SKYLINE lOGGING PRODUCTIVITY UNDER 

Al lERNA liVE HARVESTING PRESCRIPTIONS 

AND lEVELS OF UTILIZA liON IN lARCH-FIR STANDS 

Rulon B. Gardner 

USDA Forest Service Research Paper INT-247 

Intermountain Forest and Range Experiment Station 

U.S. Department of Agriculture, Forest Service 

This file was created by scanning the printed publication.

Errors identified by the software have been corrected;

however, some errors may remain.
~! 

THE AUTHOR 

RULON B. GARDNER was principal research engineer (now retired) , 

stationed at the Forestry Sciences Laboratory in Bozeman, 

Montana. He was involved in logging and road construction 

in National Forest Systems and Research for 25 years--the 

last 17 years in a research capacity. 

RESEARCH SUMMARY 

Little information is available to assess the economic and 

environmental feasibility of harvesting timber at more intensive 

levels of utilization in steep terrain. In this study in a larchfir stand, four levels of wood utilization, ranging from conventional saw log to almost total fiber recovery, were harvested 

using running skyline and live skyline yarding equipment. All four 

levels of utilization were applied under each of three silvicultural prescriptions--shelterwood, group selection, and clearcut 

harvesting. 

The general objectives of the study were to determine the 

influence of intensive levels of wood utilization upon skyline 

system productivity under each silvicultural prescription, and to 

determine the important variables influencing rates of production. 

The highest average production experienced, in total cubic 

feet of fiber removed, occurred in group selection cutting units 

for the running skyline yarding downhill in treatment 4--1,047 

ft3/h (29.3 m3/h). The least productive logging occurred with 

the running skyline logging uphill in shelterwood cutting in 

treatment 3--353 ft 3/h (10.0 m3/h. 

The most important variables influencing rate of production 

were yarding distance, lateral yarding distance to the skyline, 

and number of pieces per turn, in that order. 
USDA Forest Service 

Research Paper INT-247 

June 1980 

SKYLINE LOGGING PRODUCTIVITY UNDER AL lERNA liVE 

HARVESTING PRESCRIPTIONS AND LEVELS OF 

UTILIZA liON IN LARCH-FIR STANDS 

Ru I on B. Gardner 

INTERMOUNTAIN FOREST AND RANGE EXPERIMENT STATION 

U.S. Department of Agriculture 

Forest Service 

Ogden, Utah 84401 

.... , .. 
CONTENTS 

INTRODUCTION . 

OBJECTIVES . 

EXPERIMENTAL HARVESTING UNITS .. 

Logging Area and Blocks . . 

PLANNING AND CONDUCTING HARVESTING . 

Equipment . • 

YARDERS. 

LOADERS. 

TRUCKS .. 

Layout and Operation 

Logging by Utilization Prescription 

TIMBER VOLUMES LOGGED 

HARVESTING PRODUCTIVITY 

Felling and Bucking . 

Yarding . 

Loading . 

Hauling . 

FACTORS AFFECTING PRODUCTIVITY 

ESTIMATING TURN TIME AND PRODUCTIVITY 

SUMMARY AND CONCLUSIONS 

PUBLICATIONS CITED 

APPENDIX A--YARDER SPECIFICATIONS 

Page 

1 

2 

2 

2 

4 

4 

4 

6 

7 

7 

9 

10 

10 

15 

15 

15 

15 

17 

17 

19 

20 

21 

APPENDIX B--PRODUCTIVITY AND STATISTICAL ANALYSIS 23 

The use of trade, firm, or corporation names in this publication is 

for the information and convenience of the reader. Such use does not 

constitute an official endorsement or approval by the u.s. Department of 

Agriculture of any product or service to the exclusion of others which 

may be suitable. 
INTRODUCTION 

The broad objective of the study on which this report is based was to evaluate 

skyline harvesting feasibility (economic and environmental) under the full array of 

silvicultural and utilization practices that could be used in managing a larch-fir timber 

stand. 

Intensive wood utilization would reduce the waste of a valuable resource and extend 

an ever-shrinking wood fiber supply. Reductions in land available for growing timber 

because of urbanization and removal for other uses such as recreation, wildlife habitat, 

and wilderness, come at a time when demand for wood products continues to increase. 

Utilization of forest residues, estimated at 6 billion cubic feet (0.17 billion m3 ) 

annually, could increase the total fiber yield by as much as 50 percent on a national 

basis. 

Intensive wood utilization can have pos1t1ve or negative environmental impacts, 

depending on the level of utilization, harvesting methods, and ecosystem response. 

Although some general information is available from past studies about responses--

hydrology, flora, and fauna--the net results of applying increasing levels of timber 

utilization have not been adequately determined. Hence, a study was designed for the 

larch-fir type in Montana (fig. 1) to monitor biological-ecological responses to an array 

of alternative silvicultural and utilization timber harvesting prescriptions. 

Figure I.--Experimental road and 

logging location. 

"-CORAM EX PER I MENTAL FOREST 

Kalispelle ~ 

\ MONTANA Missoulae 

KEY MAP 

LEGEND: 

EXPERIMENTAL ROAD •••••• 

ABBOT BAS IN ROAD --NO. 590. B ---

1 
Because of the relatively steep slopes (45 to 60 percent) on the study area, cable 

yarding was appropriate. Past experience in the Rocky Mountain area has been largely 

with Idaho jammers or high-lead systems that require dense road networks because of 

limited skidding capabilities--300 to 500 ft (91 to 152 m) for jammer skidding and 

slightly more, 400 to 700 ft (122 to 213 m) for high-lead yarding. 

