derosa and P•nuscontorta on compacted soilm central Washington For Ecol Manage 15:285-294. FRO•U.•CH, H.A. 1979.Soilcompaction fromlogging equipment:effectson the growth of youngponderosapine. J. SoilWaterConserv. 34:276-278. FRolics, H.A. 1978.Soilcompaction fromlow ground-pressure torsion-suspension logging vehicles on three forest soils. For. Res. Lab. Oreg.StateUniv. Res.Pap.36, 13p. GIRL, W.R., .•a4oR.D. M•LL•I•. 1956. A method for FIELD study of the influenceof mechamcalimpedanceand aerationon the growth of seedling fect of tractorloggingon softand regeneration in the Douglas-fir region of southwestern roots. P. 154-157 in Soil Sci. Soc. Proc. Washington. P. 77-80 in SOc.Am. For. Pzoc Ho•, G.T., F.B. KNIGHT, • R.A. STRUC•- TEkeZER.1978. The effects of mechanized har- vestingon soil conditionin the spruce-firregion of north-centralMaine. Bull. Maine Life Sci.Agric.Exp.Stn.No. 751. Lcv•L,H.W. 1959.Soilcompaction on forestand rangelands.USDA For. Serv.Misc. Publ.No. 768.33p. STEU•RENNER,E.C., • S.P. G•SS•. 1955. Ef- PatrickC. West, StevenR. Brechin, and Dale]. Blahna 4 In this articlewe discussa studyof residential wood energy use and needsof the rural elderly.This topic hasreceived verylittleattention,yetis potentiallyvery importantto the well beingof the rural elderly.On the one needsand problemsof the rural elderly. A studyby Force(1986)among hand sample,in particular,tended to be nonusersof residentialwood energy. However, she did not analyzethese findingsfurtheror followup on their implications for wood energyand the elderly. for home heatingcanbe an importantsourceof cost savingsfor elderly personson fixed incomes; and on the other hand the elderly may be forcedto reduce theiruseof woodenergydue,in part, perhapsto increasing healthproblems and increasing frailty and loss of strengthandendurance dueto normal biological aging. Therehas been a growingbody of literatureon residentialwoodenergy, but much of this literature has focused on supplyand marketsfor residential fuelwood (e.g., Palmer et al. 1980, rural Idaho residents found that non- users of residential wood energy tendedto be older, on average,than users, and that retired members in the AND The StudyRegion Six counties in northern Third Central Hardwood conf., Univ. Mo. A randomsampleof 1864property ownersin the six studycountieswas selectedfrom the 1986property tax rollsin eachCountyEqualizationOfrice.The targetsampleratiowas2.8% of landowners.A samplingquotawas calculatedfor eachcountyand each municipality(township,city, or village)within the sixcountiesbasedon the numberof real propertydescriptions.Propertyownerswere selected at randomfrom the alphabeticlist of all property ownersin each county Commercialand tax exempt owners were not countedas part of the sampling frame. Owners of multiple parcelswere counted only once in orderto reducesamplingbias.Names were selecteduntil the quotafor both the county and each municipahty within the countywere reached.Both absenteeand permanentresidents wereincludedin the sample,but only the resultsfor permanentresidents are shown here because of the focus of Michiganwere selectedto serveasthe regionfor the study.The selectionof A four wave mail surveywas sent out. The first wave includeda survey the counties and cover letter. The second wave was was based on the fol- forest resources,at least 50% forested, vate land. The selected counties were and with a balanceof publicand priBenzie, Leelenau,Kalkaska,Ostego, Alpena,and Alconacounties. a reminderpost card. The third wave was anothersurveyand coverletter, followed by a final reminder post card.Of the 767 surveyssentout to permanent residents in the full sample,384werereturned,a response rate of 50%. contributions from our readersdescribing usefulideas, shortcuts,and findingsfor the field for- Table1. Ageand wood use. Age ester. 2 Thisresearch wasfundedby a McIntireStennisForestryResearchgrant. The senior author would like to thank the Univer- sityof Michigan,Instituteof Gerontology, for a SeniorFellowshipthat providedtime for literature review, improved understandingof the aging process,data analysis,and paperwriting. • University of Michigan,School of Natural Resources, Dana Bldg.430 E. University, Ann Arbor, M148109-1115. • Collegeof NaturalResources, UtahState University,Logan,UT 84322. 