Wetlands in the Anacostia River Watershed

By: Brandon PaceEcology EN.575.415.81.FA15

William HilgartnerDecember 2015

Anacostia River WatershedAs shown by the map from the Anacostia Watershed Society (AWS), the Anacostia River Watershed is approximately 175 square miles. Within the watershed lies the eastern part of the District of Columbia, large portions of Montgomery County, Maryland and Prince George’s County, Maryland.

Efforts to restore areas of the Anacostia Watershed include invasive species control (Phragmites australis) with fencing and revegetation; modification of goose habitat with vegetative buffers, fencing, and egg oiling; and intensive community volunteerism and outreach.

The areas of focus for the site assessment are the areas defined in this map from the National Parks Service. A site assessment was completed incorporating all areas of the Anacostia Watershed restoration efforts at Kingman Marsh (10) and Kingman Island (11). Here is a link to the whole map and brochure: Anacostia Water Trail Map

Kingman Marsh

This image from Google Earth (courtesy of AWS) shows the Kingman Marsh site in relation to the Langston Golf Course and the Kenilworth Aquatic Gardens. Kingman Marsh is downstream of the Aquatic Gardens and the water level in the marsh is affected by the tidal movements of the Anacostia River.

Kingman MarshImmediate questions:• What is the fencing for? • What is the benefit of

the fencing? • What is the fencing

trying to enclose, or keep out?

• Why is the fencing not maintained? This photo was taken at low tide one afternoon

while doing a site visit at Kingman Marsh. There is evidence of fencing on the southern edge of a phragmites patch. Credit to Brandon Pace.

Kingman Island

Kingman Island is located south of Kingman Marsh and just north of RFK Stadium in North East Washington D.C. Kingman Island is affected by the tide of the Anacostia River. These pictures were taken as the tide was coming in. RFK Stadium is located in the background and both pictures indicate there is an area between the land of the island and the start of a phragmites patch where other vegetative plants exist. Credit to Brandon Pace.

Kingman IslandImmediate Questions:• What happened to the fence? • Was Phragmites on both sides of

the fence, and then removal occurred?

• How was the area from the land to the edge of the current phragmites patch restored?

• What types of plants are living in the restored area?

• Will these plants propagate and inhibit further restoration into the phragmites patch?

• Will these plants survive from outside influences such as geese?

There is evidence that a man made fence was constructed along the edge of a phragmites patch. The picture also reveals there are other species of plants present. Credit to Brandon Pace.

Research Derived From Visiting Kingman Marsh and Kingman Island

• Impacts of Phragmites on Wetlands

• Impacts of Canadian Geese on Wetlands

After the formulation of ecological questions during the site assessments, topics of research originated dealing with improving the quality of tidal wetland habitat, and the overall environmental health of the Anacostia Watershed. Photo credit to Google Images.

Impacts of Phragmites on WetlandsPhragmites australis or common reed, frequently referred to simply as Phragmites, is a perennial grass that grows in wet areas such as marshes and wetlands. The invasive non-native variety of Phragmites forms dense masses, causing degradation by crowding out native plants and animals. It is an aggressive plant that reproduces primarily through the dispersal of its seeds by wind. Rhizomes allow lateral spread of the plant, supported by thick deep roots that can reach up to six feet deep. Stolons with nodes every foot, each with the ability of growing a plant, also serve as a secondary source of propagation. This allows the plant to rapidly spread on wetlands and riparian habitats. (USDA Forest Service).

Photo: Bank of Anacostia River between Kingman Marsh and Kingman Island. Credit to Anacostia Watershed Society.

Impacts of Phragmites on WetlandsOnce established, the non-native invasive Phragmites tends to displace native vegetation. Phragmites form a monoculture of tall stems and dense growth, obstructing sunlight from lower-growing plants and animals. In addition, Phragmites are successful nutrients competitors and tend to release chemicals which attack the protein in the roots of competing plants. Thus increasing the survival rate of the Phragmites population. (USDA Forest Service).

Photo: Kingman Island with RFK Stadium in background. Credit to Brandon Pace.

