Maple Syrup Production in Ohioand the Impact of Ohio StateUniversity (OSU) ExtensionProgramming

Gary W. Graham, P. Charles Goebel, Randall B. Heiligmann,and Matthew S. Bumgardner

The maple syrup industry in Ohio, which ranks fifth in total production in the United States, is comprisedprimarily of small family owned operations that are served by The Ohio State University (OSU)Extension system. We evaluated the effectiveness of OSU Extension educational programming designedto improve sugarbush and sugarhouse management through a survey administered at the three 2004Ohio Maple Days workshops. Most survey respondents indicated that after attending past maple syrupworkshops they implemented changes that were relatively simple and inexpensive; however, mostindicated they are interested in learning more about technologies that increase production and maplesyrup quality.

Keywords: maple syrup, sugarbush, forest management, Extension

M aple syrup production is a sus-tainable family forestry activitythat has a long tradition in North

America. Maple syrup was an integral part ofmany Native American communities, usedas the primary sweetener in the NativeAmerican diet (Wittstock and Kakkak1993). Sap was collected in the spring andboiled down to make syrup or sugar usingequipment such as clay pots and open fires,which often remained at the site year-round.In many Native American cultures, therights to these “sugarbushes” were heredi-tary, passed down from generation to gener-ation. With the arrival of Europeans in the16th and 17th centuries, maple syrup pro-duction in many areas increased providing acheap and high-quality source of sugar as thetariffs and expense of cane sugar importedfrom the West Indies made it an unafford-

able luxury (Lawrence et al. 1993, Lockhart2000).

In many ways, the methods used byearly European settlers to produce maplesyrup have not changed dramatically overthe past 400 years. The major refinements inthe process of producing maple syrup havebeen associated with collection and evapora-tion technologies (Huyler 1982, Walters1982, Koelling and Heiligmann 1996), al-though there has been considerable researchon the factors affecting the sap sugar concen-tration (e.g., Stevenson and Bartoo [1940],Moore et al. [1951], Morrow [1955], Taylor[1956], Kriebel [1961], and Larsson[1967]), tree physiology and sap chemistry(e.g., Marvin 1958, Marvin et al. 1967), theeconomics of maple product production(e.g., Kearl [1970], Huyler and Garrett[1979], Huyler [1982], Sendak and Ben-

nink [1985], and Huyler and Williams[1992, 1994]), and the genetic improve-ment of sugar maple for higher sap sugarcontent (Kriebel 1960, 1989, 1990).

The Maple Syrup Industry InOhio

During the 19th century, Ohio was oneof the largest producers of maple syrup(924,000 gal annually), the third largest pro-ducer of maple sugar (614,000 lb annually),and the largest producer of total maple prod-ucts (equivalent to more than a million gal-lons annually) in the United States (UnitedStates Census Office 1840, 1870, Bryan etal. 1912). Additionally, many maple syrupequipment industries were based in north-ern Ohio. Ohio generally has ranked aboutfifth among states in syrup production overthe past 10 years, occupying a position rang-ing from fourth to eighth in any given year(Table 1). In 2003, maple syrup productionin the United States totaled 1.24 million gal,down 11% from a 10-year average, withOhio contributing 75,000 gal, down 15.7%from a 10-year average (USDA–NationalAgricultural Statistic Service [NASS] 2003).

Ohio’s decline in maple productionsince 1840 is in response to several factors.One of the most important has been the dra-matic shift in forest cover. In the mid-1800s,Vermont (representative of much of the

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northeastern United States) was only 20%forested because of timber harvesting andland clearing (Vermont Agency of NaturalResources 2005); however, Vermont cur-rently is dominated by forest cover (87%)with sugar maple being the dominant spe-cies. Ohio essentially has experienced theopposite trend. In 1840, at the time of thefirst census of agricultural products, Ohiowas 93% forested (Ohio Forestry Associa-tion 2003). Ohio’s forest cover declined toaround 10% by 1900 and has since recov-ered to approximately 30% today (OhioForestry Association 2003).

