Friends of Thrifton Hill Park
Here are some frequently asked questions about invasive plants at the park.
What are invasive plants?
They are plants that have been introduced from other areas of the world, and because of that, they have few natural controls, such as herbivores, parasites, and disease, to keep them in check. They rapidly take over large areas eliminating native plants and the animals that depend on them. They change the composition of the landscape destroying the ecological balance of plants, animals, soil, and water achieved over many thousands of years.
Why are invasive plants so bad?
Invasive vines kill trees by growing up the trunk and then either blocking out photosynthesis (for a slow death) or weighing them down and making them susceptible to blowing down in winter (for a quick death). (The picture at right shows english ivy choking trees on the 2700 block of 23rd Road.) These vines even make it difficult for new seedlings to grow because vines like English ivy provide such a tight layer that sunlight cannot even get through. As native plants are displaced, animal populations that rely on the plants for food and shelter also decline. Some invasives like English ivy actually attract invasive animals like rats. These plant are green, and green is good, right? No way. Make no mistake. These invasive plants are definitely the bad guys.
Invasive plants also:
What invasive plants are taking over Thrifton Hill Park?
Many of the above descriptions are from Plant Invaders of Mid-Atlantic Natural Areas by the National Park Service and the U.S. Fish and Wildlife Service. This booklet is a great way to start learning about common invasive plants in our area.
What is the long-term plan for managing invasive plants at the park?
Since Thrifton Hill Park is so overrun with invasives, their removal will be long-term project requiring many years to get them under control. One of the best ways to reduce invasive plants is to have a sustainable tree canopy, which shades out many highly invasive vines. Then, moderately invasive vines like English Ivy and periwinkle can be pulled out. Once invasive are better controlled, the park will regularly need to be monitored and have invasives removed before they spread.
Starting August 2006, Invasive Plant Control Inc. removed and applyied herbicide treatments to invasive plant species in two areas of the park -- the area to the right of the main entrance and the area along the sound wall between Fillmore and Edgewood Streets. This is funded through a Neighborhood Conservation Grant and includes a retreatment during the summer of 2007.
The Maywood Community Association's (MCA) Parks Committee is working with Arlington County's Park Service and Invasive Plant Program to create an invasive plant control plan and a tree planting plan to remove invasive plants and achieve a better shade canopy. These plans will be achieved through Arlington County Park Service, Invasive Plant Program, and volunteer efforts. Arlington County Park Service expects tree planting efforts to begin in late September or in October. Volunteer invasive removal efforts will take place during park cleanup days.
MCA Parks Committee also hopes to secure future county grants. In May 2007, we can apply for a Park Enhancement Grant (up to $12,000) to help with invasive removal efforts. Unfortunately, the Neighborhood Conservation (NC) program has placed a moratorium on new NC grants for two years because of past overruns. Maywood received an $80,000 grant in 2004, so it is uncertain when we would next qualify for more funding at the park. MCA needs to update the Maywood NC Plan and establish invasive plant control at Thrifton Hill Park as a top priority to even consider future NC funding.
What improvements can I expect to see once invasive plants are better controlled at the park?
You should see:
• More trees. Arlington County Park Service will be able to plant trees once areas are free of the invasive vines that could kill new trees.
• More new tree seedlings and saplings. With the dense cover of invasive vines removed, there will be room for seedlings to sprout, grow into saplings, and mature into healthy trees that provide shade canopy and improved air quality.
• Healthier plants. Once established in an appropriate area, most native plant species are hardier than exotic plantings and do not require watering, fertilizers, pesticides, or intensive pruning.
• More native wildlife. Native plants will have an opportunity to thrive providing wildlife with familiar sources of food and shelter. In developed areas like Arlington, urban nature parks like Thrifton Hill Park provide essential shelter for displaced wildlife and nesting areas for migratory birds.
• Less rats and mosquitoes. English ivy forms the perfect hiding places for urban rats and moist habitat for mosquitoes. Once english ivy is gone, they do not have the habitat they are looking for.
• Less erosion. English ivy's shallow root system increases the likelihood of erosion and slope failure. With invasive removal, erosion is a concern since native plants needs some time to get established. Planting suitable native plant communities and mimicing nature being allowing leaves to matt down will help secure soil and minimize erosion.
What can I do to prevent invasive plants from spreading into natural areas?
• Keep english ivy down. from climbing up trees, houses, walls, or other vertical surfaces where it starts producing berries that birds then spread and where it kills trees. For practical advice on how to remove English ivy, see the brochure by Arlington's Invasive Plant Program.
Where can I find more information?
Arlington County's Invasive Plant Program - Volunteers and Arlington Staff work to control invasive plants at more than 30 Arlington County sites. Learn more about the program and see work site photos at:
National Park Service and U.S. Fish and Wildlife Service's Plant Invaders of Mid-Atlantic Natural Areas is a great booklet describing common invasive species and native plants to use in their place. A must have for fixing up your yard or the park!
Native Plants for Wildlife Habitat and Conservation Landscaping
Mid-Atlantic Exotic Pest Plant Council
Virginia Department of Conservation's Invasive Plants of Virginia. They have a invasive plant species listing that ranks how invasive certain plants are (highly, moderately, occasionally).
Native Plants for Conservation, Restoration, and Landscaping in Virginia
Southeast Exotic Pest Plant Council Invasive Plant Manual
Silent Invaders by the U.S. Bureau of Land Management with movie clips that make it really easy to understand how invasives take over, their impact, and what to do. Great for kids and adults.
“Invasive plants are killing native trees” -- look at "How invasive ivy kills" a short animation of English Ivy killing a tree
Weeds Gone Wild Home Page http://www.nps.gov/plants/alien/
Center for Invasive Plant Management
A good background on invasive species
Thrifton Hill Park, 2814 23rd Street North, Arlington, VA 22201