Forest Service
Northeastern
Research Station
Forest Resource Statistics for the
White Mountain National Forest,
1997
Tonya W. Lister
Thomas S. Frieswyk
Eric H. Wharton
William McWilliams
Michael Jimenez
Bryan Arnel
Contents
Page
Introduction
1
Reliability of the Estimates
2
Comparison Between Inventories
3
Highlights
4
Index to Tables
7
Total Land Area
8
Forest-land and Timberland Area
9
Number of Trees
10
Growing-stock Volume
14
Sawtimber Volume
22
Total Tree Biomass
28
Definitions of Terms
37
Tree Species of New Hampshire
43
Species Groups of New Hampshire
45
Tree-Grade Classification
47
Metric Equivalents
51
Literature Cited
52
_____________________________________________________________________
Authors
Tonya W. Lister, Research Forester, USDA Forest Service, Northeastern Research Station, Forest
Inventory and Analysis, Newtown Square, Pennsylvania
Thomas S. Frieswyk. Forester, USDA Forest Service, Northeastern Research Station, Forest Inventory
and Analysis, Newtown Square, Pennsylvania.
Eric H. Wharton, Forester, USDA Forest Service, Northeastern Research Station, Forest Inventory and
Analysis, Newtown Square, Pennsylvania.
William McWilliams, Research Forester, USDA Forest Service, Northeastern Research Station, Forest
Inventory and Analysis, Newtown Square, Pennsylvania.
Michael Jimenez, USDA Forest Service, White Mountain National Forest, 719 Main Street
Laconia, New Hampshire
Bryan Arnel, USDA Forest Service, White Mountain National Forest, 719 Main Street
Laconia, New Hampshire
_____________________________________________________________________
The sampling procedure used during this current
inventory involved a two-stage approach, and
included a sample of both new and remeasured
plots. A grid of points was overlaid on aerial
photos, and then these photo points were
classified into land-use and cubic-foot volume
classes. From this intensive aerial photo sample
of points, new plots were located on the ground.
Data were then collected on these plots, as well
as on plots established during earlier inventories.
The White Mountain National Forest was
included in this sample base (Figure 1).
Abstract
Between 1994 and 2002, the Forest Inventory and
Analysis Unit of the Northeastern Research Station
conducted its fifth forest inventory of New Hampshire
and a series of annual inventories in Maine, covering the
extent of the White Mountain National Forest. Results
obtained from analyzing data from the White Mountain
National Forest indicate that forestland covers 783,500
of the 787,183 total acres of land and that there is
almost 12 times more productive than unproductive
forest. Pole- and saw-timber stands are the most
dominant size classes in the National Forest, and trees
greater than 15 inches in diameter are generally of high
quality.
This report details the results of an analysis of
data collected on the White Mountain National
Forest. It is not the intent of this publication to
make suppositions regarding overall changes in
New Hampshire or Maine’s forest resources.
Separate and comprehensive statistical reports
have been published (Frieswyk and Widmann,
2000; Laustsen and Griffith, 2002; Griffith and
Alerich, 1996) and publications analyzing, in
greater detail, the forest resources of New
Hampshire and Maine are being prepared.
Introduction
The forests of the White Mountain National Forest
are an abundant, valuable resource. Information
about their extent, condition, and potential use is
essential for managers and other stakeholders. To
assess the status of the forest, inventories are
periodically conducted.
The Forest Inventory and Analysis Unit (FIA) of the
USDA Forest Service is responsible for conducting
periodic forest inventories in order to provide
current information on the forest resources of the
Nation. This is done under the authority of the
McSweeney-McNary Forest Research Act of 1928,
and subsequent acts that include the Renewable
Resources Planning Act of 1974 and the
Renewable Resources Research Act of 1978.
