Criterion 1. Conservation of Biological Diversity
National Report on Sustainable Forests—2010
Indicator 1.01.
Area and Per­cent of Forest by Forest Ecosystem Type, Successional Stage, Age Class, and
Forest Ownership or Tenure
This indicator uses age-class distribution by broad forest type
as a coarse measure of the landscape-scale structure of the
Nation’s forests. Within forest types, this serves as a surrogate
for stand development or successional stage. A diverse distribution of forest lands across forest types and age classes is an
indicator of tree-size diversity and is important for determining
timber growth and yield, the occurrence of specific wildlife
and plant communities, the presence of other nontimber forest
products, and the forest’s aesthetic and recreational values.
What does the indicator show?
Forest area in the United States stands at 751 million acres, or
about one-third of the Nation’s land area. Forest area was about
one billion acres at the time of European settlement in 1630.
Of the total forest land loss of nearly 300 million acres, most
occurred in the East (divided into North and South regions
in the accompanying charts) between 1850 and 1900, when
broadleaf forests were cleared for agriculture (fig. 1-1). For the
past 100 years, the total forest area has been relatively stable,
although the U.S. population has nearly tripled.
Broadleaf forests. Broadleaf forests cover 290 million acres
nationwide (fig. 1-3), predominantly in the North and South
(239 million acres). With 139 million acres in the United States,
oak-hickory is the largest single forest cover type. It constitutes
more than 19 percent of all forest land in the United States and
nearly one-half of all broadleaf forests. Covering 54 million
acres, maple-beech-birch forests, are also dominant in the
Eastern United States. Combined, these two upland forest
types constitute nearly two-thirds of all broadleaf forests and
have increased 25 and 39 percent, respectively, since 1977.
Broadleaf types have a fairly normal age distribution, showing
a bulge in the 40- to 79-year age-class, as second- and thirdgrowth forests in the East continue to mature (fig. 1-4).
Conifer forests. Conifer forests cover 409 million acres in
the United States and are found predominantly in the West
(314 million acres) and South (69 million acres). Pines are
the single-most dominant group of conifer forests. Loblollyshortleaf
400 pine and longleaf-slash pine types in the South and
South
ponderosa
and lodgepole
pine types in the West combine to
350
North
cover300121 million acres, or more than one-fourth of all conifer
forest
types.
250
Acres (millions)
What is the indicator and why is it important?
200
00
20
50
19
10
19
70
18
30
18
90
17
17
17
16
16
800
400
Acres (millions)
South
350
Acres (millions)
50
Figure 1-2. Area of natural Years
forest, planted forest, and
nonforest land by geographic region, 1630 and 2007.
10
Figure 1-1. Historic forest area in the United States by
geographic region, 1630–2007.
70
The 150
largest single conifer
type, with 58 million acres in interior
Rocky Mountain
Alaska
Alaska,
is
the
spruce-birch
type. Douglas-fir follows closely,
100
Pacific Coast
with 39
million acres found predominantly in the Pacific Coast
50
Region.
0 Conifer forests are somewhat bimodal in age structure
30
Today, regional forest cover ranges from a low of 19 percent
of the land area in the Rocky Mountain Region (fig. 1-2) to
45 percent in the Pacific Coast Region, 41 percent in the North,
40 percent in the South, and 34 percent in Alaska.
North
300
250
200
150
Alaska
100
Rocky Mountain
Pacific Coast
600
400
200
0
50
0
0
20
0
0
Years
Source: USDA Forest Service, Forest Inventory and Analysis
19
5
19
1
0
0
18
7
0
18
3
17
9
0
0
17
5
0
17
1
16
7
16
3
0
0
1630 2007 1630 2007 1630 2007 1630 2007 1630 2007
North
South
Rocky
Pacific
Alaska
Mountain
Coast
Region and year
Natural forest
Planted forest
Nonforest
Source: USDA Forest Service, Forest Inventory and Analysis
800
lions)
Last Updated June 2011 600
160
140
1977
2007
1
an
d
0
20
150
20
100
2
1
1
1
1
1
1
1
Acres (millions)
Acres (millions)
Braodleaf
Mixed
Conifer
Braodleaf
Mixed
Conifer
Braodleaf
Mixed
Conifer
Braodleaf
Mixed
Conifer
Mixed
Conifer
Conifer
Braodleaf
Mixed
Conifer
Braodleaf
Mixed
Conifer
Mixed
Mixed
Braodleaf
Braodleaf
Conifer
Braodleaf
Mixed
Braodleaf
r
de
9
19
9
14
99
59
39
79
Conifer
19
ol
d
an
0
0
15
10
0
to
to
80
to
60
to
40
to
20
to
0
to
20
1977
2007
250
20
200
r
ol
de
9
an
d
to
0
15
0
Stand-age class (years)
19
9
0
to
14
99
80
to
79
60
to
59
to
40
50
to
100
39
1500
Private
250
250
Public
200
200
150
150
100
100
50
500
0
ol
an
d
Private
Public
1977
2007
llions)
0
0
1953
40
300
Nonstocked
0–4.9
5–9.9
10+
Average stand-diameter class (inches)
Rocky
Pacific
Alaska
Mountain
Coast
Region
Source: USDA Forest Service, Forest Inventory and Analysis
Private
Public
250
20
15
0
10
80
60
40
20
Nonstocked
0–4.9
5–9.9
10+
Average stand-diameter class (inches)
Stand-age class (years)
Source: USDA Forest Service, Forest Inventory and Analysis
Conifer
Broadleaf
Mixed
0
60
r
de
9
to
19
9
to
14
99
to
79
to
59
to
39
to
19
50
0
300
200
Mixed
Conifer
Broadleaf
Mixed
Nonstocked
0–4.9
5–9.9
10+
Source: USDA Forest Average
Service, Forest
Inventory and
Analysis
stand-diameter
class
(inches)
2007
40
200
1953
Broadleaf
Figure 1-6. Forest land ownership1953
in the United
States
1977
2007
300
by geographic
region, 2007.
