Long Island's tree cover

How much tree cover exists in your neighborhood?

There is a spot in your neighborhood that could probably use more trees. Apart from the immediate benefits of a lush green canopy providing shade on a summer day, increasing tree cover equally across neighborhoods promises big gains.

In New York, winters have warmed three times faster than summers, according to data from the state Department of Environmental Conservation, bringing in less rain and snow. The number of heat waves per year is also expected to increase.

However, not everyone will be impacted the same way. A detailed analysis by nextLI of satellite data from the U.S. Geological Survey of every census tract on Long Island shows that tree cover is disproportionately spread across the region. With almost as many inhabitants as Suffolk County but less than a quarter of its size, only 27% of Nassau County has tree cover compared to Suffolk’s average of 42%.

Let’s put that in context. If the area of tree cover was measured in Olympic-size swimming pools, about six people in Nassau would share one pool. Meanwhile, every individual in Suffolk could have their own.

The term “tree cover” refers to all kinds of trees - those in government parks and on other properties from federal to village jurisdictions as well as trees in private backyards and those along sidewalks and parking lots.

Long Island’s most populous town, Hempstead, with 793,000 residents, has as little as 14% tree cover, according to the analysis. In contrast, more than half of Shelter Island, where around 3,000 people reside full time, is covered in trees.

Lower rates of tree cover can create “islands” of heat which cause concentrated areas of high temperature. The “urban heat island effect,” according to the nonprofit American Forests which advocates for increased tree equity, often disproportionately affects vulnerable populations, low-income communities and people of color.

In April 2023, President Joe Biden announced a $1 billion grant to increase tree cover in urban spaces through the U.S. Forest Service and local communities. Numerous census tracts in both Nassau and Suffolk have been identified by the program as disadvantaged, as per the Climate and Economic Justice Screening tool. The program is intended to tackle issues of “extreme heat, storm-induced flooding, and other climate impacts” through increasing urban forest cover.

It is estimated that more than 100,000 acres in Suffolk County and around 26,800 acres in Nassau can be used to plant more trees, according to The Nature Conservancy’s Reforestation Hub. Ensuring there is equitable access to green spaces across Long Island will be a promising step in the region’s future.

Methodology

To calculate tree cover for Long Island per census tract, LANDSAT satellite data from the U.S. Geological Survey’s 2021 National Land Cover Database was used. Applying a method in spatial analysis called zonal statistics, the average tree cover for each tract, city and town was calculated by overlaying municipal boundaries.