RESOURCE UPDATE FS-XXX

Forests of Pennsylvania, 2017 

RESOURCE UPDATE FS-175

Forest Service October 2018

1

This resource update provides an overview of the forest 

resources in Pennsylvania based on inventories conducted by 

the USDA Forest Service, Forest Inventory and Analysis 

(FIA) program of the Northern Research Station. Estimates 

are based on field data collected using the FIA annualized 

sample design and are updated yearly.1 Information about 

the national and regional FIA program is available online at 

http://fia.fs.fed.us. FIA began annual inventories in 

Pennsylvania in 2000. For the 2017 inventory, estimates of 

current resource attributes, such as area, volume, and 

biomass, are based on 4,520 (3,015 forested) plot samples 

collected from 2011 to 2017. Estimates of components of 

change, such as net growth, removals, and mortality, are 

based on 4,143 (2,666 forested) samples collected from 2006 

to 2011 and revisited from 2011 to 2017. Estimates from 

earlier inventories are shown for comparison. See 

Bechtold and Patterson (2005), Gormanson et al. (2018), and

Burrill et al. (2018) for definitions and technical details. A 

complete set of inventory tables is available at 

https://doi.org/10.2737/FS-RU-175.

Overview

Pennsylvania forest land remained stable at 16.8 million 

acres in 2017 and the proportion dominated by large 

diameter stands continued to rise. Net volumes increased as 

well, totaling 39 billion cubic feet, 6 percent over the 2012 

estimate. Sawtimber volume on timberland increased 10 

percent to 120 billion board feet.

Though forest area remained stable and volumes increased, 

net growth decreased 13 percent since 2012 and mortality 

increased 18 percent. Removals were also down compared to 

the 2012 estimate. Despite these differences in the 

components of annual volume change, the growth to 

removals ratio remained at 2.1 overall on timberland.

1One-fifth of the plots was measured annually from 2000 thru 2013 

resulting in a full cycle every 5 years. In 2014, this changed to 7 years, 

wherein 1/7th (14.3 percent) of the plots are measured annually.

Table 1.—Pennsylvania forest statistics, 2017 and 2012. Volume estimates are for trees 5 inches and larger in 

diameter. Numbers of trees and biomass estimates are for trees 1 inch and larger in diameter. Sampling errors in 

tables and error bars in figures represent 68 percent confidence intervals.

2017 

Estimate

Sampling 

error (%)

2012 

Estimate

Sampling 

error (%)

Change from 

2012 (%)

Forest land

Area (thousand acres) 16,790.0 0.6 16,748.4 0.7 0.2

Number of live trees (million trees) 8,076.1 1.7 8,168.8 1.7 -1.1

Aboveground biomass of live trees (million oven-dry tons) 1,107.1 1.0 1,052.8 1.0 5.2

Net volume of live trees on (million ft3) 38,960.4 1.0 36,881.7 1.1 5.6

Annual net growth of live trees (thousand ft3/yr) 746,251.9 2.7 855,118.4 3.0 -12.7

Annual mortality of live trees (thousand ft3/yr) 382,317.2 3.6 324,790.3 4.0 17.7

Annual harvest removals of live trees (thousand ft3/yr) 331,116.1 7.9 387,699.1 7.2 -14.6

Annual other removals of live trees (thousand ft3/yr) 9,311.7 27.2 12,731.1 27.3 -26.9

Timberland

Area (thousand acres) 16,178.5 0.7 16,146.0 0.8 0.2

Number of live trees (million trees) 7,821.9 1.8 7,919.4 1.8 -1.2

Aboveground biomass of live trees (million oven-dry tons) 1,060.1 1.0 1,009.1 1.1 5.0

Net volume of live trees (million ft3) 37,304.6 1.1 35,350.0 1.2 5.5

Net volume of growing stock trees (million ft3) 34,089.1 1.2 32,322.1 1.3 5.5

Annual net growth of growing stock trees (thousand ft3/yr) 629,007.3 2.6 703,617.7 2.7 -10.6

Annual mortality of growing stock trees (thousand ft3/yr) 265,748.3 4.1 233,380.0 4.5 13.9

Annual harvest removals of growing stock trees (thousand ft3/yr) 275,049.4 8.1 328,766.8 7.4 -16.3

Annual other removals of growing stock trees (thousand ft3/yr) 8,892.7 47.3 19,796.1 26.9 -55.1

United States Department of Agriculture
Forest Area

Forest area in the Commonwealth has been relatively stable 

for five decades (Fig. 1). Estimates of forest land since the 

beginning of annual inventories in Pennsylvania fluctuated 

between 16.6 million acres and 17.0 million acres. The 2017 

total of 16.8 million is only 42,000 acres higher than 2012, a 

change that is not statistically significant. Timberland is 96 

percent of forest land and 4 percent (592,000 acres) is 

reserved forest land (Fig. 2), i.e. public forest land 

prohibited by law from active management. Family 

ownership makes up 51 percent of forest land. Private 

ownership together accounts for 70 percent of forest land.

