non-native invasive species. In addition, 400 of the 958 (42%) Threatened and Endangered species listed by the Federal Government have been negatively affected by non-native invasive species.
Non-native invasive plant impacts include:
- displacement or hybridization of native plant species;
- reduction of native species diversity;
- habitat degradation (especially in areas where threatened, endangered, sensitive, and important plant and animal species reside);
- decline of overall forest health and productivity (particularly in areas with economically important resources)
- alteration of ecosystem processes (nutrient cycling, fire frequency, hydrologic cycles and erosion); and
- intrinsic loss along recreational areas.
USDA Forest Service Strategy for Controlling Invasive Species
In response to the growing threat of non-native invasive species in our nation’s lands, the National Strategy and Implementation Plan for Invasive Species Management (FS-805) was developed by the USDA Forest Service in October 2004; the goal being to “reduce, minimize, or eliminate the potential for introduction, establishment, spread, and impact of (non-native) invasive species across all landscapes and ownerships.”
The National Strategy is based on these four elements:
- Early Detection and Rapid Response
- Control and Management
- Rehabilitation and Restoration