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VlNaNT F. WATEISbK811Y8 Edl DR. IONALD G. MACDONALD

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YOLo 40, No.5 MAY, 1977

News 7

12Forests For Tomorrow's MillsBy Leo V. Cheeseman, Southern Forest Institute

Cepyri,hiM 1 977

~ H. Abemethy PuWllhilll c... -.

Harvesting Southern Pines With Taproots Is EconomicWay To Boost Tonnage Pe,r Acre 20 Percent'

By Peter Koch. Southern Forest Experiment Station17AllEN W. Hill

Pr8,I_nl

OtAllES FlAMVlw P,..ldent =Jntensive Forest Management And The Quality Of The

Wood Supply In the Southern Pine RegionBy Dr. Bruce Zobel, N. C. State University

24ROIERT L McDONALDs.cr.tory ond Control\er f

30Industry Meetings

32API Celebrates First 100 YearsBy Dr. R. G. MacDonald. Senior Editor

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VERIFIED IY

~Y8ffled AMit Orcvlation Corpora""

May '977 /Southern Pulp and Paper Manufacturer .

Repr inted from: Southern Pulp and Paper Manufacturer 40(5): 17, 18', 20, 22.May 1977.

Acre 20 PercentBy Peter Koch

Chief Wood ScientistSouthern Forest Experiment Station

ground level and is 1.5. to 2 timesstem diameter at breast height.

In structure, rootwood varies COD-siderably from stemwood. Roots makevirtually uninterrupted growththroughout all 12 months of the year.Although distinct bands of latewoodare sometimes found, growth incre-ments are more often distinguished byseveral rows of radially flattened cells,whose walls may be no thicker thanthose of earlywood. Frequency, size,and distrubution of bordered pits inrootwood tracheid walls are morevariable than in stemwood, and fibrilangles may be larger. The pit structureis not likely to affect pulping processesgreatly, but large fibril angles maylead to inferior paper properties.Except for a greater incidence of raytracheids elongated perpendicularly tothe rays and the virtual absence of

At the Southern Forest ExperimentStation, we've been trying to extendthe pulpwood resource by bringingmore of each pine tree to the millyard. The taproot of a 1 S- to 30-year-old southern pine weighs about 20%as much as the merchantable stemITable I). Harvesting and pulping thiswasted material would greatly increasepulpwood tonnage Yield per acre. Butis it feasible to do so?

To answer that question, we begana series of studies aimed at (1) deter-mining if the taproot is physically andchemically suited for kraft pulpingand (2) developing the needed har-

I vesting machinery.

Taproots Suitable for PulpPine taproots are carrot-shaped and

, ,merally 3 to 5 feet long. MaximumI . occurs a few inches below

thick-walled parenchyma cells, root-wood rays and rt4in canals resemblethose of stemwood.

In a sample of 20 southern pinesaged 12 to 89 years, Manwiller (1972)found that rootwood tracheids wereone-third larger in diameter than stem-wood tracheids measured at stumpheight; rootwood cell walls were 18%thinner, and lumens were almost two-thirds larger (Table 11). Observationson the taproot of a single tree furtherrevealed that all cell dimensions in-creased to a maximum at a pointabout 1.5 feet below ground level andthen diminished. In this tree, mini-mums of length (3.2 rom), diameter(44 II. m), and wall thickness (4 II. m)occurred about 10 inches below thepoint where the maxima were ob-served.

To provide some data on chemicalconstitutients, Howard (1973) up-rooted three 22-year-old slash pinesgrowing in central Louisiana on well-drained sandy loam soil in an un-thinned plantation. Lateral roots weresevered at a radius of 3 feet. Root-wood had slightly more extractives,lignin, and ash and slightly less cellu-lose than stemwood (Table ill). Theroots had a moisture content of 111percent and specific gravity of 0.38(basis of un extracted, ovendry weightand green volume); stemwood aver-aged 116 percent in moisture contentand 0.47 in specific gravity. In short,it seems likely that taproots of thesouthern pines are pulpable by thekraft process, a conclusion supportedby the work of Sproull et al. (1957).Because of chemical composition.slightly lower yields than those ob-tainable from stemwood can beexpected More recently Keays (1974)concluded that use of naturallyoccurring percentages of stumps androots of mature conifers would havetittle effect on strength of kraft pulps.