The Forest Inventory and Analysis Unit, located at
the Northeastern Research Station (NE-FIA),
located in Newtown Square, PA, performs forest
inventories in 13 northeastern states. The first
such inventory of New Hampshire’s forest
resources was conducted in 1948 (Larson and
others, 1954), and in Maine in 1954-58 (Ferguson
and Longwood, 1960). Successive inventories
were carried out at 10-15 year intervals. The fifth
and most recent inventory in New Hampshire was
conducted between 1996 and 1997 (Frieswyk and
Widmann, 2000), and the most recent series of
annual inventories in Maine was conducted in
1999-2002 (Laustsen and Griffith, 2002). The
inventory was done in cooperation with the New
Hampshire and Maine State Forestry Departments,
the White Mountain National Forest, and the
landowners of the two states.
Figure 1. Location of Forest Inventory and Analysis
plots, White Mountain National Forest, New
Hampshire (shown) and Maine.
Not all of the information that was collected is
contained within this publication. Forest area,
numbers of trees, timber volume, biomass, and
change statistics reported here, are only a
summary. Other information may be available,
2
and additional summaries may be developed upon
request. For more information, contact:
it is between 759,813 and 806,811 acres.
Similarly, we are 95 percent confident that the
true area is 783,312 + 46,998 acres (at two
standard deviations).
USDA Forest Service
Forest Inventory and Analysis
11 Campus Boulevard, Suite 200
Newtown Square, PA 19073-3200
Phone: 610-557-4075
Fax:
610-557-4200
Web: www.fs.fed.us/ne/fia/
However, estimates become less precise with
increasing detail, both spatially and in terms of
more specific forest and tree attributes. For
example, while the sampling error for all forest
land on the White Mountain National Forest is 3
percent, the sampling error for the area in
sawtimber stands is 12 percent, for the area in
poletimber stands is 12 percent, and for the area
in seedling and sapling stands is 24 percent.
Reliability of the Estimates
The data in this report are based on a carefully
designed sample of forest conditions within New
Hampshire and Maine. However, because the field
crews did not measure every tree or every acre in
the state, the data are estimates. The reliability of
the estimates can be judged by two important
statistical criteria: accuracy and precision.
The reason for these higher sampling errors is
that as the size of the sample in a particular
condition decreases, sampling error increases.
County estimates were not provided in this report
for that reason. In many cases, the sampling
errors were too large for the estimates to be
meaningful.
Estimates with sampling errors
greater than 25 percent are suspect, and those
larger than 50 percent are unusable because the
resulting estimate is not significantly different
from zero (at two standard deviations).
Accuracy refers to the success of estimating the
true value; while precision refers to the clustering
of sample values about their own averages or to
the variation among repeated samples. We are
interested primarily in the accuracy of the inventory
but in most cases we can only measure its
precision.
For many of the tables in this report, both the last
column and last row are labeled "SE." These
values are the sampling errors of the column and
row totals. The last sampling error (SE) given is
for the table total. As a helpful tool, individual
table cells have been annotated to indicate their
level of reliability. Those marked by (†) have
between a 25 and 49 percent sampling error, so
are suspect and should be used with caution.
Those marked by (‡) have a sampling error of 50
percent or greater, and as such should not be
used unless combined with another table cell
estimate with a smaller sampling error. However,
its possible to approximate the actual sampling
error for a table cell within certain tables.
To do so, use the following formula:
Although accuracy cannot be measured exactly, it
can be checked. Preliminary tables are sent to
other agencies and to outside experts familiar with
the forest conditions in New Hampshire and Maine.
If questions arise, the data are reviewed and
reanalyzed to resolve differences. Great care is
taken to minimize sources of procedural error
through careful training of both field and office
personnel, frequent inspection of field and office
work, and application of the most reliable inventory
methods.
Because of the care exercised in the inventory
process, estimates of precision afford a reasonable
measure of the inventory's adequacy. The
precision of each estimate is described by its
sampling error. Sampling errors are given with
several tables in this report. The others are
available upon request.
NOTE: this formula is reliable only for estimating
sampling errors of individual cells in the area
tables.
