Idaho's forests, 1991

74 Pages·1996·4.1 MB·English

by  Brown, Mark J

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Historic, archived
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A99.9 F764Ub
Idaho's Forests,
ForestService
Intermountain Mark J. Brown
Research Station
David C. Chojnacky
Resource Bulletin
INT-RB-88
November 1996
The Authors
Mark J. Brown is a Resource Analyst in the Forest Statewide forest inventories are part of an ongoing,
InventoryandAnalysisProjectattheSouthernResearch nationwideeffortofthe ForestService, U.S. Department
Station in Asheville, NC 28802. He holds a Masters ofAgriculture,toassesstheNation'sforestlands. Forest
degree in forestry from Clemson University. Inventory and Analysis (FIA), a subgroup within Forest
DavidC.ChojnackyisaResearchForesterintheInterior Service Research, is responsible for this task. It uses
West Resource Inventory, Monitoring, and Evaluation periodic, State-by-State, sample-based inventories. FIA
ProgramattheIntermountainResearchStationinOgden, was initially authorized by the McSweeney-McNary Act
UT 84401. He holds a Ph.D. degree in forest biometry of 1928.Thecurrentauthorizationisthroughthe Renew-
able Resources Research Act of 1978.
-'-radc State University.
In the Western States of Arizona, Colorado, Idaho,
Montana, New Mexico, Nevada, Utah, and Wyoming,
Research Summary FIA inventories are conducted by the Interior West Re-
sourceinventory, Monitoring,andEvaluation Programat
Thisreportpresentstheresultsofthe 1990-1991 inven- theIntermountainResearchStationinOgden, UT.These
toryof Idaho's forest lands, and includes discussions of inventories provide dataon land areaand wood volume
forest land area, tree numbers, wood volume, annual that can be classified for many resource uses. Most of
mortality, netgrowth, and removals. Most information is theseinventoriescoverState,privatelyowned,andother
organized by ownership, stand, and tree classification forestlands notintheNational ForestSystem.Thedata,
variables.Thereportalsoexplainsinventoryterminology when combined with similar information on National
and inventory design and discusses data reliability. Forest lands, provide an extensive database for forest
Results show there are more than 22 million acres of lands. This 1991 inventory of Idaho incorporates infor-
forest land in Idaho. About 96 percent of this area is mation from National Forest System lands to provide a
covered by timberland forest types (predominantly comprehensive database forthe State's forests.
Douglas-fir),and4percentiscoveredbywoodlandtypes
(predominantlyjuniper). Nearly85percentoftheforests
Acknowledgments
are administered by government agencies. About 17 per-
cent of the forests are reserved from being utilized for
The authors gratefully acknowledge the cooperation
wood products. Most of the nonreserved forests (17.6
and assistance from Idaho's State Forester and other
millionacres)areclassifiedastimberland.Netvolumeon
Idaho Department of Lands personnel; the Bureaus of
this timberland is almost 40 billion cubic feet of wood.
Land Management and Indian Affairs, U.S. Department
cDoouugnltasf-ofrimr,osgtroafntdhefirt,imabnedrllaonddgveopolluemep.iTnehespteicmbieerslaancd- of the Interior; and the Intermountain RWeegion, Forest
Service, U.S. DepartmentofAgriculture. alsoappre-
mortality averaged 290 million cubicfeet annually. As a
ciatetheassistanceprovidedbytheIntermountainForest
result, netgrowth averaged 816 million cubicfeet annu-
Industry Association and thank the private landowners
ally(46.3cubicfeetperacreperyear). Removalstotaled
who provided information and access to field sample
390 million cubic feet in 1990. True firs and Douglas-fir
made up close to half ofthe volume removed. plots.
Intermountain Research Station
32425th Street
Ogden, UT84401
Highlights • Just over one-half (51 percent) of the total cubic-foot
volume is in trees less than 15 inches diameter at
Area breast height (d.b.h.).