For this experimental harvesting study, where one of the objectives was to reduce 

environmental impacts, it was decided to use a running skyline system to reduce road 

requirements. Road spacing was to be on the order of 1,500 to 2,000 ft (457 to 610 m); 

thus, the requirement for the basic system was a 1,000-foot (305 m) yarding capability 

uphill or downhill. Because of road width limitations and landing restrictions, the 

yarding equipment also had to be able to swing logs to the road. This report describes 

the logging methods, logging equipment, productivity, and factors affecting productivity. 

OBJECTIVES 

The specific objectives of the harvesting study were as follows: 

1. Determine the influence of successively more intensive levels of wood utilization upon harvesting productivity for skyline systems operating under clearcut, 

shelterwood, and group selection silvicultural prescriptions. 

2. Identify and quantify the stand and operation variables that significantly 

affect harvesting productivity. 

3. Develop a statistical data base for estimating system yarding productivity, 

given some measure of the important variables describing the harvesting situation. 

4. Develop, field test, and demonstrate harvesting practices and techniques that 

can improve the efficiency of running skyline systems, and thus enhance the opportunities 

for increased utilization. 

In this report, the productivity experienced in each harvesting situation is 

presented and identified with the variables that influenced production. 

The report further develops and illustrates procedures for estimating yarding turn 

time and associated productivity--a major cost determinant for the system. 

EXPERIMENTAL HARVESTING UNITS 

Logging Area and Blocks 

Two blocks of each silvicultural prescription were laid out as shown in figure 1. 

In each block, four levels of utilization were prescribed as shown in table 1. 

Treatment units run perpendicular to the slope. 

The topography is generally steep (45 to 60 percent) and loggable only with cable 

equipment. To reduce hydrologic, esthetic, and biological impacts, logging equipment was 

needed that would reduce both the impacts from logging and attendant roads. The system 

also had to be portable and relatively easily rigged. The running skyline system was 

best for satisfying all of these requirements. 

2 
Table 1.--Logging area treatments and utilization prescriptions 

Prescribed 

utilization 

Conventional 

saw log 

Close log 

utilization, 

trees 7 inches 

(17.8 em) d.b.h.+ 

(sawtimber 

trees) 

Close log 

utilization, 

trees 5 inches 

(12. 7 em) 

d.b.h.+ 

Close fiber 

utilization, 

all trees 

Material removed 

Green and recent dead logs, 

to 5-1/2 inch (14 em) top; 

1/3 or more sound 

Green logs, to 3 inches x 8 

ft (7.6 em x 2.4 m); dead 

and down logs, to 3 inches x 

8 ft (7.6 em x 2.4 m), if 

sound enough to yard 

Green logs, to 3 inches x 8 

ft (7.6 em x 2.4 m); dead 

and down logs to 3 inches x 

8 ft (7.6 em x 2.4 m), if 

sound enough to yard 

Green 1-5 inches (2.5-12. 7 

em) d.b.h. material tree 

length, in bundles; 2 green 

trees >5 inches (12. 7 em) 

d.b.h., tree length; dead and 

down, to 3 inches x 8 ft 

(7.6 em x 2.4 m), sound enough 

to yard 

Postharvest 

treatment 

Remaining understory 

slashed; broadcast 

burned 

Understory retained; 

left as is 

Remaining understory 

slashed; broadcast 

burned 

Remaining understory 

slashed; left as is 

Treatment 

designationl 

1 

2 

3 

4 

1Treatment designation numbers used in this report are assigned in successive 

order of utilization intensity, 1 through 4. They do not correspond to the random 

treatment numbers assigned and used on the ground, which appear in various other 

reports based on this study site. 

2Trees 1-5 inches (2.5-12. 7 em) d.b.h. cut and prebundled prior to logging 

activity on the site. 

The upper part of blocks 11 and 12, all of 13, and the lower part of 21 were 

loggable from Abbott Basin Road 590-B, built in the 1950's (fig. 1). New access was 

needed for upper 21, 22, 23, and lower 11 and 12. Whenever it is desired to reduce road 

spacings in steep areas, it is usually efficient to gain elevation by switching back at 

favorable locations on the terrain and then log with a cable system with a fairly long 

reach. Figure 1 shows the new section of road that started from 590-B, near the upper 

part of block 11, and switched back on the gentle terrain of broad ridges to gain access 

above blocks 21, 22, and 23. A new short section of road was also built to access lower 

11 and 12, as shown in figure 1. (A separate report by the author [Gardner 1978] 

describes the road portion of the study.) 

3 

'• :', 
.. ·.··.· 

YARDERS 

PLANNING AND CONDUCTING HARVESTING 

Equipment 

The contractor selected a Skagit GT-3 (fig. 2) to meet the requirements for logging. 

Initial logging was done with the GT-3; later, two sides were logged simultaneously when 

a Link Belt 78 Log Mover (fig. 3) was put on the job. Both yarders had 1,000-foot (305 m) 

yarding capability. The Link Belt 78 was rigged as a live skyline using a gravity return 

carriage and, therefore, only able to log uphill. Figures 4 and 5 show how each system 

is rigged and operates (specifications for the yarder are in appendix A). 

4 

Figure 2.--Skagit GT-3 located 

at fan-shaped set below 

block 21 . 

Figure 3.--Link Belt 78 Log 

Mover logging block 23. 
Head spar 

/ 

Carriage 

~ Haulback Line 

/ 

Figure 4.--Running skyline. Drums 1 and 2 on the yarder are interlocked 

for horsepower exchange during yarding operation, drum 3 operates the slack puller. 