SEij = 1/Pij((Pij (1- Pij))/n)1/2
Here is an example of how the sampling error is
used to indicate reliability. The estimate of total
forest land for the White Mountain National Forest
is 783,312 acres. It has an associated sampling
error of 3 percent, or 23,499 acres. This means
that if there are no errors in the procedure, we are
68 percent confident that the true area is 783,312
+ 23,499 acres (at one standard deviation), or that
where:
SEij =
n
=
Pij =
Aij =
A
=
ij
=
3
actual sampling error) for a table cell
total number of samples in a population
Aij / A
cell estimate
total land area of a population
row(i) and column(j)
Comparison Between Inventories
Levels of Stocking
As a result of ongoing efforts to improve the
efficiency of the inventory, several changes in
procedures and definitions have been made since
the previous inventory. These changes prevent
direct comparison between some of the current
estimates with those published previously. The
changes in methods and definitions include: (1) a
new plot design, (2) changes in land area
determination, and (3) procedures to calculate
levels of stocking as it relates to stand size and
forest type.
Stocking is a quantitative expression of live tree
stand density. It may be expressed in absolute
or relative terms (Arner and others, 2000). For
the 1983 inventory statistics, the stocking value
of a tree was calculated using the basal area of
the tree as a percent of 75 square feet per acre,
which is the basal area standard for full use of
the site (USDA Forest Service, 1967).
Basal area stocking describes current timber
volume well, but inadequately measures present
site utilization, stand composition, and smalldiameter stands. A relative measure of stand
density is more appropriate for interpreting
findings of extensive inventories where a variety
of stands are sampled, such as those performed
by FIA. It more adequately reflects species
composition, stage of development, and the
social position of the trees present. A procedure
using relative density to calculate stocking using
relative density, which represents site occupancy
based on normal yield tables, was developed and
accepted as a standard for FIA units throughout
the country.
New Plot Design
To improve data consistency at the national level,
a standard plot design is being used by FIA units
throughout the country. The new plot design, a
cluster of four 24-foot-radius subplots covering a
1/6-acre area, was used during the most recent
inventory on both new and previously measured
plot locations.
In addition to the new plot configuration, field
crews recorded different conditions on the plot if
certain attributes (land use, forest type, stand
origin, stand size, tree density, owner) differed
from those at plot center, along with information
that described the boundaries of the conditions.
This procedure was designed to reduce bias in the
estimates. In previous inventories, ground plots
were wholly within the condition that the plot was
chosen to represent.
Stand size is a classification (sapling/seedling,
poletimber, sawtimber, or nonstocked) of forest
land based on the size of the trees that dominate
an area, and forest type is a classification of
forest land based on the species found in the
area. Both stand size and forest type are
calculated based on stocking of all live trees, and
were therefore affected by the change in the
procedure to calculate stocking. In addition,
there were minor refinements with respect to how
several species were allocated to local types
since the previous inventory.
On all remeasured plot locations, a subsample of
trees that were recorded in past inventories was
reconciled, and growth and removals estimates
were calculated using these data.
Differing
conditions were ignored for calculations of
estimates of change because this procedure was
not used at the previous occasion.
Land Area Determination
FIA uses Bureau of Census estimates of total land
area in a state or county as the basis for estimating
land area by various classes. But between 1980
and 1990, the Bureau of Census changed its
estimating procedures. Previously, the minimum
width for streams had been 660 feet, and the
minimum area for bodies of water was 40 acres.
Now, inland-water streams more than 200 feet
wide and bodies of water 4.5 acres and larger in
area are identified. Changes to this procedure
resulted in a reduction in total land area.
4
Highlights
 Mature forests dominate
 Productive forestland abounds
The forests of the WMNF consist mostly of trees
in the pole- and sawtimber size classes (Figure
3).
On timberland, sawtimber is the most
dominant size class. When reserved and other
forest are included, however, poletimber
becomes the most dominant. Eighty-six percent
of the sawtimber on forestland consists of trees in
the northern hardwood, oak-hickory, and aspen
birch forest type groups, and 14% is in the white
and red pine and spruce-fir forest type groups.
Of the total amount of timberland in the WMNF,
12% is in seedling and sapling stands, or those
classes responsible for regeneration.
