United States

Department

of Agriculture

Forest Service

Rocky Mountain

Research Station

July 2010

Forest Resources of the 

Nez Perce National Forest

Michele Disney
About the author _____________

Michele Disney is a Forestry Technician with the Interior West Forest Inventory 

and Analysis Program, Rocky Mountain Research Station in Kalispell, Montana.

Contents______________________

Page

Description of the Nez Perce National Forest...................................................1

Forest land highlights of the Nez Perce National Forest.................................2

Nonreserved timberland highlights of the Nez Perce National Forest........9

Inventory methods................................................................................................10

Documentation......................................................................................................13

For further information........................................................................................13

Rocky Mountain Research Station

240 West Prospect Road 

Fort Collins, CO 80526-2098
1

As part of a National Forest System cooperative inventory, the Interior West Forest Inventory and Analysis 

(IWFIA) Program of the USDA Forest Service conducted 

a forest resource inventory on the Nez Perce National 

Forest using a nationally standardized mapped-plot design 

(for more details see the section “Inventory methods”). 

This report presents highlights of the inventory using 

commonly requested variables and summaries. The data 

could be summarized in other ways for different purposes 

(see “For further information” on the inside back cover). 

The information presented in this report is based on 

the IWFIA inventory sample collected in 2001 (USDA 

2001). Supplementary documentation and inventory 

terminology can be located in USDA 2002b. Additional 

data collected by the Nez Perce National Forest and used 

separately or in combination with IWFIA data may produce 

varying results. Changes since the inventory, such as the 

impact of recent disturbances on the forest, have not 

been incorporated into this report. Annual inventories 

will soon replace periodic inventories to help monitor 

these changes at shorter intervals.

Description of the Nez Perce 

National Forest

The Nez Perce National Forest administers 2,111,238 acres

(USDA 2000, 2002a) of which 94 percent is forest land, 

and 6 percent is nonforest or water (fig. 1). This report 

describes characteristics of forest land sampled on the 

Nez Perce. Forest land is land that is at least 10 percent 

stocked (or formerly stocked) with live tally tree species 

and is greater than 1 acre in size and 120 feet wide. 

Forest land is subdivided into timberland, where most 

trees are timber species commonly used for industrial wood products (such as Douglas-fir and lodgepole 

pine), and woodland, where most trees have a multi-stem 

growth form and are not typically used for industrial 

wood products (such as Rocky Mountain maple). 

Forty percent of the area administered by the Nez 

Perce National Forest is in reserved designation in the 

Selway-Bitterroot, Gospel-Hump, and Frank ChurchRiver of No Return Wilderness areas. In addition, sixty 

thousand acres of Hell’s Canyon Wilderness lie within 

Nez Perce National Forest, but are administered by the 

Wallowa-Whitman National Forest. The first part of this 

report focuses on resources of all forest land administered by the Nez Perce National Forest. A subsequent 

section will address nonreserved timberland.

56% 

38% 

6% 

Forest (not reserved) 

Forest (reserved) 

Nonforest and water 

Figure 1—Percent area by land class and reserved status, Nez 

Perce National Forest, 2001.

Forest Resources of the Nez Perce National Forest

Michele Disney
2

Forest land highlights of the Nez 

Perce National Forest

Forest type—Forest resources are often described 

using a forest type classification. Forest type refers to 

the predominant tree species in a stand, based on plurality 

of tree stocking. Stocking is an expression of the extent 

to which growing space is effectively utilized by live 

trees.

Forest types are dynamic and can change slowly through 

forest succession, or rapidly due to disturbances such as 

logging, fire, or insect and disease epidemics. Figure 2 

presents the distribution of forest land area on the 

Nez Perce National Forest by forest type. The spruce-fir 

forest type is the most common at 24 percent, followed 

in abundance by grand fir and Douglas-fir, each at 22 percent, and lodgepole pine at 15 percent. The ponderosa 

pine forest type comprises 9 percent of the forest land 

area; western redcedar, 4 percent; and maple woodland 

and Engelmann spruce each 2 percent. All western larch 

and Cercocarpus woodland sampled was nonstocked.

Tree and stand size—The size distribution of trees is 

an indicator of structural diversity. Figure 3 displays the 

distribution of the 852 million live trees on the Nez Perce 

National Forest by diameter class. Overall, this shows 

a typical diameter distribution with higher numbers of 

smaller trees. Trees often reproduce prolifically, but thin 

out naturally over time due to competition for resources.