In addition to the dramatic shift in themaple resource, there have been other im-portant factors responsible for the decline ofOhio’s maple production. During the late1800s the status of maple sugar was trans-formed from a staple sweetener to a luxuryitem as cheaper cane sugar was readily avail-able in the American market. Another rea-son for the decline is the differing roles takenby the various state and government agen-cies. Although the Ohio Department of Ag-riculture has not been actively involved inpromoting or regulating Ohio’s maple syrupindustry, the Vermont Department of Agri-culture has taken a very active role in pro-moting and maintaining Vermont’s mapleindustry. This top-down government sup-port in conjunction with very proactive in-dependent producer organizations (e.g.,Vermont Sugar Makers Association andVermont Maple Syrup Promotional Board)has resulted in increased market share acrossthe United States, especially in many upscalemarkets of the northeastern United States.When contrasted with the Ohio MapleProducers Association, which does verylittle to promote Ohio maple syrup, orOhio State University (OSU) Extension,which historically has focused on provid-ing educational support to increase pro-duction practices but not marketing strat-egies, it is not difficult to understand howOhio’s maple production has declinedover the past 150 years.

Ninety percent of Ohio’s maple syrupoperations are family owned and operated,with the business typically passing fromone generation to the next (Graham2005). Although the monetary value fromthe sales of Ohio maple syrup and otherproducts is small when compared with therow crop or animal husbandry industries,income from maple syrup sales plays a vitalrole in contributing to the quality of lifeand economic well-being of many ruralOhio families.

The OSU Extension system has the pri-mary role of providing education and re-search programming for maple syrup pro-ducers across the state. For over 90 yearsOSU Extension has used a variety ofmethods to provide producers the latest inresearch-based information and trainingthat has enabled them to make effectivedecisions and implement appropriate newtechnologies and research to increase theirproductivity and profitability. Integral tothis effort has been a series of annualworkshops called Ohio Maple Days.These 1-day workshops are held across thestate every January and are attended bymaple syrup producers from Ohio andsurrounding states, including residents ofPennsylvania, New York, West Virginia,Indiana, and Michigan.

In an effort to learn more about wherethese part-time family operated forest indus-tries obtain information on sugarbush andsugarhouse management and the impact ofOSU Extension on these operations, weconducted a survey of the participants at-tending the three 1-day Ohio Maple Daysworkshops in 2004. The objectives of thisarticle are (1) to review the advancements insugarbush and sugarhouse management be-ing implemented in many family owned ma-ple syrup operations in Ohio and (2) to bet-ter understand how maple producereducational programs have influenced theproduction of maple syrup as one of Ohio’sprimary family owned forest enterprises.

Sugarbush and SugarhouseManagement

The Sugarbush. The heart of any sug-aring operation is the sugarbush—the standof maples (usually sugar maple [Acer saccha-rum Marsh.], as well as black maple [Acernigrum Michx. f.], red maple [Acer rubrumL.], and silver maple [Acer saccharinum L.])that are tapped and from which sap is col-lected. Over 95% of the sugarbushes acrossOhio are located in second-growth or third-growth forest stands; however, there are ahandful of orchard-type plantations. Theaverage Ohio sugarbush is 27 ac with a rangeof 0.25–190 ac. Within the traditional sapcollection method of buckets, the averagesize operation has 417 taps with a range of4–5,000 taps. Within the more moderntubing collection systems, the average sizeoperation has 720 taps with a range of 12–6,500 taps (Graham 2005).

Maple syrup producers must considerthe expense in adopting technology andpractices that improve profitability and sug-arbush health (Figure 1). Sap collection ingalvanized metal buckets is the traditionalmethod that is traced back to the use of tinduring the Civil War. Before metal contain-ers sap collection in wooden troths from hol-lowed-out logs and wooden buckets werethe standards (Lawrence et al. 1993). Morerecently developed tubing systems with vac-uum have been shown to dramatically in-crease profitability—they require less capitalexpense, increase production per tap, and re-quire less labor than a bucket or bag opera-tion (Huyler 1982, Walters 1982, Heilig-mann et al. 1996). Additionally, the use oftubing contributes to sugarbush health byreducing or eliminating the movement ofheavy collecting equipment in the sugarbushduring spring, when soils usually are wet andvulnerable to compaction. Ohio maple pro-ducers have been slow to implement modernsap tubing collecting systems in that 62% ofall taps are found in bucket collection oper-ations and the bucket operations make up

Table 1. Average maple syrup production values from top five producing states from 1992 to 2002.

