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A3
1
Minnesota's Forest
id States
1 Department of
Agriculture
Resources 2001
in
Forest
Service
North Central
Patrick D. Miles, Manfred E. Mielke, and Gary J. Brand
Research Station
Resource Bulletin
NC-217
warn
- -
Norih Central Research Station
U.S. Department ofAgriculture - Forest Service
1992 Folwell Avenue
Saint Paul, Minnesota 55108
2003
www.ncrs.fs.fed.us
1
CONTENTS
Results 1
Area
1
Volume 4
Biomass 5
Forest Health 5
Appendix 10
Inventory Methods 10
Sampling Phases
1
Phase 1 11
Phase 2 11
Literature Cited 13
Table Titles 13
Tables 15
Minnesota's Forest Resources
2001
in
The North Central Research StationsForest are completedinyears 4 and 5, the precision of
InventoryandAnalysis (NCFIA) program the estimateswill increase and additional data
began fieldwork forthe sixth forestinventoryof willbe released. About the Authors:
Minnesota's forest resourcesin 1999. This
inventoryinitiated thenewannualinventory Data fromnewinventoriesare oftencompared Patrick D. Miles isa
systeminwhich one-fifth ofthe field plots with data fromearlierinventories to determine researchforesterwith
(considered one panel) inthe State are mea- trends in forest resources. However, for the the Forest Inventoryand
sured eachyear. Acomplete inventoryconsists comparisons tobe valid, the proceduresusedin Analysis (FIA) unit at
ofmeasuringand compilingthe data forall the two inventoriesmustbe similar. As aresult the North Central
plots (orfivepanels). Once allpanelshavebeen ofour ongoingefforts to improve theefficiency ResearchStation, St.
measured, eachwillbe remeasured approxi- and reliabilityofthe inventory, several changes Paul, MN.
matelyevery 5 years. Forexample, in Minne- inproceduresand definitionshavebeen made
sota, the fieldplotsmeasured in 1999 will be since the lastMinnesota inventoryin 1990 Manfred E. Mielke is
remeasured in 2004. (Miles etal. 1995) (see appendix). While these a plantpathologistwith
changeswill have little impact onstatewide the Forest Health
In 2001, NCFIAcontinued the annualinven- estimates offorest area, timbervolume, and tree Protection programat
toryeffortwith the third panel ofthe sixth biomass, theymayhave significantimpacts on the St. PaulField Office
forestinventory. Reports ofpreviousinventories plotclassificationvariablessuchasforest type ofthe NortheasternArea
ofMinnesota are dated 1936, 1953, 1962, andstand-size class. Some ofthese changes State and Private
1977, and 1990. This sixthinventoryof make it inappropriate to directlycompare 2001 Forestry, St. Paul, MN.
Minnesota's forestresourceswillbe completed data tableswiththosepublished for 1990.
in 2003. However, because eachyear'ssample GaryJ. Brand isa
isasystematic sample ofthe State's forestand researchforesterwith
because timelyinformationisneededabout RESULTS the Forest Inventoryand
Minnesota's forestresources, estimateshave Analysis (FIA) unit at
been prepared from data gathered duringthe Area the North Central
first 3years ofthe inventory. Data presented in The total land area ofMinnesota is 50.9 million ResearchStation, St.
this reportrepresent 60 percentofthe field acres ofwhich 32 percent or 16.3 millionacres Paul, MN.
plots (orthree panels) fora complete inventory are forestland. There are three components to
—
and are a combination ofthe firstyear'spanel forestland: (1) Timberland1 forest land thatis
from 1999, the secondyear'spanel from 2000, notrestricted fromharvestingbystatute,
and the thirdyear'spanel from 2001. Earlier administrative regulation, ordesignationandis
reportsforthe 1999 panel (Schmidt 2000) and capable ofgrowingtrees at a rate of20 cubic
the combined 1999 and 2000 panels (Haugen
etal. 2002) have alsobeenpublished. Results 1Timberlandmaynotbe equivalentto thearea
presentedare estimatesbased on sampling actuallyavailable forcommercialtimber
techniques; estimateswere compiled assuming harvestingorotheraccess. Theactualavailabil-
ityoflandforvarious uses depends upon owner
the 1999, 2000, and 2001 data represent one
decisions thatconsidereconomic, environment,
large sample. Asadditional annualinventories andsocialfactors.
— —
feetperacre peryear; (2) Reserved forestland with the otherhalfdue toconversion to
land that isrestricted fromharvestingbystatute, timberland. The neteffectwasadecrease inthe
administrative regulation, ordesignation (i.e., areaestimate forforestland and anincrease in
national parks, wildernessareas, etc.); and (3) the areaestimate fortimberland.