Stand-size class is a classification of forest land based 

on the dominant diameter class of live trees that contribute to stand stocking. When describing stand size, large 

trees are timber-type softwoods and all woodland tree 

species 9.0 inches diameter and greater, and timber-type 

hardwoods 11.0 inches diameter and greater; medium 

trees include timber-type softwoods and all woodland 

tree species 5.0 to 8.9 inches diameter, and timber-type 

hardwoods 5.0 to 10.9 inches diameter; and saplings/

seedlings are trees under 5 inches diameter. Nonstocked 

stands are typically those that have been recently disturbed 

by tree cutting, forest fire, or other large-scale change. 

For tree stocking, fewer large-diameter trees compared 

to small-diameter trees are required to fully stock a site. 

Figure 4 shows a breakdown of forest land on the Nez 

Perce National Forest by stand-size class. Seventy-four 

percent of forest has a majority of stocking from large 

trees, while 3 percent are nonstocked.

0% 5% 10% 15% 20% 25% 

Aspen 

Western larch 

Cercocarpus woodland 

Whitebark pine 

Engelmann spruce 

Maple woodland 

Western redcedar 

Ponderosa pine 

Lodgepole pine 

Douglas-fir 

Grand fir 

Spruce-fir 

Percent forest area 

Forest type 

0 

50 

100 

150 

200 

250 

300 

350 

400 

1.0-2.9 3.0-4.9 5.0-6.9 7.0-8.9 

9.0-10.9 

11.0-12.9 

13.0-14.9 15.0-16.9 17.0-18.9 19.0-20.9 21.0-22.9 23.0-24.9 

25+ 

Million trees 

Tree diameter (inches) 

Figure 2—Percent of forest land area 

by forest type, Nez Perce National 

Forest, 2001.

Figure 3—Number of live trees on 

forest land by diameter class, Nez 

Perce National Forest, 2001.
3

Figure 5 shows the area of forest land by forest type 

and stand-size class on the Nez Perce National Forest. 

The three most common forest types in the large class 

are grand fir, spruce-fir, and Douglas-fir. Together they 

comprise 70 percent of the large tree stands and 68 percent of all forest land. Lodgepole pine is the most abundant forest type for medium diameter stands, accounting 

for 44 percent of such stands and 15 percent of all forest 

land. The whitebark pine, aspen, and western larch forest 

types collectively represent 0.5 percent of forest land on 

the Nez Perce, and are pooled in figure 5.

Number of live trees—Another way to assess forest 

diversity is by examining the composition of forest 

land by tree diameter and species. Figure 6 shows 

the 852 million live trees by species in three diameter 

classes. Sixty-five percent of all live trees are from 1.0 to 

4.9 inches diameter, 19 percent are from 5.0 to 8.9 inches 

Figure 4—Forest land area by stand-size class, Nez Perce National Forest, 2001.

0 

50 

100 

150 

200 

250 

300 

350 

400 

Spruce-fir 

Grand fir 

Douglas-fir 

Lodgepole pine 

Ponderosa pine 

Western redcedar 

Maple woodland 

Engelmann spruce 

Cercocarpus 

woodland 

Other forest types 

Thousand acres 

Forest type 

Large diameter 

Medium diameter 

Saplings/seedlings 

Nonstocked 

0 200 400 600 800 1,000 1,200 1,400 1,600 

Nonstocked 

Saplings/seedlings 

Medium diameter 

Large diameter 

Thousand acres 

Stand-size class 

Figure 5—Forest land area by stand-size class 

and forest type, Nez Perce National Forest, 2001.

0 

20 

40 

60 

80 

100 

120 

140 

160 

180 

200 

Grand fir Subalpine fir Lodgepole 

pine 

Douglas-fir Rocky 

Mountain 

maple 

Engelmann 

spruce 

Western 

redcedar 

Ponderosa 

pine 

Less 

common 

species 

Million trees 

Species 

1.0" - 4.9" 

5.0" - 8.9" 

9.0" and greater Figure 6—Number 

of live trees 1.0 inch 

in diameter and 

greater on forest 

land by species 

and diameter class, 

Nez Perce National 

Forest, 2001.
4

diameter, and 17 percent are 9.0 inches diameter and 

greater. Grand fir makes up 30 percent of the total number of trees; subalpine fir, 19 percent; lodgepole pine, 

17 percent; Douglas-fir, 14 percent; Rocky Mountain 

maple, 7 percent; Engelmann spruce, 7 percent; and 

western redcedar and ponderosa pine, each 2 percent. 

Species pooled in figure 6 are Pacific yew, whitebark 

pine, western larch, paper birch, western white pine, 

and aspen (3 percent collectively). There are an estimated 5.1 million live whitebark pines on the Nez Perce, 

62 percent of which are saplings. There are an estimated 

82,000 live western white pines, all of which are between 

5.0 and 8.9 inches diameter.