Average production (gal) Average taps (1,000) Average yield per tap (gal) Average price (per gal) Average value of US crop

Vermont 502,000 2117 0.189 $29.79 $12,311,200New York 274,000 1306 0.169 $27.97 $ 6,941,100Maine 197,500 1088 0.213 $19.68 $ 1,551,400Wisconsin 107,800 425 0.175 $26.55 $ 2,369,200Ohio 89,000 398 0.184 $33.04 $ 2,528,900

Source: USDA—NASS (2003).

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78% of all sugaring operations in Ohio(Graham 2005).

Although maple syrup producers in thepast often used the sugarbush as pasture orshelter for cattle, sheep, and hogs, livestockis rarely seen in today’s sugarbush (Koellingand Heiligmann 1996). Many producers arefocused on evaluating sugarbush and treehealth, looking for crown dieback, evidenceof forest pests, soil compaction, and treewounds, and then modifying their practicesto address the problems. Producers are tap-ping more conservatively than their prede-cessors, waiting until the trees are at least 12in. in diameter before tapping, using fewertaps per tree, and adopting smaller-diameterspouts (five-sixteenths in. instead of seven-sixteenths in.) that produce tap holes thatheal more quickly (Heiligmann et al. 1996).

Maple producers also are adoptingpractices to improve the health and produc-tivity of their sugarbush. Graham (2005)found that 34% of producers in the statefollow recommended international tappingguidelines and 62% adjusted tapping levelsto tree health. Producers also are using thin-ning or improvement cuts to encourage thedevelopment of healthier trees with larger,deeper crowns, resulting in a greater volumeof sweeter sap (Morrow 1955, Larsson 1967,Heiligmann and Staats 1996, Graham2005). Sap sugar content is tested and usedas a criterion for selecting trees for release,

along with more traditional criteria includingtree location, crown size, crown class, and treevigor. In an average year, Ohio sugar maple sapwill average about 2% sugar. Individual treeswithin stands, however, often have sugar con-tents well in excess of 3% and even 4% ormore. Increasing the average sap sugar contentfrom a sugarbush by releasing trees with highsap sugar to develop large, deep crowns trans-lates directly to increased profitability—lesssap is required per gallon of syrup producedand less energy is required for evaporation asfewer gallons of water are evaporated to pro-duce a gallon of syrup.

Finally, producers in a position to plantmaples, either in plantation, roadside, or asunder plantings in a mature stand, are plant-ing seedlings genetically selected for high sapsugar content. These seedlings have been pe-riodically available from several sources formore than 25 years. The sugar content ofseedlings grown from one such source, a seedorchard at the Ohio Agricultural Researchand Development Center, has ranged from3.7 to 5.8% for trees from 1 to 14 in. indiameter (Kriebel 1990; Graham 2003,2005). Establishing the future sugarbushwith seedlings with sap sugar contents inthat range will dramatically improve poten-tial profitability.

The Sugarhouse. The sugarhouse is theproduction center of a maple operation,where sap collected in the sugarbush may befiltered and stored for a short time, and thenprocessed into maple syrup and packaged. Insimplest terms, the production of maplesyrup from sap is the process of evaporatingthe water in the sap and concentrating thesugar into syrup. Although this evaporationprocess is simple in concept, the process iscritical for producing high-quality maplesyrup (Garrett and Dudzik 1989, Heilig-mann and Staats 1996). This process alsotakes considerable knowledge, skill, andequipment to complete.

Historically, water was removed frommaple sap and the sugar was concentratedover an open fire in a metal or iron kettle.These techniques used what often are re-ferred to as “batch-type” evaporators, requir-ing sap to be added continually to the evap-orator until the desired amount of maplesyrup was obtained. Using these techniques,it was not uncommon to take days to pro-

Figure 1. Traditional sugarbush of northeastern Ohio using a bucket collection system.(Photo by Gary Graham.)

Figure 2. Typical evaporator used in an Ohio sugarhouse. (Photo by Gary Graham.)

96 Journal of Forestry • March 2006

duce 10 gal of dark, strong-flavored maplesyrup. Since the early 1900s, most maplesyrup producers have used a “flue-type,”continuous-flow evaporator, and this tech-nology has become more efficient over time.In contrast to the “batch-type” evaporator, atypical “continuous-flow” evaporator canproduce between 2 and 10 gal/hour depend-ing on size (Huyler 1982, Garrett andDudzik 1989, Heiligmann and Staats1996).

