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Alley Pond Park

Alley Pond Park - Invasive Phragmites

This text is part of Parks’ Historical Signs Project and can be found posted within the park.

The City gradually acquired the land for Alley Pond Park, the second-largest park in Queens, between 1927 and the present. The park lies on a glacier-formed moraine, a ridge of sand and rock that formed 15,000 years ago. The glacier deposited the boulders that sit on the hillsides at the southern end of the park, and it also left buried chunks of ice that melted and formed ponds. These ponds are dispersed throughout "the Alley," the 150-acre strip of wetlands in the north end of the park. Fresh water drains into the Alley from the hills and bubbles up from natural springs, mixing with the salt water from Little Neck Bay. As a result, the park is host to freshwater and saltwater wetlands, tidal flats, meadows, and forests, making for a diverse ecosystem that supports abundant plant and animal life. In recent years, however, phragmites, a species of invasive plant, has entered the park environs, taking over areas where other plant species once thrived.

As one of the 20 most invasive plants in New York State, phragmites (Phragmites australis), also known as the common reed or “phrag,” have become a ubiquitous part of New York City’s landscape. Clusters of phragmites can be found fringing the ponds and marshes of many city parks such as this one. Great Kills Park in Staten Island, Idlewild Park and Alley Pond Park in Queens, Van Cortlandt Park in the Bronx, and Marine Park in Brooklyn have large concentrations of phrag. The plants are capable of living anywhere that stagnant or slow moving fresh water is found, including vacant lots, ditches, and along roadways, as well as in marshes and wetlands. Phragmites will take over any area where the soil has been disturbed. This aggressive reed outcompetes any pre-existing vegetation, leading to thick, choking stands that can grow to 15 feet in height. The name phragmites comes from phragma, Greek for ‘fence’ or ‘barrier.’ Phragmites grows so vigorously that it even reaches through paved streets.

Phragmites are considered to be a “cosmopolitan” species – one that grows throughout the world – but in recent years it has become particularly invasive, taking over other species’ habitats. It is not clear why phragmites suddenly began spreading so rapidly. Some ecologists believe that a new strain, genetically different from the native American species, was recently introduced from Europe. Anthropogenic, or human-caused, changes to soils also may have promoted phragmites growth. Increased nutrients and pollutants from fertilizers, sewage discharge, and urban stormwater runoff give phragmites a competitive advantage over other plants. Whatever the reason for phragmites’ spread, the population of the reed in the Northeast has skyrocketed in recent years, to the detriment of other plant and animal species.

Young phragmites is good for livestock feed, but local wildlife does not generally consume it. Occasionally, waterfowl may eat its seeds, muskrats its stems and rhizomes; but overall, phragmites provides poorer nutrition than the plant species it replaces. Although the thick strands provide good thermal cover for molting waterfowl, most birds do not nest where there is an abundance of phragmites, leading to dwindling bird populations. Phragmites adjacent to a salt marsh usually grows above the daily tides, limiting their use as a fish habitat to the rare spring tide that brings them to high elevations. In coastal areas, introducing tidal flow and planting salt marsh cordgrass (Spartina alterniflora), which is very salt-tolerant, can restrict phragmites growth. Other control efforts include herbicide use, which is effective but also leads to eradication of non-target species; cutting, which induces the same problem; and summer burning, which can actually encourage stronger growth by adding nutrients to the soil.

The invasive tendencies of phragmites are not completely negative. Thanks to their aggressive growth patterns, phragmites is able to remove enormous quantities of contaminants from degraded soils and wetlands. In England, where the plant is used to make thatched roofs, mats, and other weavings, phragmites is endangered, and ecologists there are exploring restoration methods.

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