Figure 7 shows the number of live trees 5.0 inches 

diameter and greater by species and elevation class. 

0 20 40 60 80 100 120 

1900-2999 

3000-3999 

4000-4999 

5000-5999 

6000-6999 

7000-7800 

Million trees 

Elevation class (feet) 

Lodgepole pine 

Grand fir 

Subalpine fir 

Douglas-fir 

Engelmann spruce 

Western redcedar 

Ponderosa pine 

Rocky Mountain maple 

Western larch 

Whitebark pine 

Other species 

Figure 7—Number of live trees 5.0 inches diameter and greater on forest land by species and elevation 

class, Nez Perce National Forest, 2001.

Elevation is closely correlated with variations in local climate. Precipitation generally increases with rising elevation, while temperature decreases. Aspect complicates 

this general rule; allowing relatively warmer- and dryersite species to grow at higher elevations on south- and 

west-facing slopes. These factors have a profound effect 

on competition between tree species. The Nez Perce 

National Forest displays some distinct elevation patterns 

in tree distribution: subalpine fir and lodgepole pine do 

well at higher elevations, and grand fir is most common 

in the middle elevations. Douglas-fir can be found in a 

range of elevations. Paper birch, Pacific yew, western 

white pine, and aspen each represent 0.25 percent or 

less of live trees 5.0 inches diameter and greater on the 

Nez Perce National Forest and are pooled in figure 7.
5

Number and weight of dead trees—Standing and 

down dead trees are important for wildlife and in fire 

ecology, as well as acting as nutrient sinks and erosion 

controls. Approximately 67 million standing dead trees 

(snags) and 58 million down dead trees 5.0 inches diameter and greater are on forest land on the Nez Perce 

National Forest. If trees 1.0 inch diameter and greater 

are included, there are 176 million snags and 156 million 

down dead trees.

Many animals are dependent upon snags, but the 

species, size, and density of snags required for quality 

habitat vary by wildlife species. Large diameter dead trees 

are generally scarce relative to smaller trees. An estimated 

average of 9.9 snags 11.0 inches diameter or larger occur 

per acre of forest land. Of the very large snags (19.0 inches 

diameter or larger) there are an estimated 2.3 per acre. 

Nineteen-inch and larger snags were most commonly 

grand fir (34 percent), followed by Douglas-fir (29 percent).

Dead trees are an important component of forest 

fuel loads. On the Nez Perce, about 19.7 million tons of 

standing dead trees and 13.9 million tons of down dead 

trees are on forest land. This estimate includes the merchantable bole and bark of trees 5.0 inches diameter and 

greater. Figure 8 shows the weight per acre of down dead 

trees by stand-size class and forest type. For all forest 

types combined, the large tree class has the highest 

weight at 7.6 tons per acre, followed by the medium tree 

class at 6.7 tons per acre, and the sapling/seedling class 

at 5.0 tons per acre. For all stand-size classes combined, 

the spruce-fir type has the highest weight at 11.4 tons 

per acre, followed by grand fir and western redcedar at 

8.1 and 6.5 tons per acre. No down dead trees were sampled for aspen, mountain mahogany, and western larch. 

Several of the class breakdowns displayed in figure 8 may 

not be representative due to small sample sizes.

Stand age—Stand age is estimated from core samples 

of live trees. The estimate is limited to trees with diameters in a stand’s designated stand-size class. Many factors 

affect the number of sample trees available for determining stand age. In general, stand age for dense stands that 

contain more core sample trees is more representative 

than stand age for sparse stands that contain fewer.

Figure 9 breaks out forest land area by forest type and 

stand-age class on the Nez Perce National Forest. Stand 

age can indicate the duration since the last extensive 

disturbance of the forest overstory. This figure shows the 

81- to 100-year class as the most common on the Forest, 

followed by the 101- to 120-year and 61- to 80-year age 

classes.

0 

2 

4 

6 

8 

10 

12 

14 

Spruce-fir 

 Grand fir 

Douglas-fir 

Lodgepole pine 

Ponderosa pine 

Western redcedar 

Maple woodland 

Engelmann spruce 

Other forest types 

All forest types 

Tons per acre 

Forest type 

Large trees 

Medium trees 

Saplings/seedlings 

Nonstocked 

Figure 8—Weight of down dead trees 5.0 inches diameter and greater on forest land by forest type and standsize class, Nez Perce National Forest, 2001.
6

Wood volume, biomass, and basal area of live trees—

Estimates of cubic-foot volume and basal area include 

all live trees 5.0 inches diameter and greater. Basal area 

is the cross-sectional area of a tree stem/bole (includes 

bark) at the point of diameter measurement. Biomass estimates include boles, bark, and branches of all live trees 

0% 

5% 

10% 

15% 

20% 

25% 

Nonstocked 1-20 21-40 41-60 61-80 81-100 101-120 121-140 141-160 161-180 181-203 

Percent of forest land 

Stand-age class (years) 

Engelmann spruce 

Maple woodland 

Western redcedar 

Ponderosa pine 

Lodgepole pine 

Douglas-fir 

Grand fir 

Spruce-fir 

Other forest types 

Figure 9—Percent of forest land area by forest type and stand-age class, Nez Perce National Forest, 2001.

