One of the Conservancy’s current invasive species management projects, the Hallett Nature Sanctuary now has many different plant species within its gates as a result of our efforts. Over one hundred native species have been planted in just the past few years. The Hallett looks far different from the invasive-ridden sanctuary that the ROOTS program — a semester-long ecological restoration and management program for high school students — began working on thirteen years ago. When the ROOTS program began, the Hallett was largely covered with dense populations of invasive species such as Japanese knotweed, garlic mustard, and jetbead.
This eastern slope in the Hallett used to look like this each spring filled with garlic mustard, jetbead, and Japanese knotweed. As a result of the cumulative efforts of ROOTS students and our staff, the Hallett now looks like this. There is very little knotweed or garlic mustard, and the site is now composed of different species of native grasses, wildflowers, and shrubs that will provide habitat and aesthetic value.
After years of removing these invasive species with the help of the ROOTS program, our staff’s next step was to plant native species that can offer competition to the reemergence of invasive plants, habitat for our non-human Park users, and engagement for our visitors. Three native species that we have come to depend on at this stage of invasive plant management across our woodlands are blue-stem goldenrod (Solidago caesia), late-flowering thoroughwort (Eupatorium serotinum), and white wood aster (Eurybia divaricata). All three herbaceous native species thrive in our urban soil, tolerate shade or sun, self-sow in the landscape, provide habitat for wildlife, and have engaging flowering habits.
Blue-stem goldenrod is one of the few goldenrods that thrive in shady conditions. It has a beautiful arching habit that makes it perfect for inter-planting with other fall-blooming species.
We have found late-flowering thoroughwort to be one of the more urban tolerant species in the Park, growing straight out of our Manhattan schist with minimal soil and attracting numerous pollinators such as the important Monarch butterfly. These flower heads literally hum with insect activity during the summer months and, growing five to six feet tall, offer an immersive experience when standing within them.
Perhaps the most reliable native species we use for restoration purposes is the white wood aster.
It is also highly urban tolerant, has a long bloom period, and can be found not only in our Woodlands, but growing all over the Park from North Meadow to around the American elms along the Mall. En masse, this plant is stunning with its clouds of small white flower clusters. These three native species offer just a snapshot into the benefits of native plant diversity in our park, as we manage hundreds of native species across the Park that provide similar benefits to an incredible variety of wildlife and our visitors. We will know the true impact of these efforts in the years to come, but in the meantime we can continue to educate each other and others about the need to manage invasive species.
There are numerous examples of similar restoration efforts all over the Park. Once in place, restorations need continued management in order to be successful. Our visitors, human and animal, will knowingly and unknowingly bring in plant species, and we will bring in plant material for operational purposes; all of these things can lead to the introduction of an invasive species. Invasive species management is an ongoing process that affects all of the landscapes in Central Park. We are not unique in having to contend with this management issue and we are constantly susceptible to the world’s changing ecosystem. As the invasive species debate continues, monitoring and managing these species will allow the Park’s plant diversity to continue to increase. Daniel Atha and Regina Alvarez, lead researchers of the Central Park Flora Project, a joint program of the Conservancy and the New York Botanical Garden, are finding incredible diversity within the Park. Without invasive species management, this would not be the case. That is why we will keep this conversation going and continue to educate ourselves and others about all of the ever-changing variables in managing an urban park.