Moreover, roots are more suitablefor pulping than either branches ortops; i.e., roots have higher alphacellulose and lower lignin content thantops or branches (Table 111). To takeadvantage of this wasted resource, amachine was designed to first shearthe laterals close to the taproot and

:ts

11-

..

~

Fig. 1-Tr8e puller, showing typical functioning.

then pluck the entire tree from theground (Koch and Coughran 1975,Koch 1976).

EN~

JET

c,. cc

w.

Table II.-Mean tracheid dimensions in root and stumpwood of 20 southernpines.

Rootwood.StumpwoodbStandard Standard

Dimension deviation Mean de,1:ltionLength (mm) 0.64 4.0 0.89Cell diameter (IJ. m) 9.39 52.5 11.21Lumen diameter <IL m) 1 1.06 41.7 13.08Wall thickness <IL m) 2.15 5.4 1.67

a Data from Manwiller (1972).b Stumpwood sampled from two opposed 2o.degr~ wedees (l-indl thick) removed18 to 24 inches abo~ ground level.c Sampled from disks taken alone the taproot beginning at the point where m,;or lateralswere attached.

Mean3.0

38.825.76.6

loads of stems are alternated so thaton one load the roots are forward andon the next to the rear; this procedurepermits building a maximum-weightload without exceeding height limita-tions.

. At the mill, full truckloads ofcomplete-free stems are fork-lifted in-to large cradles for subsequent massbucking (with bundle-bucking chain-saws) into 8-foot pulpwood lengths.

. The 8-foot pulpwood, as it isbucked, falls onto a chain conveyorleading to a drum debarker.

. All pieces are cleaned 'f dirt anddebarked in the drum deb..rker; hart(with considerable dirt contl-'nt) is con.veyed to the powerplant throughcleaning equipment to reduI:': dirt c0n-tent to levels tolerable by the burninsequIpment.

. BarJ..-free (and remarkablYfree) wood emerges from tho:barker to pass through di~1- chippenand hence into the pulp mi1\.This procedure is summariud iDFigure 4.

The harvesting cycle is

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Tree PuDerThe machine, manufactured by

Rome Industries, Cedartown, Georgia,can be fitted through a quick-hitchmechanism on a number of primemovers-for example, a Caterpillar 920or a John Deere 544B (Fig. 1).1 Twoclements are central to the design.The first is a scissors-type gripachieved with a pair of stout hori-zontal knife blades that close atgroundline and bite several inches intothe stem from opposite sides.

With this grip anchor, the secondelement in the design comes intoaction. It is a clamshell-hinged tubularshear, 22 inches in diameter and madeof 3/4-inch-thick steel. The shear,sharpened on the lower edge, is forcedvertically into the ground to a depthof 11 inches. thereby severing lateralroots all around the tree. At thispoint, broad steps on opposite sidesof the shear strike the ground andprevent further penetration. An ad-ditional stroke of the hydraulic cylin-der raises the grips 9 inches while thesteps remain pressed against the soilsurface. The effect is to jack the stemand break it free of the ground.Finally, the complete tree is lifted intothe air and bunched for skidding.Since shearing takes only a few sec-onds. a tree ~an be harvested andbunched in about half a minute.

Han.estiDg and Utilization SystemTo a considerable extent, the utili-

zation system is controlled by dirt thatadheres to the taproot. Such adherenceis more severe in clay soils than insandy soils: Much of this dirt is shakenfree when trees are bunched, skidded,delimbed. and stacked (Fig. 2), buta significant amount remains. Thisresidual dirt and adhering bark shouldbe removed before chipping for pulp.