Head spar 

~ 

Drum I-- Skyline drum 

Drum 2 --Main line drum 

Figure 5.--Live skyline, gravity carriage. The skyline drum is powered 

so skyline tension can be varied during yarding operation. 

5 
' .. ·-···:··. 

LOADERS 

Three different types of loaders were used in situations that were normally hot 

logging operations (hot logging means skidding, loading, and hauling are going on simultaneously). For the first setting (block 21), which was downhill logging in a shelterwood cut, a jammer or heel boom loader was used (fig. 6). For all other loading, either 

a long boom (fig. 7) or a rubber-tired, front-end (fig. 8) loader was used. All loaders 

loaded both logs and currently unmerchantable material designated for removal under the 

more intensive utilization standards. 

6 

Figure 6.--Heel boom loading 

dump truck with residue 

from block 21. 

Figure 7.--Long boom loader. 
Figure 8.--Front-end loader 

working with Link Belt 

yarder keeping loading 

area clear on 14-foot 

(4.2 m) road without 

landings. 

TRUCKS 

Because of the large amount of currently nonmerchantable material that had to be 

removed to meet the previously discussed utilization standards, dump trucks were used 

for hauling this material. Conventional tractor-trailer units were used for the 

merchantable material. 

Layout and Operation 

The layout of blocks is shown in figure 1. Treatment units are numbered (1-4) and 

run perpendicular to the slope for clearcut and shelterwood blocks. 

Planning logging sets and skyline roads is the key to successful operation of any 

cable logging system, particularly live or running skyline systems, which require deflection for suspension of the haulback line. In the generally uniform terrain (as seen by 

the contours in figure 1) of this logging chance, it was usually necessary to rig tail 

spar trees for deflection. The number and location of rigged tail spar trees are shown 

in table 2. Figure 9 shows a typical rigging, with nylon strap, block, and guylines. 

Only 14 of the 69 skyline sets did not require rigging to provide deflection. 

7 
I,:·.··, 

Table 2.--Number of trees rigged when additional deflection was needed 

Direction No. of 

Block yarded sets 

11 up 7 

(Selection 

cut) down 1 

12 up 6 

(Group 

selection down 4 

cut) 

13 up 5 

(Clearcut) 

21 up 5 

(Selection 

cut) down 1 

22 up 4 

(Group 

selection 

cut) 

23 up 7 

(Clearcut) 

Total 40 

No. of No. 

roads 

10 

12 

6 

5 

6 

10 

6 

6 

8 

69 

8 

No. of 

of trees roads without 

rigged rigged trees 

9 1 

5 7 

6 0 

1 4 

6 0 

9 1 

6 0 

5 1 

8 0 

55 14 

Figure 9.--Typical tail spar 

rigging with nylon strap, 

block, and guylines. 
For this study, the position of each skyline set was located cooperatively by the 

logger and research personnel. Potential sets were located on the topographic map and 

then investigated in the field. A field crew of two was trained to run levels from the 

set (road) to a suitable spar tree. A profile was then plotted to show the deflection 

needed to operate the set. A tree was rigged at the height necessary to provide the 

deflection. This step was done well ahead of the logging crew. 

Topping of spar trees was deemed essential primarily for safety because of the 

risk of branches and dead tops shaking loose and dropping to the ground. Also, in the 

event of tail spar failure, the "radius of danger" would be less. Initially, topping 

was performed using about 60 sticks of dynamite with a Primacord belt wrapped around an 

18- to 24-inch (45. 7 to 56.9 em) diameter tree. An improved technique was developed 

that utilized six or seven pouches of a liquid/powder mixture with holes through each 

pouch using Primacord like a string of beads. The belt of explosives was installed at 

the point of topping by a rigger who would climb the tree with conventional pole 

climbing apparatus and lower a rope to raise the belt of explosives. Then a length of 

Primacord sufficient to reach the ground was tied to the belt. Finally a detonating 

cap and a length of fuse were attached to the end of the Primacord that reached the 

ground. The fuse was of sufficient length to allow all personnel to walk several 

hundred feet from the impending blast. Before igniting the fuse, the yarder operator 

was contacted by radio, and he activated his whistle-signaling device to warn everyone 

in the area of the blast. 

The explosion caused a relatively clean, horizontal severance, with a zone of 

crushing and ring separation extending no greater than about 12 inches (30.5 em) from 

the cut. 

All skyline roads were held to a maximum width of 10 ft (3.05 m) in the shelterwood blocks, and in leave strips between group selection blocks, to reduce visual 

impacts. 

Logging for the most part was conducted as a hot logging operation. Landings were 

usually not available, with the exception of the downhill yarding in blocks 11, 12, and 

21. Downhill yarding from blocks 11 and 12 was to open, near-level areas seen from the 

contours in figure 1. A stretch of wide road between the yarder and block 21 was used 

as a landing (fig. 3) for downhill yarding in that block. A typical set yarding to the 

road is seen in figure 4. This photograph illustrates why the yarders were required to 

have swing capability so they could land the logs on the road. 

The yarding crews consisted of the operator, two choker setters, a knot bumperchaser, and a side foreman, who supervised both yarding crews. The loading and hauling 

operations were required to keep logs clear of the yarder. Merchantable material and 

unmerchantable were separated at the landing by the loaders or loaded directly to the 

truck, depending on the situation at the yarder and availability of the trucks. The 

usual situation was trucks waiting for loads. 

logging by Utilization Prescription 

Recall that the primary purpose of the study was to determine the economic and 

environmental impacts of different levels of utilization under alternative silvicultura1 

practices. Previous studies had indicated that it may be possible to utilize sawtimber 

trees down to 3-inch (7.6 em) diameters in lengths of at least 8 feet (2.4 m); i.e., 

treatment 3. Treatments 4 and 2 are respectively more and less intensive than 3 to 

adequately identify feasibility limits. 

