Green Pages May 2009

GREENTIPS:

Why should we care about invasive species? What should we do?

The following excerpts from the National Park Service and U.S. Fish and Wildlife Service’s “ Plant Invaders of the Mid-Atlantic Region� answer these questions (link to the entire online publication is provided in GREENSOURCES, below):

“Introduction
All living things - bacteria, fungi, plants, animals and other organisms - have evolved to live in specific areas on the Earth. Local climate, geology, soils, available water and other natural factors influence which plants and animals live in particular ecosystems and habitats.

“Natural areas are wild to semi-wild areas such as fields, forests, streams and wetlands, that are composed of diverse groups of native plants, animals and microorganisms. These biological groupings have evolved over thousands of years into natural communities and ecosystems. Large to small natural areas are all around us and include parks, refuges, preserves, fields, forests, open spaces, undeveloped areas on community and corporate lands, schoolyards, municipal facilities and backyard habitats.

“What are native species?
A native species is one that occurs naturally in a particular place without human intervention. Species native to North America are generally recognized as those occurring on the continent prior to European settlement. Non-native plants are species that have been introduced to an area by people from other continents, states, ecosystems and habitats. Many non-native plants have great economic value for agriculture, forestry, horticulture and other industries and pose little to no threat to our natural ecosystems. Others have become invasive and pose a serious ecological threat.

“What are invasive plants?
Invasive plants reproduce rapidly, spread over large areas of the landscape and have few, if any, natural controls, such as herbivores and diseases, to keep them in check. Many invasive plants share some important characteristics that allow them to grow out of control. These include: (1) spreading aggressively by runners or rhizomes; (2) producing large numbers of seeds that survive to germinate; and (3) dispersing seeds away from the parent plant through various means such as wind, water, wildlife and people.

“How are invasive plants introduced?
People introduce exotic plants to new areas, on purpose and by accident, through a variety of means. Some species are introduced for use in gardening and landscaping, or for erosion control, forage and other purposes. For instance, in the 1930s, the Civilian Conservation Corps planted kudzu vine (introduced from Japan), throughout the Southeast to help stabilize soil in erodible areas. Kudzu grew so prolifically that it was nicknamed the "vine that ate the South." Others come in unknowingly, on various imported products or in soil, water and other materials used for ship ballast. Many invasive aquatic plants are introduced by dumping unwanted aquarium plants into waterways. Once established in a new environment, some exotic species proliferate and expand over large areas, becoming invasive pests.

“How do invasive plants spread?
Invasive plants spread by seed, vegetative growth (producing new plants from rhizomes, shoots, tubers etc.) or both. Seeds, roots and other plant fragments are often dispersed by wind, water and wildlife. Animals spread invasive plants by consuming fruits and depositing seeds as well as transporting seeds on their feet and fur. People also help spread invasive plants by carrying seeds and other plant parts on shoes, clothing and equipment and using contaminated fill dirt and mulch. Invasive aquatic plants are often spread when plant parts attach to boat anchors and propellers.

“Why are invasive plants a problem in natural areas?
Like an invading army, invasive plants are taking over and degrading natural ecosystems. Invasive plants disrupt the intricate web of life for plants, animals and microorganisms and compete for limited natural resources. Invasive plants impact nature in many ways including growing and spreading rapidly over large areas, displacing native plants, including some very rare species, reducing food and shelter for native wildlife, eliminating host plants of native insects and competing for native plant pollinators. Some invasives spread so rapidly that they muscle out most other plants, changing a forest, meadow, or wetland into a landscape dominated by one species. Such "monocultures" (stands of a single plant species) have little ecological value and greatly reduce the natural biological diversity of an area.

“Invasive plants also affect the type of recreational activities that we can enjoy in natural areas such as boating, bird watching, fishing and exploring. Some invasives become so thick that it is impossible to access waterways, forests and other areas. Once established, invasive plants require enormous amounts of time, labor and money to control or eliminate. Invasive species cost the United States an estimated $34.7 billion each year in control efforts and agricultural losses.

“How to prevent spread of invasive plants
Become familiar with invasive plant species in your area. When selecting plants for landscaping, avoid using known invasive species and those exotic species exhibiting invasive qualities. Ask for native plant alternatives at your nursery. Obtain a list of plants native to your state from your native plant society, state natural resources agency, or the U.S. Fish and Wildlife Service, Chesapeake Bay Field Office. Carry this list with you to nurseries to help with plant selection.

“If you already have invasives planted on your property, consider removing them and replacing them with native species. When visiting a natural area, be alert for invasive species. If you see some, notify the agency or organization responsible for managing the land. Before you leave, avoid carrying "hitchhiking" plant material by taking time to brush seeds from clothing and shoes and remove plant material from boats, trailers and other items.�

__________________________________________________________________________________________

Most Wanted List:

Lynnwood Andrews, is a board member of the Little Falls Watershed Alliance and heads groups of community volunteers called “Weed Warriorsâ€� working to remove invasive species.*  She identifies the following plants as the worst offenders in our area (sorted by category with the most noxious listed first):

Vines - Porcelainberry, English Ivy, Creeping Euonymus (Winter Creeper), Mile-a-Minute and Oriental Bittersweet, Oriental Wisteria (and Kudzu to a lesser degree).

Shrubs - Multiflora Rose, Bush Honeysuckle, Russian/Thorny Olive, Privet, Japanese Barberry (Winged Euonymus), and various invasive Viburnums.

Herbaceous plants - Garlic Mustard, Lesser Celandine, Japanese Knotweed, Daylily, Purple Loosestrife, and Canada Thistle.

Grasses - BAMBOO, Japanese Stilt Grass, Pampas Grass, and Japanese Silver Grass.

*Join a local Weed Warriors group by contacting Montgomery County Parks and Recreation Dept.

__________________________________________________________________________________________

GREENSOURCES:

National Park Service, US Fish and Wildlife Service, “Plant Invaders of the Mid-Atlantic Region�

http://www.nps.gov/plants/alien/pubs/midatlantic/index.htm

Invasive Species of Concern in Maryland, WITH PHOTOS!

http://www.mdinvasivesp.org/list_terrestrial_plants.html

Maryland Department of Natural Resources, Wildlife and Heritage Service

http://www.dnr.state.md.us/wildlife/invintro.asp

Maryland Native Plant Society,  “Control of Invasive Non-Native Plants, A Guide for Gardeners and Homeowners in the Mid-Atlantic Regionâ€�

http://www.mdflora.org/publications/invasives.htm

See TOCC Green Pages from March 2009, for information on how to select native plants for your garden.