North Central Appalachians

By Kristi L. Sayler ¹

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Ecoregion Description

 

The North Central Appalachians ecoregion (fig. 1) is a forested, sedimentary upland that is punctuated by high hills and low mountains (Woods and others, 1996). The ecoregion covers approximately 30,500 km² (11,700 mi²) and is divided into two separate portions.  The unglaciated western portion lies along the headwaters of the Allegheny and Susquehanna Rivers in north central Pennsylvania with a sliver in southern New York.  This forested landscape supports the major economic activities of forestry and recreation (fig. 2 and 3).  This part of the ecoregion is also at the northern fringe of the Appalachian coal belt and includes substantial portions of Pennsylvania’s oil and gas production (Woods and others, 1996).  The eastern portion comprises the Pocono Mountains of Pennsylvania and portions of the Catskill Mountains of New York and New Jersey, which range from low mountains to rolling hills with a dissected plateau at the eastern edge of the Allegheny Front (Ackroyd-Kelly, 1987).  This area has historically provided an accessible, rural recreation oasis for generations of residents of nearby New York and Philadelphia.  The climate of the North Central Appalachians ecoregion can be characterized as continental, with cool summers and cold winters.  The average annual precipitation ranges from 825 to 1,250 mm (33 to 50 in).

 

Contemporary Land Cover Change (1973 to 2000)

 

The overall spatial change from 1973 to 2000 for the North Central Appalachians was 6.2 percent (table 1), a fairly low amount of change compared to other Eastern U.S. ecoregions (fig. 4).  Of the 6.2 percent estimated area of change, nearly half of the land changed multiple times.  The change per time period ranged between 1.5 percent and 2.9 percent with margins of error ranging from 0.7 to 1.4 percent (table 2).  The average annual rates of change (fig. 5) showed that the 1980 to 1986 period had the greatest amount of change with an average rate of 0.4 percent per year (table 2). This number would have been substantially lower had there not been an outbreak of around 42 tornadoes on May 31, 1985 (Monfredo, 1999), which deforested a significant portion of the ecoregion. The tornado damage and its subsequent return to pre-storm land cover made up about 8.1 percent of the total change between 1980 and 2000 in the ecoregion.

 

Forest made up 87.4 percent of the land cover in 1973, and it decreased only 0.8 percent during the study period to 86.7 percent in 2000 (table 3).  This decrease is mostly attributed to forest clear-cutting in the ecoregion and forest loss caused by tornado activity in 1985 (fig. 6).  These clear-cuts primarily represent the harvesting of hardwood trees for lumber and other wood products and are shown as conversions from forest to the mechanically disturbed land cover class (fig. 7).  The area is known for its exceptionally high quality of black cherry, with other hardwoods commonly harvested, including yellow poplar, white ash, red maple, and sugar maple (Napton and others, 2003). 

 

Both mining and developed lands had very small increases in all time periods.  Surface coal mining, quarries, gravel pits, and natural gas field developments all contributed to the 0.3 percent increase in mining.  Developed lands increased slightly (0.4 percent), primarily in the eastern portion of the ecoregion where the proximity to the Poconos and Catskills regions makes it possible for individuals to have second homes and still live and work near New York City (fig. 8).

 

The leading land cover conversions were all related to the vast forests of the North Central Appalachians ecoregion.  Forest to mechanically disturbed and mechanically disturbed to forest were the top two land cover conversions during all time periods (table 4).   These two conversions were related to the forest harvest and regrowth cycles of the timber industry of the ecoregion.  The other main land cover change agent was the tornado activity, shown as a forest to non-mechanically disturbed conversion in 1980 to 1986 and the subsequent conversion of non-mechanically disturbed to forest as the affected forest areas regenerated (table 4).  Overall, these conversions accounted for 82.4 percent of the area changed in the ecoregion.

 

References

 

Ackroyd-Kelly, I.H., 1987, The near country—the historical geography of Pocono resorts:  The Pennsylvania Geographer, v. 25, no. 1, p. 18-23.

 

Monfredo, W., 1999, Significant tornado activity in southwestern Pennsylvania:  The Pennsylvania Geographer, v. 37, no. 2, p. 43-63.

 

Napton, D., Sohl, T.L., Auch, R.F., and Loveland, T.R., 2003, Land use and land cover change in the North Central Appalachians ecoregion: The Pennsylvania Geographer, v. 41, no.2, p. 46-66.

 

Woods, A.J., Omernik, J.M., Brown, D.D., and Kiilsgaard, C.W., 1996, Level III and IV ecoregions of Pennsylvania and the Blue Ridge Mountains, the Ridge and Valley, and Central Appalachians of Virginia, West Virginia, and Maryland: EPA/600/R-96/077, U.S. Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Corvallis, Oreg., 50 p.