1.0 inch diameter and greater. The net volume of wood 

on the Nez Perce National Forest is estimated to be 6.8 

billion cubic feet. Total biomass of wood is estimated at 

nearly 115 million tons, and the total basal area is estimated to be about 220 million square feet. Table 1 is a breakdown of volume, biomass, and basal area by species.

Table 1—Net volume, biomass, and basal area on forest land by species, Nez Perce 

National Forest, 2001.

Volume Biomass Basal area

(≥5.0” dia.) (≥1.0” dia.) (≥5.0” dia.)

Species (Million cubic feet) (Million tons) (Million square feet)

Aspen	 0.1	 *	 *

Douglas-fir	 1,247.3	 24.5	 43.8

Engelmann spruce	 643.4	 9.5	 19.1

Grand fir	 1,924.1	 32.1	 57.5

Lodgepole pine	 1,026.5	 16.9	 34.9

Pacific yew	 0.5	 0.1	 0.2

Paper birch	 4.7	 0.1	 0.2

Ponderosa pine	 615.7	 11.3	 16.2

Rocky Mountain maple 15.1	 0.6	 1.0

Subalpine fir	 664.9	 11.1	 27.3

Western larch	 106.3	 2.1	 3.3

Western redcedar	 490.5	 6.6	 15.6

Western white pine	 0.2	 *	 *

Whitebark pine	 17.1	 0.3	 0.8

Total (not exact due to rounding)	 6,756.6 115.0 220.0

	 * – Less than 15,000
7

Figure 10 displays the percent net cubic-foot volume 

of live trees by diameter class. Eighty-seven percent of 

this volume is 9.0 inches diameter and greater. Ninetythree percent each of grand fir and Douglas-fir volume, 

and 92 percent of Engelmann spruce volume are in trees 

9.0 inches diameter and larger. Common species with 

low percentages of volume in trees 9.0 inches diameter 

and larger include lodgepole pine at 64 percent and 

subalpine fir at 74 percent. Ponderosa pine, western redcedar, and western larch are all over 96 percent in trees 

0% 

2% 

4% 

6% 

8% 

10% 

5.0-6.9 7.0-8.9 

9.0-10.9 

11.0-12.9 

13.0-14.9 15.0-16.9 17.0-18.9 19.0-20.9 21.0-22.9 23.0-24.9 25.0-26.9 27.0-28.9 29.0-30.9 31.0-32.9 33.0-34.9 35.0-36.9 37.0-38.9 39.0-40.9 41.0-42.9 

43+ 

Percent volume 

Diameter class (inches) 

Figure 10—Percent of total net cubic-foot volume of live trees by diameter class, Nez Perce National Forest, 2001.

over 9.0 inches diameter, but together these species 

represent 18 percent of volume.

Another way to look at wood volume is by forest type, 

for which per-acre estimates can be computed along with 

basal area (table 2). These numbers include the many 

different species that can occur together in each forest 

type. The highest volume and basal area per acre on the 

Nez Perce National Forest is in the western redcedar forest type. Volume and basal area per acre for whitebark 

pine, aspen, Cercocarpus woodland, and western larch 

may not be representative due to small sample size.

Table 2—Net volume per acre, basal area per acre, number of conditions, and condition 

proportions on forest land by forest type, Nez Perce National Forest, 2001.

Net cubic-foot Basal area Number of Condition

Forest type volume per acre sq. ft. per acre conditionsa proportionsa

Western redcedar	 7,758	 226	 11	 11.0

Grand fir	 4,703	 142	 71	 67.1

Ponderosa pine	 3,271	 93	 33	 30.0

Lodgepole pine	 2,939	 105	 49	 45.7

Douglas-fir	 2,824	 96	 70	 63.8

Spruce-fir	 2,754	 99	 75 71.2

Engelmann spruce 	 2,247	 79	 6	 4.8

Maple woodland	 765	 27	 6	 5.3

Whitebark pine	 628	 35	 1	 1.0

Aspen	 39	 3	 1	 0.0

Cercocarpus woodland	 0	 0	 1	 1.0

Western larch	 0	 0	 1 0.5

All forest types 3,396 111 325 301.7

a

One characteristic of the mapped-plot design is that plot area may be split between multiple conditions. 

