United States

Department of

Agriculture

Forest Service

Pacific Northwest

Research Station

Resource Bulletin

PNW-RB-245

February 2005

Oak Woodlands and

Other Hardwood Forests

of California, 1990s

K.L. Waddell and T.M. Barrett
The Forest Service of the U.S. Department of Agriculture is dedicated to the

principle of multiple use management of the Nation’s forest resources for

sustained yields of wood, water, forage, wildlife, and recreation. Through forestry

research, cooperation with the States and private forest owners, and management

of the National Forests and National Grasslands, it strives—as directed by

Congress—to provide increasingly greater service to a growing Nation.

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customers and employees

Authors

K.L. Waddell and T.M. Barrett are research foresters, Forestry Sciences Laboratory, P.O. Box 3890, Portland, OR 97208-3890.

Photo Credit

Cover photo by Dale Waddell
Abstract

Waddell, K.L.; Barrett, T.M. 2005. Oak woodlands and other hardwood forests of

California, 1990s. PNW-RB-245. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 94 p.

This report provides a multiownership assessment of oak woodlands and other

hardwood forests in California, excluding only reserved lands outside of national

forests. Because sampling intensity on woodlands was doubled from the previous

1981-84 inventory, and because national forests were inventoried, this is the most

complete assessment to date for California hardwoods. Tables provide estimates for

hardwood forest type area, hardwood volume, biomass, numbers of trees, change in

forest area, growth, harvest, and mortality. The dates of the inventories used in the

assessment, 1991-94 for unreserved lands outside national forests and 1994-2000

for national forests, also allowed an assessment of pre-epidemic conditions for

susceptible tree species and forests in a 12-county area affected by sudden oak

death.

Summary 1

For the 1990s, hardwood forests were estimated to cover more than 11.3 million

acres (±2 percent sampling error [se; see glossary for definition]), which was 40

percent of forest land in California. Hardwood forest area included 6.7 million

acres of oak woodland, 76 percent of which was privately owned, and 0.5 million

acres of non-oak woodland. Of the 4.1 million acres of hardwood timberland forest,

oak forest types constituted 53 percent.

Blue oak woodland was the most common hardwood forest type in California.

Low levels of blue oak regeneration observed in the 1980s continued into the

1990s. In descending order of occurrence, other common hardwood forest types

included canyon live oak, California black oak, tanoak, interior live oak, coast

live oak, Oregon white oak, and Pacific madrone. Other forest types, including

California laurel, Engelmann oak, and valley oak, were uncommon, estimated to

be 2 percent or less of the total hardwood forest area in California.

The net growing-stock volume of hardwood tree species on the inventoried

area was estimated as 4.7 billion cubic feet (±5 percent se) on woodland and 9.4

billion cubic feet (±3 percent se) on timberland, with California black oak having

1

 All estimates exclude reserved land outside of national forests, such as national and state

parks. These lands are excluded because they were not inventoried. Estimates of change

from the 1980s to the 1990s also exclude national forest land.
the largest growing-stock volume of any hardwood species. The aboveground

biomass of hardwood trees on forest land was estimated as 555 million tons (±2

percent se), or 29 percent of overall tree biomass in California forest lands. Combining inventory estimates with other published data indicated that about 2 percent

of the estimated board-foot volume in harvested hardwood sawtimber-sized trees

went to California sawmills.

An estimated 60,000 acres per decade of hardwood forest was converted to

developed land or roads between 1984 and 1994 (upper 68 percent confidence

interval is 130,000 acres per decade). Of the common forest types, California black

oak had the greatest percentage decrease in area from 1984 to 1994; excluding

salvage logging, 11 percent of the black oak forest type on timberland had some

black oak trees harvested or cut and left on the plot between 1981-84 and 1991-94.

However, overall net growing-stock volume increased for California black oak and

other common hardwood species.

Within the 12 counties quarantined as of summer 2004 for Phytophthora

ramorum, the pathogen associated with sudden oak death, an estimated 3.8 million

acres (±4 percent se) of forest land is dominated by the regulated host species of

tanoak, coastal redwood, Douglas-fir, coast live oak, California black oak, Pacific

madrone, California buckeye, canyon live oak, California laurel, and bigleaf maple.

Tanoak, California black oak, coast live oak, and Shreve’s oak are tree species that

can suffer trunk lesions and associated mortality from Phytophthora ramorum.

These trees are important to wildlife diversity, contributing to habitat and providing a source of acorns. Although essential characteristics of the disease are still

unknown, there appears to be a potential for very extensive changes of forest

structure and composition over a geographic range encompassing millions of acres

of California forest land, with the potential for many indirect ecosystem effects.
Contents

1 Introduction

2 Inventories Used in This Report

4 Hardwood Forest Types in the 1990s

5 Blue Oak Forest Type

10 Canyon Live Oak Forest Type

13 California Black Oak Forest Type

16 Tanoak Forest Type

19 Interior Live Oak Forest Type

21 Coast Live Oak Forest Type

23 Oregon White Oak Forest Type

25 Pacific Madrone Forest Type

27 Other Hardwood Forest Types

27 Hardwood Resources

27 Wildlife

30 Forest Product Resources

32 Hardwood Rangeland

33 Changes in California Hardwoods From 1981-84 to 1991-94

33 Methods

34 Results

36 Pre-Sudden Oak Death Forest Conditions for 12 California Counties

41 Glossary

45 Acknowledgments

46 Metric Equivalents

46 Literature Cited

53 Appendix 1. Scientific and Common Plant Names

56 Appendix 2. Inventory Procedures
List of Tables

Table 1—Area of hardwood and softwood forest types on woodland and timberland by resource area and reserve status, California, 1990s

Table 2—Area of hardwood forest types on woodland and timberland by resource

area and owner, California, 1990s

Table 3—Net growing-stock volume of hardwood species on woodland and

timberland by resource area and owner, California, 1990s

Table 4—Total stem volume of hardwood species for all live trees on woodland by

diameter class, California, 1990s

Table 5—Total stem volume of hardwood species for all live trees on timberland

by diameter class, California, 1990s

Table 6—Total stem volume of hardwood species for all live trees on woodland

and timberland by diameter class, California, 1990s

Table 7—Aboveground (oven-dry) biomass of hardwood species for all live trees

on woodland by diameter class, California, 1990s

Table 8—Aboveground (oven-dry) biomass of hardwood species for all live trees

on timberland by diameter class, California, 1990s

Table 9—Aboveground (oven-dry) biomass of hardwood species for all live trees

on woodland and timberland by diameter class, California, 1990s

Table 10—Total stem volume of hardwood species (≥4 in diameter at breast height)

on unreserved woodland and timberland by resource area and owner, California,

1990s

Table 11—Forest type area from 1984 to 1994 by owner, on unreserved woodland

outside national forests, California

Table 12—Change in forest type area from 1984 to 1994 on unreserved woodland

and timberland outside of national forests, California

Table 13—Net growing-stock volume of hardwood species, 1984 and 1994, on

unreserved woodland and timberland outside national forests, California

Table 14—Gross volume of periodic mortality, periodic removals, annual mortality,

and annual removals for hardwood trees that died during the remeasurement period

(1984 to 1994), on unreserved woodland and timberland outside national forests,

California
Table 15—Gross volume in 1984 and average annual volume change (1984 to

1994) for hardwood species, on unreserved woodland and timberland outside

national forests, California

Table 16—Total stem volume of hardwood tree mortality between 1984 and 1994,

by species and diameter class, on unreserved woodland and timberland, outside

national forests, California

Table 17—Estimated numbers of large hardwood trees on woodland and timberland, by species and diameter class, California, 1990s

Table 18—Estimated numbers of small hardwood trees on woodland and timberland, by species and diameter class, California, 1990s

Table 19—Forest type attributes (area, basal area, and trees per acre) on woodland

and timberland, for 12 counties in California quarantined for Phytophthora

ramorum as of summer 2004

Table 20—Estimated forest land area where host tree species of Phytophthora

ramorum were present on woodland and timberland, for counties in California

quarantined as of summer 2004
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Oak Woodlands and Other Hardwood Forest of California, 1990s

1

Introduction

Hardwood forests cover more than 11 million acres of land in California and provide many benefits, including wildlife habitat and food, lumber and other forest

products, grazing, watershed protection, open space for recreation, fuelwood, and

biodiversity. Hardwood species in California are diverse, including species found

throughout western North America, such as quaking aspen (Populus tremuloides),

and others that are primarily found in California, such as blue oak (Quercus

douglasii), valley oak (Quercus lobata), coast live oak (Quercus agrifolia), and

interior live oak (Quercus wislizeni) (see app. 1 for a list of species names). For

many residents, oak woodlands and savannas define the California landscape

(fig. 1).

Hardwood forests have been a subject of public focus for many years. Land

conversions and clearing have been areas of concern, with conversion to agricultural uses predominant in the first part of the 20th century, and increasing concern

over conversion to residential uses and vineyards in more recent years. In 1993,

California counties with oak woodlands were directed by the State Board of Forestry to develop oak conservation plans, and most now have mitigation policies or

permitting processes for oak removal (Light and Pedroni 2002). Slow regeneration

of some species also has been a source of concern. The concern is not new; nearly

a century ago a survey of Pacific slope trees noted sparse regeneration for valley

oak, Oregon white oak (Quercus garryana), canyon live oak (Quercus chrysolepis),

coast live oak, and blue oak (Sudworth 1908).

Concern for California hardwoods, and oak woodlands in particular, has

generated a very active research and education program. Since 1979, five symposia

on California hardwoods and oak woodlands have been held (Pillsbury and others

1997, Plumb 1980, Plumb and Pillsbury 1987, Standiford 1991, Standiford and

others 2002). The University of California, together with the California Department of Forestry and Fire Protection (CDF), the State Board of Forestry,

and the California Department of Fish and Game, established an intensive research

and extension program, the Integrated Hardwood Range Management Program

(IHRMP), in 1986. A number of nonprofit organizations, such as the California

Oak Foundation, also focus on oak and hardwood issues.

In the last few years, sudden oak death has overtaken other issues as a threat

to California hardwood forests. Sudden oak death, associated with the pathogen

Phytophthora ramorum, was first described in 1995 in tanoak (Lithocarpus
RESOURCE BULLETIN PNW-RB-245

2

densiflorus). Subsequently P. ramorum was found to affect coast live oak,

California black oak (Quercus kelloggii), Pacific madrone (Arbutus menziesii),

bigleaf maple (Acer macrophyllum), California laurel (Umbellularia californica),

and other species (fig. 2). Because of the relatively rapid spread and increased

mortality rate for some common species, the disease can be expected to have a

substantial effect on many of the hardwood and coniferous forests described in

this report. The dates of the inventories used in this assessment, 1991-94 for lands

outside national forests and 1994-2000 for national forests, allow the use of these

data to provide a pre-epidemic baseline for future monitoring.

Inventories Used in This Report

The USDA Forest Service forest inventory program, called Forest Inventory and

Analysis (FIA), inventories forest land, often dividing it into different categories

such as timberland and unproductive forest, which includes woodland. Definitions

of these and other terms are provided in the glossary. Until the 1980s, statewide

forest inventories in California sampled only timberland. In response to increased

interest in woodlands, the first statewide inventory of California woodlands and

other unproductive forest was made in 1981-84 with results reported as part of an

assessment of California hardwoods (Bolsinger 1988).

Figure 1—Oak woodlands characterize large areas of the California landscape.

Dave Azuma, Forest Inventory and Analysis.
Oak Woodlands and Other Hardwood Forest of California, 1990s

3

In 1991-94, a new statewide inventory of woodland was conducted, remeasuring the plots used in the 1981-84 FIA inventory and also doubling the number of

plots with tree measurements. Timberland was also inventoried in 1991-94, with a

sampling intensity of twice that used for woodland. Neither the 1981-84 nor the

1991-94 inventory included national forests, which contain 21 percent of the

unreserved forest land in California. However, during 1994-2000, a comprehensive forest inventory of California national forests was conducted by the National

Forest System (NFS).

This report is based on data from these combined inventories: the 1991-94 FIA

inventory of timberland, the 1991-94 FIA inventory of woodland, and 1994-2000

NFS inventories of national forests. Because of the inclusion of inventory data for

national forests and the increased number of samples for private and other public

land, these are the best estimates for California hardwoods that have been made to

date. Estimates often differ from those in the report by Bolsinger (1988). These

differences are caused by the additional data collected and by changes in estimation

procedures and do not necessarily reflect actual changes in hardwood forests. A

more limited set of information has been used to estimate change. It is very important to understand the limitations of the inventories and to use the sampling errors

that are provided to interpret the information in this report. Greater detail on

inventory methods is provided in appendix 2.

Figure 2—California laurel leaves infected by P. ramorum Sonoma County, 2002.

 Rob Gross, Sudden Oak Death Mortality Task Force.
RESOURCE BULLETIN PNW-RB-245

4

Tables of forest estimates are in a separate section at the end of the report.

Estimates are given for forest area (tables 1 and 2), volume (tables 3 through 6 and

10), biomass (tables 7 through 9), change (tables 11 through 16), and a few additional attributes. Estimates do not include savannas (land with less than 10 percent

tree cover) or land that is devoted to nonforest uses (such as golf courses or city

parks). Grazing is considered a forest use in California, and estimates include

grazed forest land, although improved pasture land is excluded. Reserved land

outside of national forests (primarily state and national parks) has not been inventoried, and it is excluded from all estimates except where noted (fig. 3).

Hardwood Forest Types in the 1990s

Excluding reserved lands outside of national forests, the total estimated area of

hardwood forest types in California was 11.29 million acres (±1.7 percent sampling

error [se; see glossary for definitions]). Hardwood forest types made up 40 percent

of all forest land in California. This included 4.07 million acres (±3 percent se)

classified as hardwood timberland and 7.22 million acres (±2 percent se) classified

as hardwood woodland and other unproductive forest (table 1). Most hardwood

forest was privately owned (70 percent), with a substantial portion in national

forest ownership (25 percent) and a relatively small portion in other public ownership (5 percent).

By order of frequency, the most common hardwood forest types were blue

oak, canyon live oak, California black oak, tanoak, interior live oak, coast live oak,

Oregon white oak, and Pacific madrone. Other hardwood forest types (valley oak,

Engelmann oak, California laurel, buckeye, and many others) were relatively

uncommon, estimated at 150,000 or fewer acres each (table 2).

California oak woodlands–forest dominated by trees from the genus Quercus

and not productive enough to be considered timberland–covered 6.7 million acres

(±4 percent se). Private ownership accounted for 76 percent of this area, with

smaller portions in national forest ownership (18 percent), and other public ownership (6 percent). Oak savannas, with less than 10 percent tree cover, also covered

large land areas, although the exact area is unknown. Bolsinger (1988) gave an

approximation that 1.8 million acres of land in California is savanna characterized

by hardwood trees in grassland, and 1.8 million acres is characterized by hardwood trees in chaparral. A chaparral inventory of 14 counties in the central and

southern coast of California estimated that substantial portions of chaparral contain

hardwood tree species, including many in the Quercus genus (Fried and others

2004).

Hardwood forest

types make up 40 percent of California’s

forest land, of which

70 percent is privately

owned.
Oak Woodlands and Other Hardwood Forest of California, 1990s

5

Some of the oak species hybridize and have overlapping ranges, and forest

typing classifies what is often a gradation of mixed species into discrete classes.

The classification process for this assessment is based on the concept of predominance of live tree cover for that species, and it is the same classification method

that has been used in other Forest Inventory and Analysis reports developed from

the 1991-94 data (for example, Waddell and Bassett 1996, 1997a, 1997b). In the

1980s assessment, classification was derived from the predominance by basal area

for that species (Bolsinger 1988). Individual trees of a particular species were also

found in other forest types. In the following sections, estimates are provided for

area where a tree species occurred, as well as area for the forest type where that

species was predominant.

Blue Oak Forest Type

The most common inventoried hardwood forest type in California was blue oak,

with an estimated 3.03 million acres (±5 percent se). As was done in the Bolsinger

(1988) report, forest initially classified as ghost pine (Pinus sabiniana) was included in the estimate for the blue oak forest type, accounting for 0.11 million

acres of the total blue oak forest type. The blue oak forest type occurred in foothill

woodlands on all sides of the central California valley with blue oak trees having

an extremely similar distribution (fig. 4). This forest type was 90 percent privately

owned, with 4 percent on national forest land and 6 percent on other public land.

The average elevation for the blue oak forest type was 1,640 feet, with two-thirds

of this forest type occurring between 680 and 2,680 feet. Blue oak forest had the

lowest average annual precipitation of any of the common forest types, with a

Figure 3—Distribution of land in California.

Blue oak was the

most common hardwood forest type in

California in the

1990s.

Land Area in California

Timberland

Hardwood woodland

Unsampled reserved forest

Other forest land

Savanna with hardwoods

Chaparral

Nonforest land
RESOURCE BULLETIN PNW-RB-245

6

median precipitation of 21 inches per year and two-thirds of the forest type having

precipitation between 19 and 25 inches per year.

Although climate is an important factor in explaining the distribution of the

blue oak forest type, it is believed that many factors have influenced the present

composition and stand structure of blue oak woodlands. Acorn production can be

influenced by rainfall and temperature (Koenig and others 1999), but recruitment

from acorns and survival can be affected by predation from insects, rodents, deer,

and cattle (Adams and McDougald 1995, Borchert and others 1989, Hall and others

1992). Survival of seedlings and saplings appears to be related to both competition

and facilitation (for example, shade) from other plants (Standiford and others 1997,

Swiecki and others 1997).

By analysis of tree rings and fire scars, Mensing (1992) concluded that the

structure of a blue oak woodland in Kern County resulted from changes in land use

practices accompanying European settlement, with a period of high regeneration

and recruitment associated with fire and browsing in the mid-1800s. McClaran and

Figure 4—Sample plot locations for the blue oak (Quercus douglasii) forest type (left) and for blue

oak trees (right). Figure includes plots for all inventories used in this report, and the plots shown did

not all have the same probability of selection. To protect landowner privacy, each plot shown has

some deliberate location error.
Oak Woodlands and Other Hardwood Forest of California, 1990s

7

Bartolome (1989) also concluded that an increase in fire frequency around the time

of European settlement had caused an increase in recruitment. More recent studies

have noted that fire can kill the tops of saplings, which then resprout. The resulting

even-aged cohorts do not necessarily denote that fire has a positive impact on

growth or recruitment (Bartolome and others 2002, Swiecki and Bernhardt 2002).

Larger blue oak trees are fairly resistant to fire (Horney and others 2002).

The stand structure of blue oak woodlands is very distinctive, often composed

of widely spaced trees over a grassy understory (fig. 5). The blue oak woodlands of

California had the lowest basal area density of any of the common hardwood forest

types: 68 percent of this forest type had less than 50 square feet per acre of basal

area, and less than 4 percent had more than 100 square feet per acre of basal area

(fig. 6). Blue oak woodlands were fairly pure in tree species composition, with 78

percent of the basal area in blue oak trees. Other tree species found in this type

included ghost pine with 11 percent of total tree basal area and interior live oak

with 5 percent of tree basal area. Vegetation found in this forest type included

grasses, poison oak (Toxicodendron diversilobum), buckbrush (Ceanothus

cuneatus), mountain mahogany (Cercocarpus betuloides), red-stem filaree

(Erodium cicutarium), greenleaf manzanita (Arctostaphylos patula), whiteleaf

manzanita (Arctostaphylos viscida), toyon (Heteromeles arbutifolia), California

juniper (Juniperus californica), hollyleaf redberry (Rhamnus crocea), silver

hairgrass (Aira caryophyllea), California scrub oak (Quercus dumosa), oat (Avena

spp.), miner’s lettuce (Claytonia perfoliata), fragrant bedstraw (Galium triflorum),

common manzanita (Arctostaphylos manzanita), and others.

Most blue oak trees were relatively small, although individual blue oaks are

capable of reaching large size. The average diameter at breast height (d.b.h.) for

blue oak trees pole size or larger was 8.3 inches. The largest blue oak tree in these

inventories had a 49-inch d.b.h. The record blue oak tree for California—also the

national champion for the species—has a d.b.h. of 88 in and a height of 112 feet

(UFEI 2004). There were an estimated 43 million sawtimber-sized blue oak trees in

the state (table 17). Blue oak trees were found in 972,000 acres of other forest

types, as shown in the tabulation on page 92

.

2

 Estimate of amount of a forest type with a particular tree species present is affected by plot

size, subplot configuration, whether fixed- or variable-radius sampling is used, and the

practice of mapping condition boundaries. Any tree of the species, including seedlings, was

used to determine species presence. Values for this forest type will differ from table 2

because not all trees within a plot are sampled.
RESOURCE BULLETIN PNW-RB-245

8

Figure 5—A common stand structure for blue oak woodlands is scattered trees over a grassy

understory. Regeneration is typically sparse.

 J.E. (Jed) and Bonnie McClellan © California Academy of Sciences.

Figure 6—Relative basal area density of common hardwood forest types. Basal area was calculated

from trees greater than 5 inches diameter at breast height.

0 10 20 30 40 50 60 70 80 90 100

Blue oak

Interior live oak

Oregon white oak

Coast live oak

California black oak

Canyon live oak

Pacific madrone

Tanoak

Hardwood forest types

Percentage of the forest type area

0-50

50-100

100-150

150-200

>= 200

Basal area class

(square feet per acre)

≥ 200

Basal area class
Oak Woodlands and Other Hardwood Forest of California, 1990s

9

Forest type with Percentage of all types

blue oak trees Area Sampling error with blue oak trees

 – – – Thousand acres – – –

Blue oak/ghost pine 2,804 156 74

Interior live oak 554 94 15

Coast live oak 92 34 2

California buckeye 74 36 2

Canyon live oak 70 38 2

California black oak 59 25 2

Valley oak 33 22 1

Other 90 25 2

Total 3,776 162 100

Bolsinger (1988) found that blue oak was one of the tree species that appeared to

have poor natural regeneration; other researchers have made similar observations

(for example, Muick and Bartolome 1987). The 1990s forest inventories also

provided evidence of sparse regeneration for blue oak. One metric that can be used

to examine regeneration is the ratio of numbers of small saplings (1 to 3 inches

d.b.h.) to numbers of medium saplings (3 to 5 inches d.b.h.). The sustainability of

blue oak depends on many factors that are not captured in this metric, including

growth and mortality rates, the periodicity of regeneration, and land conversion.

However, a diameter-class ratio that is less than 1.0 is one indication of poor

regeneration. For blue oak, the estimated ratio of 1- to 3-inch diameter trees to

3- to 5-inch diameter trees for the blue oak population in California was 0.7 (±26

percent se). Although other diameter-class ratios for small blue oak trees were

greater than 1, the species had a relatively flat diameter distribution (table 18).

One of the metrics used to evaluate regeneration in the 1980s was regeneration

stocking. The stocking classification used then could not be duplicated for this

assessment because of changes in the sampling design. We applied a similar

classification to plots with at least 90 percent of the plot area in the blue oak forest

type. The following tabulation shows the proportion of this area stocked with trees

less than 5 inches d.b.h. (blue oak seedlings and saplings). (See “regeneration

stocking” in glossary for definitions of stocking class.)

The 1990s inventories found sparse

regeneration of blue

oak.
RESOURCE BULLETIN PNW-RB-245

10

Sampling Percentage

Stocking class Area error of total

– – Thousand acres – –

Blue oak forest type evaluated

for regeneration stocking:

Nonstocked 502 88 29

Lightly stocked 825 111 48

Moderately stocked 331 71 19

Well stocked 54 37 3

All 1,712 148 100

Blue oak saplings (trees between 1 and 5 inches d.b.h.) can be old enough that

many people would not consider them regeneration. The following tabulation

shows the regeneration stocking classification applied to the same plots but using

only seedlings (trees less than 1 inch d.b.h.).

Sampling Percentage

Seedling stocking class Area error of total

 – – Thousand acres – –

Blue oak forest type evaluated

for regeneration stocking:

Nonstocked 746 104 43

Lightly stocked 706 104 41

Moderately stocked 224 59 13

Well stocked 36 32 2

All 1,712 148 100

If three subplots (rather than five) are used in evaluating stocking, as was done

for the 1980s inventory, the estimated nonstocked area for seedlings is about 60

percent for both the 1980s inventory and the 1990s inventories.

All of the metrics used to evaluate regeneration—diameter-class ratios, stocking classification, and trees-per-acre estimates—showed that the sparse regeneration of blue oak continued into the 1990s. The long-term sustainability of blue oak

woodlands is affected by many factors, and causal relationships are often best

understood through designed research studies. However, regeneration of blue oak

continues to be a concern and an important subject for future monitoring.

Canyon Live Oak Forest Type

Canyon live oak forest was the second most common inventoried hardwood forest

type in California, estimated at 1.63 million acres (±6.3 percent se). The forest type

was widely distributed, being found in the Klamath, Cascade, North Coast, Sierra

Nevada, Transverse, and Peninsular Ranges (fig. 7). Canyon live oak trees were
Oak Woodlands and Other Hardwood Forest of California, 1990s

11

found extensively in other forest types (fig. 7). The canyon live oak forest type was

estimated to have a mean elevation of 3,180 feet, with two-thirds of this forest type

within an elevation range of 1,780 to 4,600 feet. The median average annual

precipitation for this forest type was 42 inches per year, with two-thirds of the

forest type found in areas with 35 to 53 inches of precipitation per year. It was one

of the few hardwood forest types found primarily on national forests (61 percent),

with 32 percent of the forest in private ownership and 7 percent in other public

ownership.

Canyon live oak forest was distributed fairly evenly across low and moderate

density classes (fig. 6). The most common tree species in the canyon live oak forest

type were canyon live oak (59 percent of total tree basal area), Douglas-fir

(Pseudotsuga menziesii) (13 percent), California black oak (6 percent), ponderosa

pine (Pinus ponderosa) (4 percent), Pacific madrone (4 percent), incense cedar

(Calocedrus decurrens) (3 percent), sugar pine (Pinus lambertiana) (2 percent),

tanoak (2 percent), and California laurel (2 percent). Nontree vegetation occurring

in the canyon live oak forest type included poison oak, toyon, whiteleaf manzanita,

western swordfern (Polystichum munitum), western brackenfern (Pteridium

aquilinum), California honeysuckle (Lonicera hispidula), California nutmeg

(Torreya californica), and other forbs and shrubs.

Figure 7—Sample plot locations for the canyon live oak (Quercus chrysolepis) forest type (left) and

for canyon live oak trees (right). Figure includes plots for all inventories used in this report, and the

plots shown did not all have the same probability of selection. To protect landowner privacy, each

plot shown has some deliberate location error.

Canyon live oak was

the most numerous

hardwood tree

species.
RESOURCE BULLETIN PNW-RB-245

12

Canyon live oak was the most numerous hardwood tree species in California

forest lands, with an estimated 2.22 billion trees (±4 percent se). For these inventories, the canyon live oak tree with the largest diameter had a d.b.h. of 68 inches.