9 
Conventional sawlog (1).--In this treatment, the logs were yarded in a conventional 

manner with the limbs and top removed. The slash was disposed of by broadcast burning. 

Close log utilization (2, 3).--All of the material was yarded to meet the utilization prescriptions as defined in table 1. 

Close fiber utilization (4).--In treatment 4, trees were yarded as whole trees (or 

as nearly so as possible) and the merchantable logs removed in the conventional manner. 

Lirnbing and topping was accomplished on the landing. 

One operation in treatment 4 was unique to this study. The understory trees 

designated for removal (1 to 5 inches [2.54 to 12.7 ern]), were cut and bundled by 

research crews prior to any logging activity, and subsequently yarded by the contractor. 

Rope was used to make a bundle the size a choker could handle--about 3 ft (0.9 rn) in 

diameter and tree length long. A choker was put around the bundle for yarding. Handling 

the understory material in this manner was the only practical way to achieve intensive 

fiber recovery because it is not economically feasible to yard very small pieces 

individually. 

In systems other than clearcutting, it can be difficult to yard material laterally. 

Before logging began, it was thought that yarding downhill in selectively cut blocks 

could cause serious problems because the load would have to be turned downhill in a 

fairly narrow corridor when it reached the skyline road. However, this did not prove 

to be as difficult as anticipated. 

TIMBER VOLUMES LOGGED 

Preharvest inventory of all material was at a more intensive level than for ordinary 

sales because a good estimate of the total biomass was desired for estimating potential 

removals. All harvested and removed material was also measured at the landing except 

solid volumes for bundled material from treatment 4 that were estimated. Table 3 shows 

inventoried and removed volumes by block and treatment. Removals in treatment 4 for 

blocks 21 and 22 exceed inventoried estimates. Since removal measurements represent 

a 100 percent sample, it is believed they are more accurate. Inventoried merchantable 

volumes per acre in treatments varied from approximately 2,050 ft 3/acre (140 rn 3/ha) 

(8,660 bd.ft./acre) to over 6,000 ft3/acre (420 rn3/ha) (25,980 bd.ft./acre). From a 

total volume of fiber removed of 405,879 ft3 (11 494 rn3), 298,455 ft 3 (8 452 rn 3) 

(1,292,310 bd.ft.) was merchantable or 74 percent. 

HARVESTING PRODUCTIVITY 

The differences in timber composition, size, and density among blocks allows for 

productivity comparisons only between treatments within blocks. Therefore, conclusions 

about productivity differences between silvicultural prescriptions should not be attempted. 

Also, the differences in landing conditions along with the above tend to confound 

differences between uphill and downhill yarding production. 

10 
Table 3.--Preharvest and removed volumes (ft 3) 

Volumes Percent 

Block/treatment Acres Preharvest Removed removal 

11-1 14.9 98,027 21,495 21.9 

-2 6.2 37,324 17,368 47.3 

-3 6.7 47,603 17,545 36.9 

-4 7.3 48,854 48,354 99.0 

Subtotal 35.1 231,808 104,762 45.2 

12-1 2.3 14,823 6,537 44.1 

-2 1.7 16,232 8,668 53.4 

-3 1.7 14,341 10,407 72.6 

-4 1.9 18,344 16,244 88.5 

Subtotal 7.6 63,740 41,856 65.7 

13-1 3.8 26,325 14,668 55.7 

-2 3.2 24,333 18,481 76.0 

-3 2.9 26,248 9,676 36.9 

-4 3. 7 26,366 14,975 56.1 

Subtotal 13.6 103,272 57,800 56.0 

21-1 4.8 31,834 12,539 39.4 

-2 4.6 25,056 19,554 78.0 

-3 6.7 42,572 30,946 72.7 

-4 5.4 26,881 29,572 110.0 

Subtotal 21.5 126,343 92,611 73.3 

22-1 1.3 14,404 7,710 53.5 

-2 1.5 14,493 8,231 56.8 

-3 1.6 17,029 12,564 73.8 

-4 1.6 11,562 11,818 102.2 

Subtotal 6.0 57,488 40,323 70.1 

23-1 3.4 34,476 11,343 32.9 

-2 3.4 25,711 8,721 33.9 

-3 5.1 39,414 26,738 54.1 

-4 4.7 32,002 21,740 67.9 

Subtotal 16.6 131,603 68,542 52.1 

Total 100.4 714,254 405,879 56.8 

Tables 4, 5, and 6 summarize data related to each silvicultural system, including 

acreage, volumes, layout and equipment, and average yarding production by equipment 

type, treatment, and direction of yarding. The mean, standard deviation, and standard 

error by block and direction of yarding for pieces per turn, turns per hour, and pieces 

per hour are summarized in appendix B (table 9). 

Productivity data were derived from time and motion studies. These studies 

extended over the entire duration of the logging, covering over 7,200 turns made by 

the running and live skyline systems. 

