April 12, 2017 – Jenkins Arboretum & Gardens has been working diligently for many years to protect and restore the floodplain of Trout Creek. In recognition of these efforts, the Arboretum was awarded an Award of Merit at the Bowman’s Hill Wildflower Society’s Land Ethics Symposium this past spring.
Jenkins Arboretum & Gardens’ Trout Creek Watershed Restoration
Over the past few decades, parts of the once ecologically-healthy land that surrounds Jenkins Arboretum & Gardens have been significantly degraded. Nearby housing, roadways, and commercial development increased the volume, intensity, and frequency of storm water runoff. Consequent erosion has caused significant damage to the floodplain and stream bank along Trout Creek. In addition, man-made disturbances led to an increased presence of non-native, invasive plants which displaced more ecologically valuable native species. These invasive species had dominated the floodplain and forest edges and openings for many years.
As nearly all of the Arboretum’s 48 acres drain into Trout Creek, the Arboretum has developed a long-term, comprehensive restoration plan to address these concerns. The plan involves reestablishing the ecological value of the property and, at the same time, mitigating storm water runoff and stream bank erosion. This plan has 11 major goals and guidelines:
- All non-native, invasive trees and shrubs are to be removed.
- All species to be used for replanting must be carefully selected and appropriate for the conditions of each site. Each species’ mature size, light requirement, moisture requirements, and soil requirements, including pH must be considered.
- All plant selections used for replanting must be native to the eastern United States, preferably the Mid-Atlantic region. Whenever possible, plants of known local provenance should be used;
- Plants selected for replanting should, as much as possible, have high wildlife value, particularly to birds, bees, butterflies, and other insects.
- Understanding that it is a major component of a healthy ecosystem, we will work to increase species diversity of the Arboretum as a whole. In addition, if available, plants listed as rare, endangered, or threatened in Pennsylvania will be given priority over others.
- Wherever applicable, we must consider species that colonize to help prevent storm water damage and stream bank erosion.
- Because Jenkins Arboretum & Gardens is a public garden, aesthetics is always important. Many of the characteristics that make plants attractive to wildlife (fruit, flowers, fragrance, etc.) are also aesthetically pleasing. All planting design must take those characteristics into consideration.
- As long as the above guidelines are followed, there are no restrictions for species selection within the deer exclusion fencing. Plantings outside the fence however, must be deer resistant or tolerant, otherwise the plants will be caged until they are tall enough to be above the browse line.
- In areas that receive relatively little care and no irrigation, soil amendments with mycorrhizae and a generous layer of hardwood wood chip mulch will be used to give the plants the best chance of survival.
- As these are large projects and because we want to raise awareness for what we are doing as an organization, we will collaborate for completion of these projects with other community organizations such as the Boy Scouts.
- During site preparation, including the invasive species removal, all woody debris will be left on site, but must be lopped and oriented transverse to slopes. This debris will further increase wildlife habitat, but will also intercept and reduce runoff and soil erosion, break down and return nutrients back to the soil, and act as a natural mulch to retain water for new plantings.
The amount of work completed to date has been remarkable and all of this work fits into one of four work areas, or “projects”, none of which are currently accessible for public visitation, but are obvious as you drive along Devon State Road or look out from the public garden.
1) Browning Hillside: The Browning Hillside, directly above Trout Creek, is a sloped, 2-acre tract with significant water run-off from the above residential community. The consequent erosion affects not only the Arboretum property, but also Trout Creek. The hillside, which had been mowed grass, has been returned to a forested corridor that links the public garden to a section of Conservation Woodlands. Careful planning included a pathway which is surrounded by native plants suitable for bird, bee and butterfly habitat. Over 350 trees and shrubs of 61 different species and approximately 1000 pollinator-friendly herbaceous plants were planted by the Jenkins staff and the volunteers. The hillside is now fully planted with native plants which attract wildlife, control erosion, and add beauty to the Arboretum.
2) Conservation Woodlands: A roughly 2.5-acre section of Jenkins Conservation Woodlands, which includes the headwaters of Trout Creek, was restored in fall of 2016. To do this, 50 invasive trees and large shrubs, some as tall as 50 feet were removed. The invasive plants included Norway maple, burning bush and shrub honeysuckle. After clearing, the area was replanted with more ecologically valuable native species, many of which are currently caged to protect against deer browse.
The staff of Jenkins Arboretum & Gardens, its weekly volunteers, and volunteers from The Vanguard Group were instrumental in carrying out this project. Jenkins encourages volunteerism as a community service. Our volunteers are immensely valuable to us and we could not accomplish all we do without their help.
3) Devon State Road—east side: This section of Jenkins Arboretum is about 700’ long and extends 150’ in from the road edge. After several invasive species removals with help from local Boy Scout troops, the Arboretum’s staff replanted the area with more than 50 native trees and shrubs which will inhibit the reestablishment of those invasives. Additional site preparation will be done in 2017 and a substantial shrub-layer planting is being planned for spring of 2018.
4) Devon State Road—west side: This is a section of the Arboretum that includes Trout Creek and parallels Devon State Road. It is roughly 1500’ long and extends 150’ in from the road edge. Due to runoff pressures from the macadam roadway, bank erosion has been severe. Invasive plants were removed and replanting was done with native plants appropriate to holding the stream bank. Specifically, alders, willows, and sweetspire have been planted. Jenkins’ volunteers have propagated several thousand herbaceous plants with ornamental and wildlife value to help hold the bank. In addition to protecting and preserving the stream bank, this restoration beautifies a large area of road-front. In total, the project took more than 6 years to complete. Three different local Boy Scouts completed their Eagle Scout project in this area by helping to plant nearly 1,000 trees and shrubs of 64 different species. What started as a badly neglected area that was severely eroded and overgrown with invasive species is becoming a valuable habitat for birds, bees, and butterflies and will be crucial to mitigating further stream bank erosion.