The average tree size for this species was 8.5 inches, excluding seedlings and

saplings. The record big tree for this species is 110 inches d.b.h. and 69 feet tall

(UFEI 2004). However, only 2.3 percent of all canyon live oak trees were of sawtimber size (d.b.h. ≥11 inches). Canyon live oak trees were found in many forest

types, including a number of timberland types. Of the 6 million acres of forest land

where canyon live oak trees were found (see footnote 2), 76 percent was classified

as timberland rather than woodland, and 36 percent was in private ownership.

Forest type with Percentage of all

canyon live oak Sampling types with canyon

trees Area error live oak trees

 – – – Thousand acres – – –

Mixed conifer 2,129 99 35

Canyon live oak 1,621 103 27

California black oak 515 55 9

Tanoak 323 45 5

Douglas-fir 296 40 5

Pacific madrone 191 38 3

Interior live oak 185 56 3

Ponderosa pine 163 30 3

Oregon white oak 97 30 2

Blue oak 80 30 1

Coast live oak 57 17 1

California laurel 48 22 1

Other 336 48 6

All types 6,039 173 100

The statewide population of canyon live oak appeared to be regenerating

well. The estimated ratio of 1- to 3-inch diameter trees to 3- to 5-inch diameter

trees for the canyon live oak population in California was 1.97 (±40 percent se).

Other diameter-class ratios for small canyon live oak trees were also high (table

18). Within the canyon live oak forest type, the majority of plots were classified as

well stocked or moderately stocked with either canyon live oak seedlings or canyon

live oak saplings.
Oak Woodlands and Other Hardwood Forest of California, 1990s

13

Sampling Percentage

Stocking class Area error of total

– – – Thousand acres – – –

Canyon live oak area

evaluated for regeneration

stocking:

Nonstocked 70 21 6

Lightly stocked 196 45 18

Moderately stocked 429 59 39

Well stocked 395 53 36

All 1,090 91 100

California Black Oak Forest Type

California black oak is one of the most important hardwood tree species in the

state. It is valued for aesthetics, for shade, for firewood, for lumber, and for the

numerous acorns (“mast”) that can be produced by mature trees. There was an

estimated 1.25 million acres (±7 percent se) of the California black oak forest type

in the state, excluding reserved lands outside of national forests. This forest type

was evenly split between public ownership (50 percent) and private ownership.

Seventy-seven percent of this type was classified as timberland. It was the third

most common forest type, yet black oak trees had the greatest volume of any

hardwood species in the state, with a total estimated volume of 5.1 billion cubic

feet (table 6). Although occasionally used for lumber, California black oaks are

primarily harvested for firewood. California black oak is important for wildlife

because acorns provide a food source for many species. In one case study, researchers found mature black oak trees produced more than 6,000 acorns per oak, or

125,000 acorns per acre (Bowyer and Bleich 1980).

Plot data showed that this forest type and individual black oak trees have a

wide distribution (fig. 8). The average elevation for the black oak forest type was

3,280 feet, with two-thirds of the forest occurring between 1,890 feet and 5,050

feet. The median average annual precipitation for this forest type was 45 inches

per year, with two-thirds of the forest type found in areas with 39 to 52 inches of

precipitation per year.

The California black oak forest type was well distributed across a range of low

and moderate densities (fig. 6). The most common tree in this forest type was

California black oak (47 percent of total tree basal area), followed by Douglas-fir

(14 percent), incense cedar (8 percent), ponderosa pine (8 percent), canyon live

oak (6 percent), Pacific madrone (4 percent), white fir (Abies concolor) (3 percent),

and Oregon white oak (2 percent). Nontree plants in this forest type included
RESOURCE BULLETIN PNW-RB-245

14

poison oak, grass, deerbrush (Ceanothus integerrimus), sticky whiteleaf manzanita,

western brackenfern, greenleaf manzanita, snowberry (Symphoricarpos spp.),

California redbud (Cercis occidentalis), wood rose (Rosa gymnocarpa), bear clover

(Chamaebatia foliolosa), and other shrubs and forbs.

Although an estimated 1.25 million acres was classified as California black oak

forest type, California black oak trees were typically a component of other forest

types and were found on an estimated 7.21 million acres (±2 percent se) of forest

land (see footnote 2). Of the total forest land where California black oak trees were

found, 3.52 million acres (±4 percent se) was on private land, 3.49 million acres

(±3 percent se) was on national forest, and 0.21 million acres (±17 percent se) was

on other public land. Of the forest land where California black oak trees were

found, 82 percent was classified as timberland. As shown in the tabulation below,

California black oak trees were found in many different forest types.

Figure 8—Sample plot locations for the California black oak (Quercus kelloggii) forest type (left) and

for California black oak trees (right). Figure includes plots for all inventories used in this report, and

the plots shown did not all have the same probability of selection. To protect landowner privacy, each

plot shown has some deliberate location error.
Oak Woodlands and Other Hardwood Forest of California, 1990s

15

Forest type with Percentage of all types

California black with California black

oak trees Area Sampling error oak trees

 – – Thousand acres – – 

Mixed conifer 3,317 119 46

California black oak 1,255 89 17

Canyon live oak 659 64 9

Ponderosa pine 380 43 5

Oregon white oak 293 55 4

Interior live oak 210 51 3

Douglas-fir 202 35 3

Pacific madrone 172 36 2

Blue oak 165 47 2

Tanoak 96 24 1

Other 462 59 6

All 7,211 179 100

California black oak was estimated to occur on less than 75,000 acres of each

of the forest types included in “other,” which consists of coast live oak, California

laurel, valley oak, white fir, California buckeye, white alder, bigleaf maple, giant

sequoia, bigcone Douglas-fir, Jeffrey pine, knobcone pine, red alder, coulter pine,

and black cottonwood forest types.

There were an estimated 1.1 billion (±4.4 percent se) California black oak trees

in forests within the state, excluding reserved lands outside of national forests. The

largest California black oak tree in these inventories had a d.b.h. of 65 inches. The

record big tree for the species has a 76-inch diameter and is 85 feet tall (UFEI

2004). Of the estimated 59.6 million (±5 percent se) sawtimber sized (≥11 inches

d.b.h.) California black oak trees, 11 percent had d.b.h. ≥23 inches, and 4 percent

had d.b.h. ≥29 inches (table 17). Seedling and sapling stocking of black oak

appeared to be moderate within the California black oak forest type, as shown in

the tabulation below.

Stocking class Area Sampling error Percentage of total

– – – – Thousand acres – – – –

California black

oak area evaluated

for regeneration

stocking:

Nonstocked 217 43 26

Lightly stocked 243 37 29

Moderately stocked 246 40 29

Well stocked 131 34 16

All 837 75 100
RESOURCE BULLETIN PNW-RB-245

16

Although this tabulation only shows regeneration within the California black

oak type, California black oak is very frequently part of mixed-species stands.

McDonald and Tappeiner (2002) report regeneration is generally highest under

mature black oaks. Another regeneration metric, which is independent of forest

type, is the overall diameter distribution across all forest types. For a given species,

when there are fewer small trees than large trees statewide, it is an indirect indication that recruitment may not be sufficient to replace mortality. California black

oak had a relatively flat diameter distribution for small trees between 1 and 11

inches d.b.h. (table 18), although all ratios of 2-inch diameter classes were above

1.0. Where natural regeneration is problematic, planting of black oaks can be a

successful alternative (McDonald and Tappeiner 2002).

Tanoak Forest Type

The fourth most common hardwood forest type in California was tanoak, estimated

to occur on 1.25 million acres (±6 percent se), excluding reserved lands outside of

national forests. Tanoak is not in the oak genus (Quercus), but it is in the oak

family (Fagaceae) and produces acorns. Most of the tanoak forest type in this

inventory was found in the coastal counties north of San Francisco, with lesser

amounts in the northern Sierra Nevada and central coastal counties (fig. 9). Average elevation for this forest type was 1,690 feet, with two-thirds of the forest type

occurring between 750 and 2,600 feet elevation. Of all the common hardwood

forest types, tanoak was found in areas of the greatest annual average precipitation

(figs. 9 and 10). The median average annual precipitation for this forest type was

65 inches per year, with two-thirds of the forest type found in areas with 52 to 71

inches of precipitation per year. Eighty-two percent of this forest type was in

private ownership, and 18 percent was in national forest ownership.

The distribution of tanoaks has waned and waxed and waned again since

European settlement. After the California gold rush, tanoaks were used extensively

to supply bark for tannin, leading to fears it was being overharvested. Tanoak

provides an attractive wood that is used for flooring, paneling, veneer, and other

products, but despite occasional attempts to develop markets for the wood, it has

never been extensively used for this purpose. In the second half of the 20th century,

selective harvesting of the more valuable conifers, accompanied by rapid sprouting

and regrowth of tanoak, led to fears of conversion of previously conifer-dominated

areas to tanoak. Although too recent to be reflected in the inventories used for this

report, the fortunes of tanoak have once again taken a downward turn, because the

Tanoak is found in

areas with high

precipitation.
Oak Woodlands and Other Hardwood Forest of California, 1990s

17

Figure 9—Sample plot locations for the tanoak (Lithocarpus densiflora) forest type (left) and for

tanoak trees (right). Figure includes plots for all inventories used in this report, and the plots shown

did not all have the same probability of selection. To protect landowner privacy, each plot shown has

some deliberate location error.

Figure 10—Annual precipitation for California,

averaged for 1961 to 1990. Map produced with

data from the Spatial Climate Analysis Service

(2004).
RESOURCE BULLETIN PNW-RB-245

18

effects of sudden oak death seem to be particularly severe for this species (Rizzo

and Garbelotto 2003). Tanoak is an important resource for many wildlife species,

providing both cover and food.

Tanoak forest was the densest of the common hardwood forest types (fig. 6).

Within tanoak forest, the predominant tree species were tanoak (51 percent of

total tree basal area), Douglas-fir (19 percent), redwood (Sequoia sempervirens)

(11 percent), Pacific madrone (9 percent), canyon live oak (2 percent), and others

(all at 1 percent or less of tree basal area). Nontree vegetation that was found

on plots in the tanoak forest type included California huckleberry (Vaccinium

ovatum), grass, western brackenfern, western swordfern, salal (Gaultheria

shallon), poison oak, whipplea (Whipplea modesta), blueblossom ceanothus

(Ceanothus thyrsiflorus), coast rhododendron (Rhododendron macrophyllum),

redwood sorrel (Oxalis oregana), iris (Iris spp.), hairy manzanita (Arctostaphylos

columbiana), starflower (Trientalis latifolia), Pacific wax-myrtle (Myrica

californica), deerbrush, coast whitethorn (Ceanothus incanus), baccharis

(Baccharis spp.), California honeysuckle, wood rose, whitebark raspberry (Rubus

leucodermis), California red huckleberry (Vaccinium parvifolium), California

hazelnut (Corylus cornuta), mountain-grape (Berberis aquifolium), California

nutmeg, toyon, thimbleberry (Rubus parviflorus), and other shrubs and forbs.

Of the estimated 3.59 million acres (±3 percent se) where tanoak trees were

found, 69 percent was in private ownership (see footnote 2). Ninety-nine percent

of the area where tanoak trees were found was classified as timberland, where

estimated potential productivity was at least 20 cubic feet per acre per year. The

estimated area where tanoak trees were part of the forest was substantially larger

than the estimate for the tanoak forest type. Where tanoak was not itself the

predominant species, tanoak trees were typically found in conifer forest rather

than hardwood forest, as shown in the tabulation below.

Forest type with Sampling Percentage of all types

tanoak trees Area error with tanoak trees

– – – Thousand acres – – –

Tanoak 1,249 80 35

Redwood 599 59 17

Douglas-fir 534 55 15

Mixed conifer 487 50 14

Canyon live oak 175 36 5

Pacific madrone 175 34 5

California black oak 82 22 2

California laurel 70 23 2

Other 214 36 6

All 3,585 99 100
Oak Woodlands and Other Hardwood Forest of California, 1990s

19

“Other” forest types where tanoak was found included Oregon white oak, red

alder, bigleaf maple, coast live oak, ponderosa pine, knobcone pine, interior live

oak, giant chinquapin, and Bishop pine.

The record big tree for tanoak in California has an 86-inch d.b.h. and is 92

feet tall (UFEI 2004); the largest tree sampled in our inventory had a 62-inch d.b.h.

and was 89 feet tall. Despite this potential for very large trees, of the estimated

53 million (±7 percent) sawtimber sized tanoak trees with d.b.h. ≥11 inches, only 6

percent of trees had d.b.h. ≥23 inches and only 1 percent had d.b.h. ≥29 inches.

All of the diameter-class ratios for small tanoak trees were above 1.5, which is

one indication of good regeneration for the population as a whole (table 18). Using

a stocking algorithm for tanoak seedlings or saplings in tanoak forest provided

similar results: none of the area evaluated was nonstocked, 6 percent was lightly

stocked, 44 percent was moderately stocked, and 50 percent was well stocked.

Interior Live Oak Forest Type

Interior live oak was a common hardwood forest type, with an estimated 1.14

million acres (±9 percent se) in California excluding reserved lands outside of

national forests. Plot locations where the forest type was found and where interior

live oak trees were found (fig. 11) were similar to the distribution of blue oak but

were at slightly higher elevations and extended further south, and there were fewer

samples found in the coastal counties. Average elevation for the forest type was

2,140 feet, with two-thirds of the forest type found between 1,200 and 3,100 feet.

The median average annual precipitation for this forest type was 29 inches per

year, with two-thirds of the forest type found in areas with 25 to 33 inches of

precipitation per year. The interior live oak forest type was estimated to be 78

percent privately owned, 14 percent in national forest ownership, and 9 percent

in other public ownership.

Like blue oak forest, interior live oak forest was very open, with 54 percent of

area in the 0 to 50 square feet per acre basal area class (fig. 6). This forest type was

primarily composed of hardwoods but had some conifers present: 68 percent of

total tree basal area was in interior live oak trees, 8 percent was in blue oak trees,

7 percent was in ghost pine, 3 percent was in ponderosa pine, 2 percent was in

Douglas-fir, and 2 percent was in canyon live oak. Nontree vegetation in this forest

type that was found during the inventory included grass, poison oak, toyon, sticky

whiteleaf manzanita, buckbrush, fragrant bedstraw, hollyleaf redberry, and other
RESOURCE BULLETIN PNW-RB-245

20

forbs and shrubs. Only 24 percent of the forest where interior live oak trees were

found was classified as timberland. Trees were commonly found in a variety of

forest types, as shown in the tabulation below (see footnote 2).

Forest type with Percentage of all

interior live Sampling types with interior

oak trees Area error live oak trees

 – – – Thousand acres – – –

Interior live oak 1,116 116 41

Blue oak 658 98 24

Mixed conifer 197 35 7

Canyon live oak 174 49 6

California black oak 156 37 6

Coast live oak 64 30 2

California buckeye 62 29 2

Pacific madrone 55 28 2

Ponderosa pine 51 18 2

California laurel 53 22 2

Other 157 31 6

Total 2,743 151 100

Figure 11—Sample plot locations for the interior live oak (Quercus wislizeni) forest type (left) and

for interior live oak trees (right). Figure includes plots for all inventories used in this report, and the

plots shown did not all have the same probability of selection. To protect landowner privacy, each

plot shown has some deliberate location error.
Oak Woodlands and Other Hardwood Forest of California, 1990s

21

Of the total 2.7 million acres where interior live oak trees were found, 73

percent of the area was in private ownership, 20 percent was in national forest

ownership, and 7 percent was in other public ownership. The national champion

big tree for the interior live oak species has an 80-inch d.b.h., is 51 feet tall, and

has a crown diameter of 73 feet (UFEI 2004). The largest diameter tree in this

inventory had a 50-inch d.b.h. Of the estimated 12.8 million (±13 percent se) live

oak trees with d.b.h. ≥11 in, 4 percent had d.b.h. ≥23 in and 2 percent had d.b.h.

≥29 in (table 17). As one indication of good regeneration for the population, the

smaller diameter to larger diameter ratios by 2-inch diameter class ranged from

1.6 to 2.2 for seedlings and saplings (table 18). As compared to other California

oak species, a stocking classification also provided evidence of fair regeneration of

seedlings and saplings:

Stocking class Area Sampling error Percentage of total

– – – – – Thousand acres – – – –

Interior live oak forest

type evaluated for

regeneration stocking:

Nonstocked 17 10 2

Lightly stocked 298 60 41

Moderately stocked 316 69 43

Well stocked 103 40 14

All 733 104 100

Coast Live Oak Forest Type

The coast live oak forest type area was estimated as 1.07 million acres (±9 percent

se) excluding reserved lands outside of national forests. The coast live oak forest

type and coast live oak trees were distributed along the central and southern coastal

counties (fig. 12). Of the common hardwood types, the coast live oak type was

found at the lowest mean elevation (1,360 feet), with two-thirds of this forest type

within an elevation range of 600 to 2,090 feet. After the blue oak forest type, this

forest type had the lowest estimated average annual precipitation of the common

forest types. The median average annual precipitation for this forest type was 23

inches per year, with two-thirds of the forest type found in areas with 21 to 25

inches of precipitation per year. The coast live oak forest type was 79 percent

privately owned with 13 percent in national forests and 8 percent in other public

ownership.

The coast live oak forest type was primarily a single species type: 78 percent

of the total tree basal area was in coast live oak trees, 4 percent was in California

laurel, 2 percent was in Pacific madrone, 2 percent was in Douglas-fir, 2 percent
RESOURCE BULLETIN PNW-RB-245

22

was in valley oak, and 2 percent was in redwood trees. The coast live oak forest

type was denser than the blue oak or interior live oak forest types, and less dense

than the canyon live oak or California black oak forest types (fig. 6). Coast live oak

trees were predominantly found in coast live oak forest, as shown in the tabulation

below (see footnote 2).

Percentage

Forest type with of all types with

coast live oak trees Area Sampling error coast live oak trees

 – – – Thousand acres – – –

Coast live oak 1,059 88 66

Blue oak 89 28 6

Redwood 76 23 5

California laurel 68 27 4

Engelmann oak 54 16 3

Tanoak 48 20 3

Pacific madrone 39 20 2

California black oak 38 24 2

Bigleaf maple 23 13 1

Other 114 30 7

Total 1,609 102 100

Figure 12—Sample plot locations for the coast live oak (Quercus agrifolia) forest type (left) and for

coast live oak trees (right). Figure includes plots for all inventories used in this report, and the plots

shown did not all have the same probability of selection. To protect landowner privacy, each plot

shown has some deliberate location error.
Oak Woodlands and Other Hardwood Forest of California, 1990s

23

The national champion tree for the coast live oak species is found in California

and has a 108-inch d.b.h., height of 58 feet, and a crown diameter of 75 feet (UFEI

2004). The largest diameter tree in this inventory had a 69-inch d.b.h. and a height

of 63 feet. Of the estimated 42 million coast live oak trees with d.b.h. ≥11 inches,

7 percent had a d.b.h. of at least 23 inches and 2 percent had a d.b.h. of at least 29

inches. The numbers of saplings by diameter class appeared variable (table 18)

with a relatively flat distribution for trees with d.b.h. between 3 and 11 inches.

Oregon White Oak Forest Type

The Oregon white oak forest type area was estimated as 580,000 acres (±12

percent se) excluding reserved lands outside of national forests. Both the forest

type and Oregon white oak trees were found primarily in the north Coast, Klamath,

and Cascade Ranges (fig. 13). Oregon white oak forest type was found at an average elevation of 2,560 feet, with two-thirds of the forest found between 1,470 and

3,860 feet. The median average annual precipitation for this forest type was 49

inches per year, with two-thirds of the forest type found in areas with 39 to 58

inches of precipitation per year. It was a moderately open oak forest type–denser

than blue oak or interior live oak forest, but less dense than canyon live oak forest

(fig. 6). Ownership of the forest type was 74 percent private, 20 percent national

forest, and 6 percent other public.

Within the Oregon white oak forest type, individual Oregon white oak trees

contributed 63 percent of the total tree basal area. Other tree species found in this

type included Douglas-fir (12 percent of total basal area), California black oak

(9 percent), Pacific madrone (4 percent), ponderosa pine (4 percent), and canyon

live oak (2 percent).

Total area where Oregon white oak trees were found was estimated at 1.47

million acres (±7 percent se) (see footnote 2). Fifty-eight percent of this area was

privately owned, 36 percent was in national forest, and 6 percent was in other

public ownership: 61 percent of this area was in the more productive timberland

class. Oregon white oak trees were often found in the mixed-conifer type, as shown

in the following tabulation.
RESOURCE BULLETIN PNW-RB-245

24

Forest type with Percentage of all

Oregon white types with Oregon

oak trees Area Sampling error white oak trees

 – – Thousand acres – –

Oregon white oak 563 70 38

Mixed conifer 276 42 19

California black oak 155 32 10

Douglas-fir 85 24 6

Canyon live oak 65 22 5

Pacific madrone 60 22 4

Ponderosa pine 52 18 4

California laurel 48 24 3

Blue oak 35 14 2

Coast live oak 24 17 2

Other 102 28 7

Total 1,473 101 100

Regeneration for Oregon white oak appeared to be sparse, although the relatively small number of sample plots introduced substantial sampling error. The

estimated ratio of 1- to 3-inch diameter trees to 3- to 5-inch diameter trees for the

Oregon white oak population in California was 0.7 (±73 percent se). Low to

moderate regeneration was indicated by stocking of seedlings and saplings on 41

plots that had at least 90 percent of the area covered by Oregon white oak forest

type.

Figure 13—Sample plot locations for the Oregon white oak (Quercus garryana) forest type (left)

and for Oregon white oak trees (right). Figure includes plots for all inventories used in this report,

and the plots shown did not all have the same probability of selection. To protect landowner

privacy, each plot shown has some deliberate location error.

Regeneration for

Oregon white oak

appeared to be

sparse.
Oak Woodlands and Other Hardwood Forest of California, 1990s

25

Stocking class Area Sampling error Percentage of total

– – – – Thousand acres – – – –

Oregon white oak forest

type evaluated for

regeneration stocking:

Nonstocked 69 30 23

Lightly stocked 89 32 30

Moderately stocked 75 28 25

Well stocked 67 27 22

All 300 57 100

Pacific Madrone Forest Type

The Pacific madrone forest type was estimated to be just 3 percent of all hardwood

forests, or 348,000 acres (±15 percent se). However, madrone was fairly common

as a component of other forests (fig. 14), making up 9 percent of all the hardwood

sawtimber trees in the state (table 17). Next to tanoak, Pacific madrone forest was

the densest of hardwood forest types (fig. 6). Madrone forest was found at an

average elevation of 1,930 feet, with two-thirds of the forest type occurring between elevations of 910 feet and 3,020 feet. After the tanoak forest type, the

madrone forest type had the second greatest average annual rainfall of common

hardwoods. The median average annual precipitation for this forest type was 54

inches per year, with two-thirds of the for-est type found in areas with 39 to 58

inches of precipitation per year.

Douglas-fir was the most common associated species within the Pacific

madrone forest type, as indicated by the distribution of tree basal area: madrone

(37 percent of total tree basal area), Douglas-fir (26 percent), tanoak (11 percent),

canyon live oak (7 percent), California black oak (7 percent), California laurel

(3 percent), and other species (each at 1 percent or less of total tree basal area).

Private ownership of the madrone forest was estimated at 215,000 (±21 percent se),

which was 62 percent of the forest type. National forests accounted for 35 percent

of the forest type, and other public ownership was estimated as 3 percent of the

madrone forest.

Madrone trees were estimated to have occurred on 3.9 million acres (±4 percent se) of inventoried forest land (see footnote 2), where 55 percent was privately

owned, 41 percent was in national forest ownership, and 4 percent was in other

public ownership. Madrone was most commonly found in the tanoak forest type,

as shown in the tabulation below.

Pacific madrone is

typically found in

mixed-species

forests.
RESOURCE BULLETIN PNW-RB-245

26

Percentage of all

Forest type with types with Pacific

Pacific madrone trees Area Sampling error madrone trees

 – – – Thousand acres – – –

Tanoak 967 73 25

Mixed conifer 804 62 21

Douglas-fir 428 49 11

Pacific madrone 348 54 9

Canyon live oak 299 47 8

Redwood 239 42 6

California black oak 237 42 6

Coast live oak 182 47 5

Oregon white oak 105 36 3

California laurel 89 28 2

Other types 215 40 5

Total 3,912 137 100

The national champion tree for Pacific madrone is found in California, and it

has a 57-inch diameter, is 92 feet high, and has a crown diameter of 70 feet (UFEI

2004). In California, there were an estimated 32 million (±7 percent se) madrone

sawtimber trees with d.b.h. ≥11 inches (table 17). Only 10 percent of sawtimber

trees had d.b.h. ≥23 inches, and 3 percent of sawtimber trees had d.b.h. ≥29 inches.

Figure 14—Sample plot locations for Pacific madrone (Arbutus menziesii) forest type (left) and for

Pacific madrone trees (right). Figure includes plots for all inventories used in this report, and the

plots shown did not all have the same probability of selection. To protect landowner privacy, each

plot shown has some deliberate location error.
Oak Woodlands and Other Hardwood Forest of California, 1990s

27

The ratio of numbers of seedlings relative to 1- to 3-inch d.b.h. trees and the ratio

of number of 1- to 3-inch d.b.h. trees to 3- to 5-inch d.b.h. trees were both above

2.0 (table 18), which is one indication of good regeneration for the madrone

population in the state.

Other Hardwood Forest Types

All of the other hardwood forest types in California were relatively uncommon.

The next most common type after madrone, California laurel, was less than 2

percent of the total hardwood forest area in California. This uncommon forest type

was only found on 27 plots, which presented some difficulty in making a meaningful assessment of characteristics like density, species composition, or regeneration.

However, the inventory does provide good evidence that these types were indeed

uncommon.

Another uncommon oak forest type was the valley oak forest type, estimated

at 152,000 acres (±29 percent se), or just 1.3 percent of total hardwood forest area.

Engelmann oak (Quercus engelmannii) forest type is also rare estimated at 63,000

acres (±41 percent se), which is just one-half of one percent of all hardwood forest.

For both of these types, only very sparse regeneration (seedlings and saplings) was

found in the corresponding sample plots, but we do not have enough data to know

whether this was true for the statewide population. Estimates for all forest types are

shown in table 2. If sampling error is 100 percent or if forest types were not present

in the sample, it is likely that there were fewer than 100,000 acres of forest in

California where that tree species was predominant.

Hardwood Resources

Wildlife

Hardwoods, and oak species in particular, are highly important to the diversity of

wildlife found in California. About 110 bird species occupy California oak habitats

during breeding season (Verner 1980). Barrett (1980) described the many ways

mammals use oaks: hollow trees, logs, and roots serve as denning sites; small and

large herbivores forage on leaves and twigs; oaks may support fungi, mistletoe, or

insects used by mammals; and of greatest impact, oaks produce acorns, which serve

as a food source for many animals.