11 

I ,,'<- .... ~ 
Table 4.--Skyline yarding summary--shelterwood units 

LOGGING UNITS 

Block Block Number Average piece 

number size Total volume pieces size 

Acres ha Ft 3 m3 Ft 3 m3 

11 35.1 14.2 104,762 2 967 7,471 14.02 0.397 

21 21.5 8. 74 92,611 2 623 6,338 14.61 .414 

YARDING LAYOUT 

Block Number skyline roads Yarding distance 

number Uphill Downhill Average Range 

Ft m Ft m 

11 10 12 508 155 0-1,050 0-320 

21 10 6 557 170 25-1,150 8-350 

EQUIPMENT 

21 Yarding - Skagit GT-3 rigged as running skyline, yarding uphill and downhill 

Loading - Both long boom and front end loader used at times 

Hauling- 6.0 M bd.ft. truck and trailers for logs, and 10-yard dumps for 

residues 

11 Yarding Skagit GT-3 rigged as running skyline, yarding uphill and. downhill 

Link Belt 78 Log Mover rigged as a live skyline, yarding uphill 

Loading - Same as Block 21 

Hauling - Same as Block 21 

Treatment 

Conventional saw log (1) 

Close log, trees 7"+ (2) 

Close log, trees 5"+ (3) 

Close fiber (4) 

Conventional saw log (1) 

Close log, trees 7"+ (2) 

Close log, trees 5"+ (3) 

Close fiber (4) 

Close log, trees 7"+ (2) 

Close fiber (4) 

AVERAGE PRODUCTION PER HOUR1 

System 

Running skyline, uphill 

yarding 

Running skyline, downhill 

yarding 

Live skyline, uphill yarding 

Total volume 

Ft m 

497 13.6 

358 10.1 

353 10.1 

568 16.1 

644 18.2 

561 15.9 

615 17.4 

813 23.0 

321 9.1 

747 21.2 

1Production per hour includes foreign element delay time occurring within a 

turn cycle, but not nonproductive hours for rest breaks, repairs, rerigging, etc. 

Foreign element delays are those caused by machines, manpower, materials, or environmental factors. 

12 
Table 5.--Skyline yarding summary--group selection units 

LOGGING UNITS 

Block Block Number Average piece 

number size Total volume Eieces size 

Acres ha Ft 3 m3 Ft 3 m3 

12 7.60 3. 04 41,856 1 185 2,670 15.63 0.443 

22 6.0 2.40 40,323 1 142 2,585 15.60 .442 

YARDING LAYOUT 

Block Number skyline roads Yarding distance 

number U£hill Downhill Average Range 

Ft m Ft m 

12 6 5 322 98 50-760 15-232 

22 6 0 524 160 0-1,250 0-381 

EQUIPMENT 

12 Yarding - Skagit GT-3 rigged as running skyline and yarding downhill only 

Link Belt 78 Log Mover rigged as a live skyline and yarding uphill 

Loading - Both long boom and front end loader used at times 

Hauling - 6.0 M bd.ft. truck and trailers for logs, and 10 yard dumps for 

residues 

22 Yarding Skagit GT-3 rigged as running skyline and yarding uphill only 

Link Belt 78 Log Mover rigged as a live skyline and yarding uphill 

Loading - Same as Block 12 

Hauling - Same as Block 12 

AVERAGE PRODUCTION PER HOUR 1 

Treatment System Total volume 

Ft m 

Conventional saw log (1) Running skyline, uphill 500 14.2 

Close log, trees 7"+ (2) yarding 590 16.7 

Close log, trees 5"+ (3) 590 16.7 

Close fiber (4) 490 13.9 

Conventional saw log (1) Running skyline, downhill 826 23.4 

Close log, trees 7"+ (2) yarding 815 23.1 

Close log, trees 5"+ (3) 815 23.1 

Close fiber (4) 1' 04 7 29.7 

Conventional saw log (1) Live skyline, uphill yarding 511 14.5 

Close log, trees 7"+ (2) 469 13.3 

Close log, trees 5"+ (3) 605 17.1 

Close fiber (4) 816 23.1 

lsee table 4 footnote. 

13 

.. , ' 
Block 

number 

13 

23 

Block 

number 

13 

23 

13 

23 

Table 6.--Skyline yarding summary--clearcut units 

LOGGING UNITS 

Block Number Average piece 

size Total volume pieces size 

Acres ha Ft 3 m3 Ft3 m3 

13.60 5.44 57,800 1 637 3,906 14.80 0.419 

16.6 6.64 68,542 1 941 5,201 13.18 .373 

YARDING LAYOUT 

Number skyline roads Yarding distance 

Uphill Downhill Average Range 

Ft m Ft m 

6 0 478 146 50-900 15-274 

8 0 488 149 0-950 0-290 

EQUIPMENT 

Yarding Skagit GT-3 rigged as a running skyline and yarding uphill only 

Loading Both long boom and front end loader used at times 

Hauling - 6.0 M bd.ft. truck and trailers for logs and 10 yard dumps for 

residues 

Yarding - Link Belt 78 Log Mover rigged as a live skyline and yarding uphill 

Loading - Same as Block 13 

Hauling - Same as Block 13 

AVERAGE PRODUCTION PER HOUR1 

Treatment System Total volume 

Conventional saw log (1) 

Close log, trees 7"+ (2) 

Close log, trees 5"+ (3) 

Close fiber (4) 

Conventional saw log (1) 

Close log, trees 7"+ (2) 

Close log, trees 5"+ (3) 

Close fiber ( 4) 

lsee table 4 footnote, 

Running skyline, uphill 

yarding 

Live skyline, uphill yarding 

14 

Ft 

989 

622 

850 

583 

930 

503 

632 

595 

m 

28.0 

17.6 

24.1 

16.5 

26.4 

14.2 

17.9 

16.8 
Felling and Bucking 

Time and motion studies did not include felling and bucking. Production and cost 

were estimated for the sale, using Northern Region timber sale appraisal guides. The 

base cost adjusted for average d.b.h., trees/acre, slope, and tree defect was $11.86/M 

bd.ft. ($2.62/m3) (1974). This cost was assumed to be applicable to clearcut units 

under conventional saw log specification, or treatment 1. It was adjusted for the 

requirements of the other treatments as follows: 

+32.5 percent for cutting 5- to 7-inch (12.7 to 17.8 em) d.b.h. in treatment 3. 