250
Last 250
Updated June 2011 Conifer
0
AcresAcres
(millions)
(millions)
1977
Alaska
20
to
0
15
1953
300
60
to
AcresAcres
(millions)
(millions)
Figure 1-5. Trends in timber land area by average
80
stand-diameter
class, 1953–2007.
Stand-age class (years)
80
10
19
9
9
to
14
99
10
0
80
to
79
to
60
40
to
39
to
20
0
to
19
Rocky
Pacific
Alaska
Mountain
Coast
Region and cover group
Stand-age class (years)
Source: USDA Forest Service, Forest Inventory and Analysis
Conifer
Broadleaf
Mixed
Rocky
Pacific
Mountain
Coast
Region and cover group
Figure 1-4. Forest area by stand-age class for conifer,
broadleaf, and mixed forests, 2007 (excludes Alaska).
20
Conifer
ol Braodleaf
de
r
Mixed
Mixed
Braodleaf
Conifer
Mixed
Braodleaf
Conifer
Mixed
59 Braodleaf
Conifer
Braodleaf
Mixed
40
20
South
North
19
60
Conifer
Acres (millions)
Acres (millions)
100
60
80
20
0
2007
140
80
120
Nonforest
Forest land area has remained essentially stable since 2003. The
North
Southof 8 million
Rocky acresPacific
Alaska
data indicates
an increase
(about 1 percent),
2007
Mountain
Coast 1977
160 of this increase came as result of changes in the classi­but much
Region and cover group
140 of land cover types as either forest or nonforest. From
fication
120
a regional
standpoint, a general loss of forest has occurred in
100
the coastal regions of the East and West with offsetting gains
80
80
in forest
area in the interior region. Much of the loss can be at60
tributed
to
urban sprawl, and much of the gain can be attributed
40
60
to forest
encroachment
following decades of fire suppression.
20
0
Generally the forest gained is of lower productivity than the
40
forest lost.
Acres (millions)
Acres (millions)
1977
160
0
Nonforest
Coast
Region and year
What has changed
2003?
Natural forestsince
Planted
forest
South
NorthNatural forest
Figure 1-3. Area of
major cover group, 1977 and 2007.
Mountain
0
to
Mixed
Braodleaf
Conifer
Mixed
Braodleaf
Conifer
Mixed
Braodleaf
Conifer
Mixed
Braodleaf
Conifer
Mixed
Braodleaf
Rocky forest PacificNonforest
Alaska
Planted
Mountain
Coast
forest
in the
United States by
Regionland
and cover
group
20
0
00
20
50
19
10
19
70
18
30
18
90
17
50
17
10
17
70
16
30
16
Conifer
Acres
Acres (millions)
(millions)
Although trend data on forest age-class are sparse, historic data
1977
2007
160
800
are available
for average tree size in forest stands (fig. 1-5).
140
Stands
with trees averaging 0 to 5 inches in diameter increase
120
600
as older stands are harvested and regenerated. The recent trend
100
in this
diameter class is slightly downward. Although intermediate
400
80
stands60in the 6 to 10 inch diameter range have been declining,
200
stands
40averaging more than 11 inches in diameter have been
rising.20This later trend is indicative of shifts in management
0
0 1630
2007 1630
2007 1630
2007 1630
2007
1630West,
2007
that have
decreased
harvesting
on public
forests
in the
North
South
Rocky
Pacific
Alaska
thus, increasing
the acreage
of larger
diameter
stands
in
that
Mountain
Coast
region, particularly in coniferous
forests
Region and
year types.
South
Planted forest
Ownership
patterns have a profound effect on forest
600
1977manage2007
160
ment policies and activities. Although 81 percent of forests of
140
400
the North
and South are in private ownership, only 30 percent
120
of forests
in
the West are in private ownership (fig. 1-6).
100
200
Overall,
80 56 percent of U.S. forests are in private ownership.
0
Thus,60public
land policies have a more significant affect on
1630 2007 1630 2007 1630 2007 1630 2007 1630 2007
40 forests and their use.
western
North
South
Rocky
Pacific
Alaska
Acres (millions) Acres (millions)
Acres (millions)
Acres (millions)
200
200 forests. Virtually all of U.S. mixed forests are found
Mixed
Rocky Mountain
150
0
Alaska
in the
South,
where oak-pine (30 million acres) and oak-gum1630 2007 1630 2007 1630 2007 1630 2007 1630 2007
100
cypress
(20North
million acres)
are theRocky
major forest
types. Although
Pacific
SouthCoast
Pacific
Alaska
50
Mountain
Coast
oak-gum-cypress is found in the wet lowlands, oak-pine is
Region and year
0
usually found on the drier uplands of the South. The largest age
Natural forest
Planted forest
Nonforest
class for these forests is 40 to 59
years old.
Years
North
Coast
800
with800
more acreage in younger age-classes because of more
intensive management for wood production in the South and a
400
600
preponderance of olderSouth
stands in the West where most of the
350
United
States
remaining
old-growth forests occur and where
400
North
300
recent
policy changes have reduced harvesting of mature stands.
250
0
1
1
Natural forest
National Report on Sustainable Forests—2010
Years
0
20
Mountain
Years
Region and year
00
20
50
19
10
19
70
18
30
18
90
17
50
17
10
17
70
16
16
30
0
200
150
North
South
2