Hardwoods are highly

important to diversity

of wildlife.
RESOURCE BULLETIN PNW-RB-245

28

The California wildlife habitat relationships system (CDFG 2002) indicates

acorns are an essential habitat element for acorn woodpeckers (fig. 15). Fifty

vertebrate wildlife species are listed as using acorns (CDFG 2002):

Mammals Birds

Bighorn sheep (Ovis canadensis) Acorn woodpecker (Melanerpes

Black bear (Ursus americanus) formicivorus)

Brush mouse (Peromyscus boylii) Band-tailed pigeon (Columba fasciata)

California chipmunk (Tamias obscurus) California quail (Callipepla californica)

Cal. ground squirrel (Spermophilus beecheyi) California thrasher (Toxostoma redivivum)

California mouse (Peromyscus californicus) Gila woodpecker (Melanerpes uropygialis)

Deermouse (Peromyscus maniculatus) Gilded flicker (Colaptes chrysoides)

Desert cottontail (Sylvilagus audubonii) Hairy woodpecker (Picoides villosus)

Desert woodrat (Neotoma lepida) Island scrub-jay (Aphelocoma insularis)

Douglas’ squirrel (Tamiasciurus douglasii) Juniper titmouse (Baeolophus griseus)

Dusky-footed woodrat (Neotoma fuscipes) Lewis’ woodpecker (Melanerpes lewis)

Eastern fox squirrel (Sciurus niger) Mountain quail (Oreortyx pictus)

Eastern gray squirrel (Sciurus carolinensis) Northern flicker (Colaptes auratus)

Elk (Cervus elaphus) Oak titmouse (Baeolophus inornatus)

Island gray fox (Urocyon littoralis) Sandhill crane (Grus canadensis)

Long-eared chipmunk (Tamias Spotted towhee (Pipilo maculatus)

quadrimaculatus) Steller’s jay (Cyanocitta stelleri)

Merriam’s chipmunk (Tamias merriami) Varied thrush (Ixoreus naevius)

Mule deer (Odocoileus hemionus) Western scrub-jay (Aphelocoma

Northern flying squirrel californica)

(Glaucomys sabrinus) White-breasted nuthatch (Sitta

Pinyon mouse (Peromyscus truei) carolinensis)

Raccoon (Procyon lotor) Wild turkey (Meleagris gallopavo)

Rock squirrel (Spermophilus variegatus) Wood duck (Aix sponsa)

Siskiyou chipmunk (Tamias siskiyou) Yellow-billed magpie (Pica nuttalli)

Sonoma chipmunk (Tamias sonomae)

Virginia opossum (Didelphis virginiana)

Western gray squirrel (Sciurus griseus)

Wild pig (Sus scrofa)

Yellow-cheeked chipmunk (Tamias ochrogenys)

Most oaks produce abundant acorn crops intermittently, every 2 or 3 years or

at irregular intervals, so that a diversity of oak species in an area can help regulate

the food supply. Madrone trees provide wildlife food by producing extensive berry

crops (fig. 16). Other parts of hardwood trees–shoots, buds, sap, and leaves–can

serve as wildlife food, as can fungi and mistletoe species that live on hardwood

trees. Over one-third of all bird species on hardwood rangelands make use of

snags (Standiford 2001). Coarse woody debris, important for most reptiles and

amphibians and many bird species (Standiford 2001), averaged 1.2 tons/acre for

unreserved woodland outside of national forests (Tietje and others 2002).

Riparian habitat elements are used by almost 90 percent of all hardwood

rangeland wildlife species (Standiford 2001). Hardwoods are also important to
Oak Woodlands and Other Hardwood Forest of California, 1990s

29

invertebrates and aquatic vertebrates. The California Department of Forestry and

Fire Protection estimates that 95 percent of the historical range of riparian forests

has been lost (CDFFP 2003). Hardwood trees such as alder and maple are frequently more prevalent in riparian areas (fig. 17) and contribute to the coarse

Figure 15—The acorn woodpecker stores acorns in numerous small tree cavities, each large enough

to hold a single acorn.

 Gerald and Buff Corsi © California Academy of Sciences. Beatrice F. Howitt © California Academy of Sciences.

Figure 16—Berries on a Pacific madrone (Arbutus menziesii) tree.
RESOURCE BULLETIN PNW-RB-245

30

woody debris in streams and lakes. Shade provided by hardwood trees is critical in

moderating summer stream temperatures. Hardwood trees stabilize streambanks,

help to prevent erosion, and contribute to preserving overall water quality.

Forest Product Resources

Alder, California black oak, bigleaf maple, tanoak, Pacific madrone, and Oregon

white oak are all used to create manufactured forest products. These and other

California hardwoods are used to make furniture, flooring, pallets, veneer, paneling, molding, fence posts, and other items. Parts of hardwood trees and other plants

in hardwood forests are also used for many nontraditional forest products, ranging

from food and medicinal products to dye and material for artwork or crafts.

The estimated net growing-stock volume of hardwood tree species on unreserved land was 14.1 billion cubic feet (±3 percent se) (table 3). Net growing-stock

volume was calculated from a 12-inch-high stump to a 4-inch-diameter top for all

trees greater than 5 inches d.b.h. and was adjusted to account for both sound and

rotten culls. Sixty-five percent of unreserved growing-stock hardwood volume was

on private lands, and 67 percent was on timberland rather than woodland.

Net growing-stock volume does not include all hardwood volume; some species were defined as live cull in some areas (for example, blue oak on national

forests), and individual trees can be defined as cull because of their form. Utilization standards for some purposes (for example, bioenergy or pulp) may include

small trees and tree tops that are not included in the net growing-stock estimate.

Figure 17—Hardwoods such as this bigleaf maple (Acer macrophyllum) are often found

along riparian areas.

Charles Thoreau Townsend© California Academy of Sciences.

Oaks provide 90

percent of the tree

biomass in woodland

and 53 percent in

timberland hardwood

types.
Oak Woodlands and Other Hardwood Forest of California, 1990s

31

On unreserved forest land, the total sound hardwood volume, measured from the

ground to the tree tip for trees greater than 4 inches d.b.h, was estimated as 23.48

billion cubic feet (±2 percent se). Sixty-nine percent of this volume was on private

lands, and 61 percent was on timberland rather than woodland (table 10).

Estimates of biomass have been increasing in importance, in part because of

the need to estimate carbon storage. Oaks provided 90 percent of the tree biomass

in woodland (table 7) and 53 percent of tree biomass in timberland hardwood

types (table 8). The aboveground biomass of hardwood trees on forest land was

estimated as 555 million tons (±2 percent se) (table 9), or 29 percent of overall

tree biomass.

For the year 2000, the estimated volume of hardwoods harvested for industrial

use in California was 10.7 million board feet (MMBF) Scribner, distributed as 2.0

MMBF to sawmills, 2.7 MMBF burned for bioenergy (does not include firewood),

and 6.0 MMBF for other products such as pulp and paper (Morgan and others

2004). This was about 0.5 percent of total California timber harvest volume

(Morgan and others 2004). Since 1982, the hardwood proportion of annual harvest

in California has typically ranged between 0.05 and 0.50 percent of all species harvested for industrial use in California (Morgan and others 2004). The volume of

hardwoods harvested for industrial purposes in California would have been about

0.1 percent of the estimated 10,505 MMBF standing volume on unreserved lands.

The relatively low rate of harvest for industrial purposes has led many authors to

conclude that hardwoods are an underutilized resource (Delfino 1986, Huber and

McDonald 1992). In recent years, an increase in west coast red alder prices, which

now sometimes surpass Douglas-fir prices, has provided an example of the potential for relatively quick and dramatic changes in marketability of western hardwoods.

The volume harvested annually for industrial use in California was much

smaller than the total annual volume harvested. Hardwood trees can be cut for

many purposes: to clear land for building, range improvements, or agriculture;

to harvest trees for firewood; or to reduce competition against more commercially

valuable tree species. The total estimated annual harvest volume of hardwood trees

at least 5 inches d.b.h. on unreserved lands outside national forests was 56.0

million cubic feet per year (table 14). The total estimated annual harvest volume

of hardwood trees ≥11 inches d.b.h. on unreserved land outside national forests

was 98 MMBF Scribner. When compared to the 2 MMBF annual harvest volume

of hardwoods that goes to sawmills (Morgan and others 2004), it is apparent that

only a small portion of harvested sawtimber-sized hardwood trees was milled as

sawtimber.
RESOURCE BULLETIN PNW-RB-245

32

The total periodic hardwood harvest volume of net growing stock on unreserved land outside of national forests from 1981-84 to 1991-94 was estimated as

2 percent of 1991-94 hardwood inventory volume on woodland and 7 percent of

1991-94 hardwood inventory volume on timberland. The total annual mortality

volume of hardwoods that were harvested or culturally killed was 23 percent of

annual gross growth (tables 14 and 15). It is unknown how much of the harvest

volume was used for nonindustrial forest products such as firewood, and how

much was treated as unusable material. More than 200,000 homes in California are

primarily heated by wood (USDC Bureau of the Census 2004), and many more use

wood as a secondary heating source. Hardwoods are valued as firewood because

they burn slowly and form good coals.

Hardwood Rangeland

The majority of California’s woodlands are grazed. The 1981-84 inventory of

unreserved woodland outside of national forests found that 55 percent of woodland

plots were recorded as having evidence of grazing within the past year (Bolsinger

1988); because field visits occurred during different times of year and grazing

would not always be apparent, this estimate was probably low. Corresponding with

the 1981-84 woodland inventory, and selecting from private owners where oak

species were predominant, a 1985 survey provided an estimate that 77 percent of

private oak woodland was grazed (Huntsinger and Fortmann 1990); this rate might

be high if owners did not graze all of their land. A range of 55 percent to 77 percent grazing for private woodland in the 1990s corresponds to 3 to 4 million acres.

Publicly owned woodlands are also often commonly grazed, as are private and

public savannas with less than 10 percent tree cover.

The 1985 statewide survey by Huntsinger and Fortmann was intended to aid

education programs and included questions about landowner attitudes. The majority of owners who owned more than 5,000 acres valued oaks for shade, wildlife

habitat, natural beauty, and fuelwood. A majority of owners of smaller land areas

valued oaks for the same things plus property value and erosion control

(Huntsinger and Fortmann 1990).

Between 1985 and 1992, a multiagency program (the Integrated Hardwood

Range Management Program) engaged in an active program of research and

education. A followup survey in 1992 of the same landowners surveyed in the 1985

survey found small but significant changes in responses: a decrease in the percentage of owners who have livestock grazing on their property; an increase in proximity to subdivisions; an increase in valuing oaks for erosion control, browse, and

water conservation; decreases in the percentage of landowners who thinned oaks,

Clearing of oak woodlands and sparse

regeneration are

issues of concern.
Oak Woodlands and Other Hardwood Forest of California, 1990s

33

cut oaks, or sold firewood; increases in planting or protecting oak sprouts; and an

increase in owners who agreed that oaks were being lost in California (Huntsinger

and others 1997).

How changes in attitudes or practices have affected oak woodlands is largely

unknown. At the time of the 1981-84 inventory, a variety of evidence indicated

problems with oak woodlands. Bolsinger (1988) aggregated State of California

annual reports of timber harvest to estimate 1.9 million acres of hardwoods and

chaparral had been cleared in rangeland improvement projects from 1945 to 1974.

A number of oak species showed sparse regeneration, as they continue to do.

Clearing of oak woodlands for development, for agriculture, for vineyards, and for

subdivisions was noticeable in the 1980s and continued to be a focus of public

concern in the 1990s. There are many case studies discussing problems with

recruitment and retention of oaks.

Changes in California Hardwoods From 1981-84 to

1991-94

Methods

Because the spatial variability of forests is high, and mortality information requires

tracking of individual trees, the best method for estimating change is to remeasure

permanent plots over time. There were no remeasurement data for national forests

or reserved lands for this time period. On other lands, woodland forest was not

measured until the 1980s, and at that time the plot intensity was one plot per

30,000 acres. Most of the 1980s woodland plots were remeasured in the 1990s, but

a change in inventory design resulted in a reduction of the number of remeasured

trees.

This results in very uncertain estimates of how forests changed from the 1980s

to the 1990s. For tables 13 to 16, estimates were made by using 773 timberland

plots with hardwood trees and 189 remeasured woodland plots. Standard errors in

tables and confidence intervals given in the text can be used to understand uncertainty related to sampling error.

For tables 11 and 12, change in forest type on woodland was estimated from all

345 plots installed in the 1990s, including those that had not had 1980s tree measurements. Where trees were measured for the first time in the 1990s, the 1980s

measurements were modeled by using a process described in Waddell (1991). Air

photos taken in the 1980s and 1990s exist for all plots and were useful in confirming changes between forest and nonforest.

The best method of

estimating change

is to remeasure

permanent plots over

time.
RESOURCE BULLETIN PNW-RB-245

34

The estimates in this report apply 1990s methods (volume equations and forest

type classification algorithms) to data from both periods to help ensure change

estimates reflect real change rather than changes in the inventory and analysis

procedures. All estimates in this report cannot be directly compared to those in the

Bolsinger (1988) report because of changes in inventory design and estimation

procedures. Readers interested in more detail about the estimation process for

change should contact the authors.

Results

Overall, there was an estimated 3-percent decrease of unreserved woodland area

outside national forests from the 1980s to the 1990s. The majority of this decrease

(88 percent) was caused by a transfer of land to reserved or national forest status

(table 11).

Only 2 of 345 oak woodland plots (0.6 percent) changed from woodland in

1981-84 to nonforest in 1991-94. One woodland plot was converted to urban

(developed) land and one plot was converted to nonforest rangeland. Using this

conversion information, we estimated that the 1980s to 1990s rate of conversion of

woodland to nonforest on unreserved land outside of national forests was 29,000

acres per decade, with a 68 percent confidence interval (CI) of 11,000 to 69,000

acres per decade.3

 This estimate does not include conversion of oak savanna, where

tree cover is less than 10 percent, to urban or agricultural conditions.

One of the 345 plots that was oak woodland in the 1980s burned in a wildfire

and became chaparral, and one chaparral plot from the 1980s grew into an oak

woodland classification. For each process (woodland changing to chaparral and

chaparral changing to woodland), the estimated rates of change between 1981-84

and 1991-94 were 15,000 acres per decade, with a range of 4,000 to 51,000 acres

per decade at a 68 percent CI. Because it can be difficult to draw a clear distinction

between chaparral and oak woodland in all cases, it is possible that there may have

been some classification error that is not included in this estimate.

If transfers out of the population are included, there was no net change in the

area of hardwood forest on unreserved timberlands outside of national forests. If

transfers are excluded, there was an estimated 2 percent increase in the area of

hardwood timberland from 1981-84 to 1991-94.

3

 Estimates differ slightly from values in table 11 because stratification is not used.
Oak Woodlands and Other Hardwood Forest of California, 1990s

35

Net

Timberland change Area Additions Subtractions change

Thousand acres

1981-84 hardwood forest

types 2,654

Change to/from nonstocked

forest 20 (15) 5

Change to/from softwood type 212 (144) 68

Conversion to/from nonforest 15 (30) (15)

Transfer to national forests

or reserved (55) (56)

Total change 247 (245) 2

1991-94 hardwood forest

type 2,656

Four plots changed from hardwood timberland to nonforest: three tanoak forest

plots and one giant chinquapin plot were converted to developed land or roads. The

estimated rate of conversion to nonforest from 1981-84 to 1991-94 for hardwood

forest types on unreserved timberland was 30,000 acres per decade, with a range of

14,000 to 55,000 acres per decade using a 68 percent CI.

Table 12 shows estimates of change from 1981-84 to 1991-94 for individual

forest types. Estimated area in a forest type can change for a variety of reasons.

Conversion to nonforest was described above, and this is most likely the change

that is of greatest concern to people. In other cases, land was transferred to national

ownership or reserve status; these types of land were not part of the FIA inventory,

and so plots that fell into this category were not remeasured. In yet other cases,

plots changed from one forest type to another. A change in forest type might reflect

substantial change on the plot—for example, selective harvesting of all conifers on

the plot—or the change in forest type can occur with relatively small amounts of

mortality or differential growth rates among trees of different species. Estimated

areas for individual forest types that changed by large percentages were all relatively uncommon types, so that the 1991-94 estimate was within a sampling error

of the 1981-84 type (table 12). For these types, the change shown reflects sampling

error rather than real change. This does not mean that area for these types remained

constant; it means that we simply do not know what change occurred.

One change estimate of interest is the decrease in the California black oak

forest type. The California black oak forest type in 1981-84 was estimated at

751,000 acres (±11 percent se), and had a 12 percent net decrease for 1991-94,

unadjusted for transfer to national forest or reserved status (table 12). Transfers or

redefinitions of land to reserve status or national forest accounted for 37 percent of
RESOURCE BULLETIN PNW-RB-245

36

the decrease. An estimated 15,000 acres shifted into the California black oak forest

type (range 4,000 to 37,000 acres per decade at a 68 percent CI). An estimated

62,000 acres (8 plots) shifted out of the California black oak forest type to other

forest types or to a nonstocked condition (range 40,000 to 88,000 acres per decade

at a 68 percent CI). The eight plots showed the range of reasons for conversion of

black oak to other forest types: two plots shifted to other types owing to higher

growth in other species, one plot had black oaks die from natural causes, two plots

had black oaks that were killed and left on site, one plot had black oaks harvested

and removed, and fires burned over two plots, one of which was salvage logged.

Excluding salvage logging, 11 percent of all black oak timberland plots had some

black oak trees harvested or cut and left between 1981-84 and 1991-94; the corresponding estimate for the state would be 64,000 acres affected per decade.

Oaks and other hardwoods increased in net growing-stock volume between the

1980s and the 1990s (table 13). Estimated annual mortality volume for trees that

were harvested or culturally killed was about the same as natural mortality (table

14) but overall mortality and removal volume was lower than gross annual growth

(table 15). Significant net growth increases occurred for blue oak, California black

oak, Oregon white oak, bigleaf maple, California laurel, Pacific madrone, and

tanoak (table 15).

Pre-Sudden Oak Death Forest Conditions for 12

California Counties

By the end of 2003, 12 California counties had been quarantined for sudden oak

death. These were Alameda, Contra Costa, Humboldt, Marin, Mendocino,

Monterey, Napa, San Mateo, Santa Clara, Santa Cruz, Solano, and Sonoma Counties (fig. 18). As of spring 2004, the associated pathogen (Phytophtora ramorum)

had also been found in isolated instances in additional counties in California and

in Oregon and Washington. Within the range of areas where the disease is established, the distribution of the disease appears to be patchy (McPherson and others

2002). Initially symptom-free trees in affected areas can later develop the disease

(McPherson and others 2002); in one case study, remote-sensing imagery suggested

a continuing mortality rate of 0.4 trees per acre in an area where the disease was

already established (Kelly and Meentemeyer 2002).

Active measures are in place to limit the spread of the disease, but the potential

range is unknown. Although climate may play a role in limiting the disease, the

pathogen has been found in a wide range of microclimates (Rizzo and others 2002).

Portions of the Sierra Nevada, and additional areas of coastal forests in California

and Oregon, are similar in species composition and environment to the currently

Oaks and other hardwoods increased in

net growing-stock

volume.
Oak Woodlands and Other Hardwood Forest of California, 1990s

37

listed area. There are also large areas of the Central, Southern, and Eastern United

States with tree species that might be susceptible to the disease. Because the

eventual range of the disease is unknown, we have chosen to limit this assessment

of pre-epidemic forest conditions to the 12-county area in California most affected

in spring 2004.

The inventory plots used for this assessment will provide baseline information

for future monitoring of the epidemic. The Forest Inventory and Analysis program

is continuing to monitor forest change in the sudden oak death region in two ways:

(1) within the ongoing inventory system, plots are being measured each year, and

(2) FIA scientists are currently engaged in cooperative sudden oak death research

projects that remeasure a subset of plots used in this assessment. The estimates

given here are a pre-epidemic assessment of forest land in the 12-county area and

do not include any estimate of disease occurrence or spread.

Figure 18—By spring of 2004, 12 counties in California were affected by the sudden oak death

epidemic.
RESOURCE BULLETIN PNW-RB-245

38

There were approximately 5.5 million acres of forest land in these 12 counties.

This estimate is approximate, because some of the forest within these counties was

unsampled prior to 2001, and the data collected after 2001 are not yet sufficient for

analysis. This unsampled land consisted of reserved land outside of national forests, such as the southern portion of Redwoods National Park or the Point Reyes

National Seashore. There were no field measurements for these areas, but from

landowner or manager responses, the unsampled forest land would be 442,000

acres, or 8 percent of the total forest area in these counties (Waddell and Bassett

1996, 1997a, 1997b). In addition, this assessment is limited to the definition of

forest land, which excludes lands with nonforest uses, such as city parks and

residential areas.

Of the remaining 5.09 million acres of forest land in these counties, 87 percent

was outside national forests and field measurements were taken during 1991-94.

The remaining 13 percent of forest land had field measurements in 1996-98 and

are from national forests in Humboldt, Mendocino, and Monterey Counties. As

some tanoak deaths were reported as early as 1995, and the disease could have

been present before the first reports, there is a possibility of temporal overlap

between the incidence of the disease and the statistics reported here. However,

values most likely represent forests before the onset of the epidemic.

Tanoak is one of the tree species that may die after developing trunk lesions

from Phytophthora ramorum. Tanoak death observed by Marin County homeowners in 1995 was the first indication of the disease (Svihra 2001). Tanoaks are

aggressive competitors to the more commercially valuable conifers, and thus are

often viewed as a nuisance species. However, tanoak is a very important species

for wildlife cover and food. The tanoak forest type was the most common forest

type in the 12-county area, exceeding either Douglas-fir or redwood forest, and

was estimated at 20 percent of the forest area in the 12 counties (table 19).

Douglas-fir and redwood species are also listed as hosts for the pathogen

associated with sudden oak death, Phytophthora ramorum. After tanoak, the

Douglas-fir and redwood forest types were the next most common in the 12 counties, making up 14 and 13 percent of the forest area respectively (table 19). Most

of the other common forest types in the 12 counties (table 19) were also dominated

by species that are known hosts to the pathogen, including the coast live oak,

California black oak, Pacific madrone, canyon live oak, California laurel, and bigleaf maple forest types. In the 12 counties an estimated 3.8 million acres (±4 percent se), which was 74 percent of the inventoried forest land, was dominated by
Oak Woodlands and Other Hardwood Forest of California, 1990s

39

species (Acer macrophyllum, Aesculus californica, Arbutus menziesii, Lithocarpus

densiflorus, Pseudotsuga menziesii, Quercus agrifolia, Quercus chrysolepis,

Quercus kelloggii, Sequoia sempervirens, and Umbellularia californica) that were

listed as regulated hosts for the disease as of March 2004.

Tree species seem to differ in their susceptibility to the disease: tanoak, coast

live oak, California black oak, and Shreve’s oak (Quercus parvula var. shrevei)

4

are believed to be particularly subject to lethal trunk infections (Rizzo and others

2002). There have been anecdotal reports of mortality in rhododendrons and

madrones with the disease (Garbelotto and others 2003). Symptoms observed in

the field often appear to be patchy, although the reasons for this are unknown.

California laurel, California buckeye, and bigleaf maple appear to have very

limited stem infection (Garbelotto and others 2003). Symptoms for overstory

Douglas-fir and redwood trees have not been observed, although effects on sprouts

and saplings have been reported (Garbelotto and others 2003).

In the 12 counties, the area where tree host species were present was estimated

at 4.1 million acres (±3 percent se), which was 81 percent of the estimated forest

area for sampled land (table 20). For this estimate, “presence” was determined by

the occurrence of at least one host species tree of any size on a subplot. This estimate of occurrence for regulated host species was made from sampled tree data

only and would increase if shrub or understory vegetation were included. Nontree

host species include toyon, California honeysuckle, rhododendron, wood rose,

starflower, California huckleberry, and others.

Two of the acorn-producing species that can die from Phytophthora

ramorum—tanoak and California black oak—were widely found throughout

coniferous timberland forest (Douglas-fir and redwood forest types) and are thus

important ecosystem components even in places where they form a relatively small

part of the total tree species mix. Raphael (1987) describes numerous wildlife uses

of tanoak in northwestern California Douglas-fir forests; salamanders

(Dicamptodon ensatus, Plethodon elongatus, Ensatina eschscholtzi, Aneides

flavipunctatus, and Aneides ferreus) using tanoak logs for cover, bears and flying squirrels feeding on tanoak acorns (fig. 19), woodrats using tanoak for nesting, and fishers (Martes pennanti) feeding on prey associating with tanoak. Another hardwood tree found in coniferous forests—California black oak—also

produces abundant acorn crops in some years, particularly trees older than 80 years

4 Quercus parvula is not considered a tree species in these inventories. Quercus parvula v.

shrevei takes tree form and hybridizes with Q. wislizeni (Nixon 2002), Q. agrifolia, and Q.

kelloggii (Hickman 1993), so it is possible that it is partially included within estimates for

other species.

Most major tree species and many shrub

species are host for

the pathogen causing

sudden oak death, but

susceptibility and

mode of transmission

are unknown.
RESOURCE BULLETIN PNW-RB-245

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(Tappeiner and McDonald 1980). Pacific madrone is a third hardwood that is a

listed host species and common in coniferous coastal forests, and it can also be an

important wildlife food source through the production of berries. The three species

combined—California black oak, tanoak, and Pacific madrone—are critical

components of the coniferous forest, and they can complement each other by

differences in timing and amount of acorn, berry, and leaf production. Coast live

oak forest, which supplies a half million acres of oak habitat in the quarantined

counties, is also subject to lethal trunk lesions from Phytophthora ramorum.

At this time, growth and mortality effects of Phytophthora ramorum for

different plant species are largely unknown, the level of genetic resistance in host

species is unknown, the potential range of the disease is unknown, the mode of

transmission is unknown, and the environmental factors that lead to susceptibility

from the disease are unknown. However, the disease has spread fairly rapidly,

albeit patchily, and Phytophthora ramorum is now found in a wide geographic

area. All but a few of the major tree species in substantial portions of the state are

hosts for the disease, as are many of the widespread shrub species. Three of the tree

species that appear most susceptible to mortality from Phytophthora ramorum—

tanoak, coast live oak, and California black oak—were very widespread, predominant for 36 percent of the forest and also found throughout many other forest types.

These hardwood species are known to be important as food and habitat for a large Charles Webber © California Academy of Sciences.

Figure 19—Tanoak (Lithocarpus densiflorus), one of the trees particularly susceptible to

sudden oak death, produces abundant acorn crops used by wildlife.
Oak Woodlands and Other Hardwood Forest of California, 1990s

41

number of wildlife species. Although predictions of the long-term effects of the

disease are speculative, it appears that there is the potential for very extensive

changes in species composition and forest structure over a geographic range

encompassing millions of acres of California forest land with the potential for

many indirect ecosystem effects, including possible impacts on numerous wildlife

species.