Goals of Phragmites Removal• Replacement of a monoculture

invasive species by diverse native ones which in turn is more supportive of diverse wildlife populations.

• Replacement of Phragmites in areas of the Anacostia Watershed with native plant species such as Wild Rice, Pickerweed, Arrow Arum, and Nuphar.Photo: Bridge to Kingman Island from RFK

Parking Lot. Fenced in area shows where the Phragmites population started, and now receded due to conservation efforts. Credit to Brandon Pace.

Phragmites Decline

The next two slides will show a Google Earth photo from a section of the Anacostia River. The first picture is from August 2010, and the second is from October 2012.

Study the decrease in Phragmites population based on the photo evidence from the two pictures. Phragmites has decreased in this area of the Anacostia River due to conservation efforts that include fencing projects, native plant revegetation, native plant propagation, population removal, chemical and biological treatments, and an overall intensive monitoring program.

Phragmites Decline (August, 2010)

Phragmites Decline (October, 2012)

Lessons Learned- Phragmites Removal

The Anacostia Watershed Society is the main organization that works on restoration efforts located in the areas defined in the ecological site visits. According to the AWS action plan, Phragmites is removed through repeated cutting of the stalk with subsequent spraying of re-growth with a herbicide safe for use near water (Rodeo). After the herbicide application, some of the biomass of rhizomes and roots will be removed to ensure better habitat conditions for the native plants. Native wetland plants will be propagated through seed sowing and plant plugs. Species such as Wild Rice, Arrow Arum, and Nuphar will be propagated at the site.

Impacts of Canadian Geese on Wetlands

Canada Geese, Branta canadensis maxima, have thrived in the surburban environment since establishing “resident status” through introduction by wildlife managers and hunters in the past. They are herbivores that eat a large amount of plants and are capable of stripping an entire wetland ecosystem of valuable vegetation. According to the Maryland Department of Natural Resources, as of 2011 there is a population of more than 80,000 resident Canada Geese living in Maryland.

Photo credit to AWS.

Goals of Resident Goose Habitat Modification• Constructing vegetative buffers along the Anacostia

River stream banks. The construction of buffers will in essence “scare” the geese away when they are flying in to land. Geese like to be able to see what they are landing in, and the addition of buffers will persuade the geese fly elsewhere.

• Constructing fencing around native plants in the wetlands to keep the geese from eating the revegetated areas. This will allow for propagation of native plants that increase biodiversity and promote overall health of the wetland.

• Oiling goose eggs in the spring to decrease goose population growth. Oiling eggs in the spring directly correlates to slowing the growth of resident geese in the affected area.

Photo credit to Anacostia Watershed Society. Top Photo- Before goose fencing. Bottom Photo- After gooses fencing. Location Kingman Marsh.

Lessons Learned- Goose Habitat Modification

According to the AWS action plan, goose fencing and goose enclosures will prevent damages from geese on the desired project site. The fence, made of vinyl coated welded wire is resistant to damage by resident Canada Geese and is also hard to knock down. The sturdiness of the fence will deprive plants the opportunity to grow over it. Although fencing is not an optimal solution to overgrazing, it helps to alleviate the stress of losing native aquatic vegetation to resident Canada Geese. A short term solution, such as fencing, to the long term problem of overgrazing helps conservationists immediately patch up the issues of today while a solution for tomorrow is formulated.

Lessons Learned Visiting the sites along the Anacostia Watershed gave me an intimate approach to viewing the watershed as a living ecosystem. I learned how to look at aspects within this ecosystem in different ways and to ask thorough questions. This in-depth investigation led me to research ways of effectively managing wetland ecosystems along a tidal river.

Picture taken by Brandon Pace. Located on the bridge from RFK Stadium parking lot to Kingman Island.

References

• Anacostia Watershed Society www.anacostiaws.org

• Maryland Department of Natural Resources http://dnr2.maryland.gov/wildlife/Pages/plants_wildlife/ResGeeseProblem.aspx

• National Park Service www.nps.gov• USDA Forest Service http://

www.fs.fed.us/database/feis/plants/graminoid/phraus/all.html