+50.0 percent to avoid damaging residual in shelterwood units. 

+50.0 percent to avoid damage to adjoining stands near group selection units. 

+10.0 percent for limbing to 3-inch (7.6 em) top in treatments 2 and 3. 

It was assumed that production, and therefore cost, would be equal to Regional 

averages, with the above added for special treatment requirements. 

Comparing observed sawyer production with estimated production shows a slight 

overestimation in some treatments and underestimation in others, with similar averages: 

0.79 M bd.ft./h (3.58 m3/h) observed production rate vs. 0.87 M bd.ft./h (3.94 m3/h) 

estimated production rate (table 10 in appendix B). 

Yarding 

The greatest productivity for total solid volumes was from group selection units 

using a running skyline logging downhill--1,047 ft 3 (29.6 m3) per hour in treatment 

4. The least productive logging was in running skyline units logging uphill in 

shelterwood blocks--productivity was 353 ft 3 (10.0 m3) in treatment 3. Factors 

affecting productivity are discussed in detail in the next section. 

Nonproductive time--yarding.--The percentage of total yarding time actually spent 

yarding was estimated for each block from data recorded by research personnel 

(table 11, appendix B). These times could be expected to vary between organizations. 

Loading 

Time and motion studies were not made for the loading operation. However, a record 

was kept of the number and type of trucks loaded each day. In table 12 (appendix B) 

the mean, standard deviation, and standard error for trucks loaded per day are shown 

for each operation. 

Waiting and loading times for log and dump trucks were recorded for a sample of 

logging sets as shown in table 7. 

Hauling 

Hauling distance for the dump trucks was approximately 7.5 miles (12.1 km) to the 

disposal area--an average of 1 mile (1.6 km) on the new road and 6.5 miles (10.4 km) 

of single-lane, unsurfaced road with turnouts (No. 590). Hauling distance for the logs 

to the Columbia Falls, Mont., mill consisted of approximately 1 mile (1.6 km) on the new 

road, 5.8 miles (9.3 km) of single-lane, unsurfaced road with turnouts, 1.5 miles 

(2.4 km) of lane and one-half [20ft (6.1 m)] gravel surfaced, and 10 miles (16.1 km) 

of paved, double-lane (U.S. No. 2) for a total of 17.3 miles (27.8 km). A tabulation of 

transport mileages for logs and residue and estimated average speed and hours of travel 

one way is shown in table 8. 

15 
Table 7.--Waiting and loading times for log 

and dump trucks (in hours) 

Log trucks Unmerchantable trucks 

Statistic Waiting Loading Waiting Loading 

n 32 32 32 32 

X 2.43 1. 89 1. OS 0.86 

Sx 1. 56 1.18 1. 31 1. 24 

n number of observations. 

x = mean waiting or loading time. 

Sx standard error of the mean. 

Table B.--Transport distances and times for merchantable and residue material 

Road section Distance Average sEeed 

Miles km Mi/h km/h 

Residue 

New section 590B 1.0 1.6 15 24.1 

Old section 590B 6.5 10.4 17 27.4 

Total 

Logs 

New section 590B 1.0 1.6 15 24.1 

Old section 590B 5.8 9.3 17 27.4 

Country road 1.5 2.4 24 38.6 

u.s. No. 2 10.0 6.1 so 80.4 

Total 

Nonproductive time is not included. 

16 

Hours 

0.067 

.382 

0.449 

.067 

.341 

.341 

.200 

0.670 
FACTORS AFFECTING PRODUCTIVITY 

In this study, the principal variables influencing yarding were distance, lateral 

distance, slope, volume, number of logs, and weight in various combinations, depending 

on the equipment and silvicultural prescription. 

The principal variables influencing the production of logging systems and equipment 

are fairly well known from studies conducted over the years. However, the relative 

influence of some variables is still being debated by researchers. Therefore, all of 

the variables thought to be potentially significant for influencing production were 

recorded using a standardized methodology developed over the past several years by 

Intermountain Station's Engineering Research Work Unit at Bozeman, Mont. 

The final equations for logging production were selected on the basis of the 

simultaneous consideration of the following criteria discussed in more detail by Gibson 

(1975). 

1. R2 or percent of variation explained by the equation. 

2. F-ratio for significance of the regression. 

3. Standard error of the independent variable (expressed as a percentage of the 

mean). 

4. Analysis of residual plots. 

5. Subjective consideration of information available to those who may use the 

equations for predicting production. 

The principal variables retained for each equation as a result of the above criteria 

are shown in table 13 (appendix B). Also table 14 (appendix B) shows the significance of the 

variables. Distance was the major variable influencing production in every case. 

Lateral distance appears in every equation except for the live skyline in shelterwood 

units. All equations are for the conventional logging utilization treatments (1). 

ESTIMATING TURN TIME AND PRODUCTIVITY 

Harvesting productivity in general, and for the Coram sale in particular, was 

discussed under harvesting productivity (tables 4, 5, and 6). These statistics are 

useful for comparing production for different utilization standards, and equipment types 

used on the sale. They show what could be expected at other locations with conditions 

similar to those at Coram, but what about other areas and situations? 

Regression equations (appendix B, table 13) can be used to estimate production when 

information is available about the independent variables. Most of this information is 

available whenever a sale is prepared or can be derived from timber surveys and topographic maps. 