36 NJAF8(1991) saccharura Marsh. Mail Surveyand ResponseRates the residential wood energy user (e.g.,Force1986,SkogandWatterson but nonreferred J.R. DONNEgLY. 1980. De- tectionof soilcompaction relatedstressin Acer lower 1986).Of the literaturethat focuseson • Edited WmLm•S, M.H., • METHOD lowing criteria. All counties in the study area are rural, in proximityto 1983, MDNR 1981-82, Tillman 1978), under an oak forest. Minn. For. Res. Note No 257. this sub-study. DATA Cable and Warner 1988, Evans and Parker 1987, Parker 1984, MDOC scantattentionis given to the special changesin soil densityfollowingcompaction SampleSelection NOTE Residential Wood Energy and the Rural Elderly in Northern Lower Michigan2 the use of wood SOc. Am. For., Bethesda, MD. THORUV, D.B., AND S.S. FRISSELL.1976. Time Percent wood use 100% N % N % N % N % N % 51-99% 10-50% Under 10% None Under 40 40- 59 60 + 24 30.8% 31 39.7% 10 12.8% 7 9.0% 6 7.7% 31 27.2% 40 35.1% 23 20.2% 12 10.5% 8 7.0% 10 9.0% 37 33.3% 27 24.3% 18 16.2% 19 17.1% X2 = 25.2, d.f. = 8, Cramer'sV = 0.2, P < 0.001. RESULTS Table2. Ageandwooduseby income. In Table 1 it can be seen that the el- derly over 60 have reducedtheir dependenceon woodasa homeheating source. In most cases this has not re- suitedin totallygivingup wood,but ratherin reducingthe percentage of home heatingdependenceon wood. This canbe seenin particularin a reduction from 100% use of wood to lower percentages. Thesedifferences are statistically significant(X2 = 25.2, d.f. = 8, P < 0.001).Thesedifferences were not due to differences in facilities to burn wood. The elderly did not have significantlyless facilitiesfor burning wood than did younger gToups(X2 = 4.8, d.f. = 2, NS). Nor do incomedifferences seemto explain Lower income subtable (0-$19,999) Age Percent wood use Under 40 40-59 60+ 51-100% N % 13 72.2% 16 69.6% 26 43.3% 0-50% N % 5 27.8% 7 30.4% 34 56.7% X2 = 7.4, d.f. = 2, Cramer'sV = 0.27, P < 0.05. Higherincomesubtable($20,000+) Age Percent wood use Under 40 40-59 60+ 51-100% N % 39 68.4% 45 59.2% 17 42.5% 0-50% N % 18 31.6 31 40.8% 23 57.5% X2 = 6.5, d.f. = 2, Cramer'sV = 0.19, P < 0.05. these differences. Table 2 shows that the relationship between age and wood burning is about the samefor bothhigherandlowerincomegroups. Table3 indicates thatthe elderly,just as much as youngergroups,would wood. Our results indicate that for those who heat 100% with wood in dency amongthe otherwisehealthy elderly toward falling can also be problematic (Ochset al. 1985,RomickAllen and Schultz1988).Injuriesfrom falling may be more likely to cause bone breakageand slower healing. Thus,bothfallsandfearof fallingmay inhibitwoodcutting.Declineof cognitive functioningdue to Alzheimer's disease (Cohen 1987, Miller and thisregion,almost60%usefrom 16to Cohen 1981) or other forms of "de- over mentia and delirium" (Besdine1988, Kausler 1970) could also present increasinglysevere obstaclesto continued participationin wood cutting andburning. hke to heat more with wood. Oneobvious reasontheelderlymay be reducingtheir use of woodis that w•th increasing illnessandthe normal agingprocesstheymaybe lessableto handle the rigors of heating with 25 face cords of wood each heatingseason. If a personengages in all thelaborto cut,haul,cutup, and split this amount of wood it can tax the physicalcapabilities of younger people,let alonetheelderly.Otherresuitsof the studyindicatethat the elderly (probablyfor financialreasons) do not purchasefirewoodmore than younger personsin order to avoid the heavy labor (X2 = 26.11, d.f. = 20, DISCUSSION This study found that the rural elderlyin the studyregionheatedwith wood lessthan youngerage groups. This was not due to differences in NS). wood burningfacilitiesor to differen- In additionto majordiseaseaffiictons of oldagesuchascardiovascular Impairments(Wei 1988), high blood pressure(Roweand Lipsitz1988),os- tial income. Obviously, the heavy physical labor coupled with the growingrestrictionsof aging are one possiblecausefor this decrease.Programsto assistthe elderlyto maintain teoporosis (Chesnut 1985), arthritis (Tonn 1987), and cancer, the normal their use of wood energyshouldbe explored.Whilebothhighincomeand low incomeelderlyreducetheiruseof