A Crash Course in Invasive Species
As an accredited land trust, we must complete multiple tasks yearly to meet the highest national conservation and land stewardship standards. One of those tasks is visiting every site we protect at least once a year to ensure they adhere to our easement regulations and recommend solutions that could improve the ecological condition of their land. Stewards walk the property, take pictures, and compare photos from previous site visits to assess how the land has changed. Landowners are always invited to walk the property with stewards, allowing them to take an active role in caring for their property and giving the land steward insight into what has happened since the last site visit. But what if the landowner isn’t an individual but instead a county jurisdiction? Vegetation ecologist Nelson Debarros and ecologist Darko Veljkovic represented Fairfax County and accompanied NVCT on a recent site visit to Elklick Woodlands Natural Area Preserve. They provided insight into the county's involvement in caring for the property and a helpful crash course for our staff on invasive species!
Invasive species are plants or animals that thrive in areas they are not native to, often outcompeting native species. This can throw off the ecological balance of an area and have dire consequences. Thankfully, there are several ways to manage invasive plants. Biological methods involve using natural relationships to control populations. For example, one way to deal with pesky aphids eating your garden plants is to cultivate a garden that attracts native ladybugs, natural predators of aphids. Removing weeds by hand is an example of the physical method. Finally, spraying large patches of invasives with herbicide is a form of chemical management. Spraying can be problematic because, if not controlled properly, it can damage surrounding plants, which may be natives. There is also concern about the effects of herbicides on the environment, so it is essential to consider other methods for removal before spraying and researching the types of herbicides one plans to use.
The first invasive species we encountered was wineberry (Rubus phoenicolasius), a perennial shrub from Eastern Asia. This shrub grows in dense thickets that create large shade areas, making it difficult for small saplings and other plants to reach light. These thickets also make maneuvering through forests rugged for wildlife and hikers. Large patches of wineberry are dealt with through invasive pulls and spraying of herbicides on large patches. The next troublesome species we identified left several traces of its destruction. If you’ve ever seen an ash tree with small tunnels under its bark, you know an emerald ash borer (Agrilus planipennis) has been there. The emerald ash borer is an invasive beetle from Asia that accidentally made its way to the United States through packing materials in 2002. As larvae, they burrow underneath the bark of ash trees and eat the tissues that transport water and nutrients throughout the tree. This results in infested trees dying within 3 years. To manage ash borers, Fairfax County, in cooperation with the United States Department of Agriculture and the Virginia Department of Agriculture and Consumer Services, has released tiny stingless wasps to eat the ash borers. These wasps are no threat to the local environment or humans, and their favorite food is emerald ash borer eggs and larvae! Other invasives spotted during this visit include a southern magnolia sapling that was promptly removed, various patches of Japanese stilt grass (Microstegium vimineum), and Coralberry. It is worth noting that Coralberry is native to Northern Virginia but not Fairfax County.
Ash trees after hosting emerald ash borers
"I havent seen a full grown ash tree here since being hired in 2019" - Darko Veljkovic, Fairfax County Ecologist
Multiple factors lead to the success of introduced invasives. For example, deer prefer to graze on native species, and their large population size results in overgrazing of natives and tree saplings. This makes forest regeneration difficult and creates the perfect playing field for invasive plants, which deer typically avoid. Another form of disturbance is excessive rainwater runoff; concrete surfaces cannot absorb rainwater, and the runoff can erode floodplains and carry invasives from one location to another. Japanese stilt grass is often found at the bottom of stream valleys. While invasives are a significant concern for landowners and conservationists alike, they are frequently a symptom of land disturbance in general.
Conserving land means more than just leaving the land alone; stewardship requires we actively assess the land under our protection and recommend strategies for tackling problems like invasives. On properties we own, we regularly organize invasive plant pulls and explore other methods to manage non-native species. We collaborate with the county to develop comprehensive management plans for properties with shared ownership, like the Elklick Nature Preserve. Our land stewards work closely with landowners, reviewing these plans and offering resources to help enhance their properties. The Elklick Nature Preserve is just one example of the many properties we co-manage with Fairfax County, and we’re always grateful for the opportunity to partner with the county’s dedicated staff, like Nelson and Darko!
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