Prospect Park

Brooklyn is the least-forested borough in New York City. The bulk of the existing forest, totaling about 100 acres, lies within Prospect Park. When Frederick Law Olmsted (1822-1903) and Calvert Vaux (1824-95) designed Prospect Park (1865-95), they incorporated two areas of existing forest into the plan. One area, the Midwood, was left largely untouched. Situated below the terminal moraine (a ridge of boulders, gravel, and sand that marks the end of a glacier’s advance) the Midwood is dominated by tulip trees (Liriodendron tulipifera). The other area, the Ravine, is on the moraine and is a series of small hills and kettles (ponds formed by submerged chunks of glacier during the last ice age) with a small stream entrenched in a steep valley. Olmsted and Vaux planted evergreen trees in an attempt to mimic an Adirondack landscape, but over time most of the evergreens died. Native oaks, such as the pin oak (Quercus palustris), as well as non-native Norway maples (Acer platanoides) and sycamore maples (A. pseudoplatanus), have filled in the gaps. The fertile, moist, and well-drained soils of this area make for what is called a “rich forest.”

While there might not be much forest in Brooklyn, 15,000 years ago there was no forest in New York City at all. Glacial activity dominated and vegetation was scarce until the global climate warmed and forced the glacier to retreat. Grasses and mosses grew in its place and their root systems held the sand firm. Successive generations of dead plant material provided organic matter and nutrients to the developing soil, and soil accumulation, combined with continued warming trends, enabled trees to grow. Thick forests began to prevail about 8,000 years ago and, as the vegetation grew and the warming continued, droves of animals began to move from the south into these new ice-free areas.

The forests in Prospect Park are like any other in that they are ecosystems, which are self-sustaining units defined by a complex exchange of energy between plants and animals. The source of energy is the sun, and a forest’s first interaction with the sun is at the canopy layer, the dense, leafy roof of the trees. The trees absorb almost all of the sun’s light – sometimes only one percent filters through to the ground. Consequently, other forest plants have to adapt their structure, leaf emergence, and growth behaviors to get the nourishment they need from such a scarce resource. These smaller plants are divided into understory, shrub, and ground layers.

The ground layer is composed of the lowest growing plants, the wildflowers and ferns. These are the first plants to emerge in spring and many of them are therefore the first to die back. Ground layer plants vary in height from the Canada mayflower (Maianthemum canadense), which carpets the ground, to Joe Pye weed (Eupatorium fistulosum), which can rise to heights of six feet.

As ground layer plants unfurl their leaves, shrub level plant buds burgeon. This layer is made up of woodland shrubs, most of which flower first and then leaf out. Shrubs range in height from the knee-high lowbush blueberry (Vaccinium angustifloium) to the spicebush (Lindera benzoin), which reaches up to ten feet or more into the understory.

The understory is made of small trees such as sassafras (Sassafras albidum) and dogwood (Cornus florida), which flower and leaf out about the same time as shrubs. Trees in the canopy layer generally flower first, often as early as shrub layer species, but their leaves open last. The variety of flora in a forest provides excellent habitat and food sources for animals of all kinds. This self-perpetuating environment, though, can be detrimentally affected by urban factors, such as habitat loss, invasive plant and animal species, pollution and nutrient enrichment, poor awareness, and misuse or abuse of land. For that reason, Parks is actively involved in the management of the city’s forests.