Where Do Invasives Species Come From?

Invasive species are introduced to parks through a variety of intentional and unintentional avenues. Many invasive species were introduced prior to the establishment of parks. Park lands include old homesteads and mining sites from early European settlers. Settlers often brought with them plants or animals from their previous homes. Occasionally these plants or animals got loose and spread across the landscape. Many introductions of invasive plants have resulted from garden plantings of ornamental species, such as toadflax and periwinkle. Some species, such as tamarisk and red cedar, were introduced through restoration efforts, to reduce soil erosion. Today, the majority of invasive species are introduced unintentionally. Introductions can result from essentially every person, pet, or vehicle coming in and out of a park. Common sources are infested construction materials such as gravel, wood, mulch and fill, contaminated vehicles such as equipment and passenger vehicles, personal gear such as boots, wetsuits, and tools, and wind and water born seed materials. Given the variety of pathways through which invasive species can enter a park, invasive species management affects all aspects of park operations.