Northeastern Highlands

By Steve Kambly ¹

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Ecoregion Description

 

The Northeastern Highlands ecoregion consists of four physically separate areas, which occupy 127,109 km² (49,077 mi²) in Maine, New Hampshire, Vermont, New York, Massachusetts, Connecticut, New Jersey, and Pennsylvania (fig. 1).  The ecoregion is “a relatively sparsely populated region characterized by nutrient poor soils blanketed by northern hardwood and spruce fir forests.  Land-surface form in the region grades from low mountains in the southwest and central portions to open high hills in the northeast” (U.S. Environmental Protection Agency, 2002).  Numerous mountain ranges, including the White Mountains in New Hampshire, the Green Mountains in Vermont, and New York’s Catskills and Adirondacks, lie within the ecoregion.  The ecoregion also shows many remnants of glaciation, including rocky soils, glacial lakes, and wetlands (fig. 2).  Annual average rainfall varies from 940 to 1,397 mm (37 to 55 in), with significantly higher amounts in mountainous areas.  The average daily temperature ranges from below –7^oC (20^o F) in January to between 16 and 21^oC (60 and 70^oF) in July. 

Though the ecoregion was heavily forested at the beginning of European settlement, much of it was cleared for farmland in the 19^th century.  Farmland abandonment, beginning in the mid-1800s and continuing through the study period, has led to a natural regrowth of forest.  Forest harvesting for wood products has been an ongoing activity since the early 1800s—and clear-cutting of forest was evident during the study period in western Maine, where timber companies control large tracts of land.  Paper and pulp processing is the leading manufacturing activity in Maine.  Further south, in New Hampshire, Vermont, and New York, tourism and small-scale farming are more prevalent.

 

Change from 1973 to 2000

 

A moderate amount of change was observed in the Northeastern Highlands ecoregion, with an estimated 8.9 percent of its area converting to another land cover at least once during the study period (fig. 3).  Approximately 3.1 percent changed only once, while 3.6 percent and 2.1 percent changed two and three times, respectively.  About one-tenth of 1 percent of the ecoregion’s area was converted four times.  Of the thirty-five sample blocks in the ecoregion, five blocks in western Maine had rates of change exceeding 25 percent.  The high rates of change were due primarily to forest clear-cutting and regrowth (fig. 4).  Thirteen blocks had less than 2 percent change, most of which fell within State or Federally owned lands such as parks, forests, or refuges where forestry practices are restricted or disallowed altogether (fig. 5).  Total change per interval increased from 2.3 percent between 1973 and 1980 to 6.2 percent between 1992 and 2000 (
).  Average annual rates of change increased steadily in the first three intervals from 0.3 percent to 0.9 percent and then slowed to 0.8 percent between 1992 and 2000 (fig. 6).

Forest harvesting and regrowth was the dominant pattern of change observed.  Both the selective cutting and clear-cutting of forest created mechanically disturbed lands, which in turn became grassland/shrubland.  Eventually, grassland/shrubland areas tended to become re-forested.  This cycle of change, in which mechanically disturbed lands and grassland/shrubland are transitional land covers, occurred over an increasing area between 1973 and 1992, but contracted in the last interval.

Primarily as a result of clear-cutting and some selective harvesting, forest decreased by an estimated 3.8 percent (table 2) or approximately 4,830 km² (1,865 mi²).  However, forest remained the dominant land cover, extending over an estimated 81.4 percent of the ecoregion in 2000.  As the amount of tree harvesting increased, the percent of mechanically disturbed land also increased—from 0.6 percent in 1973 to 2.1 percent in 2000.  The amount of estimated land area in grassland/shrubland increased between 1973 and 1992 from 0.2 percent to 2.2 percent and then decreased slightly in the last interval to 2.1 percent.  Developed land increased from 1.8 percent to 2.3 percent between 1973 and 2000, while farmland remained unchanged with approximately 3.3 percent of the ecoregion’s land area.  Forest, mechanically disturbed land, and grassland/shrubland were by far the most active land covers, accounting for most of the net change in the ecoregion during the study period (fig. 7). 

In terms of individual conversions, forest to mechanically disturbed land was the most common conversion overall, as well as in the first three intervals (table 3).  An estimated 9,322 km² (3,603 mi²) converted from forest to mechanically disturbed land between 1973 and 2000.  The second most common conversion both overall and in each interval was mechanically disturbed land to grassland/shrubland with 6,983 km² (2,696 mi²) in conversions.  Grassland/shrubland to forest was the third most common conversion.  Approximately 4,641 km² (1,792 mi²) of land area converted from grassland/shrubland to forest during the study period.

While 150 years of farmland abandonment has led to regrowth of forests in the Northeastern Highlands, forest harvesting was clearly the dominant type of land cover change between 1973 and 2000.  Strong demand for forest products spurred timber companies to harvest vast tracts of forested land in sparsely populated regions of central and northern Maine.  State and Federally owned reserved lands, however, may have played a role in limiting forest harvesting.  Farming was scattered and generally small-scale in the ecoregion and did not change significantly during the study period (fig. 8).  The amount of developed land did increase slightly, in the form of new residential communities and tourist resorts, primarily due to conversion of forested land.