• Forests cover 22.3 of the 53.5 million acres within Mortality
Idaho's boundaries.
• Annual mortality of growing stock totaled 290 million
• Most forests, 21.4 million acres, are classified as tim- cubicfeet. Overthree-fourths (76 percent) ofthe mor-
berland.Theremaining0.9millionacresareclassedas tality occurred on National Forests.
woodland.
• Douglas-fir accounted for 22 percent of mortality, fol-
• A substantial portion of the timberland, 3.8 million lowed by subalpine firwith 17 percent.
acres, is reserved.
• Insectswereresponsiblefor31 percentofthegrowing-
• National Forests account for 73 percent (12.8 million stockmortalityandwerethe leading identifiablecause
acres) of the nonreserved timberland and nearly 99 of death.
percent of the reserved timberland.
Growth
• Douglas-fir is the predominant forest type on the
nonreservedtimberlands, occupying6.1 million acres. • Net annual growth of growing stock averaged 816
Lodgepole pine is next with 2.5 million acres. Lodge- million cubic feet.
pole, ponderosa, and western white pine types have
decreased in area. • Douglas-firprovided31 percentofthegrowth,followed
bygrandfirwith21 percent. Lodgepolepineaccounted
• Stands classified as sawtimber size comprise 70 per- for 14 percent.
cent (12.3 million acres) of Idaho's nonreserved
• Overall, net growth of growing stock on timberland
timberlands.
averaged 46.3 cubic feet per acre per year.
• Woodland is primarilyfound in southern Idaho, where
Removals
juniper is the predominant species.
Volume • About 309 million cubic feet of growing-stock volume
were harvested in 1990, including 1,584 million board
• Idaho's nonreserved timberlands contain almost 40 feet (Scribner rule).
billioncubicfeetofwoodingrowing-stocktrees, includ-
ing 143 billion board feet of sawtimber (Scribner rule). • Sawlogs accounted for 75 percent of growing-stock
removals. Veneer logs were second with 8 percent.
• National Forests contain 76 percent of the cubic-foot
volume and 77 percent of the board-foot volume • True firs made up 24 percent of the growing-stock
volume removed, and Douglas-fir made up another
(Scribner rule).
22 percent.
• Douglas-fir forest type contains one-third of Idaho's
growing-stock volume. The Douglas-fir species indi-
vidually accounts for 31 percent of the volume.

Contents Page Number of Trees Page
Introduction 1 12. Numberof growing-stock trees on
Area 2 timberland by species and diameter
Ownership 3 class, Idaho, 1991 46
Type 3 13. Number of cull and salvable dead trees
Age 7 on timberland by owner groupfor softwoods
Size 8 and hardwoods, Idaho, 1991 46
Numbers of Trees 9 Volume
Volume 12
Mortality 12 14. Net volume of growing stock on timberland
Net Growth 15 by forest type and stand-size class, Idaho,
Removals 16 1991 47
Net Change 19 15. Net volume of sawtimber (International
Forest Products Industry 21 1/4-inch rule) on timberland by foresttype
Methods 23 and stand-size class, Idaho, 1991 47
Standard Forest Survey Terminology 25 16. Net volume of sawtimber (Scribner rule)
References 30 on timberland by forest type and stand-size
class, Idaho, 1991 48
Forest Survey Tables
17. Net volume of growing stock on timberland
1. Total area by ownership class and land class, by species and owner group, Idaho, 1991 48
Idaho, 1991 31 18. Net volume of sawtimber (International
2. Standard error for sampling area, volume, 1/4-inch rule) on timberland by species
growth, and mortality for nonreserved and owner group, Idaho, 1991 49
timberland in Idaho 32 19. Net volume of sawtimber (Scribner rule)
3. Summary of inventory design information on timberland by species and owner group,
forthe 13 sample areas that were combined Idaho, 1991 49
for reporting Idaho's forest resources 33 20. Net volume of growing stock on timberland by
4. Area of forest land by forest type, owner species and diameter class, Idaho, 1991 50
group, and land class, Idaho, 1991 34 21 Net volume of sawtimber (International
.
