There are many aspects to managing a park like Central Park. The landscapes throughout the Park are highly varied - playgrounds, ballfields, lawns, water bodies, woodlands, etc., and each type requires its own set of management practices. Managing the more natural areas involves controlling invasive plants, improving soil conditions, planting natives and protecting the areas just restored. In this blog post I want to share with you some of the species of native plants the Conservancy has used to restore the natural areas of the Park. Many have been quite successful. Some are a bit slower to establish, but will hopefully flourish given time.
When I first started working for the Conservancy in 1993, most of the landscapes were quite degraded from trampling. One of the few native wildflowers that survived those conditions was the white wood aster, Eurybia divaricata (formerly called Aster divaricatus). As we began working on restoring some of these woodland landscapes, we protected the stands of asters and allowed them to spread. White wood asters are still the backbone of many landscapes in the Park as they do so well on their own.
- One of the first planting jobs I did as a seasonal back in 1993 was in the newly restored Great Hill area. We planted along the woodland edge along the paths leading up to the Great Hill from the West Drive. One of the species we used was the spring ephemeral, Virginia bluebell, Mertensia virginica. Although spring ephemerals are perennials (the same plant comes back year after year), they go dormant early in the season. This species leafs out and flowers in spring, by early summer they have formed and released their seeds, the foliage dies back and the plant goes dormant until next spring. Some ephemerals, such as trout lilies, go dormant in an even shorter time span.
- Virginia bluebells are a successful restoration species. The stands that have been planted have persisted for many years and have even spread. They add wonderful colors to the spring landscape - the flower buds are pink and they open into beautiful blue flowers.
In the early days of restoration work in the Park, we limited ourselves to planting species that we knew would survive the harsh conditions of a public park. The soil had been compacted and impoverished for many years and we were working to add compost and protect it from trampling. This took a long time and a lot of outreach to the public to convince them to stay on paved paths. As the years passed, this outreach worked and soil improved in many areas. We were eventually able to start trying new species. Now that areas were more protected, we could use species that were more sensitive to compacted soil and trampling.
One of the most successful native species the Conservancy introduced was American ginger (Asarum canadense). This is not the species of ginger we use in cooking (that one is Zingiber officinale, in the Zingiberaceae, the ginger family). Our ginger is in the Aristolochiaceae, the Birthwort family. American ginger spreads very rapidly and makes a nice groundcover on the woodland floor. Unlike some of the other woodland wildflowers, it is not an ephemeral, so it keeps its leaves all season until it goes dormant for the winter. It has an interesting looking flower which is usually not seen because one has to crouch down on the ground and lift up the leaves to find them near the soil. Flowers this close to the ground are often pollinated by ants or other ground-dwelling insects. American ginger is one of the host plants for Pipevine swallowtail butterfly larvae.
One wetland species that has been used for restoration in Central Park is Blue Flag (Iris versicolor). There is an invasive iris, called Yellow Flag (Iris pseudacorus) that grows in the same habitat and is very difficult to distinguish from the native until they are flowering. Because the only sure way for a gardener to tell them apart is with the flowers, gardeners pull the Yellow Flag only when it is flowering. This is always a challenge in a public park. Park patrons don't often understand about the problems of invasive plants and get very upset when they see a gardener yanking out beautiful yellow flowers from the landscape. But the Yellow Flag eventually dominates the water's edge and pushes out other native plants, so it is important to remove them and replace with a variety of native species.
It is interesting to look at restoration species in the same genus and see differences in success. The white violet pictured below is Viola striata and has done very well since being introduced into several landscapes. Plantings survived and spread nicely over the years. The second violet species pictured below is Viola labradorica, which was introduced around the same time as V. striata. However, the Labrador violet petered out after a while and there are only a handful of them left.
Herbaceous plants are not the only types of plants used for restoration projects. Trees and shrubs are also introduced into the landscapes.
Many people are familiar with the small tree called Flowering dogwood. There are also several species of shrubby dogwoods that are part of woodland and wetland landscapes. The dogwood pictured below is called Gray dogwood, or Northern swamp dogwood (Cornus racemosa). Daniel and I are not sure yet if this species is spreading by seed, but it certainly spreads by sprouting new stems and suckers, each stand getting larger over time. Aside from being an excellent habitat plant -the fruit is eaten by many bird species and it is a very full shrub that provides good cover for wildlife - the flowers and fruit are very attractive.
Many areas that have been restored in Central Park are now very well protected, and not just by fences. Years of outreach - staff speaking with Park Patrons and other types of outreach - has led to a great deal of respect and cooperation from the public. Many Park users understand what the restoration is all about and see the success of these efforts. This has led to more people staying on pathways and other behavioral changes that help protect the Park landscapes.
Because of this, the Conservancy has been able to begin introducing species that years ago would have been too delicate or too picky to survive in Central Park.
Twin leaf (Jeffersonia diphylla) is one such species. Although technically not native to New York City, this is a threatened species in the forests of New York and New Jersey, so it is gratifying to see it surviving and beginning to spread in Central Park. This is another species whose flowers are close to the ground and are pollinated by ants. It produces green capsules as fruit, as you can see in the photo below.
Skunk cabbage (Symplocarpus foetidus) is not a threated species - some people consider it a weed - yet it is very slow to establish in Central Park. It has a wonderfully odd looking flower which comes out at the end of the winter. It is one of the few species of plants that can generate its own heat. This warmth, coupled with the rotting-flesh color and smell of the flower attracts flies or other early insects as pollinators. The leaves, seen in the second photo below, are lush as this plant can be fairly large. Crushing the leaves and taking a sniff tells you how this species got its common name! If you look closely at this photo, in front of the skunk cabbage you see a small yellow flower, a Trillium, another spring ephemeral.
The last species I'd like to leave you with today is one that in all my years working for the Conservancy, I never thought would survive. My staff and I planted this clump of orchids over 10 years ago. I thought it was a long shot, but the plant made it and has very slowly spread into a larger clump. This Yellow Lady's Slipper orchid (Cypripedium parviflorum var. pubescens) started as three plants and has grown into about a dozen stems. Not much for a decade of growth, but considering Central Park lost all of its orchid species in the early years of the Park's creation, and orchids in natural areas throughout the state are threatened, this is a triumph.