Urban Woodland Species Inventory
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Park. The species inventory took place in an approximately 3.84-acre section of urban forest within Fort Circle Park, situated in Northeast Washington, DC. The studied forest is abutted to the west by a large open grass field, to the east by a wooded grove and grass field smaller than the one to the west, and immediately to the north and south by low-density residential neighborhoods. About 100 meters to the east is another patch of woods, smaller and denser than the woods studied here (see map below).
Approximately 200 meters to the west of the park is a very busy four-lane road, South Dakota Ave NE (2019 Average Annual Daily Traffic Volume of 19,858 - See Note 1), and about the same distance to the east another fairly busy road, Sargent Road NE (2019 AADT: 9,326), dissects the park in which the woods sit. To the north and south pass two much less busy residential side streets, Galloway (2019 AADT: 5,161) and Gallatin Streets NE (2019 AADT: 6,003). South Dakota Avenue and Sargent Road in particular both present significant challenges to wildlife as they dissect the park and present boundaries to moving along an otherwise undisturbed park greenway.
There are no formal trails or human amenities in the woods, there are several informal trails that have been made, with the number increasing in recent years, as determined by historical satellite and Google Street View photos.
The only natural source of water nearby is a stream about 650 meters to the southeast which emerges from a storm sewer at the DC-Maryland border and which feeds into the Northwest Branch of the Anacostia River just to the south of its convergence with Sligo Creek. The stream is located in the same narrow stretch of parks as the forest studied here. Terrestrial animals frequenting this patch of woods need to cross Sargent Road NE to access fresh water.
This woodland patch is part of a slender, uninterrupted corridor of protected green spaces. This network of parks forms a crucial ecological link, connecting the Anacostia River's tributary system to conservation areas in northeast and wider DC. The strategic location of this study site within this green corridor underscores its potential significance in urban ecology and biodiversity conservation.
Forest Canopy. Dendrological characteristics of the forest were estimated primarily through LiDAR data and modeling, as reported by the DC Trees dataset regularly updated by the DC Department of Transportation's (DDOT) Urban Forestry Division. While these estimates provide valuable context, it's important to note that they are based on remote sensing and statistical modeling, rather than comprehensive ground surveys. The 2015 DC State Wildlife Action Plan identifies the forest as a Southern Atlantic Coastal Plain Mesic Hardwood Forest.
According to DDOT’s DC Trees dataset, the forest is predominantly native and deciduous. Estimates suggest that approximately 90% of the trees are deciduous and 10% evergreen. About 76% of the trees are believed to be native to the region.
The forest structure appears diverse in age and size, based on the modeled data. Roughly 52% of the trees are estimated to reach heights of 20 feet or more, with roughly a quarter of the trees potentially exceeding 50 feet.. Trunk diameter estimates, derived from height data using statistical modeling, indicate that about 44% of the trees may have a diameter at breast height (DBH) of 10 inches or greater, with 19% possibly reaching or surpassing 20 inches DBH.
While these figures suggest a mix of established trees and younger growth that contribute to the forest's structural complexity, the nature of the data collection methods present limitations. The tree diameter estimates, in particular, were based on a statistical relationship between height and DBH, which may not have captured the full variability present in the forest.
Field observations during the inventory process largely confirmed the overall picture presented by the LiDAR and modeling data, validating its general reliability. While specific measurements like individual tree heights or DBH may not be precise, the broader characterization of the forest structure and composition proved to be accurate.
Invasives. While the forest canopy is predominantly composed of native trees, with an estimated three-quarters of the upper story being indigenous species, the understory presents a markedly different picture. Ground-level observations reveal a forest floor largely overtaken by non-native and invasive plant species. This contrast between the native canopy and the invasive-rich understory highlights a common challenge in urban forest management. The prevalence of invasive plants in the lower stratum not only alters the forest's ecological dynamics but also poses potential long-term threats to the regeneration of native tree species.
Non-exhaustive list of invasive plants present in the understory:
Bush/Amur Honeysuckle
Japanese Honeysuckle
Wineberry
English Ivy
Baltic Ivy
Winter Creeper
Green Panic Grass
Wood Melick
Non-exhaustive list of common native plants present in understory:
Common greenbrier (Smilax rotundifolia)
Virginia Creeper
Blackberry
American Holly
American Pokeweed
Soil sampling for toxic chemicals. It is also critical to note that an adjacent part of the same park across South Dakota Avenue has a well-documented issue of toxic waste stemming from construction of the Green Line of the Metro in the late 1980s and early 1990s. While there is no known direct evidence that this park was also contaminated, part of this area underwent construction at the same time, and it is not outside of the realm of possibility that some of the contaminated soil that made it into the adjacent park could have also ended up here. Comprehensive soil testing surveys, particularly for heavy metals and persistent organic pollutants, should be carried out throughout this park in the future. Doing so was explored as part of this study but ruled out due to budget concerns (the likely cost for the number of soil samples needed was at least $2,500). Alternative funding sources should be sought out to carry out these tests in the future.
3D locator map of the project study woods and surroundings on the DC side of the border