Glossary

aboveground biomass—The oven-dry weight of a tree in tons, including the bark,

live branches, and total stem (from ground to tree tip).

annual gross growth volume—An annual estimate of the increase in the gross

volume of trees during the remeasurement period (1981-84 to 1991-94), for trees

that were ≥5 inches d.b.h. in 1994 or ≥5 inches d.b.h. at the time of harvest. Annual

growth volume includes ingrowth, growth of survivor trees, and growth

of harvested trees.

annual mortality volume—An annual estimate of the gross volume of all trees

≥5 inches d.b.h. that were alive at the previous inventory (1981-84) and died

during the remeasurement period (1981-84 to 1991-94). Cull trees were included

in this estimate.

annual net growth volume—An annual estimate of net growth for the remeasurement period (1981-84 to 1991-94), calculated as gross growth volume – mortality

volume – removal volume. See definitions for mortality and removal volume.

annual removals volume—An annual estimate of the gross volume of all trees ≥5

inches d.b.h. that were alive at the previous inventory (1981-84) and were cut as a

result of commercial harvesting, silvicultural activities, or were damaged and killed

by logging activities during the remeasurement period (1981-84 to 1991-94). Cull

trees were included in this estimate.

average annual precipitation—Annual precipitation in inches, averaged from

1961 to 1990. This was estimated for forest type by combining inventory data with

the precipitation GIS theme produced by the Spatial Climate Analysis Service

(2004).

basal area—The cross-sectional area of tree stems at 4.5 feet above the ground.

Estimates classifying forest into basal area categories will be affected by plot size

and condition mapping.

canopy cover (tree)—The percentage of land area covered by the vertical projection of tree crowns.

cull tree—Live trees of noncommercial species, and live trees of commercial

species that are more than 75 percent defective because of poor form or rot.
RESOURCE BULLETIN PNW-RB-245

42

cull trees, rotten—Cull trees that are more than 75 percent defective owing to rot

caused by pathogens or other biotic organisms.

cull trees, sound—Trees of noncommercial species or cull trees of commercial

species with defect caused primarily by poor form and roughness. Noncommercial

hardwood species outside of national forests are Pacific dogwood (Cornus

nuttallii), walnut (Juglans spp.), ailanthus (Ailanthus altissima), apple (Malus

spp.), water birch (Betula occidentalis), and willow (Salix spp.). Noncommercial

hardwood species in national forests include boxelder (Acer negundo), walnut, and

blue oak.

culturally killed trees—Trees that were killed by human activity but not harvested. Includes trees killed from girdling or from damage by mechanical equipment during logging.

d.b.h. (diameter at breast height)—Diameter outside bark measured at

4.5 feet above the ground.

forest condition—An area of forest that is homogenous in some attributes. When

two or more distinct conditions occurred on a plot, the boundaries were mapped

and attributes were assigned separately to each. For example, separate conditions

could be used for boundaries between forest and nonforest, between hardwood and

coniferous forest types, or between uncut and partially harvested areas.

forest land—Land at least 10 percent stocked with live trees, or land that had this

minimum tree stocking in the past and is not currently developed for nonforest use.

For hardwood forest types in California, at least 10 percent stocked is interpreted

as at least 10 percent tree canopy cover. The minimum area recognized is 1 acre.

forest type—Forest type is assigned to conditions by applying a classification

algorithm to the field plot data. Forest conditions with more than 50 percent of the

stocking in hardwoods are classified as hardwood forest types. The classification

process is intended to give results similar to using tree canopy cover, so that the

type assigned would be named after the species with the highest amount of cover.

See Waddell (1991) for details. Forest type is sensitive to the classification algorithm used, as well as to the plot size and configuration.

gross volume—Volume in cubic feet from the top of a stump 12 inches tall to a

minimum 4-inch top (of central stem) inside the bark, with no deductions for sound

or rotten cull. This volume is calculated for both cull and noncull trees ≥5 inches

d.b.h.
Oak Woodlands and Other Hardwood Forest of California, 1990s

43

growing-stock volume—Net volume in cubic feet of live sawtimber and

poletimber-sized trees (d.b.h. ≥5 inches) excluding cull trees, from the top of a

stump 12 inches tall to a minimum 4-inch top (of central stem) inside the bark.

Net volume is gross volume less deductions for sound and rotten cull.

other public lands—Lands administered by public agencies other than the USDA

Forest Service. Other public lands do not include Native American lands, which are

included with private lands.

periodic mortality volume—The gross volume of all trees ≥5 inches d.b.h. that

were live at the previous inventory (1984) and died during the remeasurement

period (1984 to 1994). Cull trees were included in this estimate.

periodic removals volume—The gross volume of all trees ≥5 inches d.b.h. that

were live at the previous inventory (1984) and were cut as a result of commercial

harvesting, silvicultural activities, or were damaged and killed by logging activities

during the remeasurement period (1984 to 1994). Cull trees were included in this

estimate.

regeneration stocking—A classification used to show relative abundance of

seedlings and saplings (trees ≤5 inches d.b.h.). On oak woodlands, seedlings were

sampled with 16.4-foot-radius subplots and saplings were sampled with 10.8-footradius subplots. Stocking estimates are sensitive to the classification method used,

as well as to the plot size and configuration.

Nonstocked: no seedlings or saplings on all five subplots

Lightly stocked: one or more seedlings or saplings on one or two of five

subplots

Moderately stocked: one or more seedlings or saplings on three or four of five

subplots

Well stocked: one or more seedlings or saplings on all five subplots

reserved forest land—For this inventory, reserved forest land was forest land that

was dedicated to noncommodity use through statute, ordinance, or administrative

order.

resource area—A set of contiguous counties in the state used for inventory

scheduling and reporting in the 1980s and 1990s. Resource areas in California are:

Central Coast: Alameda, Contra Costa, Marin, Monterey, San Benito, San

Francisco, San Luis Obispo, San Mateo, Santa Barbara, Santa Clara, Santa

Cruz, Solano, and Ventura Counties

North Coast: Del Norte, Humboldt, Mendocino, and Sonoma Counties

North Interior: Lassen, Modoc, Shasta, Siskiyou, and Trinity Counties

Sacramento: Butte, Colusa, El Dorado, Glenn, Lake, Napa, Nevada, Placer,

Plumas, Sacramento, Sierra, Sutter, Tehama, Yolo, and Yuba Counties
RESOURCE BULLETIN PNW-RB-245

44

San Joaquin and Southern: Alpine, Amador, Calaveras, Fresno, Imperial, Inyo,

Kern, Kings, Los Angeles, Madera, Mariposa, Merced, Mono, Orange,

Riverside, San Bernardino, San Diego, San Joaquin, Stanislaus, Tulare, and

Tuolumne Counties

sampling error (se)—Sampling error is shown either in the same units as the

estimate or as a percentage. The percentage sampling error is calculated as the

square root of the estimated variance of the estimate, divided by the estimate itself.

A common interpretation of sampling error is that there is a 68-percent chance that

the estimate is within the sampling error of the true population value, assuming

that estimates are normally distributed, and there is a 95-percent chance that the

estimate is within twice the sampling error of the true population value. Tables in

this report display values for all cells, even when sampling error is high and there

is no meaningful difference among cell values; readers are advised to use the

sampling error in interpreting the estimates. Sampling error is displayed as 100

percent for cases with a single observation. For details on how sampling error was

calculated for these inventories, please see Barrett (2004).

saplings—Live trees between 1 and 5 inches d.b.h.

savanna—Wildland characterized by widely spaced trees and less than 10 percent

total tree canopy cover. For hardwood forests, savanna was not considered forest

land.

sawtimber trees—For hardwoods, live trees that are at least 11 inches d.b.h.

seedlings—Live trees less than 1 inch d.b.h.

timberland—Forest land capable of growing 20 cubic feet or more per acre per

year (mean annual increment at culmination in fully stocked, natural stands) of

industrial wood. Timberland is often referred to as productive forest land. In this

report, timberland can be both unreserved and reserved.

total stem volume—The volume of an entire tree bole, from the ground to the tree

tip. No volume has been deducted because of rot or poor form.

tree—The determination of what plants are trees is made by species and is specific

to an inventory. For these inventories, mountain mahogany, buckthorn (Rhamnus

spp.), elderberry (Sambucus spp.), and rhododendron were not considered trees,

but willows were considered trees. A full list of tree species for these inventories

can be found in appendix 1.

unproductive forest—Forest land that does not meet the definition of timberland.

Unproductive forest is forest that is not capable of producing 20 cubic feet per acre

per year at the culmination of mean annual increment.
Oak Woodlands and Other Hardwood Forest of California, 1990s

45

vegetation, nontree—Understory vegetation is not estimated in this report, but for

descriptive purposes we have listed it for common forest types in descending order

of occurrence when found at more than 3 plot locations for plots that were entirely

within that forest type. Vegetation information came from five 5-meter-radius

subplots per plot; where species were unknown, plants are listed as “grass,”

“forbs,” or “shrubs.” Common and scientific names for species are shown in

appendix 1. Understory vegetation information for national forests is not incorporated into the report.

woodland—Unless otherwise noted, estimates in this report labeled “woodland”

include all unproductive hardwood forest. “Oak woodland” refers specifically to

unproductive oak forest types.

Acknowledgments

Special thanks to all the landowners who allowed field crews access to their lands

to visit plots and measure trees.

Many people were involved in the collection of data, database development,

and design of the FIA inventory: Tony Akins, Dale Baer, Shelly Belin, Chris

Berger, Steve Bolon, Sarah Butler, Perry Colclasure, Vince Condon, Jim

Critchfield, Brian Daum, Pete Delzotto, John Donathon, Paul Dunham, Tim Ferrell,

Mariah Fink, Jen Gomoll, Eric Green, Erica Hanson, Jim Harrow, Joanne Hildreth,

Bob Hinds, Bruce Hiserote, Eric Johnson, John Kloster, J.D. Lloyd, Doug Magee,

Colin MacLean, Michelle Marshall, Neil McKay, Tom Meade, Nick Monkevich,

Rich Randle, Jeff Rose, Sarah Phillips, Sam Solano, Janet Steffani, Paul Tufts, Stan

Wageman, Mike Weiser, and Karen Williams. Chuck Bolsinger provided the first

assessment of California hardwoods and continues to patiently answer questions

about FIA inventories.

The help of Ralph Warbington, Deb Beardsley, and other Region 5 personnel in

California allowed us to include hardwoods on national forests in this assessment.

We thank Rick Standiford, Chuck Bolsinger, Olaf Kuegler, and Bill Stewart for

their helpful comments on a draft version of the manuscript.
RESOURCE BULLETIN PNW-RB-245

46

Metric Equivalents

When you know: Multiply by: To find:

Inches 2.54 Centimeters

Feet .3048 Meters

Miles 1.609 Kilometers

Acres .405 Hectares

Cubic feet .0283 Cubic meters

Cubic feet per acre .06997 Cubic meters per hectare

Square feet .0929 Square meters

Square feet per acre .229 Square meters per hectare

Tons per acre 2.24 Megagrams per hectare

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Oak Woodlands and Other Hardwood Forest of California, 1990s

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Appendix 1. Scientific and Common Plant Names

Scientific namea Common name

Trees

Ailanthus altissima (Miller) Swingle ailanthus

Malus L. spp. apple

Pseudotsuga macrocarpa (Vasey) Mayr bigcone Douglas-fir

Acer macrophyllum Pursh bigleaf maple

Pinus muricata D. Don Bishop pine

Populus balsamifera L. ssp. trichocarpa

Torrey & A. Gray black cottonwood

Quercus douglasii Hook. & Arn. blue oak

Acer negundo L. var. californicum

(Torry & A. Gray) Sarg. boxelder

Quercus kelloggii Newb. California black oak

Aesculus californica (Spach) Nutt. California buckeye

Juniperus californica Carrière California juniper

Umbellularia californica

(Hook. & Arn.) Nutt. California laurel, bay laurel

Torreya californica Torrey California nutmeg, California torrey

Platanus racemosa Nutt. California sycamore

Quercus chrysolepis Liebm. canyon live oak

Quercus agrifolia Nee coast live oak

Pinus coulteri D. Don Coulter pine

Pseudotsuga menziesii (Mirbel) Franco Douglas-fir

Quercus engelmannii E. Greene Engelmann oak

Eucalyptus L’Her. spp. eucalyptus

Pinus sabiniana Douglas ghost pine, gray pine, foothill pine

Castanopsis chrysophylla

(Hook.) Hjelmq. giant chinquapin, golden chinkapin

Sequoiadendron giganteum

(Lindley) Buchholz giant sequoia

Calocedrus decurrens (Torry) Florin incense cedar

Quercus wislizeni A.DC. interior live oak

Pinus jeffreyi Grev. & Balf. Jeffrey pine

Pinus attenuata Lemmon knobcone pine

Fraxinus latifolia Benth. Oregon ash

Quercus garryana Hook. Oregon white oak

Cornus nuttallii Audubon Pacific dogwood

Arbutus menziesii Pursh Pacific madrone

Pinus ponderosa Laws. ponderosa pine

Populus tremuloides Michaux quaking aspen

Alnus rubra Bong. red alder

Sequoia sempervirens (D. Don) Endl. redwood, coastal redwood

Pinus lambertiana Dougl. sugar pine

Lithocarpus densiflorus

(Hook. & Arn.) Rehder tanoak
RESOURCE BULLETIN PNW-RB-245

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Scientific namea Common name

Quercus lobata Nee valley oak, California white oak

Juglans L. spp. walnut

Betula occidentalis Hook. water birch

Alnus rhombifolia Nutt. white alder

Abies concolor (Gordon & Glend.)

Lindley white fir

Salix L. spp. willow

Nontree vegetation

Baccharis L. spp. baccharis

Chamaebatia foliolosa Benth. bear-clover

Ceanothus thyrsiflorus Eschsch. blueblossom ceanothus

Ceanothus cuneatus (Hook.) Nutt. buckbrush

Rhamnus L. spp. buckthorn

Corylus cornuta var. californica

(A. DC.) Sharp California hazelnut

Lonicera hispidula Dougl. California honeysuckle

Vaccinium ovatum Pursh California huckleberry

Torreya californica Torrey California nutmeg

Cercis occidentalis Torrey California redbud

Quercus dumosa Nutt. California scrub oak

Rhododendron macrophyllum D. Don coast rhododendron

Ceanothus incanus Torrey & A. Gray coast whitethorn

Arctostaphylos manzanita C. Parry common manzanita

Ceanothus integerrimus Hook. & Arn. deerbrush

Sambucus L. spp. elderberry

Galium triflorum Michx. fragrant bedstraw

Gramineae spp. grass

Arctostaphylos patula E. Greene greenleaf manzanita

Arctostaphylos columbiana Piper hairy manzanita

Rhamnus ilicifolia Kellogg hollyleaf redberry

Iris L. spp. iris

Claytonia perfoliata Willd. miner’s lettuce

Cercocarpus betuloides Torrey & A. Gray mountain mahogany

Berberis aquifolium Pursh mountain-grape

Avena L. spp. oats

Myrica californica Cham. & Schldl. Pacific wax-myrtle

Toxicodendron diversilobum

(Torr. & Gray) Greene poison oak

Vaccinium parvifolium Smith red huckleberry

Erodium cicutarium (L.) L’Hèr red-stem filaree

Oxalis oregana Nutt. redwood sorrel

Rhododendron macrophyllum

D. Don ex G. Don rhododendron
Oak Woodlands and Other Hardwood Forest of California, 1990s

55

Scientific namea Common name

Gaultheria shallon Pursh salal

Quercus parvula var. shrevei

(C.H. Muller) K. Nixonb Shreve’s oak

Aira caryophyllea L. silver hairgrass

Symphoricarpos sp. Duham. snowberry

Trientalis latifolia Hook. starflower

Arctostaphylos viscida C. Parry sticky whiteleaf manzanita

Rubus parviflorus Nutt. thimbleberry

Heteromeles arbutifolia (Lindl.)

M. Roemer toyon

Pteridium aquilinum (L.) Kuhn western brackenfern

Polystichum munitum (Kaulfuss) K. Presl western swordfern

Whipplea modesta Torrey whipplea

Rubus leucodermis Dougl. ex Torr. & Gray whitebark raspberry

Rosa gymnocarpa Nutt. wood rose

a We are using Hickman (1993) for scientific names. Munz and Keck (1959) was a primary reference

source during the planning and field collection for Forest Inventory and Analysis inventories during

the 1980s and 1990s.

b

 Quercus parvula is not considered a tree species in these inventories. Quercus parvula v. shrevei

takes tree form and hybridizes with Q. wislizeni (Nixon 2002), Q. agrifolia, and Q. kelloggii

(Hickman 1993), so it is possible that it is partially included within estimates for other species.
RESOURCE BULLETIN PNW-RB-245

56

Appendix 2. Inventory Procedures

Outside of national forests and reserved lands, two Forest Inventory and Analysis

(FIA) inventories were used to collect information on hardwoods and hardwood

forests. The first was an inventory of timberland that used a sampling intensity of

one field plot per every 7,400 acres. The second was an inventory of woodland that

used one field plot per 14,800 acres. Both inventories used the same field protocols, plot configuration, and analytical procedures such as volume equations and

forest typing algorithms. Plots were located by superimposing a grid over the land

and randomly locating plots within each grid cell; plots are treated as a random

sample for analysis. Field measurements began in 1991 and were completed in

1994.

Plots used for field visits are a subset of plots established and interpreted on air

photos. Air photos are used for double sampling for stratification, which improves

the precision of estimates. Stratification for results reported here used air photos

taken before the 1980s inventory, with the exception of the stratification for the

north coast region, which used air photos taken before the 1990s inventory. All

field plots also had recent air photos that were used by the field crew in navigating

to the plot. Overall, there were 4,824 field plots in California, 2,245 of which fell at

least partially in forest land, and 78,223 photointerpreted plots used for stratification. There were 2,412 field plots on the woodland field grid in California, and

woodland trees were measured on 540 of these field plots.

Each plot consisted of a cluster of five subplots, with one central subplot, three

subplots at 210 feet away to the north, east, and west, and one subplot 141 feet

away to the south. On each subplot, trees between 6.9 and 35.5 inches diameter at

breast height (d.b.h.) were selected with variable-radius sampling by using a Basal

Area Factor (BAF) 30.5 prism (BAF 7 metric prism). Trees greater than 35.7

inches d.b.h. were sampled by using a fixed radius of 55.8 feet. Trees smaller than

6.9 inches were sampled by using a 10.8-ft fixed radius.

When two or more distinct conditions existed on a plot–areas different by

broad forest type, size of trees, stocking density, or cutting history—the areas were

mapped on the subplots, and the resulting mapped areas used in calculating attributes. In the previous 1980s inventory of California forests, plots were shifted so

that they fell in a single condition. In addition, in the 1980s, a three-subplot configuration was used in woodlands rather than a five-subplot configuration, and

woodland plots were sampled at a reduced intensity of one plot per 29,600 acres.

The net result is that the calculation of 1990s estimates was straightforward, but

the calculation of change between 1980 and 1990 was complicated and in some

cases involved modeling of tree attributes such as diameter and height.
Oak Woodlands and Other Hardwood Forest of California, 1990s

57

Most national forest data came from a Pacific Southwest Region inventory

conducted in 1993-2000. The underlying base grid for plot selection was the same

as for the FIA inventories. However, remote sensing data were used to stratify the

area, with classification into broad vegetation types. Plots were sampled with

increased intensity for some vegetation types. Because of this intensification,

estimates for national forests often have greater precision than estimates for private

or other public lands.

The national forest inventory used a five-subplot configuration similar to that

of FIA, with subplots spaced at 127 feet from the central subplot. Trees between 1

and 4.9 inches d.b.h. were sampled within an 11.8-ft fixed radius of subplot center.

Trees of 5 inches d.b.h. or greater were sampled with either a BAF 20 or BAF 40

prism. If a BAF 20 prism was used, trees 30.4 inches d.b.h. and larger were

sampled with a 58.9-foot fixed radius. If a BAF 40 prism was used, trees 42.9

inches d.b.h. and larger were sampled with a 58.9-foot fixed radius. Volume

equations and forest typing algorithms used were the same as for FIA. Subplots

were assigned to different conditions, but individual subplots were not mapped by

condition.

A very small number of plots from the Rogue River and Siskiyou National

Forests (Pacific Northwest Region) were also used in the hardwoods assessment.

Plots were sampled from a fixed 3.4- or 1.7-mile grid, depending on whether or not

they were located in wilderness. As with the other inventories, the plot contained

five subplots, but they were located 133.9 feet from the central subplot’s center.

Trees less than 5 inches d.b.h. were sampled within an 11.8-foot fixed radius of

subplot center. Trees between 5 and 12.9 inches were sampled with a 24-foot fixed

radius, and trees between 13 and 31.9 inches d.b.h. (east side) or 13 and 47.9

inches d.b.h. (west side) were sampled with a 51.1-foot radius. The largest trees

were sampled within a 185.1-foot radius from the central subplot’s center. Conditions were not mapped in the field. Forest typing algorithms and volume equation

assignments were identical to the FIA inventories.

Volume equations for oaks and most other California hardwoods come from

Pillsbury and Kirkley (1984). Volume equations for alder, aspen, and cottonwood

come from Brackett (1973). Forest typing was done by a two-step process. If the

stocking in hardwood trees was greater than the stocking in coniferous trees, the

area would be classed as a hardwood forest type. Then the area would be assigned

a specific hardwood forest type according to which hardwood tree species had the

greatest stocking. These inventory procedures have been kept consistent with other

reports from the 1990s inventories (for example, Waddell and Bassett 1996, 1997a,
RESOURCE BULLETIN PNW-RB-245

58

1997b). Statistical procedures are described in Barrett (2004). Owing to lack of

space, sampling errors are not included for every estimate in the tables, but these

can be obtained from the authors upon request.

Although ownership information and plot locations are confidential, other data

used in developing this report are available to the public. The four inventories

described here have been combined with other inventories into a single database.

To request a copy of this “PNW-FIA Integrated Database,” please visit the Web site

http://www.fs.fed.us/pnw/fia.

Monitoring and assessment of California hardwoods and oak woodlands are

continuing. Beginning in 2001, a new forest inventory system was implemented

that includes all land in California, both public and private, and both reserved and

unreserved forest. One-tenth of all plots are being sampled each year. Over a

decade, sampling intensity on woodland will increase to about one plot per 6,000

acres as compared to the one plot per 14,800 acres (current estimates) and one plot

per 29,600 acres (change estimates) used in this report. More information on this

annual Forest Inventory and Analysis system is available at http://

www.fia.fs.fed.us/.
Oak Woodlands and Other Hardwood Forest of California, 1990s

59

Table 1—Area of hardwood and softwood forest types on woodland and timberland by resource area and reserve status, California, 1990s

Timberland Woodland Total

Resource area and Unreserved Reserved Total Unreserved Reserved Total Unreserved Reserved Totalforest type group Area SE Area SE Area SE

– – – – – – Thousand acres – – – – – – % – – – – – – Thousand acres – – – – – – % – – – – – – Thousand acres – – – – – – %

North Coast:

Hardwoods 1,831.6 33.2 1,864.9 4 534.8 6.3 541.1 7 2,366.4 39.5 2,406.0 4Softwoods 1,497.5 140.9 1,638.4 5 3.8 — 3.8 65 1,501.3 140.9 1,642.2 5Other a 69.1 12.2 81.3 27 6.9 — 6.9 79 76.0 12.2 88.2 26

Total 3,398.2 186.4 3,584.6 545.5 6.3 551.8 3,943.7 192.7 4,136.4SE (%) 2 14 2 7 100 7 2 14 2

North Interior:

Hardwoods 790.9 89.5 880.4 8 714.2 32.2 746.4 6 1,505.1 121.7 1,626.8 5Softwoods 5,160.5 633.7 5,794.2 2 227.8 37.5 265.3 15 5,388.3 671.2 6,059.5 2Other a 334.6 73.4 408.1 11 76.2 33.5 109.7 30 410.8 106.9 517.8 10

Total 6,286.0 796.6 7,082.6 1,018.2 103.2 1,121.4 7,304.2 899.8 8,204.0SE (%) 1 8 1 6 29 5 1 7 1

Sacramento:

Hardwoods 580.3 26.9 607.2 9 1,605.8 23.1 1,628.9 4 2,186.1 50.0 2,236.1 4Softwoods 3,744.6 126.7 3,871.3 2 42.1 16.8 58.9 35 3,786.7 143.5 3,930.2 2Other a 259.0 24.9 283.9 14 40.6 30.6 71.2 28 299.6 55.5 355.1 12

Total 4,583.8 178.5 4,762.3 1,688.5 70.5 1,759.0 6,272.3 249.0 6,521.3SE (%) 1 17 1 4 32 4 1 15 1

Central Coast:

Hardwoods 157.6 34.8 192.3 15 1,503.8 131.5 1,635.3 5 1,661.4 166.3 1,827.6 5Softwoods 137.4 55.2 192.5 16 7.0 0.0 7.0 100 144.4 55.2 199.5 16Other a 13.0 28.7 41.6 36 47.7 49.6 97.3 25 60.7 78.3 138.9 20

Total 307.9 118.6 426.5 1,558.5 181.1 1,739.6 1,866.4 299.7 2,166.1SE (%) 9 18 8 5 19 5 4 13 4
RESOURCE BULLETIN PNW-RB-245

60

Table 1—Area of hardwood and softwood forest types on woodland and timberland by resource area and reserve status, California, 1990s (continued)

Timberland Woodland Total

Resource area and Unreserved Reserved Total Unreserved Reserved Total Unreserved Reserved Totalforest type group Area SE Area SE Area SE

– – – – – – Thousand acres – – – – – – % – – – – – – Thousand acres – – – – – – % – – – – – – Thousand acres – – – – – – %

Southern:

Hardwoods 428.3 101.1 529.4 9 2,530.2 134.6 2,664.8 3 2,958.5 235.7 3,194.2 3Softwoods 1,812.5 977.5 2,790.0 2 189.4 129.4 318.8 17 2,001.9 1,106.9 3,108.8 3Other a 153.0 122.8 275.8 14 343.5 162.3 505.8 12 496.5 285.1 781.6 9

Total 2,393.9 1,201.4 3,595.3 3,063.1 426.3 3,489.4 5,457.0 1,627.7 7,084.7SE (%) 3 5 2 3 13 3 2 5 2

Total, California:

Hardwoods 3,788.7 285.5 4,074.2 3 6,888.8 327.7 7,216.5 2 10,677.5 613.2 11,290.7 2Softwoods 12,352.5 1,933.9 14,286.4 1 470.1 183.7 653.8 11 12,822.6 2,117.6 14,940.2 1Other a 828.7 262.1 1,090.7 7 514.9 276.0 790.9 10 1,343.6 538.1 1,881.6 6

Total 16,969.8 2,481.5 19,451.3 7,873.8 787.4 8,661.2 24,843.6 3,268.9 28,112.5SE (%) 1 4 1 2 9 2 1 3 1

Note: Excludes reserved lands outside of national forests because these areas were not sampled.SE = sampling error.— = less than 50 acres.

a Other includes nonstocked and unclassified types.
Oak Woodlands and Other Hardwood Forest of California, 1990s

61

Table 2—Area of hardwood forest types on woodland and timberland by resource area and owner, California, 1990s

Woodland Timberland Total

Resource area National Other Total National Other Total National Other Total

and forest type forest public Private Area SE forest public Private Area SE forest public Private Area SE

– – – – – – – Thousand acres – – – – – – – % – – – – – – – Thousand acres – – – – – – – % – – – – – – Thousand acres – – – – – – %

North Coast:

