Invasive Plant Management

What are invasive plants?

Groups of plants that are called invasive have been introduced by humans—either accidentally or intentionally—into areas where they were not originally found. Because those areas often lack the right predators and diseases to keep populations in check, invasive plants quickly reproduce and spread to cover large areas and even entire regions! In the process, they displace their native neighbors. Invasive plants negatively impact natural ecosystems, the local biodiversity, and the economy.

Why are native plants important?

Species diversity plays an important role in the health of all ecosystems. Different animals rely on the presence of a variety of different native plants (and vice versa) to provide food, shelter, and other life necessities. Disturbances among the members of one species in these chains of interdependence often spells disaster for many others.

What are the specific threats of Invasive Plants in the Anacostia Watershed?

There are many technical reasons invasive plants are harmful to the local region.  Invasive plants in the Anacostia and Chesapeake Bay Watershed:

• form green carpets (ground covers) that block sunlight and inhibit the germination and growth of other plants underneath
• threaten populations of some native animals that depend on the native plants (e.g. West Virginia White butterfly) 
• hybridize with native plant species (e.g. native mulberry with the invasive white mulberry)
• inhibit the growth of tree seedlings and herbaceous plants thus affecting forest regeneration and reducing species diversity
• change soil chemistry therefore affecting nutrient cycling
• provide habitat and increase the abundance of Lyme disease tick vectors such as Black-Legged Ticks and Lone Star Ticks, therefore increasing public health risks
• decrease the area of wetlands by invading restored wetland sites (e.g. the invasive strains of Phragmites or Common reed)
• pollute air by emitting gases that after a chemical reaction end up producing ozone, a gas that is fine in the upper parts of the atmosphere, but is a hazard to human health at ground level. (e.g. Kudzu, a vine native from Japan)

How do we remove them?

At AWS we use different invasive plant removal techniques. Since the bulk of our work force are volunteers, we employ tools and methods that are easy to operate and safe for everybody. Also, since we are a watershed stewardship organization, we use the most appropriate herbicide application techniques and formulations to avoid damages to non-targeted plants, wildlife and water resources.

During our year-round volunteer events we use pulling by hand and with pitchforks, and cutting with hand pruners, saws, and other tools as removal techniques. Separately, our certified staff will combine mechanical control techniques alongside minimal targeted applications of herbicides. Herbicide use is mostly Glyphosate, which is readily biodegraded by microorganisms.

AWS conducts invasive plant surveys to choose sites for invasive plant control plans. First, we identify the invasive species present and the native species we are trying to protect. After surveying, we get an understanding of the distribution and abundance of the invasive plants in the sites we choose to work. Then we prepare Invasive Plant Control Plans where we define the management strategy by prioritizing species, control timing, and the sites and their conservation value. We try to focus our efforts, and limited resources, on the highly invasive species that are widely known to cause negative impacts to biodiversity.
  
AWS has noted some great successes in every area where this invasive protocol has been employed. Once-threatened native plants quickly reassert themselves, while invasive species die off and do not return.

How can I help?

Help our invasive plant control efforts by volunteering with us!

AWS volunteers remove Multiflora Rose, Oriental bittersweet, English Ivy, Garlic Mustard and other invasive plants at parks in Maryland and the District of Columbia. The target species we remove depend on the time of the year and our management needs and priorities at the different restoration sites.

Visit our event calendar to find out when and where the next invasive pull will take place.

Invasive Plant Resources

• Invasive and Exotic Species of North America
• Least Wanted: Alien Plant Invaders of Natural Areas
• EDD Maps
• Maryland Invasive Species Council
• National Invasive Species Information Center