To facilitate the use of the regression equations and foreign element delay times 

derived from the study, tables 15 through 23 in appendix B were prepared. They can be 

used to estimate turn time computed from each equation in table 13, appendix B. 

To illustrate how productivity can be estimated, the following examples are 

presented. 

17 
Computation of Turn Time and Productivity for Assumed Yarding Conditions (all tables 

used are in appendix B) 

Case 1: Running skyline, shelterwood cut, uphill yarding 

--Average yarding distance--500 feet (152 m) 

--Average lateral yarding distance--60 feet (18. 3 

--Average number of logs--4.0 

--Average weight of load--2,800 lb (1,270 kg) 

--Average piece size--14 ft 3 (0. 33 m3) 

Estimating Turn Time (T.T.) 

from table 15: 

Matrix A, factor = 5.87 (extrapolated) 

Matrix B, factor= 1.027 

T.T. 5.87 x 1.027 = 6.03 min 

from table 22: Percent foreign element 14.4 

T.T. = 6.03 X 1.144 = 6.72 

Estimating Productivity 

Turn time = 6. 72 

from table 23: 

4.0 logs, 14 ft 3 (0.33 m3) piece size 

V = 501 ft 3/h (14.2 m3/h) (extrapolated) 

(These are productive hours for all estimates.) 

Case 2: Live skyline, clearcut, uphill yarding 

--Average yarding distance--400 feet (122 m) 

m) 

--Average lateral yarding distance--90 feet (27.4 m) 

--Average number of logs--5.0 

--Average slope--60 percent 

--Average piece size--12 ft3 (0.29 m3) 

Estimating Turn Time (T.T.) 

from table 21: 

Matrix A, factor= 10.16 (extrapolated) 

Matrix B, factor= 0.612 

T.T. 10.16 x 0.612 = 6.22 

from table 22: Percent foreign element 10.8 

T.T. = 6.22 x 1.108 = 6.89 

Estimating Productivity 

Turn Time= 6.89 

from table 23: 

5. 0 logs, 12 ft 3 (0. 29 m3) piece size 

V = 512 ft 3/hr (14.5 m3/hr) (extrapolated) 

(These are productive hours for all estimates.) 

18 
, .. 

SUMMARY AND CONCLUSIONS 

For shelterwood and group selection units, the cubic foot volume of material removed 

per hour was greatest in treatment 4, as would probably have been expected. However, 

cubic foot volume removed per hour in clearcut units was greatest in treatment 1 

(conventional logging). Production per hour was generally greater for all treatments in 

clearcut units. This may have been due to greater ease of lateral skidding. 

The important measured variables influencing turn cycles, and therefore production, 

were (1) distance, (2) lateral distance, (3) slope, (4) number of logs, (5) volume, and 

(6) weight. In table 14 (appendix B), the relative importance of these variables for 

each harvesting situation is shown by their contribution to the correlation coefficient 

(R2 ). Distance was the most important variable in every case, and lateral distance 

appears in every equation. Number of logs appears in every equation except the running 

skyline yarding uphill in a shelterwood cut. If information is available for these 

three variables, a reasonably good estimate of production is possible. 

The room to maneuver yarders, trucks, and loaders on this sale was rather restricted 

because of the 14-foot (4.3 m), single-lane road, few turnouts, and no planned landings. 

In fact, landing construction was prohibited. However, turnouts could be used effectively as could the relatively flat areas below blocks 11 and 12. These landing areas 

in blocks 11 and 12 were undoubtedly partly responsible for the greater production 

experienced from downhill yarding in these blocks. 

19 
PUBLICATIONS CITED 

Gardner, Rulon B. 

1978. Cost, performance, and esthetic impacts of an experimental forest road in 

Montana. USDA For. Serv. Res. Pap. INT-203, 28 p. Intermt. For. and Range Exp. 

Stn. , Ogden, Utah. 

Gibson, David F. 

1975. Evaluating skyline harvesting productivity. Winter Meet., Am. Soc. Agr. Eng. 

Proc. [Chicago, Ill.], 38 p. 

20 
APPENDIX A--YARDER SPECIFICATIONS 

GENERAL YARDER SPECIFICATIONS 

Skagit GT-3 

Dimensions: Boom Height- 38 1 6" (11.7 m) 

Working Height - 44 1 (13.4 m) 

Overall Width - 12 1 6" (3.8 m) 

Ground Clearance- 1 1 4" (0.4 m) 

Drum Capacity: 

Mains - 1,700 1 (518 m) - 5/8" (1. 6 em) 

1,100 1 (335 m) - 3/4" (1. 9 em) 

Haul back - 2,400 1 (732 m) - 3/4" (1. 9 em) 

2,600 1 (792 m) - 3/8" (1. 0 em) 

dia. 

dia. 

dia. 

dia. 

cable 

cable 

cable 

cable 

Guyline - 109 1 (33.2 m) - 1" (2.54 em) dia. cable 

Power Unit - Cummings NH 220 with Allison Torque Converter 

Shipping Weight - 95,040 lb (43,110 kg) 

Dimensions: 

Drum Capacity: 

Link Belt HC-78B 

Boom Height - 35 1 0" (1 0. 7 m) 

Working Height - 41 1 5" (12. 6 m) 

Overall Width- 9 1 0" (2.7 m) 

Minimum Ground Clearance - 0 1 10" (2.1 em) 