Oak group—

Blue oaka — — 29.0 29.0 63 — — — — — — 29.0 29.0 63

California black oak 10.1 — 45.3 55.4 43 12.7 1.1 131.0 144.7 20 22.8 1.1 176.3 200.1 19Canyon live oak 27.4 — 29.1 56.5 43 14.0 23.8 84.4 122.2 23 41.4 23.8 113.5 178.7 21Coast live oak — 11.9 85.2 97.1 29 — — 23.8 23.8 46 — 11.9 109.0 120.9 25Interior live oak 5.2 — — 5.2 100 — 1.9 12.3 14.2 63 5.2 1.9 12.3 19.4 53

Oregon white oak 31.8 2.3 133.0 167.2 24 — — 126.1 126.1 21 31.8 2.3 259.1 293.2 17Valley oak — — 40.3 40.3 57 — — 13.2 13.2 62 — — 53.5 53.5 47

Total 74.5 14.2 362.0 450.7 26.7 26.8 390.8 444.2 101.2 41.0 752.8 894.9

Non-oak group—

Bigleaf maple — — 9.1 9.1 100 — — 22.0 22.0 58 — — 31.1 31.1 51

Buckeye — — 4.3 4.3 100 — — — — — — 4.3 4.3 100California laurel — — 27.0 27.0 68 2.0 — 74.7 76.7 27 2.0 — 101.7 103.7 27Cottonwood/aspen — — — — — — 5.2 5.2 100 — — 5.2 5.2 100Eucalyptus — — — — — — 3.6 3.6 100 — — 3.6 3.6 100Giant chinquapin — — — — 6.6 — 6.2 12.8 59 6.6 — 6.2 12.8 59Oregon ash — — 16.5 16.5 100 — — — — — — 16.5 16.5 100Pacific madrone — — 29.5 29.5 70 18.7 11.4 124.9 155.0 21 18.7 11.4 154.4 184.5 22Red alder 4.1 — — 4.1 100 2.1 — 75.8 77.9 30 6.2 — 75.8 82.0 29Tanoak — — — — 131.2 — 926.8 1,058.0 7 131.2 — 926.8 1,058.0 7Willow — — — — — — 9.6 9.6 71 — — 9.6 9.6 71

Total 4.1 — 86.4 90.5 160.6 11.4 1,248.8 1,420.8 164.7 11.4 1,335.2 1,511.3

Total, North Coast 78.6 14.2 448.4 541.2 187.3 38.2 1,639.6 1,865.0 265.9 52.4 2,088.0 2,406.3SE for total (%) 26 45 8 7 15 46 5 4 13 34 4 4 
RESOURCE BULLETIN PNW-RB-245

62Table 2—Area of hardwood forest types on woodland and timberland by resource area and owner, California, 1990s (continued)

 Woodland Timberland Total

Resource area National Other Total National Other Total National Other Totaland forest type forest public Private Area SE forest public Private Area SE forest public Private Area SE

– – – – – – Thousand acres – – – – – – % – – – – – – Thousand acres – – – – – – % – – – – – – Thousand acres – – – – – – %

North Interior:

Oak group—

Blue oaka 15.8 24.6 221.6 262.0 18 — — — — 15.8 24.6 221.6 262.0 18

California black oak 26.2 — 37.5 63.7 40 105.4 8.7 148.1 262.2 15 131.6 8.7 185.6 326.0 14Canyon live oak 113.7 9.3 34.1 157.2 20 166.3 9.6 75.2 251.2 16 280.0 18.9 109.4 408.3 13Interior live oak 6.2 — 29.3 35.5 61 12.2 — — 12.2 60 18.4 — 29.3 47.7 48Oregon white oak 46.2 26.0 113.5 185.7 21 29.6 9.2 35.2 74.0 28 75.8 35.2 148.7 259.7 17Valley oak — — 17.5 17.5 93 8.0 — — 8.0 100 8.0 — 17.5 25.5 71

Total 208.1 59.9 453.6 721.7 321.5 27.6 258.5 607.6 529.6 87.5 712.2 1,329.3

Non-oak group—

Bigleaf maple 5.7 — — 5.7 100 12.4 3.4 9.6 25.4 53 18.1 3.4 9.6 31.1 47California laurel — — — — — — 9.6 9.6 100 — — 9.6 9.6 100Cottonwood/aspen — — 7.2 7.2 100 20.6 1.7 — 22.3 48 20.6 1.7 7.2 29.5 44Dogwood — — — — — — 3.2 3.2 100 — — 3.2 3.2 100Giant chinquapin — — — — 11.6 — — 11.6 98 11.6 — — 11.6 98Pacific madrone 9.3 — — 9.3 100 57.0 — 22.5 79.5 29 66.3 — 22.5 88.8 28Red alder — — — — 10.4 — — 10.4 82 10.4 — — 10.4 82

Tanoak 2.6 — — 2.6 100 87.0 — 23.7 110.7 24 89.6 — 23.7 113.3 24

Total 17.6 — 7.2 24.8 199.0 5.1 68.6 272.7 216.6 5.1 75.8 297.5

Total, North Interior 225.7 59.9 460.9 746.5 520.5 32.7 327.1 880.3 746.2 92.6 788.0 1,626.8SE for total (%) 13 22 7 6 10 43 14 8 8 22 7 5 
Oak Woodlands and Other Hardwood Forest of California, 1990s

63

Table 2—Area of hardwood forest types on woodland and timberland by resource area and owner, California, 1990s (continued)

Woodland Timberland Total

Resource area National Other Total National Other Total National Other Total

 and forest type forest public Private Area SE forest public Private Area SE forest public Private Area SE

– – – – – – Thousand acres – – – – – – % – – – – – – Thousand acres – – – – – – % – – – – – Thousand acres – – – – – %

Sacramento:

Oak group—

Blue oaka 1.4 35.8 992.0 1,029.2 8 — — — — 87.1 35.8 992.0 1,029.2 8

California black oak 36.6 — 60.1 96.7 29 164.4 — 149.1 313.5 13 201.0 — 209.2 410.2 12Canyon live oak 118.6 21.0 76.2 215.8 19 85.7 19.7 73.9 179.3 18 204.3 40.7 150.1 395.1 13Interior live oak 7.4 — 243.3 250.7 21 3.5 — 33.7 37.2 40 10.9 — 277.0 287.9 19Oregon white oak 8.4 — — 8.4 100 — — — — 8.4 — — 8.4 100Valley oak 1.4 — 17.5 18.9 93 — — — — 1.4 — 17.5 18.9 93

Total 173.8 56.9 1,389.0 1,619.7 253.6 19.7 256.7 530.0 513.1 76.6 1,645.72,149.7

Non-oak group—

Bigleaf maple — — — — 2.9 — — 2.9 100 2.9 — — 2.9 100Buckeye 6.3 — — 6.3 100 — — — — 6.3 — — 6.3 100California laurel — — — — — — 15.6 15.6 71 — — 15.6 15.6 71

Dogwood — — — — 1.9 — — 1.9 100 1.9 — — 1.9 100Pacific madrone — — — — 10.2 — 13.7 23.9 52 10.2 — 13.7 23.9 52Tanoak — — — — 10.2 — 19.6 29.8 38 10.2 — 19.6 29.8 38White alder — — — — — — 3.1 3.1 100 — — 3.1 3.1 100Willow — — 2.9 2.9 100 — — — — — — 2.9 2.9 100

Total 6.3 — 2.9 9.2 25.2 — 51.9 77.1 31.5 — 54.8 86.3

Total, Sacramento 180.1 56.9 1,391.9 1,628.9 278.8 19.7 308.6 607.1 544.6 76.6 1,700.5 2,236.0SE for total (%) 13 22 5 4 11 49 14 9 8 21 5 4 
RESOURCE BULLETIN PNW-RB-245

64Table 2—Area of hardwood forest types on woodland and timberland by resource area and owner, California, 1990s (continued)

Woodland Timberland Total

Resource area National Other Total National Other Total National Other Total

 and forest type forest public Private Area SE forest public Private Area SE forest public Private Area SE

– – – – – – Thousand acres – – – – – – – % – – – – – – Thousand acres – – – – – – % – – – – – – Thousand acres – – – – – – %

Central Coast:

Oak group—

Blue oaka 66.7 91.1 429.7 587.4 13 — — 3.9 3.9 100 66.7 91.1 433.6 591.3 13

Canyon live oak 63.6 — — 63.6 27 36.5 — 12.8 49.3 35 100.1 — 12.8 112.9 21Coast live oak 122.8 57.6 585.0 765.4 11 3.7 — 39.6 43.3 50 126.5 57.6 624.6 808.7 10Interior live oak 7.3 — 13.7 21.0 71 4.4 — — 4.4 72 11.7 — 13.7 25.4 60Oregon white oak — — 5.9 5.9 77 — — — — — — 5.9 5.9 77Valley oak — — 53.7 53.7 50 — — — — — — 53.7 53.7 50

Total 260.4 148.6 1,087.9 1,496.9 44.6 — 56.3 100.9 305.0 148.6 1,144.2 1,597.8

Non-oak group—

Bigleaf maple 17.9 — 3.5 21.4 50 — — — — 17.9 — 3.5 21.4 50California laurel 4.8 — 41.2 46.0 53 1.8 — 11.5 13.3 88 6.6 — 52.7 59.3 46Eucalyptus — — 17.5 17.5 100 — — — — — — 17.5 17.5 100Pacific madrone 8.3 — 17.5 25.8 74 18.6 — 6.6 25.2 45 26.9 — 24.1 51.0 43Sycamore — 19.5 — 19.5 100 — — — — — 19.5 — 19.5 100Tanoak — — — — — — 47.7 47.7 36 — — 47.7 47.7 36

Willow — — — — — — 2.4 2.4 100 — — 2.4 2.4 100Other hardwoods 8.3 — — 8.3 100 3.0 — — 3.0 80 11.3 — — 11.3 77

Total 39.3 19.5 79.6 138.4 23.4 — 68.2 91.6 62.7 19.5 147.8 230.0

Total, Central Coast 299.7 168.1 1,167.6 1,635.4 68.0 — 124.4 192.4 367.7 168.1 1,292.0 1,827.8SE for total (%) 11 16 6 5 22 20 15 9 16 6 5
Oak Woodlands and Other Hardwood Forest of California, 1990s

65

Table 2—Area of hardwood forest types on woodland and timberland by resource area and owner, California, 1990s (continued)

Woodland Timberland Total

Resource area National Other Total National Other Total National Other Total

 and forest type forest public Private Area SE forest public Private Area SE forest public Private Area SE

– – – – – – Thousand acres – – – – – – % – – – – – – Thousand acres – – – – – – % – – – – – – Thousand acres – – – – – – %

Southern:

Oak group—

Blue oaka 46.8 18.7 1,051.3 1,116.8 8 — — — — 46.8 18.7 1,051.3 1,116.8 8

California black oak 50.3 2.5 18.7 71.5 32 198.5 6.7 41.8 247.0 14 248.8 9.2 60.5 318.6 13Canyon live oak 251.5 19.5 59.3 330.3 15 119.8 11.5 68.4 199.7 15 371.3 30.9 127.7 529.9 11Coast live oak 57.2 12.0 61.6 130.8 21 0.8 — 6.7 7.5 74 58.0 12.0 68.3 138.3 20Engelmann oak — — 63.3 63.3 41 — — — — — — 63.3 63.3 41Interior live oak 88.7 97.7 531.9 718.2 12 20.6 — 20.9 41.5 35 109.3 97.7 552.8 759.7 11Oregon white oak — — 12.9 12.9 100 — — — — — — 12.9 12.9 100

Total 494.5 150.4 1,799.0 2,443.8 339.7 18.2 137.8 495.7 834.2 168.5 1,936.8 2,939.5

Non-oak group—

Bigleaf maple 2.4 — — 2.4 100 — — — — 2.4 — — 2.4 100Buckeye 28.8 — 74.0 102.8 35 6.2 — — 6.2 100 35.0 — 74.0 109.0 34California laurel 17.0 — — 17.0 54 — — — — 17.0 — — 17.0 54Cottonwood/aspen 24.6 — — 24.6 55 5.3 12.7 — 18.0 75 29.9 12.7 — 42.6 45Eucalyptus — — 8.5 8.5 100 — — — — — — 8.5 8.5 100Oregon ash 4.0 — — 4.0 100 — — — — 4.0 — — 4.0 100Sycamore 1.5 — — 1.5 100 — — — — 1.5 — — 1.5 100Walnut — — 5.7 5.8 100 — — — — — — 5.7 5.8 100White alder 8.2 — 16.1 24.3 71 5.6 — 3.5 9.1 51 13.8 — 19.6 33.4 54Willow — — 11.4 11.4 100 — — — — — — 11.4 11.4 100Other hardwoods 18.6 — — 18.6 52 0.4 — — 0.4 100 19.0 — — 19.0 50

Total 105.1 — 115.8 220.9 17.5 12.7 3.5 33.7 122.6 12.7 119.3 254.6

Total, Southern 599.6 150.4 1,914.8 2,664.8 357.2 30.9 141.3 529.4 956.8 181.3 2,056.1 3,194.2SE for total (%) 7 18 4 3 11 48 20 9 5 17 4 3
RESOURCE BULLETIN PNW-RB-245

66Table 2—Area of hardwood forest types on woodland and timberland by resource area and owner, California, 1990s (continued)

Woodland Timberland Total

Resource area National Other Total National Other Total National Other Total

and forest type forest public Private Area SE forest public Private Area SE forest public Private Area SE

– – – – – – Thousand acres – – – – – – % – – – – – – Thousand acres – – – – – – % – – – – – – Thousand acres – – – – – – %

Total, California:

Oak group—

Blue oaka 130.7 170.2 2,723.6 3,024.5 5 — — 3.9 3.9 100 216.4 170.2 2,727.5 3,028.4 5

California black oak 123.2 2.5 161.6 287.3 17 481.0 16.5 470.0 967.5 8 604.2 19.0 631.6 1,254.8 7Canyon live oak 574.8 49.8 198.8 823.4 9 422.3 64.6 314.7 801.6 9 997.1 114.4 513.5 1,625.0 6Coast live oak 180.0 81.5 731.8 993.3 9 4.5 — 70.1 74.6 33 184.5 81.5 801.9 1,067.9 9Engelmann oak — — 63.3 63.3 41 — — — — — — 63.3 63.3 41Interior live oak 114.8 97.7 818.2 1,030.6 10 40.7 1.9 66.9 109.5 22 155.5 99.6 885.1 1,140.1 9Oregon white oak 86.4 28.3 265.4 380.1 15 29.6 9.2 161.2 200.1 17 116.0 37.5 426.6 580.1 12Valley oak 1.4 — 129.0 130.4 33 8.0 — 13.2 21.2 54 9.4 — 142.2 151.6 29

Total 1,211.3 430.0 5,091.6 6,732.8 986.1 92.2 1,100.1 2,178.4 2,283.1 522.2 6,191.6 8,911.2

Non-oak group—

Bigleaf maple 26.0 — 12.6 38.6 41 15.3 3.4 31.6 50.3 37 41.3 3.4 44.1 88.9 28Buckeye 35.1 — 78.3 113.4 32 6.2 — — 6.2 100 41.3 — 78.3 119.6 31California laurel 21.8 — 68.2 90.0 36 3.8 — 111.3 115.1 24 25.6 — 179.5 205.1 21Cottonwood/aspen 24.6 — 7.2 31.9 48 25.9 14.4 5.2 45.5 39 50.5 14.4 12.4 77.3 31Dogwood — — — — 1.9 — 3.2 5.1 73 1.9 — 3.2 5.1 73Eucalyptus — — 25.9 25.9 79 — — 3.6 3.6 100 — — 29.5 29.5 69Giant chinquapin — — — — 18.2 — 6.2 24.4 56 18.2 — 6.2 24.4 56Oregon ash 4.0 — 16.5 20.5 85 — — — — 4.0 — 16.5 20.5 85Pacific madrone 17.6 — 47.0 64.6 46 104.5 11.4 167.7 283.6 15 122.1 11.4 214.6 348.1 15Red alder 4.1 — — 4.1 100 12.5 — 75.8 88.3 28 16.6 — 75.8 92.4 27Sycamore 1.5 19.5 — 21.0 91 — — — — 1.5 19.5 — 21.0 91Tanoak 2.6 — — 2.6 100 228.4 — 1,017.9 1,246.3 6 231.0 — 1,017.9 1,248.9 6Walnut — — 5.7 5.8 100 — — — — 0.0 — 5.7 5.8 100White alder 8.2 — 16.1 24.3 71 5.6 — 6.6 12.2 46 13.8 — 22.7 36.5 51Willow — — 14.4 14.4 84 — — 12.0 12.0 60 — — 26.4 26.4 54Other hardwoods 26.9 — — 26.9 47 3.4 — — 3.4 71 30.3 — — 30.3 43

Total 172.5 19.5 292.0 483.9 425.7 29.2 1,441.0 1,895.9 598.2 48.7 1,732.9 2,379.8

Total, California 1,383.8 449.5 5,383.5 7,216.7 1,411.8 121.4 2,541.1 4,074.3 2,881.3 570.9 7,924.6 11,291.0SE for total (%) 5 10 2 2 5 24 4 3 3 9 2 2

Note: Excludes reserved lands outside of national forests because these areas were not sampled.SE = sampling error.— = less than 50 acres.a The blue oak forest type includes 110,000 acres initially classified as ghost pine (Pinus sabiniana).
Oak Woodlands and Other Hardwood Forest of California, 1990s

67

Table 3—Net growing-stock volume of hardwood species on woodland and timberland by resource area and owner, California, 1990s

Woodland Timberland Total

Resource area National Other Total National Other Total National Other Total  and species forest public Private Volume SE forest public Private Volume SE forest public Private Volume SE

– – – – – – Million cubic feet – – – – – – % – – – – – – Million cubic feet – – – – – – % – – – – – – Million cubic feet – – – – – –%

North Coast:

Oak group—

Blue oak — — 32.3 32.3 53 — — — — — — 32.3 32.3 53California black oak 16.9 — 81.8 98.7 22 35.4 22.7 257.7 315.8 15 52.3 22.7 339.6 414.5 12Canyon live oak 49.5 — 47.2 96.7 37 82.4 37.5 188.9 308.7 17 131.9 37.5 236.1 405.5 16Coast live oak — 4.8 55.1 59.8 36 — — 22.6 22.6 37 — 4.8 77.7 82.5 29Interior live oak — — 5.3 5.3 71 3.0 2.3 25.5 30.7 39 3.0 2.3 30.8 36.0 34Oregon white oak 46.8 .7 164.0 211.5 26 3.0 6.2 178.1 187.3 19 49.8 6.9 342.1 398.8 17Valley oak — — 28.8 28.8 55 — — 25.5 25.5 44 — — 54.4 54.4 37

Total 113.3 5.4 414.5 533.2 123.7 68.6 698.4 890.7 236.9 74.1 1,112.9 1,423.9

Non-oak group—

Bigleaf maple 3.6 — 6.0 9.6 51 26.6 4.8 69.9 101.2 22 30.2 4.8 75.8 110.8 20Black cottonwood — — — — — — 6.8 6.8 94 — — 6.8 6.8 94California buckeye — — 1.3 1.3 75 — — — — — — 1.3 1.3 75California laurel — — 58.9 58.9 50 6.6 6.4 194.4 207.3 15 6.6 6.4 253.3 266.3 17Eucalyptus — — — — — — 15.3 15.3 80 — — 15.3 15.3 80Giant chinquapin — — — — 29.6 — 20.8 50.5 35 29.6 — 20.8 50.5 35Oregon ash — — — — — — 1.3 1.3 99 — — 1.3 1.3 99Pacific madrone 9.6 1.7 69.2 80.6 35 154.2 52.5 688.7 895.5 9 163.9 54.3 758.0 976.1 9Red alder — — — — 2.5 — 203.6 206.1 23 2.5 — 203.6 206.1 23Tanoak — — — — 278.6 35.7 1,499.0 1,813.3 7 278.6 35.7 1,499.0 1,813.3 7White alder — — — — 1.0 — — 1.0 74 1.0 — — 1.0 74

Total 13.2 1.7 135.4 150.3 499.2 99.3 2,699.9 3,298.4 512.5 101.1 2,835.3 3,448.8

Total, North Coast 126.5 7.2 549.9 683.6 622.9 168.0 3,398.2 4,189.1 749.4 175.1 3,948.1 4,872.7SE for total (%) 35 87 12 11 19 22 5 5 17 21 5 5 
RESOURCE BULLETIN PNW-RB-245

68

Table 3—Net growing-stock volume of hardwood species on woodland and timberland by resource area and owner, California, 1990s (continued)

Woodland Timberland Total

Resource area National Other Total National Other Total National Other Total and species forest public Private Volume SE forest public Private Volume SE forest public Private Volume SE

– – – – – – Million cubic feet – – – – – – % – – – – – – Million cubic feet – – – – – – % – – – – – – Million cubic feet – – – – – –%

North Interior:

Oak group—

Blue oak — 1.5 86.4 87.9 27 — — — — — 1.5 86.4 87.9 27California black oak 53.8 4.1 38.1 96.0 26 355.6 30.3 358.1 744.0 8 409.4 34.4 396.2 840.0 8Canyon live oak 112.0 12.6 17.4 142.0 25 452.7 26.2 188.2 667.1 11 564.7 38.9 205.6 809.2 10Coast live oak — — — — .2 — — .2 100 .2 — — .2 100Interior live oak 12.0 — 13.1 25.1 47 21.7 — .5 22.1 33 33.7 — 13.6 47.2 29Oregon white oak 27.5 12.6 43.4 83.5 30 31.5 7.2 37.6 76.4 20 59.0 19.8 81.1 159.9 18Valley oak .7 — 18.9 19.6 60 2.1 — .7 2.8 39 2.8 — 19.6 22.4 53

Total 206.0 30.8 217.3 454.1 863.8 63.8 585.1 1,512.7 1,069.8 94.7 802.4 1,966.8

Non-oak group—

Bigleaf maple 21.7 — 1.7 23.4 57 62.4 3.1 34.9 100.4 21 84.0 3.1 36.6 123.8 20

Black cottonwood — — 9.0 9.0 100 .1 1.3 — 1.4 95 .1 1.3 9.0 10.4 88

California laurel — — — — 1.8 — 8.0 9.8 68 1.8 — 8.0 9.8 68Eucalyptus — — — — — — — — 100 — — — — 100Giant chinquapin 1.3 — — 1.3 100 21.6 — 4.5 26.1 32 22.9 — 4.5 27.4 31Oregon ash — — — — .8 — — .8 100 .8 — — 0.8 100Pacific madrone 21.6 — 2.1 23.6 74 305.6 — 39.6 345.3 13 327.2 — 41.7 368.9 13Quaking aspen — — — — 26.1 — 11.3 37.4 55 26.1 — 11.3 37.4 55

Red alder .4 — — .4 100 13.5 — — 13.5 39 13.9 — — 13.9 38Tanoak 3.1 — — 3.1 100 132.8 — 27.3 160.2 24 136.0 — 27.3 163.3 24White alder .7 — — .7 100 6.3 — 8.6 14.9 46 6.9 — 8.6 15.5 45

Total 48.7 — 12.8 61.6 571.0 4.4 134.3 709.7 619.8 4.4 147.1 771.3

Total, North Interior 254.7 30.8 230.1 515.7 1,434.8 68.3 719.3 2,222.4 1,689.5 99.1 949.5 2,738.1SE for total (%) 22 49 18 14 7 33 9 6 7 27 8 5 
Oak Woodlands and Other Hardwood Forest of California, 1990s

69

Table 3—Net growing-stock volume of hardwood species on woodland and timberland by resource area and owner, California, 1990s (continued)

Woodland Timberland Total

Resource area National Other Total National Other Total National Other Total 

 and species forest public Private Volume SE forest public Private Volume SE forest public Private Volume SE

– – – – – – Million cubic feet – – – – – – % – – – – – – Million cubic feet – – – – – – % – – – – – – Million cubic feet – – – – – –%

Sacramento: 

Oak group—

Blue oak — 10.0 432.3 442.3 12 — — 2.6 2.6 100 — 10.0 434.9 444.8 12California black oak 58.4 — 78.6 137.0 21 450.7 14.4 513.6 978.7 8 509.1 14.4 592.2 1,115.8 8Canyon live oak 124.0 10.5 51.8 186.3 22 223.8 32.6 135.1 391.5 14 347.8 43.0 186.9 577.8 12Interior live oak — 3.6 75.9 79.5 25 4.5 .1 16.3 20.9 36 4.5 3.7 92.2 100.4 21Oregon white oak .2 — — .2 100 .9 — .5 1.4 75 1.2 — .5 1.6 66Valley oak 2.5 — 33.0 35.5 78 2.5 — 33.0 35.5 78

Total 185.2 24.1 671.6 880.8 679.9 47.1 668.1 1,395.1 865.1 71.1 1,339.7 2,275.9

Non-oak group—

Bigleaf maple 6.0 — 8.7 14.6 54 8.8 — 29.1 37.9 25 14.8 — 37.7 52.6 24Black cottonwood — — — — — — 5.0 5.0 83 — — 5.0 5.0 83California laurel .2 — — .2 100 3.6 — 10.1 13.7 53 3.8 — 10.1 14.0 52California sycamore .2 — — .2 100 — — — — .2 — — .2 100Oregon ash .2 — — .2 100 — — — — .2 — — .2 100Pacific madrone .3 — — .3 72 42.7 2.0 55.1 99.9 20 43.0 2.0 55.1 100.2 20Quaking aspen .2 — — .2 100 1.7 — 2.3 4.0 64 1.9 — 2.3 4.2 62Red alder — — — — 2.5 — 10.4 12.9 53 2.5 — 10.4 12.9 53Tanoak — — — — 41.6 — 50.5 92.1 21 41.6 — 50.5 92.1 21White alder .9 — — .9 100 1.7 — 10.3 12.1 47 2.7 — 10.3 13.0 44

Total 8.0 — 8.7 16.6 102.7 2.0 172.8 277.6 110.7 2.0 181.5 294.2

Total, Sacramento 193.1 24.1 680.3 897.4 782.6 49.1 840.9 1,672.7 975.8 73.2 1,521.2 2,570.1SE for total (%) 15 42 12 9 8 26 10 6 7 22 8 5
RESOURCE BULLETIN PNW-RB-245

70Table 3—Net growing-stock volume of hardwood species on woodland and timberland by resource area and owner, California, 1990s (continued)

Woodland Timberland Total

Resource area National Other Total National Other Total National Other Total 

and species forest public Private Volume SE forest public Private Volume SE forest public Private Volume SE

– – – – – – Million cubic feet – – – – – – % – – – – – – Million cubic feet – – – – – – % – – – – – – Million cubic feet – – – – – – %

Central Coast:

Oak group—

Blue oak — 20.8 160.3 181.1 17 — — 1.2 1.2 100 — 20.8 161.5 182.3 17California black oak — — 15.2 15.2 63 6.9 — 2.0 8.8 59 6.9 — 17.2 24.1 45Canyon live oak 2.3 — 6.9 9.2 75 18.3 — 47.3 65.6 74 20.7 — 54.2 74.8 66Coast live oak 54.2 35.8 583.9 673.9 14 1.4 — 109.6 111.0 43 55.6 35.8 693.6 784.9 14Interior live oak — — 33.6 33.6 100 2.4 — — 2.4 94 2.4 — 33.6 36.0 93Oregon white oak — — 13.4 13.4 80 — — 1.5 1.5 101 — — 14.9 14.9 72Valley oak — — 90.7 90.7 36 — — — — — — 90.7 90.7 36

