Crossways Preserve Deer Exclosure
The overabundance of deer in southeastern Pennsylvania is increasingly damaging the delicate matrix of connected species that comprise our many diverse ecosystems. To protect native plants from deer herbivory and to further study the effects of deer predation on native plant communities, the Wissahickon Valley Watershed Association (WVWA) will be installing a deer exclosure at the Crossways Preserve in 2015, which will encompass 2.5 acres and consist of roughly 1,500 feet of fencing to prevent deer from browsing an enclosed area. The selected site at Crossways consists of a wet meadow, encircled by a wet-to-dry scrub/shrub area – a form of habitat that is important for many insect species, including butterflies, dragonflies, and other important pollinators, as well as to many bird species which are facing decline. The area is rich with native plants, and few invasive species. During recently completed Natural Resource Inventories of WVWA’s preserves, the botanists, entomologist, and herpetologist leading each study independently noted the large diversity of native species at Crossways, and recommended that maintaining the integrity of the preserve be a high priority. Installing a deer exclosure is an important step toward that goal.
Crossways has one of the richest landscapes of WVWA’s preserves, and consists partly of a 6.5-acre meadow of warm-season grasses and perennials that is beneficial to insects, birds, and mammals. By protecting the adjacent wet meadow and scrub-shrub area, we will increase and diversify habitat and food sources for wildlife, and create a more resilient ecosystem. WVWA plans to do minimal planting in the exclosure, only focusing on missing species and potentially adding species of concern with state rakings of S1 (critically imperiled) or S2 (imperiled). Documenting what species successfully reemerge and grow from the seed bank already in the ground will also be an important aspect of this study, and will indicate what species would, and should, be present in a healthy landscape free of deer predation.
Camp Woods Deer Exclosure Project
In the spring of 2014, a deer exclosure was constructed in Camp Woods where fallen beech trees had created a sunny opening and native species were planted inside the protected area. The overabundance of deer decreases plant diversity in the preserves, and this project will help us understand their impact and re-establish native plants. The project goals include:
- Study deer herbivory
- Establish missing native plants, including Pennsylvania species of concern
- Allow native plants to regenerate from the forest floor
- Create a protected plant repository
- Create a seed source that can spread to the surrounding areas
- Create a seed source to use in propagating plants for future restoration projects in other WVWA preserves
The Stewardship staff monitored the status of the new native plants. Damage from insects, disease, and environment was noted, as well as information about bloom time, seed setting and growth. The deer exclosure proved to be a great success, and all of the project goals have been achieved. The lush vegetated interior was in stark contrast to the barren ground surrounding the deer exclosure and provides vivid proof of the severity of deer herbivory. Native plants emerged from the forest floor and were protected inside the exclosure. The numbers speak for themselves, 94 % of the newly planted species have successfully established and 50% of these plants have set seed. The plant diversity in Camp Woods was increased and included the addition of four Pennsylvania species of concern. The project illuminates the destructive consequences of deer overpopulation and gives a glimpse of what the forest should look like, in a perfect world. The success of this project will hopefully set a standard for future innovative projects.