The White Mountain National Forest (hereafter
referred to as the WMNF) contains an impressive
forest resource. Of its 787,183 acres of total land
area, 783,312 acres or over 99% are forested.
The definition of forest land includes timberland
(productive forest that could potentially be
harvested), reserved forest (forest withdrawn
from timber utilization, such as wildlife
preserves), and other forest. Reserved forest is
classified as either productive (capable of
producing more than 20 cubic feet of wood per
year) or unproductive. Other forest includes
forest land that is unproductive and not reserved.
There is almost 12 times more productive than
unproductive forest on the WMNF. Timberland
makes up 73% of the total forest area of the
WMNF and the remaining productive forestland is
classified as reserved (19% of total forest land
area) (Figure 2).
The proportion of reserved forestland on the
WMNF is also impressive. Nearly 161 thousand
acres, or 21% of total forest land is protected
from timber utilization. This is comparable to the
proportion of reserved forestland on the nearby
Green Mountain National Forest (24%).
Unproductive Reserved
Forest Land 2%
Other
Forest Land 6%
Figure 3. Area of forest land and timberland by
stand size class , White Mountain National Forest
_____________________________________
Productive Reserved
Forest Land 19%
 Balsam fir is the most abundant species
By far, balsam fir is the most abundant species in
the WMNF. It makes up 32% of all trees
measured on forest land (Figure 4). Sixty-six
percent of these trees are in the 1-3 inch
diameter class; however, balsam fir is still the
most numerous when considering just trees
greater than five inches in diameter. Including all
trees greater than one inch in diameter, the next
most abundant species is red spruce, followed by
American beech. When considering just trees
greater than five inches, however, paper birch
precedes red spruce in abundance. Softwood
species, making up 54 % of the total number of
trees, have a thin majority over hardwoods.
Timberland 73%
Timberland =
Reserved Forest Land =
Other Forest Land =
576,417acres
160,942acres
45,953acres
Total Forest Land =
783,312acres
Figure 2. Components of total forest land area,
White Mountain National Forest
_____________________________________
5
 Half of sawtimber is of highest quality tree
grade
Sawtimber volume in trees greater than 15
inches in diameter within the WMNF is of high
quality. Fifty-two percent of timberland and 49%
of forest land is classified as the highest tree
grade, grade 1 (Figure 6).
About 70% of
sawtimber volume on forest land within the
WMNF is of tree grade 1 or 2, which compares to
47% in the nearby Green Mountain National
Forest. Sawtimber quality distribution is similar
on both forestland and timberland.
Figure 4. Prevalence of leading tree species, White
Mountain National Forest.
_____________________________________
 Diameter distribution peaks between 7
and 13 inches
The diameter distribution of trees found on
the WMNF is positively skewed. On forest
land, the greatest amount of net volume is
found in the 7-9 inch diameter class, while on
timberland, the greatest amount of volume is
found in the 11-13 inch diameter class.
Above the 11-13 inch diameter class, nearly
all of the net volume is found on timberland;
in other words, below that, reserved and other
forest contain a more significant portion of
the volume on the WMNF.
Figure 6. Distribution of sawtimber volume by tree
grade in trees >15 inches dbh on forest land and
timberland, White Mountain National Forest
_____________________________________
 Growing stock trees contain 75% of
biomass
Growing stock trees make up roughly 75% of
the total tree biomass found on the WMNF
(Figure 7). Roughly two thirds of this 75%
consists of the main stem, while the
remainder consists of tops, branches, foliage
and stump-root systems. The other 25% of
the total tree biomass is comprised of non
growing stock seedlings and saplings (15%),
and cull and dead material (8%). Sixty-eight
percent of the biomass is composed of
hardwood, however hardwoods have a
greater proportion of dead and cull (9%) than
do softwoods (3%) (Figure 8).
Figure 5. Diameter class distribution of live volume on
forest land and timberland, White Mountain National
Forest.