Steady increases in large diameter stands2 have led to 71 

percent of timberland being dominated by sawtimber, a rise 

of five percentage points since 2012 (Fig. 3). During the 

same time period, small diameter stands dropped from 10 

percent to 8 percent of timberland area.

Of the 15 forest-type groups identified in Pennsylvania, 

oak/hickory and maple/beech/birch account for the 

majority of timberland with 53 and 32 percent, 

respectively. The percentage of oak/hickory stands in the 

large diameter class rose from 67 percent in 2012 to 72 

percent in 2017 (Fig. 4). Large diameter 

maple/beech/birch stands are 77 percent of the total 

timberland area in the forest-type group. Most of the gains 

in large diameter maple/beech/birch were offset by 

decreases in small diameter. Decreases in medium 

diameter oak/hickory were greater than decreases in the 

area of small diameter stands.

Reserved, 

3.5%

Other forest 

land, 0.1%

National 

forest, 

2.9%

Other 

federal, 

0.5% State, 

20.4%

Local gov't, 

3.0%

Family, 

51.3%

Corporate, 

13.9%

Conservation 

NGO, 0.9%

Club, 

3.5%

Timberland, 

96.4%

Forest land

Reserved Other forest land National forest

Other federal State Local gov't

Family Corporate Conservation NGO

Club

Timberland

2 

RESOURCE UPDATE FS-175

Figure 1.—Area of forest land and timberland by year, 

Pennsylvania, 1955 to 2017. 

Figure 2.—Proportion of forest land by ownership class and 

land use, Pennsylvania, 2017.

Figure 4.— Area of timberland by stand-size class2 for the top 

two forest-type groups by inventory year, Pennsylvania, 2012 

and 2017. 

Figure 3.—Area of timberland by stand-size class and 

inventory year, Pennsylvania, 1955 to 2017.

2 Small diameter (seedling/sapling) stands: dominated by trees less than 

5.0 inches d.b.h.; Medium (poletimber): 5.0 to 8.9 inches d.b.h. for 

softwoods and 5.0 to 10.9 inches d.b.h. for hardwoods; Large 

(sawtimber): ≥ 9.0 inches for softwoods and ≥11.0 d.b.h. for hardwoods.

0

2

4

6

8

10

12

1950 1960 1970 1980 1990 2000 2010 2020

Timberland Area (million acres)

Year

Large diameter

Medium diameter

Small diameter

14.5

15.0

15.5

16.0

16.5

17.0

2004 2006 2008 2010 2012 2014 2016

Area (million acres)

Year

Forest land

Timberland

15

16

17

1955 1970 1985 2000 2015

0 20 40 60 80

2012

2017

2012

2017

2012

2017

Large

diameter

Medium

diameter

Small

diameter

Percentage of timberland area

Stand size class and year

Maple/beech/birch

Oak/hickory
Volume, Biomass, and Trends

3 

RESOURCE UPDATE FS-175

Net volume on forest land totals 39.0 billion cubic feet, a 

5.6 percent increase over the 2012 estimate (Table 2). The 

10 species having the most net volume remained 

unchanged from 2012, though shifts of rank within the top 

10 occurred. A 13 percent increase in the net volume of 

sweet birch moved the species from the tenth spot in 2012 

to eighth in 2017. White ash was the only species that 

decreased in net volume (-7 percent). Mortality, likely 

caused by emerald ash borer throughout most of the 

Commonwealth, led to white ash falling to the tenth most 

voluminous species. 

Overall, the 2017 estimate of 120.5 billion board feet 

(bdft.) is 9.8 percent higher than 2012. All species had 

higher percentage increases in sawtimber volume than 

cubic foot volume. Red maple increased 13 percent in 

sawtimber volume over 2012 and has the highest volume 

at 18.5 billion bdft. Sawtimber increases among other 

species were greatest for sweet birch (17 percent), and 

white oak (13 percent). Additionally, other softwood 

species (all softwoods except eastern hemlock) had an 

increase in sawtimber volume of 22 percent since 2012.