When plots are split, the proportion of a plot represented by each condition is calculated. Condition proportions across a landscape can be added to indicate the amount of area sampled for different forest types (or

any other condition attribute). Table 2 shows the number of conditions (usually the number of different plots

containing that forest type) and condition proportions (area sampled as a multiple of the area of an FIA plot).
8

Stand density index—Many factors influence the rate 

at which trees grow and thrive, or die. As tree size and 

density increase, competition for available resources 

also increases. Stand density index (SDI), as developed 

by Reineke (1933), quantifies the relationship between 

trees per acre and average stand diameter. The concept 

was developed for even-aged stands dominated by one 

or two related size classes (based on diameter and/or 

height), but can also be applied to uneven-aged stands 

composed of three or more size classes (Long and Daniel 

1990; Shaw 2000). SDI is usually presented as a percentage of the maximum SDI for each forest type (Van Dyck 

2002). Maximum SDI values for the forest types on the 

Nez Perce National Forest were estimated using FIA plot 

data, and formulated specifically to match the procedure used by FIA to calculate SDI (Shaw 2000). Resulting 

percentages were grouped into four classes (fig. 11), 

whose thresholds have ecological and management 

significance. A site is considered to be fully occupied at 

35 percent of SDI maximum, which marks the onset of 

competition-related stresses and slowed growth rates 

(Long 1985). An estimated 60 percent of forest stands on 

the Nez Perce National Forest are considered to be fully 

occupied.

Components of change: growth—Another measure of 

forest vigor is net annual growth. Net annual growth is 

the difference between gross annual growth and losses 

due to mortality. Gross annual growth of live trees 

(5.0 inches diameter and greater) on forest land on the 

Nez Perce National Forest is estimated to be 144 million 

cubic feet, and net annual growth is 102 million cubic 

feet. Gross annual growth is compared to mortality for 

seven high volume species in figure 12. Mortality on 

forest land on the Nez Perce National Forest is about 

29 percent of gross annual growth.

0 

100 

200 

300 

400 

500 

600 

700 

800 

<25 25-34.9 35-59.9 60+ 

Thousand acres 

Percent of maximum stand density index 

Other forest types 

Engelmann spruce 

Maple woodland 

Western redcedar 

Ponderosa pine 

Lodgepole pine 

Douglas-fir 

Grand fir 

Spruce-fir 

Figure 11—Area of forest land by forest type and stand density index, Nez Perce National Forest, 2001.

Components of change: mortality—Field crews assess 

which trees have died in the past 5 years; these trees are 

used to estimate an average annual mortality. Based on 

this estimate, 41.6 million cubic feet of wood is from trees 

(5.0 inches diameter and greater) that died on the Nez 

Perce National Forest in 2000. About 22 percent of the 

mortality was caused by root disease, 20 percent by fire, 

and 12 percent by mountain pine beetles. The following 

five species account for 98 percent of overall mortality: 

Douglas-fir (26 percent), lodgepole pine (23 percent), 

grand fir (22 percent), subalpine fir (19 percent), and 
9

0 10 20 30 40 50 

Ponderosa pine 

Western redcedar 

Engelmann spruce 

Subalpine fir 

Lodgepole pine 

Douglas-fir 

Grand fir 

Million cubic feet 

Species 

Gross annual growth 

Annual mortality 

Figure 12—Gross annual growth and mortality of live trees 5.0 inches diameter 

and greater for seven high volume species on forest land, Nez Perce National 

Forest, 2000.

ponderosa pine (7 percent). Whitebark pine mortality is 

estimated to be 451 thousand cubic feet or 63 percent of 

whitebark pine gross annual growth. No western white 

pine mortality was recorded during the inventory.

Understory vegetation—Understory vegetation provides forage and cover for wildlife, contributes to forest 

fuel load, and can be an indication of the successional 

stage of the forest community. Figure 13 shows the average percent cover of four plant groups on forest land by 

forest type. Grand fir is the most abundant understory 

seedling/sapling species, followed by subalpine fir and 

Rocky Mountain maple. The most abundant understory 

shrubs are huckleberry, fool’s huckleberry, and grouse 

whortleberry. Beargrass, Idaho goldthread, and heartleaf 

arnica are the most abundant forbs; and pinegrass and 

elk sedge are the most abundant understory graminoids 

on the forest.

0 

5 

10 

15 

20 

25 

30 

35 

Douglas-fir Engelmann 

spruce 

Grand fir Lodgepole 

pine 

Ponderosa 

pine 

Spruce-fir Subalpine fir Western larch Western 

redcedar 

Average percent cover 

Forest type 

Trees 

Shrubs 

Graminoids 

Forbs 

Figure 13—Average percent cover of trees (seedlings/saplings), shrubs, forbs, and graminoids on forest land by forest 

type, Nez Perce National Forest, 2001.