1/4-inch rule) on timberland by species
Nonreserved Timberland Tables
and diameter class, Idaho, 1991 50
22. Net volume of sawtimber (Scribner rule) on
Area
timberland by species and diameter class,
5. Area of timberland by forest type, stand-size Idaho, 1991 51
class, and productivity class, Idaho, 1991 35 23. Net volume of timber on timberland by
6. Area of National Forest timberland by class of timberfor softwoods and hardwoods,
forest type, stand-size class, and Idaho, 1991 51
productivity class, Idaho, 1991 37 24. Net volume of growing stock on timberland
7. Area of other publicly owned timberland by forest type and species, Idaho, 1991 52
by forest type, stand-size class, and 25. Net volume of sawtimber (International
productivity class, Idaho, 1991 39 1/4-inch rule) on timberland by forest type
8. Area of forest industry owned timberland and species, Idaho, 1991 52
by forest type, stand-size class, and 26. Net volume of sawtimber (Scribner rule)
on timberland by forest type and species,
productivity class, Idaho, 1991 41
9. Area of nonindustrial private timberland Idaho, 1991 53
by forest type, stand-size class, and Mortality
productivity class, Idaho, 1991 43
10. Area of timberland by stand volume 27. Annual mortality of growing stock on
and owner group, Idaho, 1991 45 timberland by species and owner group,
1 1. Area of timberland by forest type and Idaho, 1990 54
stocking condition, Idaho, 1991 45
Page Growth Page
28. Annual mortality of sawtimber (International 36. Net annual growth of growing stock on
1/4-inch rule) on timberland by species and timberland by species and owner group,
owner group, Idaho, 1990 54 Idaho, 1990 59
29. Annual mortality of sawtimber (Scribner 37. Net annual growth of sawtimber (International
rule) on timberland by species and owner 1A-inch rule) on timberland by species and
group, Idaho, 1990 55 owner group, Idaho, 1990 59
30. Annual mortality of growing stock on 38. Net annual growth of sawtimber (Scribner
timberland by species and diameter rule) on timberland by species and owner
class, Idaho, 1990 55 group, Idaho, 1990 60
31 Annual mortality of sawtimber (International 39. Net annual growth of growing stock on
. 1/4-inch rule) on timberland by species and timberland by species and diameter class,
Idaho, 1990 60
diameter class, Idaho, 1990 56
32. Annual mortality of sawtimber (Scribner 40. Net annual growth of sawtimber (International
rule) on timberland by species and diameter 1/4-inch rule) on timberland by species and
class, Idaho, 1990 56 diameter class, Idaho, 1990 61
33. Annual mortality of growing stock on 41. Net annual growth of sawtimber (Scribner
timberland by species and cause of rule) on timberland by species and diameter
death, Idaho, 1990 57 class, Idaho, 1990 61
34. Annual mortality of sawtimber (International Removals
1/4-inch rule) on timberland by species and
cause of death, Idaho, 1990 57 42. Removals of growing stock by product
35. Annual mortality of sawtimber (Scribner and owner group, Idaho, 1990 62
rule) on timberland by species and cause 43. Removals of growing stock by species
of death, Idaho, 1990 58 and owner group, Idaho, 1990 63
Idaho's Forests, 1991
Mark Brown
J.
David C. Chojnacky
Introduction
This resource bulletin summarizes Statewide findings ofthe latest forest
inventory ofIdaho and covers all major ownership groups. It combines data
recently reported for land outside National Forests in northern Idaho
(Wilson and Van Hooser 1993) and southern Idaho (Chojnacky 1995) with
data from National Forests provided by the Intermountain and Northern
RegionsoftheNationalForestSystem(NFS). Theinventoryoflandsoutside
National Forests was performed by the Intermountain Research Station
Interior West Resource Inventory, Monitoring, and Evaluation (IWRIME)
Program as partofits ForestInventoryandAnalysis (FIA)activity. Datafor
timberlandacreswerecollectedbetween 1990and 1991;woodlanddatawere
collected duringthe 1981 survey. Data collection dates forNFS landsvaried
by individual forest, ranging from 1974 to 1993, with most forests sampled
in the 1980's and 1990's.