_____________________________________
6
on growth and removals are based on a small
subset of inventory plots. On the WMNF we are
about 95 percent confident that annual net
growth is between 3.7 and 18.1 million cubic feet.
The FIA data for harvest removals on the WMNF
is also limited due to the small sample size. The
estimate of 15 million cubic feet of harvested
forest volume has an associated standard error
of 33 percent, suggesting that harvest removals
are between 5.1 and 25.1 million cubic feet (at
two standard deviations). This estimated range
of harvest removals overlaps with the estimates
for net growth on the WMNF; therefore, the
relationship between growth and removals is
inconclusive. It is not possible to say with
confidence whether total net growth is less or
more than harvest removals.
Net
Growth
Harvest
Removals
Figure 8. Components of softwood and hardwood
biomass on forestland, White Mountain National Forest.
Mortality
30
25
20
15
10
5
Gross
Growth
Million cubic feet
Figure 7. Components of biomass on forest land, White
Mountain National Forest.
_____________________________________
Figure 9. Average annual components of change in live
volume, White Mountain National Forest. (Bars indicate
sampling error at one standard deviation)
 Growth and removals data is inconclusive
Growth and removals data are often used as
indicators of forest resource sustainability.
Concern is raised when removals exceed net
growth. Net growth includes increases in tree
volume due to ingrowth and accretion, and
excludes mortality. Overall, there is positive net
growth on the WMNF, which indicates that on
average, tree volume is increasing at a greater
rate than is being lost to mortality due to natural
causes including age, insect and disease
damage, and other disturbances such as ice
damage (Figure 9).
Although it can be said with confidence that net
growth on the WMNF is positive for the period
from 1983 to 1997, the growth estimate is subject
to a large sampling error. This is because data
7
Index to Tables
Table
Page
Total Land Area
1
Total land area by land class, New Hampshire and White Mountain National Forest
8
Forest-land and Timberland Area
2a Area of forest land by forest type, forest type group, and stand-size class
9
2b Area of timberland by forest type, forest type group, and stand-size class
9
Number of Trees
3a Number of all live trees (1.0-inch d.b.h. and larger) on forest land by species and diameter class
10
3b Number of all live trees (1.0-inch d.b.h. and larger) on timberland by species and diameter class
12
All live and growing-stock Volume
4a Net volume of all live trees (5.0-inch d.b.h. and larger) on forest land by species and diameter class
14
4b Net volume of all live trees (5.0-inch d.b.h. and larger) on timberland by species and diameter class
16
5a Net volume of growing-stock trees (5.0-inch d.b.h. and larger) on forest land by species and diameter class
18
5b Net volume of growing-stock trees (5.0-inch d.b.h. and larger) on timberland by species and diameter class
20
Sawtimber Volume
6a Net volume of sawtimber trees on forest land by species and diameter class
22
6b Net volume of sawtimber trees on timberland by species and diameter class
23
7a Net volume of sawtimber trees (15.0-inch d.b.h. and larger) on forest land by species and tree grade
24
7b Net volume of sawtimber trees (15.0-inch d.b.h. and larger) on timberland by species and tree grade
25
8a Net volume of sawtimber trees on forest land by species, size class, and tree grade
26
8a Net volume of sawtimber trees on timberland by species, size class, and tree grade
27
Total Tree Biomass
9a Net sound biomass of growing-stock trees on forest land by species and component
28
9b Net sound biomass of growing-stock trees on timberland by species and component
29
10a Net sound biomass of all trees on forest land by species and component
30
10b Net sound biomass of all trees on timberland by species and component
31
10a Net biomass of all live trees (1.0-inch d.b.h. and larger) on forest land by species and diameter class
32
11b Net biomass of all live trees (1.0-inch d.b.h. and larger) on timberland by species and diameter class
34
12
Growth and Removals
Average annual net change of live tree volume on timberland by species and component of change
Note: In the tables, a zero indicates that the data are negligible or the condition was not encountered
in the sample. A dash indicates that the condition is not possible under current Forest Service
definitions. Rows and columns in all tables may not sum due to rounding.
7
36