Nonreserved timberland 

highlights of the Nez Perce 

National Forest

Reserved lands are those that have been withdrawn 

from management for production of wood products, 

such as wilderness areas and national parks. Sixty percent of forest land on the Nez Perce is nonreserved, of 

which 99 percent is designated as timberland. There 

are 494 million live growing-stock trees on nonreserved 

timberland.

Forest type—Grand fir is the most common forest 

type on nonreserved timberland on the Nez Perce at 

29 percent, followed by Douglas-fir (21 percent) and 

lodgepole pine (17 percent). Spruce-fir, the most common forest type on all forest land, is 16 percent of 

nonreserved timberland.
10

Dead trees and fuels—There are approximately 45 million 

standing dead trees (snags) and 38 million down dead 

trees 5.0 inches diameter and greater on nonreserved 

timberland. Snags at least 11.0 inches diameter are found 

at densities of 10.1 per acre, and there are 2.5 snags per 

acre that are 19.0 inches diameter or greater. The merchantable bole and bark of dead trees at least 5.0 inches 

in diameter on reserved timberland is about 6.2 million 

tons in standing dead trees, and 5.4 million tons in down 

dead trees.

Weight of dead and down trees per acre is about 

1.4 percent greater on nonreserved timberland than 

on all forest land. For large stand sizes, this difference 

is nearly 4 percent (7.9 tons per acre versus 7.6 tons per 

acre for all forest land). For most forest types, weight per 

acre of dead and down trees is greater on nonreserved 

timberland than on all forest land. Forest types with the 

largest differences are western redcedar (32 percent more), 

lodgepole pine (11 percent more), grand fir (8 percent 

more), and ponderosa pine (8 percent less).

Stand age—The distribution of stand ages on nonreserved timberland is similar to that of all forest land with 

the exception of a smaller proportion of stands with ages 

from 1 to 21 years. As with all forest land, the 81- to 

100-year age class is the most common, followed by the 

101- to 120-year and 61- to 80-year age classes.

Wood volume, biomass, and basal area of growing-stock 

trees—Table 3 displays a breakdown of net volume, tons 

of wood biomass, and square foot basal area for growingstock trees 5 inches diameter and greater by species on 

nonreserved timberland. Estimated total net volume is 

4.4 billion cubic feet. Grand fir had the most net volume 

(32 percent), followed by Douglas-fir (18 percent) and 

lodgepole pine (16 percent). Total wood biomass is estimated at 72 million tons. Grand fir had the most wood 

biomass (31 percent), followed by Douglas-fir (21 percent) and lodgepole pine (16 percent). Total basal area is 

estimated at 141 million square feet, 30 percent in grand 

fir, 20 percent in Douglas-fir, and 17 percent in lodgepole 

pine.

Sawtimber volume on nonreserved timberland is estimated to be nearly 23 billion board feet (International 1⁄4-inch 

rule). This includes all growing-stock trees 9.0 inches diameter and greater for softwoods, and 11.0 inches diameter and greater for hardwoods. Figure 14 illustrates 

the sawtimber volume on nonreserved timberland by 

diameter. The 11.0- to 12.9-inch diameter class has the 

most volume at 9.8 percent, followed by the 9.0- to 10.9-

inch class at 9.6 percent and the 21.0- to 22.9-inch class 

at 9.3 percent. Thirty-four percent of the total sawtimber 

volume on the Nez Perce National Forest is from grand 

fir, 19 percent from Douglas-fir, 12 percent from ponderosa pine, and 11 percent from lodgepole pine.

Stand density index—Seventy percent of the nonreserved timberland stands on the Nez Perce National 

Forest are at 35 percent or more of SDI maximum, or 

considered to be fully occupied. Eighty-one percent of 

grand fir stands, 79 percent of lodgepole pine stands, 

and 50 percent of Douglas-fir stands are fully occupied.

Components of change: growth and mortality—Gross 

annual growth is estimated at 96 million cubic feet, while 

mortality is an estimated 28 million cubic feet, or 29 percent of gross annual growth. Figure 15 displays the gross 

annual growth and mortality of growing-stock trees for 

seven high-volume species on Nez Perce nonreserved 

timberland. High gross annual growth coincided with 

relatively low mortality for grand fir. Gross annual growth 

is estimated at 35.6 million, 17.4 million, 15.0 million, and 

7.8 million cubic feet for grand fir, Douglas-fir, lodgepole 

pine, and Engelmann spruce. Annual mortalities for the 

same four species are estimated at 4.4 million, 10.0 million, 7.5 million, and 17 thousand cubic feet.