To this end, a harvesting systemfor pine plantations on sandy soils isproposed as follows:

. Trees are pulled entire andbunched.

. Bunched trees are thrust tops firstthrough a delimbing gate (Fig. 3) andskidded to roadside.

. At roadside, tops and taprootsare cut to 2- or 3-inch diameter insidebark with a chainsaw, and potentia11ytroublesome stubs of lateral roots aretrimmed.

. Complete trees are grapple-loaded<Fig. 2) onto trucks with 20-ton pay-load for transport to the mill. Grapple-

) Mention of trade names is solely for in-formation purposes and does not imply."An~._."' 1 T C n.." ", nf

by replanting the well-prepared site.Holes left after harvesting vary frominconspicuous indentations to cavities22 inches wide and a foot ~. Skid-ding activity in combination with nor-mal rainfall partially fills most holes.

lS,~30,~

7,(kM)

$112,00)

landing2 truck driversSupervision (assumes super-

visor is handling 3 or 4logging sites)

Total labor OpentioD8l Expenses

Annual operating expenses for oil.fuel, maintenance, and parts shouldbe about as follows:

Macbiue Ann.. ~

(1,081 operatiq boaII)PuUer-buncher, $16 per

hour $17,296Two arapple skidders, $14

per hour each 30,268Roadside grapple loader,

$12 per hour 12.972Two tractor-traiJer highway

b11Cks (with 4 trailers),

utilization, or 0..563 hour out of everyscheduled hour.

The machines will be scheduled .5days per week, 8 hours per day, 48weeks per year (allowing 4 weeks forvacation and holidays). Thus, a total1,920 hours will be scheduled eachyear. Actual operating hours willtherefore total 0..563 x 1,920 hours,or 1,081 hours per year.

At two trees per operating minuteand .500 trees per acre, 0.24 acreshould be harvested per operatinghour. Acres harvested annually shouldtherefore total 2.59.

Labor CostSeven men are needed to operate

the harvesting and delivery system.Cost of manpower, including super-vision (but excluding mechanic's labor,which is covered under operationalexpense) should total about $112,000:

",,#

,;

,-'"

$24 per bour 25,944Supper truck, $6 per hour 9,(KX)Total $95,480 -

'Ibis total is 1.9 tima annual depra.tion charge.

Total AnnD81 Co~ts~

itemDepreciationLabor and supervisionOil. fuel, maintenan~.

and pansTotal

'"

~

Cost of Wood DeU.ered 80 MiDThe harvestina system envisioned

(Fig. 4) is designed for clearcuttinaunthinned stands perhaps 25 years oldthat average about 8 inches in dbh(12-inch maximum on any tree). It isassumed that each acre carries 500trees averaging 600 pounds in greenweight when shorn of limbs andlateral roots. Puller-buncher produc-tivity with an experienced operatorshould average two b'ees per operatingminute (Fig. 5).

Equipment Cost ADd DepreciationTotal investment in equipment

should be approximately as follows:

Machine CostPuller-buncher $60,0002 grapple skidders 86,000Portable delimbina grate 1,000Roadside grapple loader 31,0004 set-out log trailers 24,0002 diesel truck-tractors 64,000Support truck 15,000

Investment in system $281,000

Under 5-year straight-line depreci..tion with 10% residual value, annualdepreciation is

, ,A,/- .:W, "" ,, -'

'..-

The equipment in the system issimple, highly practical, and thorough-ly field-tested; therefore, all four~ machines in combination shouldbe mechanically functional (available)7S percent of the time. Of this avail-able time, they should be operating7S percent of the time. Net operatingtime is thus O.7S availability x O.7S

4 machine operatoR$lS,CXX> each (forbuncher, 2 skiddegrapple-loader)

1 chainsaw operator

$7,

It's 1textbo(contrii:

It m6guratiin attaifeJt life.many v

Sha:perforn

Annual C8III BeDefilsBenefits from the system includc

site preparation, here assumed to be$30 per acre, as weD as recei~ 1«wood:

ItemSite preparation$30/acre x 259 acres/yearComplete-tree stems deliver~d

to mill$6.4443/ton x 500 tr~/ac~..x 0.3 areen ton/treex 259 acres/year- $6.4443/ green ton x 38,850

toni/yearTotal

From the foregoing computatioo.evident that harvestina costs ofper green ton delivered resultthis system.