Increases in aboveground biomass on forest land followed 

increases in net cubic foot volume. The 2017 estimate of 

1.1 billion tons is 5 percent higher than the 2012 total.

While there were changes in the components of annual 

volume change, the overall net growth to removals ratio 

(G:R) on timberland remained at 2.1, the same as 2012. An 

18 percent increase in annual mortality contributed to a 13 

percent decrease in net growth, since 2012.

Total removals for all species decreased 16 percent from 

2012 to 345 million cubic feet. 

The majority of the 12 most voluminous species had G:R 

ratios similar to those in 2012. A notable exception is black 

cherry for which net growth outpaced removals by a factor 

of 1.8 (Fig. 5), down from 3.0 in 2012, driven by a 58 

percent increase in mortality and a 22 percent increase in 

removals. Yellow-poplar G:R increased to 6.0 from 2.8 in 

2012. White ash and beech both had removals exceeding 

net growth with G:Rs of 0.3 and 0.5, respectively. Sweet 

birch and white pine were the only species of the top 12 to 

have increases in both net growth and G:R ratios.

Table 2.—Net volume and percentage change on forest land; sawtimber volume and percentage change on 

timberland, and aboveground biomass on forest land, Pennsylvania, 2017, (top 10 species by net volume). 

Volume estimates are for trees 5 inches and larger in diameter. Biomass estimates are for trees 1 inch and larger 

in diameter. 

Figure 5.—Average annual net growth, removals, and mortality 

volume on timberland, with growth to removals ratios (G:R) in 

parentheses, for the top 12 species ranked by total net volume, 

Pennsylvania, 2017. 

0 20 40 60 80 100 120 140

Red maple (2.5)

Black cherry (1.8)

N. red oak (3.2)

Sugar maple (2.2)

Chestnut oak (1.7)

E. hemlock (1.9)

Yellow-poplar (6.0)

White oak (1.8)

Sweet birch (5.3)

White ash (0.3)

E. white pine (4.6)

A. beech (0.5)

Volume (million ft3)

Species 

(G:R)

Net Growth

Removals

Mortality

Net volume 

of live trees 

(million ft3)

Sampling 

error 

(percent)

Percent 

change 

since 

2012

Net volume 

of sawtimber

(million 

bd.ft.)

Sampling 

error 

(percent)

Percent 

change 

since 

2012

Aboveground 

biomass (million 

dry tons)

Sampling 

error 

(percent)

Red maple (Acer rubrum) 7,225.0 2.5 7.2 18,504.4 3.6 12.9 195.6 2.4

Black cherry (Prunus serotina) 4,128.3 3.9 2.5 13,512.1 5.1 5.1 105.7 3.7

N. red oak (Quercus rubra) 3,842.1 3.8 6.8 15,521.0 4.4 10.5 122.8 3.7

Sugar maple (Acer saccharum) 2,866.8 4.8 6.8 8,839.5 5.9 9.5 90.3 4.6

Chestnut oak (Quercus prinus) 2,653.2 4.4 5.3 7,493.6 5.3 11.2 86.3 4.4

E. hemlock (Tsuga canadensis) 1,965.5 5.9 3.2 5,880.3 6.7 6.1 37.3 5.8

Y-poplar (Liriodendron tulipifera) 1,941.5 7.5 9.5 8,392.2 8.5 10.1 40.1 7.3

Sweet birch (Betula lenta) 1,756.9 4.4 12.7 3,302.4 6.2 16.8 63.3 4.0

White oak (Quercus alba) 1,714.3 5.2 6.3 6,063.1 6.4 12.9 55.4 5.2

W. ash (Fraxinus americana) 1,627.3 5.3 -6.9 5,333.2 7 -2.5 48.5 5.2

Other softwood species 1,869.4 6.7 12.8 6,554.0 7.7 22.1 35.3 6.4

Other hardwood species 7,370.0 2.3 4.4 21,060.5 3.3 8.7 226.4 2.2

All species 38,960.4 1 5.6 120,456.4 1.6 9.8 1,107.1 1.0
Spotted Lanternfly

Spotted lanternfly (SLF, Lycorma delicatula) is a 

planthopper native to China and first discovered in North 

America on the border of Pike and District Townships, 

Berks County in September 2014. Currently found in 13 

counties of southeastern Pennsylvania, a quarantine is in 

place to slow further spread of this invasive insect (Fig. 6).