 

References

 

Colgan, C.S., Irland, L.C., and Benson, J., 1986, The natural resource industries of Maine—An assessment and statistical portrait: Augusta: Financial Authority of Maine and Maine State Planning Office.

 

Hart, John Fraser, 1968, Loss and abandonment of cleared farm land in the Eastern United States: Annals of the Association of American Geographers, v. 58, no. 5, p. 417–440.

Irland, L.C., 1999, The Northeast’s changing forest: Petersham, Mass., Harvard Forest [distributed by Harvard University Press], 427 p.

 

Prescott, Richard, and Vail, David, 1988, The transformation of farming in Maine, 1940–1985: Maine Historical Quarterly, v. 28, p. 66–84.

 

U.S. Environmental Protection Agency, 2002, Primary distinguishing characteristics of Level III ecoregions of the continental United States [draft]: EPA, available online at ftp://ftp.epa.gov/wed/ecoregions/us/useco_desc.doc.

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Table 1.  Change per time period

 

	Period
	1973–1980	1980–1986	1986–1992	1992–2000
Total change (% of ecoregion)	2.3%	3.9%	5.5%	6.2%
Margin of error (85% confidence level)	+/–1.3%	+/–1.7%	+/–2.1%	+/–2.4%
Average annual rate of change (%/year)	0.3%	0.7%	0.9%	0.8%

 

 

Table 2.  Percent change per interval by category

 

	1973		1980		1986		1992		2000		Net change 1973–2000
Land-use/land-cover class	km²	%	km²	%	km²	%	km²	%	km²	%	km²	%
Water	6,487	5.1	6,482	5.1	6,500	5.1	6,516	5.1	6,496	5.1	9	0.0
Developed	2,317	1.8	2,420	1.9	2,499	2.0	2,674	2.1	2,949	2.3	632	0.5
Mechanically disturbed	773	0.6	1,716	1.4	2,532	2.0	2,553	2.0	2,622	2.1	1,849	1.5
Mining	65	0.1	77	0.1	85	0.1	104	0.1	122	0.1	56	0.0
Naturally barren	142	0.1	142	0.1	142	0.1	142	0.1	142	0.1	0	0.0
Forest	108,325	85.2	106,703	83.9	104,564	82.3	103,672	81.6	103,421	81.4	–4,904	–3.9
Grassland/Shrubland	243	0.2	852	0.7	2,090	1.6	2,768	2.2	2,688	2.1	2,445	1.9
Agriculture	4,210	3.3	4,165	3.3	4,165	3.3	4,157	3.3	4,160	3.3	–51	0.0
Wetland	4,546	3.6	4,553	3.6	4,532	3.6	4,523	3.6	4,500	3.5	–46	0.0
Non-mechanically disturbed	0	0	0	0	0	0.0	0	0.0	0	0.0	0	0.0

 

 

Table 3.  Leading conversions by interval and for the entire study period

 

			Area changed	% of all
Period	From class	To class	(km2)	changes
1973–1980	Forest	Mechanically disturbed	1,715	60
	Mechanically disturbed	Grassland/Shrubland	724	25
	Grassland/Shrubland	Forest	127	4
	Forest	Developed	85	3
	Agriculture	Forest	80	3
	Other classes	Other classes	132	5
			2,863	100
1980–1986	Forest	Mechanically disturbed	2,519	50
	Mechanically disturbed	Grassland/Shrubland	1,684	34
	Grassland/Shrubland	Forest	481	10
	Forest	Agriculture	81	2
	Forest	Developed	67	1
	Other classes	Other classes	179	4
			5,010	100
1986–1992	Forest	Mechanically disturbed	2,517	36
	Mechanically disturbed	Grassland/Shrubland	2,266	32
	Grassland/Shrubland	Forest	1,619	23
	Mechanically disturbed	Forest	244	3
	Forest	Developed	161	2
	Other classes	Other classes	213	3
			7,020	100
1992–2000	Forest	Mechanically disturbed	2,571	32
	Grassland/Shrubland	Forest	2,413	30
	Mechanically disturbed	Grassland/Shrubland	2,309	29
	Forest	Developed	194	2
	Mechanically disturbed	Forest	160	2
	Other classes	Other classes	278	4
			7,925	100
Overall:
1973–2000	Forest	Mechanically disturbed	9,322	41
	Mechanically disturbed	Grassland/Shrubland	6,983	31
	Grassland/Shrubland	Forest	4,641	20
	Forest	Developed	506	2
	Mechanically disturbed	Forest	454	2
	Other classes	Other classes	912	4
			22,818	100

 

 

 

Figure 1.  The Northeastern Highlands and surrounding ecoregions.  The randomly selected sample blocks are shown along with land use/land cover data from the 1992 National Land Cover Dataset.

 

 

 

Figure 2.  The many wetlands in the ecoregion are a result of glaciation.

 

 

 

Figure 3.  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.

 

 

Figure 4.  Most landcover change in the ecoregion is the result of extensive clear-cutting in Maine.

 

 

 

Figure 5.  Reserved lands such as Adirondack State Park place restrictions on timber harvesting and development.

 

Figure 6.  Estimates of land cover change per time interval normalized to annual rates of change.

 

 

Figure 7.  Net land cover changes by categories for each time interval and for the entire study period.

 

 

 

Figure 8.  Although there are many prosperous farms in the ecoregion, generally agriculture is in decline.