Invasive Invasion
The Arlington County 2007 Natural Resources Inventory of Upton Hill, a copy of which was obtained from NOVA Parks under the Virginia FOIA, documents the extensive invasive plant problem at that time. NOVA Parks has done little to nothing to remove invasives from the park since then.
The 2007 inventory noted extensive Miscanthus grass, Japanese stilt grass and Kudzu in the western parts of the park. Akebia had taken over the southern part of the park. A patch of bamboo was growing in the central-eastern part of the park next to Livingston St.
Rather than implementing a comprehensive invasive removal, NOVA Parks has relied volunteer efforts to remove invasives. While volunteers efforts are appreciated (FoUH has participated in some!), they are no substitute for a sustained, professional effort in a park of this size with a sizable problem.
NOVA Parks needs to allocate the new revenue it is receiving from its projects at Upton Hill for a comprehensive invasive removal program.
If this is done, volunteer efforts to keep invasives out of the park could succeed.
English Ivy Overgrowing Mature Trees
Japanese Stilt grass spread further in the park. It is also spreading to private residences along the border with the park.
Extensive Japanese honeysuckle bush infestation throughout the park. Along pathways, at entrance ways, and in the forest area.
INVASIVE PLANTS:
Within a typical urban environment, it would not be unusual to find 40% or more of all plant species present to be of alien origin, particularly with the presence of roadways and turf grass areas. While not all alien species are considered to be invasive, many are. It is well documented that invasive plants can have devastating affects upon native plant communities. Many alien species thrive in new habitats and can quickly out-compete or replace native species. In the extreme, aggressive vining species, such as English Ivy, Akebia, and Porcelain Berry, can blanket entire trees or large areas of forest and literally starve native vegetation of sunlight.
As part of the countywide Natural Resource Heritage Inventory (NHRI) it was considered important to assess in a general way the impact of alien invasive plants upon our natural flora. Within each park surveyed, the most highly impacted areas were mapped and the major offending species documented.
Upton Hill Regional Park was found to be "highly invaded" by non-native plants. Some of these species are considered to represent a serious threat to the ecological balance of the natural plant communities present. A map showing the areas of greatest invasiveness within the park is included as an attachment to this report. While non-native species can be found throughout the park, only those areas recommended for management and control are shown on the map.
Highly invasive species present —
Kudzu (Pueraria montana). Of Asian origin and highly invasive. Also known as "mile a minute" vine. This plant is capable of quickly enveloping living trees and blanketing shrubs and herbs. Considered one of the worst potential invasive plants in Arlington.
Five-leaved Akebia (Akebia quinata). Akebia appears to prefer sunlit sections of disturbed forest and meadow environments. It is capable of rapid growth, spreads by vines, and can blanket large areas. The only significant infestation of this species in Arlington parkland appears to occur at Upon Hill.
Porcelain Berry (Ampelopsis brevipedunculata). One of the most pervasive, destructive and widely distributed invasive plant in Arlington.Grows as a dense vine and can quickly blanket large areas of natural forest. Spread by birds that eat the small grapelike fruits.
English Ivy (Hedera helix). Another widely distributed invasive plant in Arlington. Primarily grows by vining along the ground and creating a solid green blanket. Common escape from residential backyards. Capable of ascending trees. Because it only produces seed (eaten by birds) in the aerial form, one method of slowing the spread of this vine is to cut all vines observed growing up the trunks of trees.
Japanese Stiltgrass (Microstigium vimineum). This small grass is a relative newcomer to the invasive world, but is spreading with great rapidity. In a park environment, Microstigium is often found growing in disturbed, sunlit pockets within the forest and along walking trails.
Other invasive species observed —
Bamboo (sp?)
Wineberry (Rubus phoenicolasius)
Japanese Honeysuckle (Lonicera japonica)
Periwinkle (Vinca minor)
Chinese Privet (Ligustrum sp.)
Linden Vibumum (Viburnum dilitatum)
Double-file Viburnum (Viburnum plicatum var. tomentosa)
Bird Cherry (Prunus padus)
Norway Maple (Acer platanoides)
Miscanthus grass (sp?)
Bush Honeysuckle (multiple species of Lonicera sp.)
Asian Clematis (Clematis sp.)
Japanese Maple (Acer japonica?)
Park Areas with High Invasiveness — See Map
1. Several acres of woodland and woodland edge lying down slope of the mowed field, and including the upland meadow adjacent to the field is marked AKEBIA on the map. While this section includes a mixture of invasive plants, the Akebia represents a particular threat. Observations and photos show a broad area currently being blanketed by the vine and in some cases trees are beginning to be affected.
2. A several acre patch, including much of the Early Successional Forest, continuing along the crest of the hill below the parking lot is marked KUDZU and MISCANTHUS on the map. Again a mixture of invasives occur within this section, but Kudzu represents the greatest threat. Growth of this vine begins at the top of slope where mowing operations stop, and is rapidly moving down slope to envelop all vegetation that lie in the path. Attached photos document current conditions. The Miscanthus does not appear to be as aggressive as some of the other species, but has been observed to have spread significantly within the past nine months.
3. A small, but significant growth of Japanese Stiltgrass is located upslope from the playground area in a sunlit pocket of young forest. This central infestation could easily spread to other parts of the park, especially along walking trails. This pocket is marked STILTGRASS on the map.
4. Three small and unmarked sections of invasiveness are mapped in the southeast corner of the park, and along N. Livingston Street on the eastern border. These three areas contain mixed invasive species, but also contain small, but growing infestations of English Ivy.
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MANAGEMENT RECOMMENDATIONS:
4. Invasive Plants. This report has discussed the ecological threats associated with uncontrolled alien plants, has provided a list of species observed, and has mapped the most pervasive problem areas. It is suggested that an aggressive invasive plant removal plan be considered, focusing first on the English Ivy infestations in the southeast portion of the park as a form of prevention to safeguard the most pristine section of Acidic Oak — Hickory Forest remaining in the park. Upon completion, work should then move to treatment of Akebia and Kudzu. If funding is not readily available to hire contractors, volunteers can often be recruited for this type of on-going park project.
Photos above from "Upton Hill Regional Park Natural Resource Photo Library, June 2007, attachment to the Natural Resource Inventory of Upton Hill Regional Park
Bamboo grove noted 13 years ago still thriving plus English Ivy everywhere on the ground along Livingston St. despite Natural Resources Inventory report recommending this area as a priority for invasive removal as it likely is the oldest part of the forest
Japanese holly grove in center of park with mysterious excavation
English Ivy taking over ferns in wetland area
Akibia infested area in southern area of park along storm water outflow channel from expanded parking lot and path leading to Longfellow St. Volunteer attempts at removal are beginning.