Comparisonsto 1980NFSstatisticspreviouslyreportedforIdaho(Benson
and others 1987) should be restricted to area figures. Methods forobtaining
areadataarefairlyconsistentovertime,butvolumeestimationcanvarydue
to field sample selection, data collection, and data processing methods.
Historic data collection ignored lands producing less than 20 cubic feet per
acre per year; now all nonreserved lands are sampled. Previous volume
estimates from NFS lands were not derived in the same manner as current
volume figures; therefore, direct comparisons should be avoided. Greater
effortsweretakentoensuretheaccuracyofcurrentvolumedataconsidering
the constraints ofblending NFS and FIA sample data. The current volume
data are believed to portraythe most accurate assessmentofIdaho's timber
volume available to date.
This report describes Idaho's forest resources by area, ownership, forest
type, volume, growth, removals, and mortality (tables 1-43). Woodland,
forest land where timber species make up less than 10 percent stocking,
provides important wildlife habitat but constitutes only a small part ofthe
State's forest resources and contains even less of the timber resource.
Therefore, the primary focus of the report is on timberland; woodland is
addressed only briefly. Tabular information including woodland is found
only in tables 1, 3, and 4.
Timberlandisforestlandwheretimberspeciesmakeupatleast 10percent
stocking. After the initial discussion by area and table 1, the report focuses
on nonreserved timberland. Nonreserved timberland is timberland not
withdrawn from tree utilization. From that point on, the terms timberland
andnonreservedtimberlandareusedsynonymously,withnonreservedused
intermittently for emphasis. The findings are initially highlighted, then
shown graphically and explained in more detail through text. Abroad scale
1
.
map offorest resource occurrence and type distribution is included. Inven-
tory procedures and standard forest survey terminology follow. Last, 43
supplementaltables areincludedasafurthersourceforstatisticspresented
inthe text and forthose readers interested in pursuingindividual analysis.
In general, these tables describe timberland bytree, stand, ownership, and
volume related variables.
Area
Idaho's boundaries encompass 53.5 million acres (table 1). About 22.3
million acres, or42 percent ofthe State, are forested to some degree (fig. 1).
Most ofthe forests, 21.4 million acres, are at least 10 percent stocked with
treespeciestraditionallyusedforindustrialwoodproductsandareclassified
as timberland. The remainingforests, 0.9 million acres, while stocked with
suchspeciesasRockyMountainjuniper(Juniperusscopulorum)andcurlleaf
mountain-mahogany (Cercocarpus ledifolius), lack sufficient stocking of
timber species to be included in the timberland base and are classified as
woodland.
Legislation has reserved nearly 4.3 million acres, or 8 percent, of the
land area in Idaho. These reserved lands are composed of3.8 million acres
oftimberland, 0.5 million acres ofnonforest land, and a trace ofwoodland.
Just 1 percentoftheState'swoodlandandjustover 1 percentofitsnonforest
land are reserved, but 18 percent of its timberland is set aside. Lands
administeredbyNFS,primarilythoseintheWildernessSystem, accountfor
93 percent of reserved areas. The remainder consists of National Park,
National Monument, miscellaneous Federal, State, and other areas pro-
tected for their unique aesthetics, history, or recreational value.
Nonforest 30.7
Timberland 17.6
nonreserved
Water0.5
Woodland 0.9
Reservedtimberland3.8
Woodland 0.9
Timberland 21.4
Idaho's landscape Idaho's forest
53.5 million acres 22.3 million acres
—
Figure 1 Areawithin Idaho's boundaries by land class and portion that is forest by class offorest, 1991
2