Non-Native Invasive Species (Plants)

Introduction

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.  

The Problem

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.

The Solution

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:

  • Prevention
  • Early Detection and Rapid Response
  • Control and Management
  • Rehabilitation and Restoration




https://www.fs.usda.gov/detail/r8/landmanagement/resourcemanagement/?cid=fsbdev3_066408