 

 

 

 

Table 1.  Amount of overall spatial change detected in ecoregion and proportion of ecoregion that experienced change during one or multiple time periods

 

	Overall	Number of changes
	spatial change	1	2	3	4
Percent of ecoregion	6.2	3.5	2.6	0.1	0.0

 

 

 

Table 2.  Raw estimates of percent change in ecoregion computed for each of four time periods and associated margin of error at 85-percent confidence level

 

	Period
	1973-1980	1980-1986	1986-1992	1992-2000
Total change (% of ecoregion)	1.5%	2.3%	2.2%	2.9%
Margin of error (85% confidence level)	+/-0.8%	+/-1.4%	+/-0.7%	+/-0.7%
Average annual rate of change (%/year)	0.2%	0.4%	0.4%	0.4%

 

 

 

Table 3.  Proportion of ecoregion covered by each land cover class during each of five mapped dates

 

	1973		1980		1986		1992		2000		Net change 1973-2000
Land-use/land-cover class	km²	%	km²	%	km²	%	km²	%	km²	%	km²	%
Water	451	1.5	447	1.5	451	1.5	455	1.5	428	1.4	-22	-0.1
Developed	400	1.3	409	1.3	426	1.4	452	1.5	481	1.6	81	0.3
Mechanically disturbed	298	1.0	358	1.2	251	0.8	420	1.4	448	1.5	151	0.5
Mining	118	0.4	117	0.4	143	0.5	195	0.6	247	0.8	129	0.4
Barren	1	0.0	1	0.0	1	0.0	1	0.0	1	0.0	0	0.0
Forest	26684	87.4	26621	87.2	26638	87.3	26490	86.8	26417	86.6	-267	-0.9
Grassland/Shrubland	1	0.0	1	0.0	1	0.0	1	0.0	1	0.0	0	0.0
Agriculture	2256	7.4	2252	7.4	2186	7.2	2171	7.1	2175	7.1	-82	-0.3
Wetland	313	1.0	315	1.0	312	1.0	309	1.0	321	1.1	8	0.0
Non-mechanically disturbed	0	0.0	0	0.0	112	0.4	28	0.1	2	0.0	2	0.0

 

 

Table 4.  Leading land cover conversions during each of four time periods

 

			Area changed	% of all
Period	From class	To class	(km2)	changes
1973-1980	Forest	Mechanically disturbed	210	45
	Mechanically disturbed	Forest	162	35
	Forest	Mining	22	5
	Agriculture	Forest	16	3
	Mining	Mechanically disturbed	14	3
	Other classes	Other classes	39	8
			463	100
1980-1986	Mechanically disturbed	Forest	268	39
	Forest	Mechanically disturbed	162	23
	Forest	Non-mechanically disturbed	108	16
	Agriculture	Forest	63	9
	Forest	Mining	35	5
	Other classes	Other classes	58	8
			694	100
1986-1992	Forest	Mechanically disturbed	305	45
	Mechanically disturbed	Forest	136	20
	Non-mechanically disturbed	Forest	83	12
	Forest	Mining	61	9
	Forest	Developed	27	4
	Other classes	Other classes	64	9
			676	100
1992-2000	Forest	Mechanically disturbed	379	42
	Mechanically disturbed	Forest	362	40
	Forest	Mining	56	6
	Forest	Developed	27	3
	Non-mechanically disturbed	Forest	26	3
	Other classes	Other classes	48	5
			898	100
Overall:
1973-2000	Forest	Mechanically disturbed	1,055	39
	Mechanically disturbed	Forest	928	34
	Forest	Mining	174	6
	Non-mechanically disturbed	Forest	110	4
	Forest	Non-mechanically disturbed	108	4
	Other classes	Other classes	355	13
			2,730	100

 

 

 

Figure 1.  North Central Appalachians and surrounding ecoregions. The 10 randomly selected 400-km² sample blocks are shown along with land use/land cover from the 1992 National Land Cover Dataset.

 

 

Figure 2.  Predominately forested area with scattered agriculture.

 

 

Figure 3.  Pennsylvania Fish and Boat Commission Tidioute recreation area along the Allegheny River

 

 

Figure 4.  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 5.  The estimates of land cover change per time interval normalized to an annual rate of change. North Central Appalachian ecoregion is highlighted in black.

 

 

Figure 6.  Per period net change for each land cover class. Areas above zero represent net gains for a land cover class, while areas below represent a net loss.

 

 

 

Figure 7.  Small sawmill 10 miles northwest of Port Jervis, New York.

 

 

 

Figure 8.  Modular homes waiting to be transferred to housing site.