Profit OD CapitalIf 30% profit on investment

fore income taxes) is required.profit must amount to 0.3 xor $84,300. If this profit is -over the 38,850 tons of greenwood delivered to the mill eachit amounts to $2.17 per greellPulpwood price, delivered to(including woodlands profit on

~

Fig. 3 - Grate-type delimber.Bunched trees are thrust tops firstthrough this opparatus, which shearslimbs from the stems.-

FUDCtioD--

Annual cost

IncludingfriaKe benefits

at $60,000puller-

rs, and

at the

.,

~ ~ .7 LOADING Q'C TRUCK

t:'~ ~8

~~r=~'i)-

... DLE- ~.::-m9 10 WOOD TH~ ~RKING ~UM

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III CLEAN WOOD TQ CHIPPER112

8ARI<. ~EE PULP CHIPS

Fig. 4-Harvesting and utilization system.

meat inv~tment) should therefore ..$6.44 plus $2.17, or $8.61 per ar-ton, plus stumpage price.

ConclusionOne can draw the following ~

clusions about harvesting eVta-aaedsouthern pine plantations with IIxIUI500 trees per acre averaging 8 iDchain dbh and weighing 600 pounds ar=

. when stripped of lateral roots aDd

branches:. Using a puller-buncher instead of

a feUer-buncher should increase pulp.wood tonnage harvested per acre byabout 20 percent.

. Drum debarkers can clean butand dirt from pine taproots and Iteaso harvested.

. Bark-free rootwood mixed wi6stemwood in its naturally oc:aIrriD&proportions should not adversely affectkraft pulp properties in any imPOrtlDtway.

. Harvesting equipment for a b-.pulling system will likely cost a~$281,000; the equipment needed iD-cludes a tree puller-buncher, twograpple skidders, two log trucks, ffUset-out log trailers, and a IUppcxttruck. With this system, about 1Stacres can be harvested annuany _.ing 48 forty-hour weeks.

. Cost of wood (mcluding st=bark) so harvested and delivered *'the miD yard, including 30% 1ft"income-tax profit on equipment ..vestment, should be a~ut $8.61 PS'green ton plus cost of stumpage.

Literatuft CitedHoward, E. T. 1973. Physical lad

chemical properties of slash pine traparts. Wood &i. 5(4):312-317.

Keays, J. L. 1974. Full-n. ladcomplete-tree utilization for pulp ladpaper. For. Prod. J. 24(11):13-16.

Koch, P. 1976. New techniqIX fmharvesting southern pines with ta~attached can extend pulpwood Ie-sources significantly. Appl. Polym.Symp. 28:403-420. John Wiley &Sons, Inc.

Koch, P., and S. J. Coughran: 1975.Development of a puner-buncher f«harvesting southern pines with tap.root attached. For. Prod. J. 25(4):23-30.

Manwiller, F. G. 1972. T~dimensions in rootwood of soutbdpine. Wood Sci. 5(2):122-124.

Moore, W. E., and D. B. JobD-.1967. Procedures for chemicalof wood and wood products.For. Serv., For. Prod. Lab.,WIS.

Sproull, R.. C., R.. B. Parker,W. L. Belvin. 1957. Whole tree hIrevesting. For. Prod. J. 7(4):131-134.

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~40

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~,...10.:201 I I I I I I I I

45 6 7 8 t 10 111215TREE D.B.H. (INCHES)

Fig. 5-Relationship between tree dbh and time to pull and bunch planta-tion-grown loblolly pines 15 years of age. (Data source: D. M. Tufts, Pine-ville Kraft).

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