—
Otherforestland low-productivity forestland
thatisnotcapable ofgrowingtreesata rate of The estimate oftimberland inpublic ownership
20 cubic feetperacre peryear. increased from 7.584millionacresin 1990 to
8.064million acresin 2001 whileprivate
The estimatedarea offorest land declined from ownership declined from 7.1392 millionacres
16.7 millionacresin 1990 to 16.3 millionacres to 6.9185 millionacres overthe same period
in 2001. Duringthe same period, timberland (fig. 2). Nearly four-fifthsofallconifer forest
showed a slightincrease from 14.7 millionacres types are found onpubliclyownedland. Over
in 1990 to 15.0millionacresin 2001 (fig. I)2. four-fifths ofall private timberland isin the
The decrease inforestlandand the increase in hardwood forest types.
timberlandare due inlarge partto changes in
the reservedandotherforestlandcomponents. Changesinthe plotdesign, stocking, and forest
The estimate ofreserved forestlanddecreased typingalgorithmslimitcomparisonsofthe 1990
from 1,117 thousandacresin 1990 to 962 and 2001 inventories. Thisis especially true
thousand acresin 2001, and the areaestimate of withplotclassificationvariablessuchas forest
otherforestlanddecreased from 840 thousand type and stand size. Wheneverpossible,
acres to 349 thousand acres. Nearlyhalfofthis comparisonsshouldbebased on observed
acreage decreaseinreservedandotherforest variablessuchas tree speciesand diameter.
landwas due to conversionto non-forestland
The aspen-birch forest type, with6.7 million
2The errorbarsatopeach barin figure 1 acresoftimberland, is the dominant forest type
providesameasureofreliabilityofthese figures. in the State (fig. 3) and isanimportant resource
In2001 there wasa twooutofthree chance that forMinnesota's forestindustries. Three-fourths
ifa 100-percentinventoryhadbeen taken, using ofall the coniferous timberlandin the State is in
thesamemethods, theresultwouldhave—been
within thelimitsindicatedbythebracket the spruce-fir forest type (3.1 million acres).
14,982.5thousandacresplusorminus 128.9 Betweeninventories, the estimate ofhardwood
thousandacres. forest typesincreased from 10.2 millionacresin
20,000
-,
Figure 1 . Area of w 15,000
timberlandin 0u)
Minnesota by CO
10,000
inventory year. n
(3A
O
£
5,000
1936 1953 1962 1977 1990 2001
Inventory year
2
—
1990 E2001
Aspen/Birch
Maple/Beech/Birch
Figure 3. Area of
Q. timberlandin
3
2 Elm/Ash/Cottonwood Minnesota in 1990
U) and2001 by forest
a>
a.
type.
Oak/Hickory
Spruce Fir
White/Red/Jack Pine
2,000 4,000 6,000 8,000
Thousand acres
—
1990 to 10.9 millionacresin 2001,while the despite an8-percent decline in the numberof
estimate forconiferforest typesdecreased from poletimber-size trees. Overthe same period the
4.4millionacresin 1990 to 4.0 million acresin area classifiedaslarge stands (sawtimberstands
2001. Thisappears tobe the resultofnew where apluralityofthe stockingisin treesat
stockingand forest typingalgorithmsused in least9.0 inchesd.b.h. forconifersor 11.0
conjunctionwithanewplot designratherthan inches d.b.h. fordeciduoustrees) decreasedby
a change inspecies compositionbecause 17percent (819 thousandacres) from 1990
roughly31 percentofthe Statesgrowing-stock (4,890.3 thousand acres) to 2001 (4,072.9
volumewasinsoftwoodtree speciesinboth thousandacres), despite a 2-percentincreasein
1990 and 2001. the numberofsawtimbertrees. Three-fifthsof
thisdecrease occurredinthe aspen-birch type.
The area classified assmall-diameterstands
(sapling/seedlingstandswhere a pluralityofthe Volume
stockingisintreesless than 5.0 inches at Historically volume hasbeenreportedaseither
diameterbreastheight (d.b.h.)) increasedby 16 growingstockorsawtimber. However, there are
percentorby701 thousandacresfrom 1990 volumesinnoncommercial trees, rough trees,
(4,444.2 thousand acres) to 2001 (5,144.8 and rotten treesthat do notqualifyasgrowing
thousand acres). Most ofthisincrease occurred stockbut thatareutilized forwood fiberand
in the aspen-birch forest type where the area of fuelwood. Suchtrees alsomake important
sapling/seedlingstandsis estimated to have ecological contributions (suchas forwildlife
increasedby692 thousandacres. These changes habitat, and soilandwaterprotection). Withthe
inareabystand-size class are due inpart to annualized inventorysystem and increased
changesinthe plotdesign and changesinthe interestinFIAdata from anecological perspec-
stand-size classificationalgorithm (see Inven- tive, agreater focushasbeen placed on all live
toryMethodsin the appendix). volume. In 2001, Minnesotahad 17.4billion
cubic feet ofalllive volume onits 16.3 million
The areaclassifiedasmediumstands acres offorestland. Thisequates toanaverage
(poletimberstandswhere a pluralityofthe of1,068 cubic feet ofall live volume foreach
stockingisin trees from 5 to 9 inches d.b.h. for forest land acre in Minnesota. Unfortunately, all
conifersand 5 to 11 inchesd.b.h. forhard- livevolumeisnotreadilyavailable from the
woods), rose from5.3 millionacres oftimber- historic inventoriesand thuscomparisonsover
land in 1990 to 5.7 million acres in 2001, time consideronlygrowing-stockvolume.
mLarge nMediumnSmallmNonstocked
Figure 4. Area of
timberlandin Minne-
sota bystand-size
class andinventory
year.
1962 1977 1990 2001
Inventory year
4