Total 56.5 56.5 904.0 1,017.1 29.0 — 161.6 190.5 85.5 56.5 1,065.6 1,207.6

Non-oak group—

Bigleaf maple 1.3 — 20.6 21.9 77 — — .9 .9 72 1.3 — 21.5 22.8 74California buckeye — — 2.2 2.2 100 — — — — — — 2.2 2.2 100California laurel .4 3.8 80.6 84.8 38 .8 — 48.6 49.4 59 1.2 3.8 129.2 134.2 33California sycamore 3.4 11.2 31.7 46.3 41 — — — — 3.4 11.2 31.7 46.3 41Eucalyptus — — 96.0 96.0 100 — — 4.3 4.3 100 — — 100.3 100.3 95Pacific madrone 2.0 25.5 22.7 50.2 63 4.9 — 77.1 82.0 32 6.9 25.5 99.8 132.2 30Tanoak — — — — 2.1 — 163.7 165.8 39 2.1 — 163.7 165.8 39Other hardwoods — — — — 11.3 — — 11.3 73 11.3 — — 11.3 73

Total 7.2 40.5 253.8 301.5 19.1 — 294.5 313.7 26.3 40.5 548.4 615.1

Total, Central Coast 63.7 97.0 1,157.9 1,318.6 48.1 — 456.1 504.2 18 111.8 97.0 1,614.0 1,822.8SE for total (%) 39 43 13 12 30 20 18 25 43 11 10
Oak Woodlands and Other Hardwood Forest of California, 1990s

71

Table 3—Net growing-stock volume of hardwood species on woodland and timberland by resource area and owner, California, 1990s (continued)

Woodland Timberland Total

Resource area National Other Total National Other Total National Other Total 

 and species forest public Private Volume SE forest public Private Volume SE forest public Private Volume SE

– – – – – – Million cubic feet – – – – – – % – – – – – – Million cubic feet – – – – – – % – – – – – – Million cubic feet – – – – – –%

Southern:

Oak group—

Blue oak — 17.4 409.0 426.4 13 — — — — — 17.4 409.0 426.4 13California black oak 67.2 9.1 8.6 84.9 29 290.4 10.3 203.7 504.5 10 357.6 19.4 212.3 589.4 9Canyon live oak 162.9 19.4 84.8 267.0 20 122.3 20.2 95.8 238.3 16 285.2 39.6 180.6 505.3 13Coast live oak 47.5 16.4 45.2 109.2 16 .8 — 1.5 2.3 68 48.3 16.4 46.8 111.5 16Engelmann oak — — 38.6 38.6 58 — — — — — — 38.6 38.6 58Interior live oak 31.1 12.0 197.2 240.3 18 3.7 — 2.0 5.7 51 34.9 12.0 199.2 246.0 17Oregon white oak — — 1.1 1.1 100 — — .2 .2 100 — — 1.4 1.4 85Valley oak — — 19.4 19.4 55 — — 7.7 7.7 54 — — 27.1 27.1 43

Total 308.7 74.3 804.0 1,187.0 417.3 30.6 310.9 758.8 726.0 104.8 1,114.9 1,945.7

Non-oak group—

Bigleaf maple 6.5 — — 6.5 64 6.4 — 2.1 8.5 41 12.9 — 2.1 15.0 36Black cottonwood .2 — — .2 75 — — — — .2 — — .2 75California buckeye — 1.3 12.2 13.4 46 — — — — — 1.3 12.2 13.4 46California laurel 3.8 — — 3.8 54 — .3 1.1 1.4 81 3.8 .3 1.1 5.3 45California sycamore .8 — — .8 55 — — — — .8 — — .8 55Eucalyptus — — 10.1 10.1 100 — — — — — — 10.1 10.1 100Oregon ash 4.9 — — 4.9 98 .8 1.5 — 2.3 75 5.7 1.5 — 7.2 71Pacific madrone — — — — — — 2.3 2.3 101 — — 2.3 2.3 101Quaking aspen 2.2 — — 2.2 100 2.6 — 2.7 5.3 63 4.8 — 2.7 7.5 53Red alder — — — — .8 — — .8 100 .8 — — .8 100Tanoak — — — — — — .7 .7 79 — — .7 .7 79Walnut — — — — — — 1.1 1.1 100 — — 1.1 1.1 100White alder 6.8 — 2.4 9.2 44 13.0 — 11.7 24.7 33 19.8 — 14.1 33.9 27

Total 25.3 1.3 24.7 51.2 23.6 1.8 21.7 47.1 48.9 3.1 46.4 98.3

Total, Southern 334.0 75.5 828.7 1,238.2 7 440.9 32.4 332.6 805.9 774.9 107.9 1,161.3 2,044.1 5SE for total (%) 10 36 9 7 9 33 17 9 6 28 8 5 
RESOURCE BULLETIN PNW-RB-245

72Table 3—Net growing-stock volume of hardwood species on woodland and timberland by resource area and owner, California, 1990s (continued)

Woodland Timberland Total

Resource area National Other Total National Other Total National Other Total 

 and species forest public Private Volume SE forest public Private Volume SE forest public Private Volume SE

– – – – – – Million cubic feet – – – – – – % – – – – – – Million cubic feet – – – – – – % – – – – – – Million cubic feet – – – – – – %

Total, California:

Oak group—

Blue oak — 49.6 1,120.2 1,169.9 8 — — 3.8 3.8 75 — 49.6 1,124.0 1,173.7 8California black oak 196.4 13.2 222.4 431.9 12 1,139.0 77.7 1,335.2 2,551.9 5 1,335.3 90.9 1,557.5 2,983.8 4Canyon live oak 450.8 42.5 208.1 701.3 12 899.5 116.5 655.3 1,671.3 7 1,350.2 159.0 863.4 2,372.6 6Coast live oak 101.7 57.0 684.3 842.9 12 2.4 — 133.8 136.2 36 104.1 57.0 818.0 979.1 11Engelmann oak — — 38.6 38.6 58 — — — — — — 38.6 38.6 58Interior live oak 43.2 15.6 325.0 383.8 15 35.2 2.4 44.2 81.9 20 78.4 18.0 369.3 465.6 13Oregon white oak 74.5 13.3 222.0 309.8 20 35.4 13.4 218.0 266.8 15 110.0 26.7 439.9 576.6 13Valley oak 3.2 — 190.8 194.0 25 2.1 — 33.9 36.0 34 5.2 — 224.7 230.0 21

Total 869.6 191.1 3,011.4 4,072.2 2,113.6 210.1 2,424.1 4,747.8 2,983.3 401.2 5,435.5 8,820.0

Non-oak group—

Bigleaf maple 39.0 — 36.9 75.9 30 104.2 7.9 136.8 248.9 13 143.2 7.9 173.8 324.9 12Black cottonwood .2 — 9.0 9.2 98 .1 1.3 11.8 13.2 60 .3 1.3 20.8 22.4 54California buckeye — 1.3 15.6 16.9 39 — — — — — 1.3 15.6 16.9 39California laurel 4.5 3.8 139.6 147.9 30 12.8 6.7 262.2 281.7 16 17.3 10.5 401.7 429.5 15California sycamore 4.4 11.2 31.7 47.3 40 — — — — 4.4 11.2 31.7 47.3 40Eucalyptus — — 106.1 106.1 93 — — 19.6 19.6 66 — — 125.7 125.7 78Giant chinquapin 1.3 — — 1.3 100 51.2 — 25.3 76.5 25 52.5 — 25.3 77.8 25Oregon ash 5.1 — — 5.1 94 1.6 1.5 1.3 4.4 52 6.7 1.5 1.3 9.5 56Pacific madrone 33.5 27.2 94.0 154.8 29 507.5 54.6 862.9 1,425.0 7 541.0 81.8 956.9 1,579.7 7Quaking aspen 2.4 — — 2.4 93 30.4 — 16.3 46.8 45 32.8 — 16.3 49.2 43Red alder .4 — — .4 100 19.4 — 214.0 233.3 21 19.8 — 214.0 233.7 21Tanoak 3.1 — — 3.1 100 455.2 35.7 1,741.2 2,232.0 7 458.3 35.7 1,741.2 2,235.2 7Walnut — — — — — — 1.1 1.1 100 — — 1.1 1.1 100White alder 8.4 — 2.4 10.8 39 22.1 — 30.6 52.7 23 30.4 — 33.0 63.4 20Other hardwoods — — — — 11.3 — — 11.3 69 11.3 — — 11.3 69

Total 102.4 43.5 435.4 581.2 1,215.7 107.6 3,323.2 4,646.6 1,318.1 151.1 3,758.6 5,227.8

Total, California 972.0 234.6 3,446.8 4,653.4 3,329.4 317.7 5,747.3 9,394.3 4,301.4 552.3 9,194.0 14,047.7 3SE for total (%) 9 22 6 5 5 15 4 3 4 12 3 3Note: Excludes reserved lands outside of national forests because these areas were not sampled.Excludes cull trees and cull volume; includes growing-stock trees ≥5 inches diameter at breast height.

SE= sampling error.— = less than 50,000 cubic feet.
Oak Woodlands and Other Hardwood Forest of California, 1990s

73

Table 4—Total stem volume of hardwood species for all live trees on woodland by diameter class, California, 1990s

Diameter class (inches at breast height) All classes

1.0- 5.0- 9.0- 13.0- 17.0- 21.0- 25.0- 29.0- 33.0- 37.0-

Species 4.9 8.9 12.9 16.9 20.9 24.9 28.9 32.9 36.9 40.9 41.0+ Total SE

– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – Million cubic feet – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – %

Oak group:

Blue oak 104.9 522.3 761.6 463.0 375.2 248.0 149.5 74.9 11.4 19.0 — 2,729.6 6California black oak 26.6 134.5 155.5 148.4 96.1 78.7 53.5 20.2 22.6 15.7 11.9 763.7 11Canyon live oak 108.5 403.9 356.3 214.0 121.7 77.8 52.5 48.1 25.8 13.5 69.1 1,491.1 10Coast live oak 17.3 149.7 332.3 507.7 420.8 225.0 155.9 113.7 92.8 34.1 26.2 2,075.6 11

Engelmann oak 5.8 10.1 7.2 15.6 3.5 28.4 10.6 14.1 — — — 95.3 50Interior live oak 223.2 407.6 241.3 126.1 88.0 32.9 11.5 23.5 3.3 2.4 12.8 1,172.6 12Oregon white oak 35.7 163.8 128.0 78.7 70.8 32.3 17.5 22.3 12.0 11.4 10.1 582.5 17Valley oak .6 4.9 64.3 34.8 39.4 25.6 46.6 46.6 43.8 11.6 43.2 361.4 21

Total 522.4 1,796.8 2,046.5 1,588.4 1,215.5 748.7 497.6 363.4 211.6 107.7 173.2 9,271.8 4

Non-oak group: 

Bigleaf maple 6.1 42.3 32.9 25.5 22.1 9.7 4.8 6.7 4.1 6.8 10.2 171.1 26Black cottonwood — — .1 — .2 — — — — — 9.8 10.1 98California buckeye 13.9 63.3 29.3 19.1 — .2 — — — — — 125.8 20California laurel 27.3 71.9 63.2 48.0 23.7 15.7 20.5 — — — — 270.5 27California sycamore 1.8 7.1 1.0 16.0 3.5 21.2 14.1 5.3 5.5 — — 75.7 42Eucalyptus 1.1 19.8 32.8 17.7 25.0 15.6 — — — 5.8 — 117.8 94Giant chinquapin — — — 1.8 — — — — — — — 1.8 100Oregon ash .4 4.1 1.0 2.6 1.5 .6 .7 — — — — 11.0 71Pacific madrone 12.6 38.4 104.6 36.4 18.1 14.4 13.4 3.8 — — — 241.8 26Quaking aspen 3.1 3.6 — — 1.3 — — .7 — — — 8.7 78Red alder — .4 — — — — — — — — — .5 95Tanoak 1.8 3.1 2.7 1.6 5.9 4.3 4.2 .7 .5 — — 24.8 64White alder 1.1 1.3 5.8 2.8 1.5 1.3 .2 2.4 — — 3.0 19.4 42Willow 3.2 10.4 16.3 6.3 7.0 11.1 6.8 — — — — 61.1 58Other hardwoodsa 2.5 10.5 6.3 7.5 4.1 1.9 1.2 — — 2.4 — 36.5 41

Total 74.9 276.4 295.9 185.3 114.0 96.1 66.1 19.7 10.1 15.0 23.0 1,176.5 14

Total, California 597.4 2,073.1 2,342.5 1,773.8 1,329.4 844.8 563.7 383.0 221.7 122.7 196.2 10,448.3SE for total (%) 8 6 5 6 6 8 9 11 17 23 21 4

Note: Excludes reserved lands outside of national forests because these areas were not sampled.Includes sound and rotten cull trees.SE= sampling error.— = less than 50,000 cubic feet.a Other hardwoods includes apple, walnut, and unknowns.
RESOURCE BULLETIN PNW-RB-245

74Table 5—Total stem volume of hardwood species for all live trees on timberland by diameter class, California, 1990s

Diameter class (inches at breast height) All classes

1.0- 5.0- 9.0- 13.0- 17.0- 21.0- 25.0- 29.0- 33.0- 37.0-

Species 4.9 8.9 12.9 16.9 20.9 24.9 28.9 32.9 36.9 40.9 41.0+ Total SE

 – – – – – – – – – – – – – – – – – – – – – – – – – – – – – Million cubic feet – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – %

Oak group:

Blue oak 0.2 1.7 — 2.4 4.8 1.6 — — — — 3.9 14.6 51California black oak 148.0 687.8 856.7 717.5 534.8 474.1 315.9 262.6 143.1 91.5 141.9 4,373.7 4Canyon live oak 176.2 660.2 678.4 453.0 327.6 237.4 149.1 116.7 78.5 52.0 59.3 2,988.4 6Coast live oak 2.6 25.3 53.7 61.9 69.8 32.7 25.3 6.8 2.7 8.9 — 289.7 33Interior live oak 25.7 39.8 26.9 24.4 20.6 17.3 6.4 4.4 4.7 7.2 2.4 179.7 18

Oregon white oak 37.5 181.3 124.9 60.8 52.1 38.7 10.1 10.5 3.5 10.9 7.7 538.0 13Valley oak 2.9 11.4 11.6 6.2 4.9 7.3 8.7 5.4 — — — 58.4 32

Total 392.9 1,607.6 1,752.2 1,326.1 1,014.6 809.0 515.4 406.3 232.5 170.5 215.3 8,442.4 4

Non-oak group:

Bigleaf maple 32.7 98.8 97.5 68.7 51.6 33.0 6.5 15.2 1.7 9.2 5.6 420.6 12Black cottonwood .3 2.2 1.0 .1 .2 5.2 1.4 — 4.5 — — 14.9 56California buckeye 1.3 3.9 2.4 — — 1.8 — — — — — 9.4 38California laurel 44.7 117.0 110.9 96.6 43.5 30.5 12.4 9.9 7.6 — 3.4 476.5 14Eucalyptus — — — — — 5.7 2.9 2.6 — — 9.9 21.1 67Giant chinquapin 9.0 25.2 30.2 24.1 14.8 6.8 11.1 4.2 — — — 125.4 22Oregon ash 1.3 .4 1.9 2.9 — — — — 1.0 — — 7.6 53Pacific dogwood 17.4 3.4 4.6 — .8 — — — — — — 26.2 17Pacific madrone 65.6 284.0 368.9 430.4 331.6 235.0 162.0 84.7 58.9 45.6 76.5 2,143.1 6Quaking aspen 2.2 6.4 15.7 20.5 4.3 11.5 .2 — .5 — — 61.3 38Red alder 20.5 80.3 111.3 46.8 18.8 11.5 8.6 3.7 2.5 — 4.2 308.2 19Tanoak 429.4 1,059.1 1,074.4 744.2 563.3 335.4 201.0 123.2 38.2 11.2 38.2 4,617.6 6White alder 3.4 10.3 13.8 16.6 13.0 5.2 3.6 .2 1.5 1.6 — 69.3 22Willow 4.7 6.4 7.5 3.6 1.0 — — — — — — 23.2 33Other hardwoods a 3.6 4.8 4.7 3.8 4.0 6.6 6.4 .5 .8 .3 2.2 37.9 35

Total 636.2 1,702.2 1,844.8 1,458.4 1,047.1 688.2 416.0 244.1 117.2 68.0 140.0 8,362.3 4

Total, California 1,029.0 3,309.8 3,597.0 2,784.6 2,061.7 1,497.2 931.4 650.4 349.7 238.4 355.3 16,804.7SE for total (%) 4 4 4 4 5 5 6 7 9 12 13 3 

Note: Excludes reserved lands outside of national forests because these areas were not sampled.Includes sound and rotten cull trees.SE= sampling error. — = less than 50,000 cubic feet.a Other hardwoods includes apple, walnut, and unknowns.
Oak Woodlands and Other Hardwood Forest of California, 1990s

75

Table 6—Total stem volume of hardwood species for all live trees on woodland and timberland by diameter class, California, 1990s

Diameter class (inches at breast height) All classes

1.0- 5.0- 9.0- 13.0- 17.0- 21.0- 25.0- 29.0- 33.0- 37.0-

Species 4.9 8.9 12.9 16.9 20.9 24.9 28.9 32.9 36.9 40.9 41.0 + Total SE

– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – Million cubic feet – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – %

Oak group:

Blue oak 105.0 524.0 761.6 465.4 380.0 249.5 149.5 74.9 11.4 19.0 3.9 2,744.2 6

California black oak 174.5 822.3 1,012.2 865.9 630.9 552.8 369.3 282.8 165.7 107.2 153.8 5,137.4 4Canyon live oak 284.7 1,064.1 1,034.7 667.0 449.3 315.1 201.6 164.8 104.3 65.4 128.4 4,479.5 5Coast live oak 19.8 175.1 386.1 569.6 490.6 257.7 181.2 120.5 95.5 43.1 26.2 2,365.3 11

Engelmann oak 5.8 10.1 7.2 15.6 3.5 28.4 10.6 14.1 — — — 95.3 50Interior live oak 248.8 447.4 268.2 150.5 108.6 50.1 17.9 27.9 8.0 9.6 15.2 1,352.3 11Oregon white oak 73.1 345.1 252.9 139.5 123.0 71.1 27.6 32.8 15.5 22.3 17.8 1,120.5 11Valley oak 3.4 16.3 75.9 41.0 44.3 32.9 55.3 52.0 43.8 11.6 43.2 419.8 19

Total 915.3 3,404.3 3,798.8 2,914.5 2,230.1 1,557.7 1,013.0 769.7 444.1 278.2 388.5 17,714.2 3

Non-oak group:

Bigleaf maple 38.8 141.1 130.3 94.2 73.7 42.8 11.3 22.0 5.8 16.0 15.8 591.7 11

Black cottonwood .3 2.2 1.1 .1 .4 5.2 1.4 — 4.5 — 9.8 25.0 52

California buckeye 15.2 67.2 31.7 19.1 — 2.0 — — — — — 135.2 19California laurel 72.0 188.9 174.1 144.7 67.2 46.2 33.0 9.9 7.6 — 3.4 747.0 13California sycamore 1.8 7.1 1.0 16.0 3.5 21.2 14.1 5.3 5.5 — — 75.7 42Eucalyptus 1.1 19.9 32.8 17.7 25.0 21.2 2.9 2.6 — 5.8 9.9 138.9 79Giant chinquapin 9.0 25.2 30.2 25.9 14.8 6.8 11.1 4.2 — — — 127.2 22Oregon ash 1.8 4.5 2.9 5.5 1.5 .6 .7 — 1.0 — — 18.6 47Pacific dogwood 17.4 3.4 4.6 — .8 — — — — — — 26.2 17Pacific madrone 78.2 322.4 473.5 466.9 349.7 249.3 175.4 88.5 58.9 45.6 76.5 2,384.9 6Quaking aspen 5.2 10.0 15.7 20.5 5.6 11.5 .2 .7 .5 — — 70.0 34Red alder 20.5 80.7 111.3 46.8 18.8 11.5 8.6 3.7 2.5 — 4.2 308.7 19Tanoak 431.2 1,062.2 1,077.0 745.8 569.2 339.8 205.2 124.0 38.7 11.2 38.2 4,642.4 6White alder 4.6 11.5 19.6 19.5 14.5 6.5 3.8 2.6 1.5 1.6 3.0 88.8 20Willow 7.9 16.8 23.8 9.9 8.0 11.1 6.8 — — — — 84.4 43Other hardwoods a 6.1 15.4 11.2 11.4 8.1 8.6 7.6 .5 .8 2.7 2.2 74.6 27

Total 711.1 1,978.6 2,140.9 1,643.8 1,161.1 784.3 482.1 263.8 127.4 83.0 163.0 9,539.0 4

Total, California 1,626.4 5,383.0 5,939.7 4,558.4 3,391.2 2,342.0 1,495.1 1,033.4 571.5 361.2 551.4 27,253.2SE for total (%) 4 3 3 3 4 4 5 6 9 11 11 2

Note: Excludes reserved lands outside of national forests because these areas were not sampled.Includes sound and rotten cull trees.SE= sampling error. — = less than 50,000 cubic feet.a Other hardwoods includes apple, walnut, and unknowns.
RESOURCE BULLETIN PNW-RB-245

76Table 7—Aboveground (oven-dry) biomass of hardwood species for all live trees on woodland by diameter class, California, 1990s 

Diameter class (inches at breast height) All classes

1.0- 5.0- 9.0- 13.0- 17.0- 21.0- 25.0- 29.0- 33.0- 37.0-

Species 4.9 8.9 12.9 16.9 20.9 24.9 28.9 32.9 36.9 40.9 41.0 + Total SE

– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – Thousand tons – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – %

Oak group:

Blue oak 1,962.8 9,778.1 14,257.3 8,666.6 7,023.2 4,641.7 2,798.0 1,401.5 213.1 356.1 — 51,098.5 6

California black oak 464.6 2,348.9 2,716.8 2,593.3 1,678.9 1,374.9 934.4 353.3 394.3 274.3 208.0 13,341.6 11Canyon live oak 2,707.5 10,080.4 8,893.2 5,341.3 3,037.7 1,941.1 1,309.3 1,201.6 644.9 335.9 1,723.7 37,216.7 10Coast live oak 431.3 3,737.6 8,295.2 12,672.5 10,503.3 5,616.4 3,891.3 2,837.4 2,316.2 852.1 653.5 51,806.8 11

Engelmann oak 108.3 188.3 134.5 292.6 65.7 531.8 198.9 263.6 — — — 1,783.6 50Interior live oak 5,569.6 10,174.4 6,023.3 3,147.6 2,195.7 820.3 287.9 587.5 82.2 60.7 318.4 29,267.8 12Oregon white oak 667.7 3,066.0 2,395.2 1,473.8 1,326.3 605.5 328.1 416.9 223.8 213.2 188.4 10,904.7 17Valley oak 11.1 91.3 1,204.1 652.3 737.1 479.9 872.7 871.7 819.1 216.3 809.2 6,765.0 21

Total 11,922.8 39,465.1 43,919.6 34,839.9 26,567.9 16,011.6 10,620.5 7,933.5 4,693.8 2,308.6 3,901.2 202,184.6 4

Non-oak group:

Bigleaf maple 83.2 580.6 451.0 349.9 303.2 133.4 66.3 92.2 56.1 93.9 139.5 2,349.2 26

Black cottonwood — — 1.3 — 2.8 — — — — — 181.3 185.3 98California buckeye 165.1 750.8 347.7 225.8 — 2.0 — — — — — 1,491.5 20California laurel 503.0 1,324.3 1,164.3 884.2 436.2 289.8 378.2 — — — — 4,980.1 27California sycamore 26.1 102.0 14.8 229.9 50.7 304.4 202.5 75.9 79.5 — — 1,085.7 42Eucalyptus 36.3 629.2 1,037.2 575.7 819.6 520.7 — — — 188.6 — 3,807.3 93Giant chinquapin — — — 26.5 — — — — — — — 26.5 100Oregon ash 6.9 63.6 15.4 40.2 24.1 9.3 11.6 — — — — 171.1 71Pacific madrone 270.9 827.4 2,252.8 784.1 390.4 309.7 289.1 81.8 — — — 5,206.3 26Quaking aspen 82.6 63.1 — — 21.6 — — 11.7 — — — 179.0 79Red alder .5 9.2 — — — — — — — — — 9.7 95Tanoak 31.7 56.0 48.0 28.3 107.3 78.5 76.6 13.1 9.2 — — 448.6 64White alder 25.0 25.8 107.8 63.0 36.1 26.7 4.9 46.6 — — 55.5 391.5 40Willow 36.2 116.9 182.7 70.7 78.4 125.2 76.1 — — — — 686.2 58Other hardwoods a 45.3 194.5 115.4 137.3 74.8 35.9 21.6 — — 43.1 — 667.8 42

Total 1,312.8 4,743.3 5,738.4 3,415.7 2,345.1 1,835.6 1,126.9 321.3 144.8 325.6 376.3 21,685.9 18

Total, California 13,235.7 44,208.4 49,658.0 38,255.6 28,913.0 17,847.2 11,747.4 8,254.8 4,838.5 2,634.2 4,277.5 223,870.4SE for total (%) 9 6 5 6 6 8 9 11 17 22 21 4

Note: Excludes reserved lands outside of national forests because these areas were not sampled.Includes sound and rotten cull trees.Excludes foliage and dead branches.SE= sampling error.— = less than 50 tons.a Other hardwoods includes apple, walnut, and unknowns.
Oak Woodlands and Other Hardwood Forest of California, 1990s

77

Table 8—Aboveground (oven-dry) biomass of hardwood species for all live trees on timberland by diameter class, California, 1990s

Diameter class (inches at breast height) All classes

1.0- 5.0- 9.0- 13.0- 17.0- 21.0- 25.0- 29.0- 33.0- 37.0-

Species 4.9 8.9 12.9 16.9 20.9 24.9 28.9 32.9 36.9 40.9 41.0+ Total SE – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – Thousand tons – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – %

Oak group:

Blue oak 3.1 31.9 — 44.7 90.1 29.5 — — — — 73.5 272.8 51California black oak 2,584.6 12,016.5 14,966.6 12,534.2 9,342.2 8,283.2 5,518.0 4,587.1 2,499.8 1,597.8 2,478.8 76,408.8 4

Canyon live oak 4,397.8 16,478.6 16,932.9 11,308.1 8,177.6 5,924.6 3,721.5 2,911.6 1,959.5 1,296.9 1,480.5 74,589.6 6Coast live oak 63.8 632.6 1,341.4 1,545.6 1,741.8 815.7 630.5 169.8 67.4 222.7 — 7,231.3 33

