Invasive and Non-Native Species

Rugosa rose, a non-native shrub from Asia, is often used to stabilize sand near beaches and dunes.

NPS Photo

Ecosystems throughout the world are impacted by introductions of non-native and invasive species; plants, animals, and invertebrates which are not naturally occurring components of local biological communities. Increased global movements of humans, livestock, crops, and material via ships, railroads, trucks, and aircraft dramatically increased the occurrence of non-native species through the 20^th century. Non-native and invasive species occur in virtually all taxa and have affected most habitats in most parts of the world to one degree or another. In the United States, thousands of non-native and invasive species have been documented throughout the National Park system.

Invasive and non-native species have different definitions and are therefore managed differently based on their classification. The National Park Service defines an invasive species as a type of non-native species that causes harm to the environment, economy, or human, animal, or plant health. Typically, native species evolved over thousands of years with co-occurring species under specific physical, chemical, and biological habitat conditions. When a invasive species suddenly invades a habitat, it may outcompete native species for food, grow tall enough to shade out native plants, or become so dominant over an area that other species are crowded out. The National Park Service works to manage invasive species that are negatively impacting native species. Invasive species found on Cape Cod include common reed (introduction from European ships in the late 18^th or early 19^th century), bush honeysuckle (native to Asia and Europe and introduced as ornamental landscape plants), and green crabs (a European species that most arrived on merchant ships in the 1800s).

 

Emerging Threats

• Spotted Lanternfly
• Beech Leaf Disease

Non-native species are organisms that do not occur naturally in an area, but are introduced as the result of deliberate or accidental human activities. Unlike invasive species, non-native species may not hinder or prevent the survival of others within the ecosystem. They simply exist where they have not naturally occurred. When a non-native species becomes a regularly seen component of a local habitat it is said to be “naturalized” and is often mistaken as a naturally-occurring native species. Familiar species seen on Cape Cod which are naturalized non-natives include rugosa rose (an Asian shrub, often planted near beaches and dunes to stabilize sand), beach wormwood (a native of Asia, Russia, Canada, and Alaska's Aleutian Islands this species is widely cultivated as an ornamental, and has naturalized on dunes and other sandy coastal areas) and rainbow trout (a fish indigenous to western North America, widely introduced for recreational fishing).