Inventory methods

The Forest Inventory and Analysis (FIA) program samples forest across all ownerships. The resulting data can 

be used for planning and analysis at local, state, regional, 

and national levels. IWFIA uses a two-phase sampling 

procedure for all inventories. Phase one is based on a 

grid of sample points systematically located every 1,000 

meters across all lands in a state. Phase one points are 

assigned ownership and vegetative cover attributes using 

maps and remotely sensed imagery.

Table 3—Net volume, biomass, and basal area of growingstock trees 5 inches diameter and greater by 

species on nonreserved timberland, Nez Perce 

National Forest, 2001.

Volume Biomass Basal area

(Million (Million (Million

Species cubic feet) tons) square feet)

Douglas-fir	 813.1	 15.4	 27.7

Engelmann spruce	 342.8	 4.8	 10.2

Grand fir	 1,407.5	 22.2	 42.6

Lodgepole pine	 722.0	 11.2	 23.8

Pacific yew	 0.3	 *	 0.1

Paper birch	 4.7	 0.1	 0.2

Ponderosa pine	 442.2	 8.0	 11.3

Subalpine fir	 284.5	 4.2	 11.1

Western larch	 104.1	 2.0	 3.2

Western redcedar	 314.0	 4.2	 10.4

Western white pine	 0.1	 *	 *

Whitebark pine	 9.3	 0.2	 0.4

Total (not exact 4,444.8 72.4 141.1

due to rounding)

* – Less than 50,000
11

0 

500 

1000 

1500 

2000 

2500 

9.0-10.9 

11.0-12.9 

13.0-14.9 15.0-16.9 17.0-18.9 19.0-20.9 21.0-22.9 23.0-24.9 25.0-26.9 27.0-28.9 29.0-30.9 31.0-32.9 33.0-34.9 35.0-36.9 37.0-38.9 39.0-40.9 41.0-42.9 

43-52.9 

Million board feet 

Tree diameter (inches) 

Figure 15—Gross annual growth and mortality of growing-stock trees 5.0 inches 

diameter and greater for seven high volume species on nonreserved timberland, Nez 

Perce National Forest, 2000.

Figure 14—Sawtimber volume (International 1⁄4-inch rule) on nonreserved timberland by diameter class, 

Nez Perce National Forest, 2001.

0 5 10 15 20 25 30 35 40 

Ponderosa pine 

Western redcedar 

Engelmann spruce 

Subalpine fir 

Lodgepole pine 

Douglas-fir 

Grand fir 

Million cubic feet 

Species 

Gross annual growth 

Annual mortality 

Field crews conduct phase two of the inventory on the 

subsample of phase one points that occur on forest land. 

The sampling intensity is one field plot every 5,000 meters, or about every 3 miles. Phase two plots are stratified 

based on phase one ownership and vegetation information, and weights are assigned to each stratum based on 

the proportion of phase one points in that stratum.

About the mapped-plot design—The mapped-plot 

design was adopted by FIA nationwide by 1995. Its predetermined subplot layout uses boundary delineation 

to quantify and distinguish between multiple conditions. 

Most plots sample one forest condition; therefore, mapping condition boundaries is often unnecessary.

Conditions are delineated based on differences in any 

of five attributes: forest/nonforest, forest type, stand-size 

class, stand origin, and stand density. The condition proportion is the fraction of plot area sampled in each condition, with the sum of all condition proportions for an 

accessible plot equal to 1.00. Therefore, the number and 

relative size of plot conditions determines the weighted 

area used for sample expansion. There were 339 field 

plots on the Nez Perce National Forest, 18 of which were 

hazardous and/or inaccessible. A total of 291 field plots 

sampled only forest conditions, 15 sampled both forest 

and nonforest conditions, 1 sampled both forest and 

water conditions (rivers, reservoirs, lakes, etc. at least 
12

30 feet wide or 1 acre in area), 12 sampled only nonforest conditions, 1 sampled both nonforest and water, and 

1 sampled forest, nonforest, and water. A total of 325 forest conditions were sampled on 308 plots that contained 

301.7 forest, 5.4 nonforest, and 0.8 water condition proportions. No stocked stands were sampled for Cercocarpus woodland or western larch forest types.

Standard errors—The sample was designed to meet 

national standards for precision in state and regional estimates of forest attributes. Standard errors, which denote 

the precision of an estimate, are usually higher for smaller subsets of the data. Forest-level estimates and percent 

standard errors by land class or type of trees for various 

attributes are presented in table 4. Standard errors for 

other estimates are available upon request (see “For further information” section on the inside back cover).

