A quick look at invasive plant species in Massachusetts
Posted by Tyler
Invasive plant species are exotic, or non-native, plants that are able to grow and thrive in locations different from where they originally evolved. Specifically, invasive species are exotic species that are detrimental to their native neighbors. In some cases, the presence of exotic species in a habitat can have negative effects on local biodiversity and on the health of native plant and animal populations. However, this is not always the case, in part because most species of plants and animals are not able to survive – let alone thrive – when removed from the environments that they are adapted for. As a result, many popular garden plants are “exotic.” However, only a few are ever considered “invasive.”
Exotic species might come to an area for any number of reasons. Often, the term “invasive” is reserved for plants or animals that have been moved to a new area specifically by humans, rather than migrating on their own. The Department of Agriculture recognizes 147 different species of invasive / noxious weeds within the Commonwealth of Massachusetts. Among their number is the ornamental shrub Japanese Barberry (Berberis thunbergii), the biannual herb Garlic Mustard (Alliaria petiolata), and the fast-growing Mile-A-Minute Vine (Mikania cordata).
Japanese Barberry was brought to the USA in the late 1800’s to serve as a decorative hedge for gardens in the north-east. It was quickly found to be shade tolerant, it grows thickly, and it is resistant to deer. Unfortunately, the same qualities that make it a valuable shrub for someone’s backyard also allow it to grow extensively in the forest understory. Its presence in the understory blots out light, which makes it extremely difficult for other plants to grow. Garlic Mustard, which was likely imported as an edible garden plant, flourishes in fringe habitats (like those found alongside highways) and could possibly poison the soil it grows in leaving it uninhabitable for other species of plants. Finally, Mile-A-Minute Vine, first seen in the continental US in Oregon around 1890, is capable of completely covering and killing small trees and shrubs if not removed quickly.
Other invasive plants exist across the world, some species take advantage of niches in the ecology left unfilled before their arrival, others are able to thrive because they have no predators in their new home. Some species are largely harmless. Others, like the three mentioned above, are dangerous not only to the plants and animals directly effected by their presence, but can also negatively impact human activities in areas they have infested. As a result, both state and federal government agencies are devoted solely to the removal of invasive species from areas where they have become prevalent.