Producers also have adopted a variety ofancillary equipment (Figure 2) to improveefficiency and syrup quality during the evap-oration process, including in-line ultravioletlight units to minimize microbial contami-nation; reverse osmosis units for concentrat-ing sap sugar content before boiling, whichreduces labor and energy costs and often im-proves syrup quality; steam hoods (metalcovers over the evaporator that trap thesteam and exhaust it from the sugarhouse)that preheat the sap and begin the evapora-tion process; electronic takeoff devices thatautomatically sense when the syrup hasreached the proper finished density andopen the draw-off valve; and pressure filtersfor syrup that use diatomaceous earth as afiltering medium, producing a syrup with analmost “polished” appearance.

Syrup Packaging. Finished syrup maybe graded and then immediately must bepackaged properly at a temperature above180° F for storage, sale, or later processinginto candy or other confections. Not all ma-ple syrup is graded. Some states, includingVermont and New Hampshire, have statemaple grading standards and require that allsyrup be graded according to those stan-dards. Most other states do not have suchstandards and do not require that maplesyrup be graded but allow those who wish tograde to use USDA maple grading standards(United States Department of Agriculture1980). Ohio has state grading standardssimilar to those of Vermont and NewHampshire, but grading is voluntary (OhioAdministrative Code 2004, Ohio RevisedCode 1997). Syrup made in Ohio may besold by grade using either the Ohio or theUSDA maple grades or it can be sold simplyas maple syrup. Packaging of syrup in plas-tic, metal, or glass containers is done in avariety of ways, and there is a wide variety oftraditional and modern equipment used.Similarly, for producers who wish to diver-sify their products and earn additional“value added” income, a variety of equip-

ment is available for making maple candy,cream, spread, and granulated sugar (Heilig-mann 1992, 2002).

Associated Costs of Sugaring. One ofthe greatest challenges to maple producers isthe large capital investment required forboth sugarbush (e.g., land costs, propertytaxes, and land management activities) andsugarhouse equipment. There is no doubtthat “sugaring” is very labor intensive. How-ever, many small forestland owners find thesize of the required capital investment to en-ter the industry prohibitive. There also areno cost sharing programs available from thefederal or state government to improve sug-arbush production and management. Forexample, an individual wishing to develop asmall 100-tap bucket operation startingfrom scratch and using all newly purchasedmaple equipment can easily invest $5,000–10,000. Most small family owned producersdo not invest anywhere near this much; theyreduce their investment by a variety ofmeans, including buying used equipment orusing less expensive alternatives such as aflat-pan evaporator rather than a continu-ous-flow flue-type evaporator.

The challenge to getting into the maplebusiness is not one of profitability, but oneof initial investment. Studies from 1985 to1994 (Sendak and Bennink 1985, Buth1988, Huyler and Williams 1994) reportedthe cost of producing a gallon of maple syrupbetween $14.41 and $19.89/gal, dependingon the size of the operation and the collec-tion and processing technology used. Dur-ing this period syrup was selling for between$23.00 and $38.00/gal—certainly an ac-ceptable profit. Unfortunately, many poten-tial maple producers do not calculate profit-ability by depreciating equipment over itsusable life (perhaps 20–30 years for an evap-orator); they look instead at the initial in-vestment and the expected return, define thepoint of profit making as the time when theywill have paid for all the equipment, anddecide based on that criteria that it is “tooexpensive” to get into maple syrup produc-tion. Since USDA–NASS started to reportOhio maple production within the New En-gland report, the average price per gallon ofOhio maple syrup has been $28.13, with$29.80/gal in 2002 being the highest and$15.00/gal in 1996 being the lowest.

Evaluating OSU ExtensionMaple Programs

Survey Methods. At each of the threeOhio Maple Days workshops in January of

2004, participants were surveyed on thecharacteristics of their sugarbush, the useful-ness of different maple educational pro-grams and publications, the impact that pastOhio Maple Days workshops have had onhow they manage their sugarbush and sug-arhouse, the major problems associated withimplementing newer technologies, and theirlevel of interest in a variety of subjects per-taining to sugarbush and sugarhouse man-agement. The written survey instrument wasdeveloped through a review of past work-shop topics, discussions with producers, anda pilot focus group of professionals in themaple industry in other states. The surveywas administered at the beginning of eachworkshop and returned during the noonlunch break.