Interior live oak 640.4 993.7 671.7 607.9 514.4 431.1 158.7 109.0 116.9 179.9 60.4 4,484.1 18Oregon white oak 701.2 3,393.3 2,338.4 1,137.8 975.7 724.6 188.9 196.3 66.1 204.3 144.3 10,070.8 13Valley oak 53.4 214.1 216.9 115.6 91.8 136.8 163.3 101.6 — — — 1,093.4 32

Total 8,444.3 33,760.5 36,467.8 27,293.9 20,933.8 16,345.4 10,380.9 8,075.3 4,709.7 3,501.7 4,237.6 174,150.8 4

Non-oak group:

Bigleaf maple 449.3 1,356.9 1,338.3 942.9 708.6 453.7 89.1 209.2 24.0 126.4 76.9 5,775.4 12Black cottonwood 8.5 39.1 18.5 1.2 3.5 91.0 25.4 — 78.9 — — 266.2 55California buckeye 15.5 46.0 28.2 — — 21.8 — — — — — 111.4 38California laurel 822.3 2,154.0 2,040.9 1,779.1 801.8 561.1 228.7 181.9 139.2 — 63.0 8,771.8 14Eucalyptus .4 .7 — — — 181.3 103.0 77.2 — — 328.5 691.0 68Giant chinquapin 134.5 377.2 452.7 360.7 222.3 101.7 166.2 62.5 — — — 1,877.8 22Oregon ash 20.5 6.8 29.9 46.0 — — — — 15.1 — — 118.3 53Pacific dogwood 383.5 76.1 107.4 — 17.6 — — — — — — 584.6 17Pacific madrone 1,412.9 6,115.0 7,942.1 9,267.4 7,138.9 5,058.6 3,486.9 1,822.8 1,267.9 981.5 1,646.8 46,140.7 6Quaking aspen 57.9 108.1 257.5 334.1 70.5 187.4 3.1 — 7.6 — — 1,026.2 37Red alder 336.0 1,305.4 1,877.4 820.2 349.1 230.3 153.9 77.4 51.9 — 89.9 5,291.5 18Tanoak 7,766.9 19,163.3 19,440.8 13,466.3 10,193.3 6,069.5 3,636.4 2,229.8 691.3 202.8 691.0 83,551.5 6White alder 64.6 189.8 255.8 326.4 263.8 114.4 77.5 4.4 32.2 31.1 — 1,360.0 22Willow 52.8 71.9 84.1 40.6 11.7 — — — — — — 261.1 33Other hardwoodsa 61.4 84.4 96.1 62.7 74.2 121.0 117.1 9.0 15.3 6.1 40.7 687.9 36

Total 11,587.0 31,094.7 33,969.5 27,447.7 19,855.2 13,191.6 8,087.2 4,674.1 2,323.4 1,348.0 2,936.9 156,515.2 4

Total, California 20,031.3 64,855.2 70,437.3 54,741.7 40,788.9 29,537.0 18,468.0 12,749.5 7,033.1 4,849.7 7,174.5 330,666.0

SE for total (%) 4 4 4 4 5 5 6 7 10 12 13 3

Note: Excludes reserved lands outside of national forests because these areas were not sampled.Includes sound and rotten cull trees.Excludes foliage and dead branches.SE= sampling error. — = less than 50 tons.a Other hardwoods includes apple, walnut, and unknowns.
RESOURCE BULLETIN PNW-RB-245

78Table 9—Aboveground (oven-dry) biomass of hardwood species for live trees on woodland and timberland by diameter class, California, 1990s

Diameter class (inches at breast height) All classes

1.0- 5.0- 9.0- 13.0- 17.0- 21.0- 25.0- 29.0- 33.0- 37.0-

Species 4.9 8.9 12.9 16.9 20.9 24.9 28.9 32.9 36.9 40.9 41.0 + Total SE

– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – Thousand tons – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – %

Oak group:

Blue oak 1,965.9 9,810.0 14,257.3 8,711.3 7,113.3 4,671.2 2,798.0 1,401.5 213.1 356.1 73.5 51,371.3 6California black oak 3,049.1 14,365.4 17,683.4 15,127.4 11,021.1 9,658.1 6,452.4 4,940.4 2,894.2 1,872.1 2,686.8 89,750.4 4Canyon live oak 7,105.3 26,559.0 25,826.1 16,649.4 11,215.3 7,865.7 5,030.8 4,113.2 2,604.4 1,632.8 3,204.2 111,806.3 5Coast live oak 495.1 4,370.2 9,636.6 14,218.2 12,245.1 6,432.0 4,521.8 3,007.2 2,383.7 1,074.8 653.5 59,038.1 11Engelmann oak 108.3 188.3 134.5 292.6 65.7 531.8 198.9 263.6 — — — 1,783.6 50Interior live oak 6,210.0 11,168.1 6,695.0 3,755.5 2,710.1 1,251.5 446.6 696.5 199.1 240.5 378.8 33,751.8 11Oregon white oak 1,368.9 6,459.2 4,733.6 2,611.5 2,302.0 1,330.1 517.0 613.1 289.9 417.5 332.7 20,975.5 11Valley oak 64.5 305.4 1,420.9 767.9 828.9 616.6 1,036.0 973.3 819.1 216.3 809.2 7,858.4 19

Total 20,367.1 73,225.6 80,387.4 62,133.8 47,501.7 32,357.0 21,001.4 16,008.8 9,403.5 5,810.2 8,138.8 376,335.4 3

Non-oak group:

Bigleaf maple 532.5 1,937.5 1,789.3 1,292.8 1,011.8 587.1 155.4 301.4 80.1 220.4 216.5 8,124.7 11Black cottonwood 8.5 39.1 19.8 1.2 6.3 91.0 25.4 — 78.9 — 181.3 451.5 52California buckeye 180.6 796.9 375.9 225.8 — 23.8 — ———— 1,602.9 19

California laurel 1,325.2 3,478.3 3,205.2 2,663.3 1,238.0 850.9 606.8 181.9 139.2 — 63.0 13,751.8 13California sycamore 26.1 102.0 14.8 229.9 50.7 304.4 202.5 75.9 79.5 — — 1,085.7 42Eucalyptus 36.7 629.8 1,037.2 575.7 819.6 702.0 103.0 77.2 — 188.6 328.5 4,498.3 78

Giant chinquapin 134.5 377.2 452.7 387.2 222.3 101.7 166.2 62.5 — — — 1,904.3 22

Oregon ash 27.4 70.4 45.2 86.2 24.1 9.3 11.6 — 15.1 — — 289.4 47Pacific dogwood 383.5 76.1 107.4 — 17.6 — — ———— 584.6 17Pacific madrone 1,683.8 6,942.3 10,194.9 10,051.6 7,529.3 5,368.2 3,776.0 1,904.6 1,267.9 981.5 1,646.8 51,347.0 6Quaking aspen 140.4 171.3 257.5 334.1 92.1 187.4 3.1 11.7 7.6 — — 1,205.2 34Red alder 336.5 1,314.6 1,877.4 820.2 349.1 230.3 153.9 77.4 51.9 — 89.9 5,301.2 18Tanoak 7,798.6 19,219.3 19,488.9 13,494.6 10,300.6 6,148.0 3,712.9 2,242.9 700.5 202.8 691.0 84,000.1 6White alder 89.6 215.6 363.5 389.4 299.9 141.1 82.4 50.9 32.2 31.1 55.5 1,751.4 19Willow 89.0 188.9 266.8 111.3 90.1 125.2 76.1 ———— 947.3 43

Other hardwoodsa 106.7 278.9 211.4 200.1 148.9 156.9 138.6 9.0 15.3 49.3 40.7 1,355.8 28

Total 12,899.9 35,838.1 39,707.9 30,863.6 22,200.3 15,027.2 9,214.1 4,995.4 2,468.2 1,673.6 3,313.2 178,201.1 4

Total, California 33,267.0 109,063.7 120,095.3 92,997.4 69,702.0 47,384.1 30,215.5 21,004.2 11,871.7 7,483.9 11,452.0 554,536.6SE for total (%) 4 3 3 3 4 4 5 6 9 11 11 2

Note: Excludes reserved lands outside of national forests because these areas were not sampled.Includes sound and rotten cull trees.Excludes foliage and dead branches.SE= sampling error.— = less than 50 tons.a Other hardwoods includes apple, walnut, and unknowns.
Oak Woodlands and Other Hardwood Forest of California, 1990s

79

Table 10—Total stem volume of hardwood species (≥4 inches diameter at breast height) on unreserved woodland and timberland by resource area and owner,

California, 1990s

Woodland Timberland Total

Resource area National Other Total National Other Total National Other Total

 and species forest public Private Volume SE forest public Private Volume SE forest public Private Volume SE

 – – – – – – Million cubic feet – – – – – – – % – – – – – – Million cubic feet – – – – – – % – – – – – – Million cubic feet – – – – – – %

North Coast:

Oak group—

Blue oak — — 53.1 53.1 54 — — — — — — 53.1 53.1 54California black oak 23.3 — 138.6 161.9 21 47.6 41.0 391.4 479.9 14 70.8 41.0 530.0 641.7 12Canyon live oak 74.9 0.3 80.0 155.2 37 109.6 55.7 274.0 439.3 17 184.5 56.0 354.0 594.5 16Coast live oak — 10.2 129.8 140.0 32 — — 55.8 55.8 38 — 10.2 185.6 195.8 26Interior live oak — — 23.8 23.8 55 4.4 3.8 45.1 53.3 41 4.4 3.8 68.8 77.1 33Oregon white oak 65.9 7.3 255.6 328.7 24 4.8 8.7 311.4 324.9 18 70.7 16.0 567.0 653.6 15Valley oak — — 48.7 48.7 48 — — 41.3 41.3 43 — — 89.9 89.9 33

Total 164.1 17.8 729.5 911.3 166.4 109.1 1,118.9 1,394.4 330.4 126.9 1,848.3 2,305.6

Non-oak group— 

Bigleaf maple 4.4 — 17.1 21.5 57 33.4 6.1 98.7 138.2 21 37.8 6.1 115.8 159.7 20Black cottonwood — — — — — — 7.2 7.2 92 — — 7.2 7.2 92California buckeye .5 — 16.2 16.8 56 — — 1.9 1.9 74 .5 — 18.1 18.6 52California laurel .5 — 95.8 96.3 47 10.2 9.1 294.2 313.5 15 10.7 9.1 390.0 409.8 17Eucalyptus — — — — — — 16.5 16.5 81 — — 16.5 16.5 81Giant chinquapin — — — — 39.8 — 29.7 69.5 34 39.8 — 29.7 69.5 34Oregon ash — — — — — — 1.9 1.9 99 — — 1.9 1.9 99Pacific dogwood — — — — .6 — 1.5 2.1 53 .6 — 1.5 2.1 53Pacific madrone 11.7 4.5 95.4 111.6 34 178.1 73.6 917.4 1,169.1 9 189.9 78.1 1,012.8 1,280.7 9Red alder — — — — 2.8 — 242.7 245.4 22 2.8 — 242.7 245.4 22Tanoak — — — — 517.5 66.3 2,752.0 3,335.8 7 517.5 66.3 2,752.0 3,335.8 7White alder — — — — 1.2 — — 1.2 75 1.2 — — 1.2 75Willow — — — — — — 11.7 11.7 51 — — 11.7 11.7 51

Total 17.2 4.5 224.5 246.1 783.7 155.1 4,375.2 5,314.0 800.9 159.6 4,599.6 5,560.1 

Total, North Coast 181.2 22.3 953.9 1,157.4 950.1 264.2 5,494.0 6,708.3 1,131.3 286.5 6,447.9 7,865.7 SE for total (%) 34 58 12 11 20 22 5 5 17 21 5 4
RESOURCE BULLETIN PNW-RB-245

80Table 10—Total stem volume of hardwood species (≥4 inches diameter at breast height) on unreserved woodland and timberland by resource area and owner,

California, 1990s (continued)

Woodland Timberland Total

Resource area National Other Total National Other Total National Other Total

 and species forest public Private Volume SE forest public Private Volume SE forest public Private Volume SE

– – – – – – Million cubic feet – – – – – – % – – – – – – Million cubic feet – – – – – – % – – – – – – Million cubic feet – – – – – – %

North Interior:

Oak group—

Blue oak 3.0 6.8 191.5 201.3 22 2.5 — — 2.5 100 5.5 6.8 191.5 203.7 21California black oak 77.3 7.4 61.4 146.1 24 505.4 47.5 554.6 1,107.5 8 582.7 54.9 615.9 1,253.5 7Canyon live oak 165.4 29.5 29.9 224.8 25 638.3 54.8 316.9 1,010.0 11 803.7 84.3 346.8 1,234.8 10Coast live oak — — — — .4 — — .4 100 .4 — — .4 100Interior live oak 17.8 — 34.0 51.8 40 31.1 — .8 31.9 33 49.0 — 34.8 83.7 27Oregon white oak 46.8 24.2 90.8 161.8 26 53.9 19.2 66.5 139.6 19 100.7 43.4 157.3 301.4 16Valley oak 1.1 1.3 29.5 31.9 53 4.5 — 1.0 5.5 39 5.5 1.3 30.5 37.4 46

Total 311.3 69.2 437.0 817.6 1,236.2 121.5 939.7 2,297.4 1,547.5 190.7 1,376.7 3,114.9

Non-oak group—

Bigleaf maple 30.2 — 3.1 33.4 57 85.8 7.2 59.3 152.3 20 116.1 7.2 62.4 185.7 19Black cottonwood — — 9.8 9.8 100 .1 1.9 — 1.9 97 .1 1.9 9.8 11.8 85California buckeye .4 — .8 1.1 75 .4 — — .4 100 .8 — .8 1.6 61California laurel — — — — 2.8 1.0 12.6 16.4 66 2.8 1.0 12.6 16.4 66Eucalyptus — — — — — — — — 100 — — — — 100Giant chinquapin 1.8 — — 1.8 100 29.1 — 6.2 35.3 32 30.9 — 6.2 37.0 30Oregon ash — — — — 1.0 — — 1.0 100 1.0 — — 1.0 100Pacific dogwood — — — — 2.9 — .3 3.2 53 2.9 — .3 3.2 53Pacific madrone 28.4 — 2.5 30.9 76 362.9 — 53.3 416.2 12 391.4 — 55.8 447.1 13Quaking aspen — — — — 27.9 — 12.4 40.3 54 27.9 — 12.4 40.3 54Red alder .5 — — .5 100 14.4 — — 14.4 39 14.8 — — 14.8 38Tanoak 7.0 — — 7.0 100 228.9 — 48.6 277.5 23 235.9 — 48.6 284.4 23White alder .7 — — .7 100 7.1 — 10.4 17.6 45 7.8 — 10.4 18.3 43Willow — — — — — — .8 .8 100 — — .8 0.8 100Other hardwoodsa 1.1 — — 1.1 100 3.8 — — 3.8 100 4.9 — — 4.9 100

Total 70.0 — 16.2 86.2 767.1 10.0 203.9 981.1 832.3 10.0 220.1 1,061.5

Total, North Interior 381.3 69.2 453.2 903.7 2,003.3 131.5 1,143.6 3,278.4 2,379.8 200.8 1,596.7 4,176.4SE for total (%) 21 44 14 12 7 31 9 6 7 26 8 5
Oak Woodlands and Other Hardwood Forest of California, 1990s

81

Table 10—Total stem volume of hardwood species (≥4 inches diameter at breast height) on unreserved woodland and timberland by resource area and owner,

California, 1990s (continued)

Woodland Timberland Total

Resource area National Other Total National Other Total National Other Total  and species forest public Private Volume SE forest public Private Volume SE forest public Private Volume SE

– – – – – – Million cubic feet – – – – – – % – – – – – – Million cubic feet – – – – – – % – – – – – – Million cubic feet – – – – – – %

Sacramento:

Oak group—

Blue oak 0.3 18.3 822.2 840.9 11 — — 3.5 3.5 100 0.3 18.3 825.7 844.3 11California black oak 85.9 — 123.0 208.9 21 627.0 22.3 781.9 1,431.3 8 712.9 22.3 904.9 1,640.2 7Canyon live oak 182.0 26.7 102.6 311.4 22 312.2 47.5 216.3 576.0 14 494.2 74.3 318.9 887.4 12Interior live oak — 5.0 195.9 200.9 23 6.2 .2 35.4 41.8 35 6.2 5.2 231.2 242.7 20Oregon white oak 1.1 — — 1.1 100 1.4 — .7 2.2 74 2.6 — .7 3.3 59Valley oak 4.0 — 64.9 69.0 64 — — .2 .2 100 4.0 — 65.2 69.2 63

Total 273.4 50.1 1,308.7 1,632.1 946.9 70.0 1,038.0 2,054.9 1,220.2 120.1 2,346.7 3,687.1

Non-oak group—

Bigleaf maple 8.6 — 18.5 27.1 48 13.2 — 45.9 59.1 25 21.8 — 64.4 86.2 23Black cottonwood — — — — — — 5.5 5.5 81 — — 5.5 5.5 81California buckeye 3.5 — 13.3 16.8 44 2.4 — .2 2.6 73 5.8 — 13.5 19.4 39California laurel .7 — — .7 65 5.8 .5 17.6 23.8 49 6.4 .5 17.6 24.5 48California sycamore .2 — — .2 100 — — — — .2 — — .2 100Oregon ash .3 — — .3 100 — — — — .3 — — .3 100Pacific dogwood — — — — 1.3 — — 1.3 89 1.3 — — 1.3 89Pacific madrone .7 — — .7 61 52.1 2.3 82.4 136.8 20 52.8 2.3 82.4 137.6 20Quaking aspen .2 — — .2 100 1.9 — 2.4 4.3 63 2.1 — 2.4 4.5 61Red alder — — — — 2.6 — 11.6 14.2 54 2.6 — 11.6 14.2 54Tanoak — — — — 71.3 .1 103.6 175.0 21 71.3 .1 103.6 175.0 21White alder 1.0 — — 1.0 100 1.8 — 13.2 15.0 49 2.9 — 13.2 16.0 47Willow — — 14.7 14.7 100 — — 1.3 1.3 100 — — 16.0 16.0 92Other hardwoodsa .2 — — .2 100 .7 — 1.2 1.8 100 .9 — 1.2 2.0 100

Total 15.3 — 46.5 61.8 153.0 2.9 284.9 440.8 168.4 2.9 331.4 502.6

Total, Sacramento 288.7 50.1 1,355.2 1,694.0 1,099.9 72.9 1,322.9 2,495.7 1,388.6 123.0 2,678.1 4,189.7SE for total (%) 14 34 10 8 8 25 10 6 7 20 7 5
RESOURCE BULLETIN PNW-RB-245

82Table 10—Total stem volume of hardwood species (≥4 inches diameter at breast height) on unreserved woodland and timberland by resource area and owner,

California, 1990s (continued)

Woodland Timberland Total

Resource area National Other Total National Other Total National Other Totaland species forest public Private Volume SE forest public Private Volume SE forest public Private Volume SE

– – – – – – Million cubic feet – – – – – – % – – – – – – Million cubic feet – – – – – – % – – – – – – Million cubic feet – – – – – – %

Central Coast:

Oak group—

Blue oak 47.4 67.0 452.5 566.9 13 — — 5.5 5.5 100 47.4 67.0 458.0 572.4 13California black oak — — 20.7 20.7 63 9.0 — 2.7 11.6 58 9.0 — 23.4 32.3 45Canyon live oak 3.4 — 9.5 12.9 74 28.1 — 62.4 90.5 71 31.5 — 71.9 103.4 63Coast live oak 83.3 94.6 1,304.5 1,482.3 13 2.6 — 203.9 206.4 44 85.8 94.6 1,508.4 1,688.8 13Interior live oak .5 — 50.7 51.2 95 3.3 — — 3.3 93 3.8 — 50.7 54.5 89Oregon white oak — — 32.1 32.1 63 — — 2.0 2.0 101 — — 34.1 34.1 59Valley oak — — 149.9 149.9 33 — — — — — — 149.9 149.9 33

Total 134.5 161.6 2,019.8 2,315.9 42.9 — 276.5 319.4 177.4 161.6 2,296.3 2,635.3

Non-oak group—

Bigleaf maple 3.8 — 35.9 39.7 71 — — 4.1 4.1 65 3.8 — 40.0 43.8 65California buckeye — — 9.7 9.7 51 — — — — — — 9.7 9.7 51California laurel 1.0 7.7 122.4 131.1 38 1.2 — 67.8 68.9 58 2.2 7.7 190.1 200.0 32California sycamore 4.4 16.9 40.0 61.3 41 — — — — 4.4 16.9 40.0 61.3 41Eucalyptus — — 106.7 106.7 100 — — 4.5 4.5 100 — — 111.2 111.2 96Pacific madrone 3.1 35.3 31.8 70.1 61 6.6 — 93.9 100.5 31 9.7 35.3 125.6 170.6 30Tanoak — — — — 3.7 — 260.4 264.1 35 3.7 — 260.4 264.1 35Willow — — 24.9 24.9 100 — — 2.9 2.9 90 — — 27.8 27.8 89Other hardwoodsa 4.4 — — 4.4 100 16.8 — — 16.8 100 21.2 — — 21.2 100

Total 16.7 59.9 371.2 447.8 28.3 — 433.5 461.9 45.0 59.9 804.7 909.7

Total, Central Coast 151.2 221.5 2,391.1 2,763.7 71.2 — 710.0 781.2 222.4 221.5 3,101.0 3,544.9SE for total (%) 27 32 10 9 31 17 16 20 32 9 8
Oak Woodlands and Other Hardwood Forest of California, 1990s

83

Table 10—Total stem volume of hardwood species (≥4 inches diameter at breast height) on unreserved woodland and timberland by resource area and owner,California, 1990s (continued)

Woodland Timberland Total

Resource area National Other Total National Other Total National Other Total

 and species forest public Private Volume SE forest public Private Volume SE forest public Private Volume SE

– – – – – – Million cubic feet – – – – – – % – – – – – – Million cubic feet – – – – – – % – – – – – – Million cubic feet – – – – – – %

Southern:

Oak group—

Blue oak 42.9 37.5 812.1 892.6 10 0.6 — — .6 100 43.5 37.5 812.1 893.2 10California black oak 86.8 12.3 11.7 110.7 28 388.2 16.4 287.2 691.8 10 475.0 28.7 298.8 802.5 9Canyon live oak 245.6 30.4 136.9 412.9 19 178.2 27.8 155.8 361.8 16 423.9 58.2 292.7 774.7 13Coast live oak 72.3 30.4 95.2 197.9 16 1.3 — 6.6 7.9 74 73.6 30.4 101.9 205.8 15Engelmann oak — — 93.4 93.4 50 — — — — — — 93.4 93.4 50Interior live oak 52.5 47.3 517.6 617.5 17 6.3 — 7.0 13.2 38 58.8 47.3 524.6 630.7 16Oregon white oak — — 18.4 18.4 100 — — .4 .4 100 — — 18.8 18.8 98Valley oak .2 — 29.6 29.8 53 — — 10.4 10.4 53 .2 — 40.0 40.2 42

Total 500.3 157.9 1,714.9 2,373.1 574.6 44.2 467.4 1,086.2 1,074.9 202.0 2,182.3 3,459.3

Non-oak group—

Bigleaf maple 8.7 — — 8.7 66 8.7 — 3.0 11.7 40 17.5 — 3.0 20.5 36Black cottonwood .2 — — .2 75 — — — — .2 — — .2 75California buckeye 13.7 12.4 42.4 68.5 28 2.2 — — 2.2 100 15.9 12.4 42.4 70.8 28California laurel 6.1 — — 6.1 52 .2 .5 2.0 2.7 77 6.3 .5 2.0 8.8 43California sycamore 1.2 — — 1.2 55 — — — — 1.2 — — 1.2 55Eucalyptus — — 11.1 11.1 100 — — — — — — 11.1 11.1 100Oregon ash 6.9 — 3.3 10.2 73 1.1 2.3 .2 3.5 72 8.0 2.3 3.5 13.7 58Pacific dogwood — — — — 1.1 — 3.6 4.7 50 1.1 — 3.6 4.7 50Pacific madrone — — — — — — 2.8 2.8 101 — — 2.8 2.8 101Quaking aspen 5.0 — — 5.0 100 2.9 — 3.2 6.2 60 8.0 — 3.2 11.2 56Red alder — — — — .8 — — .8 100 .8 — — .8 100Tanoak — — — — — — 1.4 1.4 75 — — 1.4 1.4 75Walnut — — — — — — 3.3 3.3 100 — — 3.3 3.3 100White alder 7.6 — 3.6 11.2 46 14.0 — 13.9 27.8 34 21.6 — 17.5 39.0 28Willow — — 20.7 20.7 100 — — 2.8 2.8 100 — — 23.5 23.5 90Other hardwoodsa 23.1 — — 23.1 100 5.3 — — 5.3 100 28.4 — — 28.4 100

Total 72.6 12.4 81.2 166.1 36.4 2.8 36.1 75.2 108.9 15.2 117.3 241.3

Total, Southern 572.9 170.2 1,796.1 2,539.2 611.0 47.0 503.5 1,161.4 1,183.9 217.2 2,299.5 3,700.6SE for total (%) 9 30 8 6 9 33 17 9 6 26 7 5
RESOURCE BULLETIN PNW-RB-245

84Table 10—Total stem volume of hardwood species (≥4 inches diameter at breast height) on unreserved woodland and timberland by resource area and owner,

California, 1990s (continued)

Woodland Timberland Total

Resource area National Other Total National Other Total National Other Totaland species forest public Private Volume SE forest public Private Volume SE forest public Private Volume SE

– – – – – – Million cubic feet – – – – – – % – – – – – – Million cubic feet – – – – – – % – – – – – – Million cubic feet – – – – – – %

Total, California:

Oak group—

Blue oak 93.6 129.7 2,331.4 2,554.6 6 3.1 — 9.0 12.1 58 96.7 129.7 2,340.4 2,566.7 6California black oak 273.2 19.7 355.3 648.2 11 1,577.2 127.2 2,017.7 3,722.1 5 1,850.4 146.9 2,373.0 4,370.3 4Canyon live oak 671.3 86.9 358.9 1,117.2 12 1,266.4 185.8 1,025.4 2,477.6 7 1,937.7 272.7 1,384.3 3,594.7 6Coast live oak 155.5 135.1 1,529.5 1,820.2 11 4.3 — 266.3 270.5 35 159.8 135.1 1,795.8 2,090.7 11Engelmann oak — — 93.4 93.4 50 — — — — — — 93.4 93.4 50Interior live oak 70.8 52.4 821.9 945.1 13 51.4 4.0 88.2 143.6 20 122.2 56.4 910.1 1,088.6 12Oregon white oak 113.8 31.5 396.8 542.1 18 60.2 27.9 381.0 469.1 13 173.9 59.4 777.8 1,011.2 12Valley oak 5.3 1.3 322.5 329.1 22 4.5 — 53.0 57.4 32 9.8 1.3 375.5 386.5 20

Total 1,383.5 456.5 6,209.8 8,049.9 2,966.9 344.9 3,840.5 7,152.3 4,350.5 801.4 10,050.3 15,202.1