The adults and all nymphal stages pierce the outer bark to 

feed from the phloem of a large variety of plants including 

trees common to Pennsylvania. SLF adults are known to 

prefer an invasive tree species, ailanthus (tree-of-heaven, 

Ailanthus altissima), as a host (PA Dept. of Agriculture 

2018) and some evidence suggests that ailanthus may be 

necessary for successful completion of the life cycle. 

Additional research into alternative hosts has shown that 

species of grape (Vitis spp.) may serve as an substitute host 

in the absence of ailanthus (Pugh et al. 2016). Thus, SLF is 

a potential threat to the over $134 million in annual grape 

and orchard production of Pennsylvania (PA Dept. of 

Agriculture 2018).

SLF feeding produces honeydew secretions and weeping 

wounds that subsequently attract ancillary insects to wound 

sites. Though widespread mortality is unknown at

RESOURCE UPDATE FS-175

Figure 6.—Spotted lanternfly distribution and quarantine with 

Ailanthus altissima basal area (2009) and photo of adult 

individual. Photo by Tom Albright, USDA Forest Service.

How to Cite This Publication

Albright, Thomas A. 2018. 

Forests of Pennsylvania, 2017. 

Resource Update FS-175. Newtown Square, PA: 

U.S. Department of Agriculture, Forest Service, 

Northern Research Station. 4 p.

https://doi.org/10.2737/FS-RU-175.

Contact Information

Thomas A. Albright, Forester

USDA Forest Service, Northern Research Station

Ph: 412-523-0103

talbright@fs.fed.us

Northern FIA: http://nrs.fs.fed.us/fia/

National FIA: http://fia.fs.fed.us

USDA is an equal opportunity provider and employer

4

this early stage of the infestation, SLF is known to feed on 

many genera of hardwoods including maples, oaks,

hickories, black walnut, and yellow-poplar that make up

60 percent of net tree volume statewide and 70 percent in

the quarantine zone. There are an estimated 4 million

ailanthus trees on forest land within the quarantine, a

figure that does not include trees in backyards, rights-ofway, etc. for which FIA does not currently account and

where ailanthus is adept at colonizing. Adjacent to the 

quarantine, ailanthus accounts for over 1 percent of trees

in the South Central unit (Fig. 6), providing a pathway for

SLF to spread and threaten a major fruit-producing region 

of the State. Additionally, SLF will lay eggs on nearly any

available surface outdoors, making artificial transport by

people a real possibility. Continued study and monitoring

of this invasive forest pest with a high potential for

impacts on Pennsylvania’s fruit and timber industries will 

inform management strategies into the future.

Literature Cited

Bechtold, W.A.; Patterson, P.L., eds. 2005. The enhanced Forest

Inventory and Analysis Program: national sampling design and

estimation procedures. Gen. Tech. Rep. SRS-80. Asheville, NC: U.S. Dept.

of Agriculture, Forest Service, Southern Research Station. 85 p.

https://doi.org/10.2737/SRS-GTR-80.

Burrill, E.A.; Wilson, A.M.; Turner, J.A. [et al.]. 2018. The Forest Inventory

and Analysis Database: Database description and user guide for Phase 2, 

ver. 7.2. Washington, DC: U.S. Department of Agriculture, Forest Service.

946 p. http://www.fia.fs.fed.us/library/database-documentation/.

Gormanson, D.D.; Pugh, S.A.; Barnett, C.J.; Miles, P.D.; Morin, R.S. [et al.].

2018. Statistics and quality assurance for the Northern Research Station

Forest Inventory and Analysis Program. Gen. Tech. Rep. NRS-178.

Newtown Square, PA: U.S. Department of Agriculture, Forest Service,

Northern Research Station. 25 p. https://doi.org/10.2737/NRS-GTR-178.

Pennsylvania Department of Agriculture. 2018. Spotted lanternfly

program information. Harrisburg, PA: Dept. of Agriculture. 

https://www.agriculture.pa.gov/Plants_Land_Water/PlantIndustry/Ento

mology/spotted_lanternfly/program-information/Pages/default.aspx

(accessed September 25, 2018).

Pugh, C.V.; Johnson, C.B.; Toolan, M.; Setliff, G. 2016. Suitability of twenty

North America tree species as secondary hosts of the invasive spotted

lanternfly, Lycormadelicatula (White) (Hemiptera: Fulgoridae). Internat’l

Congress of Entomology. [poster session]. 

https://doi.org/10.1603/ICE.2016.114879.

The published report is available online at https://doi.org/10.2737/FS-RU-175