Table 4—Percent standard errors for area estimates on total forest land and 

reserved timberland; and percent standard errors for estimates of net 

volume, net annual growth, and annual mortality for live trees on total 

forest land and growing-stock trees (5.0 inches d.b.h. and greater) on 

nonreserved timberland, Nez Perce National Forest, 2001.

Land class or Area or Percent

type of trees Attribute volume standard error

Total forest land (acres)	 Area	 1,989,430	 ±1.2

Total forest land	 Volume	 6,756,560,000	 ±4.5

(all trees cubic feet)	 Growth	 102,007,970	 ±9.5

	 	 Mortality	 41,576,470	 ±19.0

Nonreserved timberland (acres)	 Area	 1,171,680	 ±1.7

Nonreserved timberland	 Volume	 4,444,760,000	 ±5.4

(growing-stock trees, cu. ft.)	 Growth	 67,848,970	 ±11.6

	 	 Mortality	 27,930,080	 ±22.4
13

Federal Recycling Program Printed on Recycled Paper

For further information ________________

Interior West Forest Inventory and Analysis Program (IWFIA)

Rocky Mountain Research Station

c/o Program Manager

507 25th Street, Ogden, UT 84401

Phone: 801-625-5388

FAX: 801-625-5723

World Wide Web: http://www.fs.fed.us/rm/ogden

Nez Perce National Forest

Supervisor’s Office

104 Airport Road

Grangeville, Idaho 83530

Phone: 208-983-1950

FAX: 208-983-4099

World Wide Web: http://www.fs.fed.us/r1/nezperce/

Selected data for this National Forest are part of a national data base that 

houses information for much of the forest land in the United States. This 

data base can be accessed on the Internet at the following web site:

http://fia.fs.fed.us/tools-data/

Documentation _______________

Long, James N. 1985. A practical approach to density 

management. Forestry Chronicle 61:23-27.

Long, James N.; Daniel, Theodore W. 1990. Assessment 

of growing-stock in uneven-aged stands. Western Journal of Applied Forestry 5(3):93-96.

Reineke, L.H. 1933. Perfecting a stand density index for 

even-aged forests. J. Agric. Res. 46:637-638.

Shaw, John D. 2000. Application of stand density index 

to irregularly structured stand. Western Journal of 

Applied Forestry 15(1):40-42.

U.S. Department of Agriculture, Forest Service. 2000. 

Land areas of the National Forest System, as of 

September 1999. FS-383.

U.S. Department of Agriculture, Forest Service. 2001. 

Forest Survey Field Procedures: April 2001 Baseline. 

Ogden, UT: USDA Forest Service, Rocky Mountain 

Research Station.

U.S. Department of Agriculture, Forest Service. 2002a. 

Land Areas of the National Forest System as of September 30, 2002. [Online]. Available: http://www.fs.fed.us/

land/staff/lar/LAR02/lar02index.htm (also available on 

file at: U.S. Department of Agriculture, Forest Service, 

Rocky Mountain Research Station, Ogden, UT).

U.S. Department of Agriculture, Forest Service. 2002b. 

Periodic mapped-plot design inventory terminology. 

[Online]. Available: http://fsweb.ogden.rmrs.fs.fed.us/

state_reports/wyoming/wy_nfs_main.html (also available on file at: U.S. Department of Agriculture, Forest 

Service, Rocky Mountain Research Station, Ogden, UT).

Van Dyck, M.G. 2002. Keyword reference guide to the 

Forest Vegetation Simulator. WO-Forest Management 

Service Center, Fort Collins, CO.
14

The Rocky Mountain Research Station develops scientific information and technology to improve management, protection, 

and use of the forests and rangelands. Research is designed to meet the needs of National Forest managers, Federal and State 

agencies, public and private organizations, academic institutions, industry, and individuals. 

Studies accelerate solutions to problems involving ecosystems, range, forests, water, recreation, fire, resource inventory, 

land reclamation, community sustainability, forest engineering technology, multiple use economics, wildlife and fish habitat, 

and forest insects and diseases. Studies are conducted cooperatively, and applications may be found worldwide.

The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, 

color, national origin, sex, religion, age, disability, political beliefs, sexual orientation, or marital or family status. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for communication of program 

information (Braille, large print, audiotape, etc.) should contact USDA’s TARGET Center at (202) 720-2600 (voice and TDD).

To file a complaint of discrimination, write USDA, Director, Office of Civil Rights, Room 326-W, Whitten Building, 1400 

Independence Avenue, SW, Washington, DC 20250-9410 or call (202) 720-5964 (voice or TDD). USDA is an equal opportunity 

provider and employer.