Producers from 40 of Ohio’s 88 counties,as well as from four other states (Indiana,Michigan, Pennsylvania, and New York), at-tended the 2004 workshops. Total attendanceat the three workshops was 289, with 65% ofthe attendees (n � 190) responding to the sur-vey. Of the 190 respondents, 92% representeda single, multiple, or cooperative family oper-ation, and 8% of the respondents representednonfamily owned maple sugaring enterprises.Most survey respondents indicated they weresecond-generation producers that had beenproducing maple syrup for an average of 17years (range, 1–61 years). Survey respondentswere representative of the maple producersacross the state because a 2004 survey of theentire state’s maple syrup industry found thatOhio maple producers on average have beenproducing syrup for 19 years and were typi-cally second-generation producers (Graham2005).

Sources of Information. Results of thesurvey indicated that 82% of the respon-dents relied primarily on the Ohio MapleDays workshops to stay current on issues re-lated to sugarbush and sugarhouse manage-ment, and 18% of the respondents reliedprimarily on workshops and materials pro-vided by the North American Maple SyrupCouncil, the International Maple Syrup In-stitute, or other states. Respondents wereasked to rate (Likert scale of 1–5) the useful-ness of common sources of information onmaple syrup production and sugarbushmanagement. Information provided at theOhio Maple Days workshops was consid-ered the most useful, receiving a 4.1 of 5,followed by other sources, such as the OhioMaple News newsletter (2.1 of 5; Graham2002), and the North American Maple SyrupProducers Manual (2 of 5; Koelling and Hei-

Journal of Forestry • March 2006 97

ligmann 1996), both publications producedby OSU Extension. These results suggestthat the primary source of information forfamily owned maple syrup enterprises inOhio are the Ohio Maple Days workshopsprovided by OSU Extension. The fact thatthe Ohio Maple News is produced jointly bythe Ohio Maple Producers Association andOSU Extension and the North AmericanMaple Syrup Producers Manual is publishedas an OSU Extension Bulletin further em-phasize the important role OSU Extensionplays in producer education.

Changes Made in Sugarbush Man-agement. On average, respondents indi-cated that they had made few changes in theproduction, economics, safety, or manage-ment of their sugarbush in response to infor-mation provided at previous Ohio MapleDays workshops. Changes that were imple-mented were associated with tapping andsap collection, particularly switching spouttypes, increasing the use of sustainable tap-ping guidelines, and changing to more effi-cient tubing systems (Figure 3).

The Ohio Maple Days workshops didinfluence management activities related tosafety and economics; however, the averageimpact of these educational programs wassmall. Finally, educational programs de-signed to inform participants on issues re-lated to stand management, particularly bestmanagement practices associated with roadand trail management, also had on averagesome, albeit small, impact on sugarbushmanagement. When asked why few changes

in sugarbush management had beenadopted, 27% of the respondents indicatedthat many were cost prohibitive under cur-rent market conditions and 18% indicatedthat they had little time available to imple-ment the newer technologies demonstratedat the workshops.

Changes Made in Sugarhouse Man-agement. When asked about sugarhousemanagement, as with sugarbush manage-ment, most respondents stated that on aver-

age they had implemented relatively fewchanges after the Ohio Maple Days pro-grams. Most changes in the management ofthe sugarhouse were associated with chang-ing or improving maple syrup handling,storage, and filtering procedures, as well asequipment cleaning procedures (Figure 4).Other important changes made were associ-ated with safety protocols, particularly re-ducing potential lead contamination of ma-ple syrup from lead-based spouts andcollecting, handling, and storage equip-ment, as well as improving maple syrup mar-keting and sales strategies (Figure 4).

Finally, on average, few respondents im-plemented new technologies introduced atprevious Ohio Maple Days workshops, such asusing in-line ultraviolet lights to treat sap, re-verse osmosis units to concentrate sap beforeboiling, or diatomaceous earth sap filters. Aswith management of the sugarbush, many ofthe improved technologies associated with in-creasing the production and quality of maplesyrup during processing were considered bymany survey respondents as too expensive fortheir maple syrup operation.

Educational Programming in Sugar-bush Management. Respondents were askedto indicate their level of interest in several top-ics related to the management and productionof their sugarbush. On average, productiontopics that were of highest interest includedinformation on improving tapping systems(including the use of power tappers), tubing

Figure 3. Level of changes made to management of the sugarbush as the result of OhioMaple Days education programs. Values are mean scores �1 standard error.

Figure 4. Level of changes made to management of the sugarhouse as the result of OhioMaple Days education programs. Values are mean scores �1 standard error.

