Native and Nuisance Plants

Exploring the Portland landscape is a visceral experience of the natural heritage thousands of years in the making. Rocky buttes cloaked in forest and prairie dapple the urban boundary. Streams and rivers flow by parks, private homes, and city tree canopies.  The plants in these habitats support the life around them.

The City of Portland recognizes the importance of ensuring the continued viability and diversity of these indigenous plant and animal communities by promoting the use of plants naturally adapted to local conditions, and educating citizens about the region’s natural heritage and the values and uses of native plants.

Portland Plant List 2016

The Portland Plant List is integral in the city’s environmental protection efforts as a guide to native plant communities and native plant species selection as well as nuisance plant impact, ranking, and eradication. Released in in June of 2016 by the City of Portland’s Bureau of Planning and Sustainability it comprises two lists and supporting information: the Native Plants List and the Nuisance Plants List.

The Native Plants List includes nine native plant communities and native plants in detail.

The Nuisance Plants List includes invasive plants that threaten the health and vitality of native habitats, humans, and cause economic harm to public and to private landowners. They are ranked to educate the public about the distribution and level of invasiveness of each species and help land managers prioritize actions.

The Portland Plant List (PPL) is a technical and educational document which is used widely by city staff, developers, local natural resource and watershed agencies and organizations, and residents throughout the Portland metropolitan region.

Overcoming Threats

Among the greatest threats to native plant and animal communities are habitat destruction (from urbanization and agriculture) and invasive species.  

You can support natives by adding them to your property, support restoration efforts in natural areas and parks, or participate in community science projects monitoring native plants and wildlife.  While hiking or strolling city streets keep an eye out for invasive species and report them on the Oregon Invasive Species Online Hotline.

When an invasive species colonizes a new environment, it leaves behind the natural enemies such as predators or parasites that controlled its population growth in its original home. It can quickly expand, out-competing and overwhelming native species. Native species have not evolved the necessary survival strategies to fend off unfamiliar species or diseases” (Oregon Department of Fish and Wildlife, Conservation Strategy, February 2006

Identification and Reporting Nuisance Plants

 Ask an Expert through Oregon State University cooperative extension service can help identify and answer questions you may have about plants or animals online. To identify a plant include photographs of different parts of the plant if possible. There is an option to share your question with the public to help others learn from the answer. Their response time is usually within two business days.

Oregon Invasive Species Online Hotline  through Portland State University can help identify unknown species of plants or animals, plot the sighting on a map, and answer questions. To identify plants include photographs of different parts of the plant if possible. After submission and identification your report will be plotted on the website map.

Wild Spotter through the University of Georgia is mapping invasive plant and animal species nationally by engaging and empowering the public to help find, map, and prevent invasive species in America’s wilderness areas, wild rivers, and other natural areas. Oregon’s Siuslaw National Forest is collaborating with 12 other U.S. national forests and grasslands.

iMapInvasives  is an on-line, GIS-based data management system used to assist citizen scientists and natural resource professionals working to protect our natural resources from the threat of invasive species. This information includes species maps, treatment efforts and effectiveness, and areas where invasive species were searched for but were not found. Since many regulatory and budgetary decisions about invasive species are made at the state level, each state/province can customize the iMapInvasives interface by selecting their tracked species list, data permission levels, and many other details.

Preventing Introduction and Movement

(Excerpts taken from Portland Plant List)
Early detection and rapid response
to invasive species management programs aim to control new plant invasions before they become large infestations. The premise is that once an infestation covers a large area, it is more difficult and to eradicate, and the native plant community has to be re-established. Controlling small populations of invasive plants before they become more widespread is a very cost effective way to prevent their spread. 

The graph called an Invasion Curve is included here to illustrate how the area of infestation expands over time. When a plant is just arriving in an area, it is at the low point of the Invasion Curve; this is the best time to identify plants as invasive and to remove them. As the plant spreads over time, the distribution increases substantially and rapidly, becoming widely distributed and established. At this later point in the curve, landowners and other individuals are often more aware of the plant and can recognize it more readily, but it is so well established that a great deal of time and expense is involved in removing it.

The City of Portland emphasizes prevention of introduction and prevention of movement of invasive plants. When new invasive plants are found, then the City emphasizes the early detection and eradication of invasive plants that are not yet widespread. Ranks provide a tool to prioritize management actions related to plants.