wood, programs should perhaps focuson low incomeelderly,as they are the ones that perhaps need it most. It would probablybe unrealisticin thisday and ageto expectmuchin the way of publicfundingfor suchprograms. Voluntary assistancegroups are the mostlikelyformof assistance. Communitygroupscouldtakeon service projectsthat would help the elderly with the heavylaborof cutting andhaulingwood.Perhapsa forester, readingthis, will considermobilizing hisor her churchor servicegroup.We for ourpart areexploringthepotential for forest landowner associations to serveas a basisfor mobilizingvoluntary"pointsof light."Priorto theinitiation of suchprograms,a socialas- sessment shouldbe donein proposed projectregionsto determineif elderly peoplein theseareaswould be interested in participationin such programs. [] aging process among otherwise healthyelderlypersonsmay create slowlyincreasing constraints to physicalactivity.Forinstance,90-95of the populationabove65 have cartilage lossthatcouldvailablyimpairparticipationin wood cutting(Caplan1989, pers.comm.;Caplan1984).Alsopart of normalhumanagingis theatrophy of skeletal musclestrength andendurancethat mayincreasingly limit strenuousphysicalactivityamongthe otherwisehealthyelderly(Faulkneret al., undated, Grimby and Saltin 1983). Evenolderpersons whoexercise regularly and stayin shapeshowmuscle atrophycomparedto their younger years. Similarly, an increased ten- Table3. Liketo heatmorewith woodby age. Like to heat more with wood? DefinitelyYes N % ProbablyYes N % Maybe ProbablyNot Age Under 40 14 25.3% 12.7% 6 5.5% 23 20.9% 14 12.7% 53 48.2% 7 8.4% N 15 % 18.1% N % DefinitelyNot N % 40-59 21 9 10.8% 31 37.3% 60+ 21 17.6% 10 8.4% 18 15.1% 10 8.3% 60 50.4% X2 = 9.1, d.f. = 8, Cramer'sV = 0.12,NS (notsignificant). NJAF8099z) 37 LITERATURE CITED BesDn•a•,R.W. 1988. Dementia and delirium. P. 375-401 in Geriatric medicine. Little Brown, Boston. CAnrE, T.T., AND T.D. WARNER.1988. Retail sales of fuelwood in Kansas. Nat. Woodlands 11:1520. CAPLAN, A. 1984.Cartilage.Sci.Am. 251:84-94. CHESNU?,C.H. III. 1985. Osteoporosis. P. 801-812 in Principlesof geriatricmedicine. McGraw Hill, New York. COHEN,G.D. 1987. Alzheimer's disease.P. 27-30 in The encyclopedia of aging.SpringerPubl., New York. FORCE, J E 1986 Resultsof a surveyon residential wood energy use in Idaho. Univ. Idaho For.,Wildl. andRangeExp.Stn.Tech.Rep.19. GRIMBY,G., AND B. SALTIN.1983. The aging muscle.Clin.Physiol.3:209-218. KAUSLER, D.H. 1970.Experimental psychology and humanaging.Wiley, New York. MDNR. 1981-2. Fuelwood use in Michigan homes:1981-82 surveyresults.Mich. Dep. Nat. Resour.,For. Manage.Div. MDOC. 1986.Michiganwood energydevelopmentplan:An addendumto Michigan'sforest resources statewide forest resourcesplan. Mich. Dep. Commerceand Mich. Dep. Nat. Resour. EVANS,A.W. III AND R.G. pARKER.1987. Fuel- wood processing in New Hampshirebecomes a mature industry.North. J. Appl. For. 4:7678. MILLER, N.E., AND G.D. COHEN (eds.). 1981. Clinicalaspectsof Alzheimer'sdiseaseand senile dementia. Raven Press, XXX. dated.Skeletalmuscleweakness andfatiguein old age: Underlying mechanisms.Unpubl. pap., Univ. Mich., Inst. Getontology. COMPUTER 1985.Neural and vestibularagingassociated with falls.P. 378-399in Handbookof the psychologyof aging.Ed. 2. Van NostrandRein- the evaluation of numerous managementalternatives,each with associated activities and cash flows. For thoseactivitiesthat may not occur until severalyearsinto the future,one or morepossibleoutcomesmayresult. It is particularlydifficult to estimate timber yieldsbecausethey generally do not occuruntil severalyearsafter project initiation. Unfortunately, many investmentanalysesdo not include any considerationof how these different outcomesmight affect the project, even in caseswhere significantrisk may exist. Methodsthat may be used to evaluate the uncertaintyfor any giveninvestment alternative include a sensi- tivity analysis(Roseet al. 1988,Marty 1964, Weaver and Osterhaus1976), a break-evenanalysis(Riggsand West 1986), and simulation techniques (Chamberset al. 1986, Lothner et al. 1986).The break-evenyieldanalysis,a treatment the Minnesota Extension Service. Contrib- uted as PaperNo. 18423of the Minnesota Agricultural Experiment Station. 