98 Journal of Forestry • March 2006

systems, and the use of genetically improvedsuper sweet maple trees (Figure 5). Addition-ally, stand management topics of interest torespondents were guidelines for thinning thesugarbush, maintaining the sugarbush (e.g.,regeneration, establishment, and maintenanceof maple trees), and managing forest pests andinsects (Figure 5).

Educational Programming in Sugar-house Management. Most respondents

stated that information on the use and effi-ciency of evaporator systems would be ofmedium to high interest at future Ohio Ma-ple Days workshops (Figure 6). Addition-ally, information on quality control andquality assurance measures, the control ofoff flavors, and the use and value of imple-menting new technologies (e.g., preheatersystems and filter press) was of medium in-terest to the respondents. In terms of mar-

keting sugar maple products, general pro-motion of maple syrup and marketingstrategies were of highest interest to respon-dents from the survey of the Ohio MapleDays workshop participants.

ConclusionsResults from our survey of maple

syrup enterprises in Ohio suggest thatOSU Extension is the primary source oftechnical information for these small fam-ily owned operations. Most contact withthese forest owners is in the form of theOhio Maple Days workshops, althoughOSU Extension publications also are acommon source of sugarbush and sugar-house management information. Al-though past educational programming fo-cused on increasing production andquality, the impact of these programs hasbeen modest, in part because costs associ-ated with implementing newer technolo-gies were high. The majority of changes toboth sugarbush and sugarhouse manage-ment after past workshops has been asso-ciated with techniques or technologiesthat are relatively inexpensive and easy toimplement. Examples include reducingthe number of taps per tree, reducing leadcontamination from spouts, collectionand processing equipment, changingequipment cleaning procedures in the sug-arhouse, and maple sap and syrup han-dling and storage procedures.

These results are not viewed in anyway as suggesting that these educationalprograms for maple producers have failedto achieve their objectives. This surveyidentified the level of adoption of practicesor technologies presented at Ohio MapleDays workshops. As identified previously,the primary objective of OSU Extension’sprogram for maple producers is to provideinformation and training that will enablethem to make effective decisions and im-plement appropriate new technologiesand research to increase their productivityand profitability. Some producers obvi-ously found various practices and technol-ogies presented at Ohio Maple Days pro-grams to be appropriate for theirenterprise and others did not. The factthat many did not, but could identify thereason as cost or some other factor, sug-gests that they received the informationneeded to make an effective decision. Weanticipate that many of the other state Ex-tension programs across the midwestern

Figure 5. Level of interest in different sugarbush educational programming. Values aremean scores �1 standard error.

Figure 6. Level of interest in different sugarhouse educational programming. Values aremean scores �1 standard error.

Journal of Forestry • March 2006 99

and northeastern United States designedto improve sugarbush and sugarhousemanagement likely face the same chal-lenges. Additionally, the results of a moredetailed survey of the entire maple syrupindustry of Ohio suggest that educationalprograms need to be designed for specificclient groups (e.g., hobby producers, com-mercial producers, and Amish producers)because each group has different needsand goals that may not be served by a“one-size-fits-all” educational program(Graham 2005).

In addition to providing an array oftopics with high producer interest for futureworkshops, this survey emphasizes the im-portance of providing information on thecost of implementing recommended prac-tices or technologies and the value received.To some extent, all maple producers have aninterest in hearing about new practices andtechnologies associated with making mapleproducts. However, when it comes to adop-tion, they will make their decision based onwhether or not the practice or technology isappropriate for their specific operation, thecost of adoption, and whether or not adop-tion will provide them with sufficient value(monetary or otherwise) to justify the cost.As OSU Extension and other educators offorestland owners design future programs, itis critical that information be provided thatsupports that decisionmaking process.

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Gary W. Graham (graham.124@osu.edu) isextension specialist, and P. Charles Goebel(goebel.11@osu.edu) is assistant professor,School of Natural Resources, Ohio Agricul-tural Research and Development Center, The

Ohio State University, Wooster, OH 44691.Randall B. Heiligmann (heiligmann.l@osu.edu) is professor, School of Natural Re-sources, The Ohio State University, Columbus,OH 43210-1085. Matthew S. Bumgardner(mbumgardner@fs.fed.us) is research scientist,USDA Forest Service Northeastern ResearchStation, Princeton, WV 24740.

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