Impacts of Invasive Plants


Invasive plant species are a considerable threat to biodiversity. Once these species are well established it is sometimes impossible to remove them. When removal is possible, it comes at a high cost financially and ecologically. For instance, researchers at Cornell University estimate that invasive species are costing Americans more than $130 billion every year. Even controlling a single unwanted invader can carry a price tag in the millions.
 
In some cases, invasive plants are driving our rarest species closer to extinction. According to the U.S. Fish and Wildlife Service, an estimated 42 percent of the nation's endangered and threatened species have declined as a result of encroaching invasive plants and animals. Recent research has shown that some invasive species can cause the populations of even common species to collapse.
 
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Ecological impacts
  • Changes in the availability or quantity of water or nutrients
  • Changes in light availability to plants in the ground layer and shrub layer or to plants and animals in lower depths of lakes and streams
  • Toxicity
  • Allelopathy (when one plant produces chemicals that are toxic to other plants)
  • Reduction or elimination of localized or specialized native plant communities
  • Disruption of insect-plant associations necessary for seed dispersal of native plants
  • Disruption of native plant-pollinator relationships
  • Reduction and elimination of host plants for native insects and other wildlife
  • Serving as host reservoirs for plant pathogens and other organisms that can infect and damage desirable native and ornamental plants
  • Replacing nutritious native plant foods with lower quality sources
  • Killing trees and shrubs through girdling
  • Preventing seedling establishment of native trees and shrubs
  • Changes in the rate of soil erosion
  • Changes in the frequency of wildfire
  • Changes to natural ecological processes, such as plant community succession
  • Genetic dilution - incidence of cross-breeding with native species, alters the natives' genetic make-up