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document Historic, archived Do not assume content reflects current scientific knowledge, policies, or practices. 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