The Northeastern Coastal Zone is a north to southwest trending ecoregion covering approximately 37,158 km² (14,347 mi²) in eight states (Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, Connecticut, New York, and New Jersey) (fig. 1). The ecoregion was glaciated in the recent geologic past, which caused it to have more irregular topographic relief than the neighboring Atlantic Coastal Pine Barrens to the southwest, but it is not as hilly and mountainous as the Northeastern Highlands to the west and north. The soils tend to be rocky and nutrient poor (U.S. Environmental Protection Agency, 1997). Natural vegetation is dominated by hardwood and mixed forests, but also includes more limited coastal and inland wetlands. The Northeastern Coastal Zone’s climate consists of cold winters and warm summers, with 1,000 to 1,500 mm (40-60 in) of precipitation occurring in an average year.

The Northeastern Coastal Zone’s land cover is dominated by forested and developed land that, according to our estimates, together account for more than 70 percent of the ecoregion. Large areas of developed land are found in the northern portion of the New York metropolitan area, east along Long Island Sound to New Haven, Connecticut, and northward along the Connecticut River to Springfield, Massachusetts (fig. 1) (Vogelmann and others, 2001). Another ring of development encircles the upper reaches of Narragansett Bay in Rhode Island (metropolitan Providence), whereas greater Boston has radial lines of urbanization to Worchester, Massachusetts, in the west; Nashua, New Hampshire, to the northwest; and toward Cape Cod, Massachusetts, in the south to southeast. Portland, Maine, forms the last urban node in the extreme northeast. According to aggregated county-level data, the ecoregion’s population increased by more than one million people between 1970 and 2000, reaching 15,269,068 (U.S. Bureau of the Census, 1973; U.S. Census Bureau, 2003). Water, wetlands, and agriculture are secondary land covers classes commonly found across the ecoregion but in smaller, less frequent concentrations than forested and developed land. The only notable concentration of agricultural land is found in the Connecticut River Valley, north of Hartford.

Figure 1: The Northeastern Coastal Zone’s Land Cover Trends sample blocks (the black hollow 10 km x 10 squares) overlay the USGS 1992 National Land Cover Database. Click on image to enlarge

The Northeastern Coastal Zone had moderately low amounts of land cover change compared with other Eastern U.S. ecoregions during the study period (fig. 2). A total of 5.7 percent of the ecoregion changed at least once during the study period (table 1). The amount of change estimated by time interval shows that the two intervals between 1973 and 1986 appeared to have considerably lower change than the two intervals between 1986 and 2000 (table 2). Normalizing the amount of change to annual rates to avoid unequal time intervals shows that the 1986 to 1992 period had the highest rate of change (fig. 3). The variability in land cover change across the ecoregion was low and relatively steady during the study period, as indicated by the margin of error in our statistical estimates, ranging from +/- 0.20 percent to +/- 0.40 percent (table 2). The dominant land cover classes, forest and development, experienced the most net change during the study period (table 3, fig. 4).

Developed land increased an estimated 4 percent (1,510 km²) to approximately 27 percent of the ecoregion’s area, one of the highest percentages of developed land of any eastern ecoregion. Much of the new development came from forest loss, with a decrease of 3.7 percent (1,361 km²) during the study period. Agricultural land cover decreased by 0.8 percent, and although this may appear to be a small amount of farmland loss, it represents a loss of approximately 10 percent of the estimated agricultural land present in the ecoregion in 1973. Other, more minor land cover changes included slight decreases in wetlands and slight increases in mechanically disturbed lands and mining. Increased development was the primary reason for these changes (i.e., wetlands converted to development, increased aggregate mining for construction materials, and forest land being cleared—mechanically disturbed—for pending development).

Table 1: The percentage of the ecoregion that experienced change. Most of the sample pixels remained unchanged (94.3 percent) whereas 5.7 percent changed at least once through the study period.

Table 2: Rates of change by time period and 85 percent confidence interval.

Figure 2: The overall spatial change in all Eastern U.S. ecoregions. Each bar chart shows the proportion of the ecoregion that experienced change on 1, 2, 3, or 4 dates. Click on image to enlarge

Figure 3: Change by Time Interval Normalized to Annual Rates. Click on image to enlarge

Table 3: Land Cover Classes, Estimated Ecoregion Percent and Area.

Figure 4: Estimated Net Percentage Change by Land Cover Class. Click on image to enlarge

Table 4: Leading Land Cover Changes by Time Interval.

Figure 5: Net Forest, Agriculture, and Wetland decreases in km². Click on image to enlarge