The web site Invasivespecies.gov first defines an invasive species as follows:
An “invasive species” is defined as a species that is 1) non-native (or alien) to the ecosystem under consideration and 2) whose introduction causes or is likely to cause economic or environmental harm or harm to human health. (Executive Order 13112).
Invasive species can be plants, animals, and other organisms (e.g., microbes). Human actions are the primary means of invasive species introductions.
The Marblehead Conservancy is interested in removing invasive plants and replacing them with native species where possible since invasives typically have few natural pests to keep them in control and can multiply rapidly, replacing or damaging native plants and habitats to the detriment of all. Controlling such invasions is difficult and is an important part of the work done by the Trails Committee and supporting volunteers.
Readers with a deeper interest in the subject of invasives many find the following term definitions helpful:
Alien species means, with respect to a particular ecosystem, any species, including its seeds, eggs, spores, or other biological material capable of propagating that species, that is not native to that ecosystem.
Control means, as appropriate, eradicating, suppressing, reducing, or managing invasive species populations, preventing spread of invasive species from areas where they are present, and taking steps such as restoration of native species and habitats to reduce the effects of invasive species and to prevent further invasions.
Ecosystem means the complex of a community of organisms and its environment.
Introduction means the intentional or unintentional escape, release, dissemination, or placement of a species into an ecosystem as a result of human activity.
Native species means, with respect to a particular ecosystem, a species that, other than as a result of an introduction, historically occurred or currently occurs in that ecosystem.
Species means a group of organisms all of which have a high degree of physical and genetic similarity, generally interbreed only among themselves, and show persistent differences from members of allied groups of organisms.
Click each image below to learn more about a particular invasive plant.