Non-oak group—

Bigleaf maple 55.7 — 74.7 130.4 29 141.2 13.3 210.9 365.4 12 196.9 13.3 285.6 495.8 12Black cottonwood .2 — 9.8 10.1 98 .1 1.9 12.7 14.6 57 .3 1.9 22.5 24.7 53California buckeye 18.1 12.4 82.4 112.9 21 5.0 — 2.1 7.1 46 23.1 12.4 84.5 120.0 20California laurel 8.4 7.7 218.1 234.2 29 20.1 11.1 394.2 425.3 15 28.4 18.8 612.3 659.5 14California sycamore 5.8 16.9 40.0 62.7 40 — — — — 5.8 16.9 40.0 62.7 40Eucalyptus — — 117.8 117.8 94 — — 21.0 21.1 67 — — 138.8 138.9 79Giant chinquapin 1.8 — — 1.8 100 68.9 — 35.8 104.7 25 70.7 — 35.8 106.5 25Oregon ash 7.2 — 3.3 10.5 71 2.1 2.3 2.1 6.4 52 9.3 2.3 5.4 17.0 48Pacific dogwood — — — — 6.0 — 5.4 11.3 29 6.0 — 5.4 11.3 29Pacific madrone 44.0 39.8 129.6 213.3 28 599.8 75.9 1,149.7 1,825.5 7 643.8 115.7 1,279.3 2,038.8 7Quaking aspen 5.2 — — 5.2 96 32.7 — 18.1 50.8 44 37.9 — 18.1 56.0 41Red alder .5 — — .5 100 20.6 — 254.2 274.8 20 21.0 — 254.2 275.2 20Tanoak 7.0 — — 7.0 100 821.4 66.4 3,165.9 4,053.7 6 828.4 66.4 3,165.9 4,060.7 6Walnut — — — — — — 3.3 3.3 100 — — 3.3 3.3 100White alder 9.3 — 3.6 12.9 41 24.1 — 37.4 61.5 23 33.4 — 41.0 74.4 21Willow — — 60.2 60.2 59 — — 19.6 19.6 37 — — 79.8 79.9 45Other hardwoodsa 28.7 — — 28.7 100 26.6 — 1.2 27.8 100 55.3 — 1.2 56.5 100

Total 191.8 76.8 739.5 1,008.1 1,768.6 170.8 5,333.5 7,272.9 1,960.3 247.6 6,073.0 8,280.9

Total, California 1,575.3 533.3 6,949.3 9,057.9 4,735.5 515.6 9,174.0 14,425.1 6,310.8 1,049.0 16,123.3 23,483.1SE for total (%) 8 18 5 4 5 14 4 3 4 11 3 2Note: Excludes rotten cull trees.Volume is for the total stem of live trees from the ground to the tree tip.SE= sampling error.— = less than 50,000 cubic feet.

a Other hardwoods includes apple and unknowns.
Oak Woodlands and Other Hardwood Forest of California, 1990s

85

Table 11—Forest type area 1984 and 1994 by owner, on unreserved woodland outside

national forests, California

1984 1994

Other Other

Forest type public Private Total public Private Total

 – – – – – – – – – – – Thousand acres – – – – – – – – – – –

Oak group:

Blue oak 178.1 2,855.3 3,033.4 157.9 2,708.7 2,866.6

California black oak — 223.1 223.1 12.7 181.0 193.7

Canyon live oak 47.6 184.2 231.8 47.6 164.4 212.1

Coast live oak 93.7 854.8 948.5 60.7 836.1 896.8

Engelmann oak — 56.3 56.3 — 75.1 75.1

Interior live oak 64.7 781.3 846.0 80.9 805.1 886.1

Oregon white oak 47.6 223.1 270.7 47.6 223.1 270.7

Valley oak 16.3 102.2 118.5 — 118.7 118.7

Total 448.2 5,280.2 5,728.4 407.5 5,112.1 5,519.6

Non-oak group:

Bigleaf maple — 16.3 16.3 — 16.3 16.3

Buckeye — 64.7 64.7 — 80.9 80.9

California laurel — 34.8 34.8 — 34.8 34.8

Eucalyptus — 37.3 37.3 — 18.5 18.5

Oregon ash — 16.3 16.3 — 16.3 16.3

Pacific madrone — 51.2 51.2 — 51.2 51.2

Sycamore 16.6 — 16.6 16.6 — 16.6

Walnut — — — — 18.8 18.8

White alder — — — — 16.2 16.2

Willow — 16.2 16.2 — 16.2 16.2

Total 16.6 236.8 253.4 16.6 269.2 285.8

Total, California 464.8 5,517.1 5,981.9 424.2 5,381.2 5,805.4

Note: Includes area reductions caused by the transfer of land to reserved status or national forest

ownership.

Forest type is determined by applying a classification algorithm to trees. For this table, some tree

measurements for 1984 were derived by backdating 1994 tree measurements, via models or other

standard protocol.

— = less than 50 acres.
RESOURCE BULLETIN PNW-RB-245

86Table 12—Change in forest type area from 1984 to 1994 on unreserved woodland and timberland outside of national forests, California 

Changed 1984

1984 status to hardwoods Changed to Changed Remained Changed 1994 hardwood Changed

hardwood reserved or forest type a different to a Changed Changed as the from a forest type area proportion from

forest type national area, hardwood softwood to non- to non- same different 1984 to 1994,

area forest adjusted

a

forest type forest type stocked forest forest type forest type Area SE

b

adjusted

a

Forest type (A) (B) (C) (D) (E) (F) (G) (H) (I) (J) (K) (L)

– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – Thousands acres– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – % %

Oak group:

Blue oakc 3,033 -95 2,938 -132 -21 2,784 82 2,867 5 -2

California black oak 751 -37 714 -16 -34 -15 650 15 665 12 -7Canyon live oak 571 -28 543 -16 -10 517 86 603 14 11Coast live oak 1,027 -34 993 -35 958 958 10 -4Engelmann oak 56 56 0 56 19 75 38 33Interior live oak 902 -9 893 -49 844 115 959 11 7Oregon white oak 483 483 -6 -18 459 5 464 15 -4Valley oak 141 141 -16 124 16 141 33 0

Total 6,964 -203 6,761 -271 -62 -15 -21 6,392 339 6,731 2 0

Non-oak group:

Bigleaf maple 76 76 -7 -8 60 60 43 -20Buckeye 65 65 65 16 81 44 25California laurel 113 113 -8 106 25 131 29 16Pacific madrone 282 -7 275 -8 -23 243 25 267 19 -3Red alder 49 49 -9 41 30 70 34 42Tanoak 955 -16 939 -22 -34 -24 859 103 962 8 2Other hardwoodsd 132 0 132 -8 -9 0 -25 90 69 159 34 0

Total 1,672 -23 1,648 -53 -82 -49 1,464 268 1,731 6 5

Total, California 8,636 -226 8,410 -325 -144 -15 -70 7,855 606 8,462 2 1

Note: The columns in this table are additive as follows: A + B = C; C + D + E + F + G = H; H + I = J; L = (J - C) / Ca Adjusted columns do not include forest that was in the inventory in the 1980s but was not inventoried in the 1990s owing to a transfer of land to reserve status or national forest ownership.

There were no transfers from reserve status or national forest into the 1990s inventory.

b The standard error includes sampling error but not measurement error. For estimates in this table, a change in plot design between 1981-84 and 1991-94 contributes to measurement error; some

tree measurements for 1981-84 were derived from backdating 1991-94 tree measurements.

c The blue oak forest type includes the area of ghost pine (Pinus sabiniana) forest type.d Other hardwood forest types included California sycamore, eucalyptus, giant chinquipin, Oregon ash, white alder, walnut, and willow.
Oak Woodlands and Other Hardwood Forest of California, 1990s

87

Table 13—Net growing-stock volume of hardwood species, 1984 and 1994, on unreserved woodland and timberland outside national forests, California

1984 1994 Change 1994-1984

Species Total SE Total SE Total SE

– – – – – – – – – – – –Million cubic feet – – – – – – – – – – – –

Oak group:

Blue oak 965.2 178.2 1,080.9 205.1 115.6 43.0

California black oak 1,477.7 115.1 1,681.3 130.5 203.5 38.2

Canyon live oak 954.9 162.4 1,080.4 159.5 125.4 57.5

Coast live oak 961.4 326.8 1,063.1 359.3 101.9 57.2

Engelmann oak 10.6 10.6 11.3 11.3 .7 .7

Interior live oak 389.4 154.6 413.0 119.4 23.6 55.7

Oregon white oak 557.4 196.8 671.4 246.2 114.0 51.9

Valley oak 513.2 276.5 600.2 330.8 87.2 61.7

Total 5,829.9 588.7 6,601.5 658.2 772.0 144.7

 

Non-oak group: 

Bigleaf maple 128.2 23.4 166.1 29.6 38.0 9.3

Black cottonwood 13.8 13.1 14.0 12.5 —

Buckeye 19.4 10.6 11.5 9.7 -7.9 7.9

California laurel 404.3 114.4 513.7 140.4 109.4 30.2

Eucalyptus 154.2 149.6 197.3 193.8 43.1 43.1

Giant chinquapin 24.4 7.8 30.5 9.7 6.1 6.1

Pacific madrone 1,026.4 120.3 1,162.8 135.8 136.4 30.0

Quaking aspen 5.2 3.2 6.1 3.7 1.0 1.0

Red alder 142.2 33.7 213.0 50.2 70.7 35.4

Sycamore 23.6 23.6 32.4 32.4 8.8 8.8

Tanoak 1,504.3 128.4 1,802.1 136.4 297.9 90.2

Walnut .7 .7 1.1 1.1 .4 .4

White alder 39.2 17.0 56.6 26.3 17.4 10.6

Total 3,485.8 270.2 4,207.2 321.9 721.4 121.7

Total, California 9,315.8 650.5 10,808.7 736.0 1,493.4 187.0

Note: Excludes cull trees and cull volume; includes trees ≥5inches diameter at breast height. Values

for 1994 may differ from those of table 3 because estimates are based only on remeasured plots that

were in the inventory in both 1984 and 1994.

This table does not include volume from land that transferred to reserved status or national forest

ownership in the 1990s.

SE= sampling error.

— = less than 50,000 cubic feet.
RESOURCE BULLETIN PNW-RB-245

88

Table 14—Gross volume of periodic mortality, periodic removals, annual mortality,

and annual removals for hardwood trees that died during the remeasurement period

(1984 to 1994), on unreserved woodland and timberland outside national forests,

California

Periodic mortality Periodic removalsa Annual Annual

Volume SE Volume SE mortality removals

1000 ft3 % 1000 ft3 % – – – – 1000 ft3 – – – –

Oak group:

Blue oak 73,610.1 47 45,182.0 51 6,031.1 3,797.9

California black oak 155,435.0 18 70,954.8 29 13,450.7 5,966.0

Canyon live oak 95,107.8 69 14,795.7 55 8,169.1 1,332.3

Coast live oak 76,484.3 61 15,890.8 93 6,392.7 1,444.7

Interior live oak 9,257.1 79 86,525.1 87 779.4 6,723.5

Oregon white oak 19,626.2 51 3,120.6 68 1,912.7 312.1

Valley oak 28,057.4 97 — 2,565.3 —

Total 457,577.8 23 236,469.0 35 39,300.9 19,576.5

Non-oak group:

Bigleaf maple 3,791.0 56 4,606.1 80 333.1 460.6

Black cottonwood 2,868.2 100 — 220.6 —

Buckeye 15,603.0 57 281.5 100 1,342.7 28.2

California laurel 13,016.9 41 10,820.6 85 1,227.8 1,087.4

Eucalyptus 19,696.4 93 — 1,534.5 —

Giant chinquapin 2,852.3 73 — 296.1 —

Pacific madrone 71,696.0 24 55,797.8 32 6,826.0 5,558.9

Red alder 12,629.7 41 40,397.2 64 1,254.8 4,001.2

Tanoak 62,500.4 18 252,870.5 25 6,249.8 25,612.0

White alder 2,442.5 79 550.9 100 208.4 45.9

Other hardwoods 12,355.8 69 5,270.4 100 1,049.4 484.3

Total 219,452.3 14 370,594.9 22 20,543.1 37,278.3

Total, California 677,030.1 17 607,063.8 19 59,844.0 56,854.8

Note: Gross volume is the volume of a tree from a 1-foot stump to a 4-inch diameter top, with no

deduction for cull sections of rot or poor form.

Includes all hardwood trees ≥5 inches diameter at breast height that were alive in 1981-84 and dead in

1991-94.

Includes sound and rotten cull trees.

Excludes volume from land that transferred to reserved status or national forest ownership in the

1990s.

Excludes volume from land that was converted from forest to developed land, roads, or other types of

nonforest in the 1990s.

— = less than 50 cubic feet.

SE = sampling error.

a

 Removals include all trees that were cut or culturally killed during the remeasurement period.
Oak Woodlands and Other Hardwood Forest of California, 1990s

89

Table 15—Gross volume in 1984 and average annual volume change (1984 to 1994) for hardwood species, on unreserved woodland and timberland outside national forests, California

Annual mortality and

1984 gross volume Annual gross growth removals Annual net growth

Species Volume SE Volume SE Volume SE Volume SE

Thousand cubic feet

Oak group:

Blue oak 1,457,529 250,442 22,737 4,215 9,829 3,336 12,908 4,497

California black oak 1,997,285 156,684 33,692 2,643 19,417 3,079 14,275 3,615

Canyon live oak 1,297,255 247,791 19,630 2,910 9,501 5,541 10,129 5,459

Coast live oak 1,317,764 422,411 22,154 7,182 7,837 4,118 14,317 7,023

Engelmann oak 10,731 10,747 73 73 — — 73 73

Interior live oak 521,333 178,920 9,034 2,098 7,503 5,778 1,531 4,931

Oregon white oak 704,753 234,744 13,502 5,118 2,225 1,018 11,277 5,155

Valley oak 546,067 282,026 10,394 5,383 2,565 2,410 7,829 5,320

Total 7,852,716 713,645 131,217 12,060 58,877 10,792 72,340 14,179

 

Non-oak group: 

Bigleaf maple 166,555 29,310 4,218 746 794 413 3,424 801

Black cottonwood 18,268 18,285 275 258 221 221 54 37

Buckeye 133,790 69,868 1,865 761 1,371 765 494 1,017

California laurel 469,997 125,234 12,413 2,844 2,315 1,042 10,097 2,865

Eucalyptus 159,279 154,733 4,796 4,796 1,535 1,414 3,262 3,262

Giant chinquapin 24,635 7,899 751 249 296 223 455 291

Pacific madrone 1,229,222 130,606 25,508 2,427 12,385 2,478 13,123 3,081

Quaking aspen 7,268 3,933 106 68 90 64 15 15

Red alder 151,601 35,108 9,495 2,471 5,256 2,647 4,239 3,525

Sycamore 36,234 36,239 818 818 649 649 169 169

Tanoak 1,556,055 122,019 56,304 4,086 31,862 6,799 24,442 7,757

White alder 42,955 17,817 1,660 884 254 206 1,406 883

Other hardwoodsa 38,841 29,418 745 293 1,091 482 -346 346

Total 4,034,700 293,667 118,953 8,089 58,118 8,975 60,836 11,201

Total, California 11,887,415 803,728 250,170 14,590 116,995 14,164 133,175 18,131

Note: Gross volume is the volume of a tree from a 1-foot stump to a 4-inch diameter top, with no deduction for cull sections of rot or

poor form.

Includes all hardwood trees ≥5 inches diameter at breast height, including sound and rotten cull trees.

Excludes volume from land that transferred to reserved status or national forest ownership in the 1990s.

Excludes volume from land that was converted from forest to developed land, roads, or other types of nonforest in the 1990s.

— = less than 50 cubic feet.

SE = sampling error.

a

 Other hardwoods includes apple, California sycamore, Oregon ash, Pacific dogwood, walnut, water birch, and willow.
RESOURCE BULLETIN PNW-RB-245

90Table 16—Total stem volume of hardwood tree mortality between 1984 and 1994, by species and diameter class, on unreserved woodland and timberland, outside

national forests, California

Diameter class (inches at breast height)

1.0- 3.0- 5.0- 7.0- 9.0- 11.0- 13.0- 15.0- 17.0- 19.0- 21.0- All classes

Species 2.9 4.9 6.9 8.9 10.9 12.9 14.9 16.9 18.9 20.9 28.9 29.0+ Total SE

 Million cubic feet

Oak group:

Blue oak .7 — — — — — — 5.3 — 48.6 33.7 8.3 96.6 45

California black oak 4.8 14.3 11.6 16.3 27.6 6.9 28.0 8.3 14.9 13.5 30.5 47.7 224.4 39Canyon live oak 3.8 3.7 2.6 .7 2.5 2.0 .1 27.5 61.7 — 12.9 14.5 131.9 90Coast live oak — .3 2.4 9.7 1.1 5.9 2.3 64.0 35.7 — — — 121.5 73Interior live oak 2.7 3.0 2.9 6.2 5.4 — .1 — — — — — 20.4 12Oregon white oak .5 3.6 2.8 1.4 1.9 .3 — — 3.7 — 15.4 — 29.7 13Valley oak .1 .3 — — 12.0 2.4 — — — — 27.1 — 41.9 39

Total 12.7 25.2 22.3 34.3 50.5 17.6 30.5 105.1 115.9 62.1 119.7 70.5 666.4

Non-oak group:

Bigleaf maple 0.7 1.0 2.5 — — .1 .5 — — 2.1 — — 6.9 3Buckeye 1.1 3.7 11.0 10.2 .8 6.4 — — — — — — 33.2 18California laurel 1.1 1.4 7.5 2.4 .1 — 1.2 1.8 2.4 .1 2.1 20.1 8Cottonwood/aspen — — 1.0 — — .6 — — — — 3.0 — 4.7 4Eucalyptus .1 .5 — — — 19.4 — 1.4 — — — — 21.4 20Pacific madrone 3.6 4.9 7.0 9.4 9.7 10.7 14.1 11.3 3.7 1.5 11.9 5.5 93.2 20Red alder 1.4 4.8 4.8 3.4 .3 1.3 — .7 1.7 — — 2.5 20.9 7Tanoak 9.8 12.3 12.9 9.3 8.6 12.3 6.3 7.6 3.9 4.7 26.1 9.2 122.9 19White alder .3 3.2 — — — — .8 — — .7 1.1 — 6.0 4Other hardwoodsa .2 — — 12.7 — — 4.5 — 2.4 — — — 19.7 19

Total 18.4 31.8 46.7 47.3 19.4 50.8 27.4 22.8 14.0 9.0 42.1 19.3 349.0

Total, California 31.1 57.0 69.0 81.6 69.9 68.4 57.9 127.9 129.9 71.2 161.8 89.8 1,015.4 165

Note: Total stem volume is the volume of a tree from the ground to the tree tip, with no deductions taken for cull sections.Includes all hardwood trees ≥1 inch diameter at breast height that were alive in 1981-84 and died during the remeasurement period.Includes sound and rotten cull trees.Excludes volume from land that transferred to reserved status or national forest ownership in the 1990s.Excludes volume from land that was converted from forest to developed land, roads, or other types of nonforest in the 1990s. — = less than 50,000 cubic feet. SE = sampling error.a Other hardwoods includes giant chinquapin, Oregon ash, sycamore, Pacific dogwood, and willow.
Oak Woodlands and Other Hardwood Forest of California, 1990s

91

Table 17—Estimated numbers of large hardwood trees on woodland and timberland, by species

and diameter class, California, 1990s

Diameter class (inches at breast height)

11.0- 17.0- 23.0- 29.0- 35.0- All classes

Species 16.9 22.9 28.9 34.9 40.9 41.0+ Total SE

– – – – – – – – – – – – – – Thousands of trees – – – – – – – – – – – – – – %

Oak group:

Blue oak 32,900 7,400 2,100 400 100 — 42,900 7

California black oak 41,700 11,600 4,100 1,500 500 300 59,700 5

Canyon live oak 39,400 8,400 2,400 900 300 200 51,600 7

Coast live oak 29,200 9,600 2,100 700 300 — 41,900 11

Engelmann oak 500 200 200 100 — — 1,000 63

Interior live oak 9,900 2,300 300 200 — — 12,700 13

Oregon white oak 8,400 2,100 500 200 100 — 11,300 15

Valley oak 2,500 700 400 200 100 100 4,000 24

Total 164,500 42,300 12,100 4,200 1,400 600 225,100

Non-oak group:

Bigleaf maple 4,500 1,200 200 100 100 — 6,100 15

Black cottonwood — — 100 — — — 100 53

California buckeye 1,000 — — — — — 1,000 44

California laurel 6,800 1,100 400 100 — — 8,400 18

California sycamore 400 100 200 — — — 700 47

Eucalyptus 1,300 600 100 — — — 2,000 77

Giant chinquapin 1,300 200 100 — — — 1,600 23

Oregon ash 200 — — — — — 200 72

Pacific dogwood — — — — — — — 77

Pacific madrone 22,800 6,300 2,200 500 200 100 32,100 7

Quaking aspen 1,300 200 — — — — 1,500 42

Red alder 3,400 400 100 — — — 3,900 22

Tanoak 39,800 10,100 2,500 600 100 100 53,200 7

White alder 1,400 400 100 — — — 1,900 20

Total 84,200 20,600 6,000 1,300 400 200 112,700

Total, California 248,700 62,900 18,100 5,500 1,800 800 337,000

SE for total (%) 3 3 4 6 8 11 3

Note: Excludes reserved lands outside of national forests because these areas were not sampled.

Includes all live hardwood trees ≥11 inches diameter at breast height.

Includes sound and rotten cull trees.

— = less than 500 trees.

SE = sampling error.
RESOURCE BULLETIN PNW-RB-245

92

Table 18—Estimated numbers of small hardwood trees on woodland and timberland, by species and

diameter class, California, 1990s

Diameter class (inches at breast height)

1.0- 3.0- 5.0- 7.0- 9.0- All classes

Species Seedling 2.9 4.9 6.9 8.9 10.9 Total SE

– – – – – – – – – – – – – – Millions of trees – – – – – – – – – – – – – – %

Oak group:

Blue oak 247 51 75 66 40 28 507 8

California black oak 698 115 90 70 52 32 1,058 5

Canyon live oak 1,401 308 185 138 80 44 2,158 4

Coast live oak 162 28 15 17 18 12 252 12

Engelmann oak 7 3 4 1 1 — 15 77

Interior live oak 396 197 120 58 26 12 810 10

Oregon white oak 178 39 49 42 23 10 341 12

Valley oak 22 2 3 3 1 2 33 31

Total 3,112 743 541 396 241 142 5,174

Non-oak group:

Bigleaf maple 60 31 21 16 9 5 142 10

Black cottonwood 1 — — — — — 3 51

California buckeye 65 27 11 9 7 3 122 15

California laurel 233 83 37 20 11 6 391 10

California sycamore 5 4 1 1 — — 10 57

Eucalyptus 5 1 1 — 3 1 11 88

Giant chinquapin 25 10 4 2 2 1 43 19

Oregon ash 11 3 1 — — — 15 52

Pacific dogwood 58 48 7 1 — — 114 13

Pacific madrone 158 80 39 30 21 15 344 8

Quaking aspen 21 11 6 2 1 1 42 32

Red alder 8 34 9 6 6 4 68 23

Tanoak 863 561 205 116 64 38 1,846 4

White alder 11 8 4 2 1 1 26 31

Total 1,525 899 346 206 125 75 3,176

Total, California 4,637 1,641 886 602 367 217 8,350

SE for total (%) 3 3 3 4 6 8 3 

Note: Excludes reserved lands outside of national forests because these areas were not sampled.

Includes all live hardwood trees <11 inches diameter at breast height.

Includes sound and rotten cull trees.

— = less than 500,000 trees.

SE = sampling error.
Oak Woodlands and Other Hardwood Forest of California, 1990s

93

Table 19 — Forest type attributes (area, basal area, and trees per acre) on woodland and timberland, for

12 countiesa

 in California quarantined for Phytophthora ramorum as of summer 2004

Land area Tree attributes within forest typeb

Privately Timber- Average basal area Average TPA

Forest typec Area SE owned land Basal area SE Trees per acre SE

Thousand % % % Sq. ft. per % Number per %

acres acre acre

Tanoak 1,031 7 92 100 182 12 256 13

Redwood 690 9 87 100 287 15 250 15

Douglas-fir 642 9 69 100 206 14 191 15

Coast live oak 532 14 81 12 114 21 135 22

Blue oak 444 16 83 1 62 24 93 24

Oregon white oak 299 16 89 42 117 25 186 26

California black oak 244 18 90 67 132 27 169 31

Pacific madrone 223 20 80 79 151 29 184 30

Canyon live oak 209 19 56 58 168 26 251 29

California laurel 163 24 99 58 116 34 153 38

Valley oak 106 35 100 13 66 50 91 51

Interior live oak 56 36 68 33 129 50 138 53

Red alder 48 39 100 100 137 58 214 58

Bigleaf maple 48 39 65 46 111 57 143 57

Mixed conifer 47 28 1 100 228 44 139 40

Other forest typesd 306 15

All forest land 5,089 2 81 68 162 5 188 5

Note: Excludes reserved lands outside of national forests because these areas were not sampled.

All data are from inventories conducted in the 1990s.

SE = sampling error.

TPA = trees per acre.

a

Includes Alameda, Contra Costa, Humboldt, Marin, Mendocino, Monterey, Napa, San Mateo, Santa Clara, Santa Cruz, Solano,

and Sonoma Counties.

b

 The average of all live trees (including sound and rotten culls) ≥5 inches diameter at breast height. c

 Forest types are ordered by the amount of acres present in the 12 counties.

d

 Other forest types include a mixture of hardwood and softwood types; no attributes are presented for this group.
RESOURCE BULLETIN PNW-RB-245

94

Table 20—Estimated forest land area where host tree speciesa

 of Phytophthora ramorum were present on

woodland and timberland, for counties in California quarantined as of summer 2004

Forest area for sampled land Forest area with sudden oak Area of host

in 12 counties death host trees presentb presence/

County Area SE Area SE forest area

Thousand acres % Thousand acres % %

Alameda 113 35 59 48 52

Contra Costa 52 54 34 66 66

Humboldt 1,615 5 1,478 5 92

Marin 26 73 25 75 97

Mendocino 1,668 5 1,454 6 87

Monterey 551 12 224 16 41

Napa 184 24 87 29 47

San Mateo 59 35 55 35 92

Santa Clara 239 23 162 27 68

Santa Cruz 184 17 180 17 98

Solano 20 68 3 100 18

Sonoma 378 13 354 13 94

Total, California 5,089 2 4,115 3 81

Note: Excludes reserved lands outside of national forests because these areas were not sampled.

All data are from inventories conducted in the 1990s.

SE = sampling error.

a

 Host tree species included: bigleaf maple, California black oak, California buckeye, California laurel, canyon live oak, coast

live oak, Douglas-fir, Pacific madrone, redwood, tanoak.

b

 Classification of presence/absence was based on whether a regulated host tree species was present on a subplot of the plot. The

estimate of area with host trees present may be underestimated because: (a) understory vegetation and shrubs were not included,

(b) seedlings were subsampled on a smaller fixed-radius plot, and (c) trees were sampled with variable-radius sampling.
Pacific Northwest Research Station

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