2 Departmentof ForestResources, Universityof Minnesota,St. Paul,MN 55108,and Pro-West & Associates, Walker, MN 56484, respectively. 38 NJAF8(1991) bloodpressure.P. 193-207 in Geriatricmedicine. Ed. 2. Little Brown, Boston. SKOG,K.E., AND I.A. WATI'ERSON. 1983. Residential fuelwood use in the United States 1980-81. USDA For. Serv., For. Prod. Lab, Madison,WI. SurveyCompletionRep. TILLMAN,D.A. 1978. Wood as an energy reTONN,E.A. 1987.Arthritis.P. 37-38 in The Encyclopediaof aging.SpringerPubl.,New York WEI, J.Y. 1988. Cardiovascular system. P 167-192 in Geriatric medicine. Ed. 2. Little Inst. 1989, Schuster 1988) and com- combinations will specificmanagementintensityis financiallyacceptable. Formulashavebeenpresentedand illustrated for hand-calculating a break-even yield (Fox 1988). Those discount 21:591-600. Several microcomputerinvestment analysisprograms(For. Resour.Syst provide a financial break-even. For thosecaseswhere normalyield data is not available,the managermust critically evaluatethe break-evenharvest yields to determinethe siteswhere a formulas I This contributionwas supportedby the Collegeof NaturalResources and the University of MinnesotaAgriculturalExperiment Stationunder ProjectMN 42-40and Biomechanics. RowE, J.W., AND L.A. LIPSITZ. 1988. Altered calculator. special case of the break-even analysis, calculatesthe minimum harvest volume required to earn a minimum specifiedrate of return on forestmanagementactivities(Fox1988).The net present value criterion (NPV) is frequentlyusedin this analysis.The calculatedbreak-evenyield then canbe comparedto localvolumetablesto determine if the proposedinvestment appearsbiologically reasonable. By comparing a seriesof break-even yield curves for different stumpage price assumptions to curves for normalyieldtabledata,a managercan quickly assesswhat stand management mechanicsof reactionsto impendingfalls J anddiscounting asappliedon a hand- CORNER Charles R. BlinnandGreggP. Hove 2 Forestry investment analysis in- 1:85-87. ROMICK-ALLEN, R., AND A.B. SCHULTZ.1988. Bio- Brown, Boston. hold, New York. Performinga Break-evenYield AnalysisUsing a Microcomputer volves BAILEY 1980.Woodand energym New England,a review andbibliography. USDA Bib.and Lit of Agfic. No. 7. Wash., DC 71 p. PARKER, R.G. 1984.Willingness of Michiganlandownersto sell firewood.North. J. App1.For source. Academic Press, New York. OCHS,A.L., J. NEWBERRY, AND M.L. LEN•,•ZDT. FAULKNER, J.A., S.V. BROOKS, ANDE. ZERBA.Un- PALMER, L R, R McKusICK, AND M future cash flows. Exceptfor the analyseswhere the effectsof inflation are disregarded,future cash flows must first be calculated by inflatingtoday'spriceat the appropriate inflationrate. While many calculatorshave function keys that can be used to facilitate the necessary computations,the analysismay be complexfor anyonethat is not familiar with the principlesof compounding puterspreadsheets currentlyareavailable to calculatecompoundingand discountingfactors and investment performancecriteria.Thosetoolsalso may be usedto calculatea break-even yield. This paper outlines the stepsrequired to perform the break-even yield analysisusing a microcomputer program. A simple hypotheticalexample is presentedto show how to perform the analysis. Two caseexamplesare then presentedto demonstrate the utility of the break-even yield analysis. All analysesassume that the landowner has a minimum ac- ceptablerate of return of 8% and that the inflation ANALYTICAL rate is 4.6%. PROCEDURES The steps required to perform an automatedbreak-evenyield analysis and to graphthe resultsare outlined below. 1. For eachforestmanagementalternative, obtain the relevant informa- tion for eachactivity--amountof the cash flow (price times quantity), year of occurrence, and real price increase,if any. For timber harvest income activities, use the appropriatestumpagerate and an estimation of volume that you mightexpectfromthe site.Alsoestablish the inflation rate and the re- quiredrateof return(discountrate) for the analysis. 2. Enter your Step1 assumptionsinto your financialanalysissoftware.If intermediatestumpagereturns are expectedfrom an alternative,you may either createone harvestactivity that occursmultipletimesor separateharvest activities.Create one harvest activity that occurs