Sky 1 in e - 1 , 1 0 0 1 ( 3 3 5 m) - 5 I 8" ( 1. 6 em) d i a . cab 1 e 

Mainline - 1,300 1 (396m) - 1/2" (1.3 em) dia. cable 

Power Unit - General Motors 6V-53 

Shipping Weight - 68,775 lb (29,958 kg) 

21 

APPENDIX B--PRODUCTIVITY AND STATISTICAL ANALYSIS 

Table 9.--Mean, standard deviation, and standard error for 

pieces per turn, turns per hour, and pieces per hour 

Pieces/turn Turns/hour Pieces/hour Blockl/; ---~2~~----~--~----------------------~~--------------------------~----------

x- Sx Sx x Sx Sx x Sx Sx 

210 (S) 

llD(S) 

21U(S) 

llU (S) 

22U(GS) 

l2D(GS) 

l3U(C) 

ALL 

22(GS) 

12(GS) 

11 (S) 

23 (C) 

ALL 

Yo 

2/ ~ 

SKAGIT 

2.39 0.63 0.18 10.64 2.96 0.86 25.58 10.30 

4.37 .59 .13 10.89 2.90 .63 47.09 11.17 

3.63 .56 .16 8.82 3.25 .60 35.42 13.15 

3.89 .55 .16 9.13 2.40 .62 .)4. 37 11.67 

4.74 . 74 . 21 6. 72 2.63 .73 31.79 13.22 

5.16 .84 .25 ll. 23 2.17 .65 57.98 14.63 

4.4 7 .61 .14 9.73 l. 65 . 39 42.40 7.49 

4.14 l. 02 10.12 6.84 39. 14 14.48 

LINK BELT 

4.60 l. 52 . 76 7.82 2. 27 l. 36 38.40 22.35 

4.60 .44 .17 9.39 l. 24 .44 43.46 6.61 

4.96 .65 .19 7.74 l. 97 .57 36.60 10.65 

4.89 .96 .19 8. 43 2. 13 .43 45.71 19.44 

4.84 .87 8.19 2.04 38.54 13.96 

downhill yarding, U = uphill yarding, S = shelterwood, GS = group selection, 

clearcut. 

mean, Sx = standard deviation, Sx = standard error of the mean. 

Table 10.--Falling statistics 

Treatment and Observed Estimated production 

si1vicultural cut production rate rate based on cost 

h/M bd.ft. (h/m 3) h/M bd.ft. (hjm 3 ) 

ll l - cc 0.58 (0. 13) 0.58 (0.13) 

- GS .69 (0.15) .87 (0.19) 

- sw .93 (0.21) .87 (0.19) 

4 - cc .59 (0. 13) .77 (O. l 7) 

4 - GS .60 (0. 13) l. 06 co. 23) 

4 - sw l. 01 (0.22) l. 06 (0. 23) 

3 - cc .68 (0.15) .82 (0. 18) 

3 - GS .74 (0.16) l. 11 (0.24) 

3 - sw 1.15 (0.25) l. ll (0.24) 

2 - cc .72 (0. 16) .64 (0. 14) 

2 - GS .81 (0. 18) .93 (0. 21) 

2 - sw 1. 21 (0.27) .93 (0. 21) 

Average .79 ( 0. l 7) . 87 (0. 19) 

y Basis for estimates. 

23 

2.97 

2.44 

2.44 

3.01 

3.67 

4.41 

1.77 

11. 17 

2.70 

3.08 

5.39 
Block 

11 

12 

13 

21 

22 

23 

Table 11.--Estimates of productive hours 

Percentage of total yarding time 

actually spent yarding 

0.66 

.70 

.79 

.67 

.59 

.65 

Average 0.67 

Table 12.--Loading statistics for each operation 

Loader 

Long boom 

Front end 

Truck 

Logs-trailer 

Residue-dump 

Loader 

Long boom 

Front end 

Truck 

Logs-trailer 

Residue-dump 

SKAGIT 

Trucks loaded per day 

X 

5.00 

3.20 

Sx 

2.85 

1. 57 

Trucks loaded per day by class 

-

X 

2.35 

3.19 

LINK BELT 

Sx 

1. 56 

2.29 

Trucks loaded per day 

-

X 

3.79 

4.44 

Sx 

1. 44 

2.50 

Trucks loaded per day by class 

-

X 

2.21 

3.23 

24 

Sx 

1.10 

1. 78 

sx 

0.49 

.40 

sx 

0.18 

.31 

sx 

0.33 

.59 

sx 

0.21 

.33 
Table 13.--Regression equations 1 (equations apply to utilization level 1) 

Running, Shelterwood, Uphill 

LN(TT) 1.458050 

+ (.001)(0.486540) Distance 

+ .001145 Lateral Distance 

+ (.001)(0.00896) Weight 

Running, Shelterwood, Downhill 

LN(TT) 0.676830 

+ .000240 (No. Logs) (Lateral Distance) 

+ .132343 LN (Distance) - 0.000032 (Slope)(Volume) 

Running, Group Selection, Uphill 

LN(TT) 0.580136 

.003076 (Slope) 

+ .001928 (Lateral Distance) + 0~191832 LN (Distance) 

+ (.00001) (0.400174) (No. Logs) (Weight) 

Running, Group Selection, Downhill 

LN(TT) 0.689134 

+ .002647 (Lateral Distance) 

+ .337807 LN (Distance) 

+ (.353655)(0.0000l)(No. Logs)(Weight) 

Running, Clearcut, Uphill 

LN(TT) 1.089454 

+ .019567 (No. Logs) + 0.001065 (Distance) 

+ .000617 (Volume) - (0.001)(0.000545)(Distance) 

+ .000043 (Lateral Distance) (Slope) 

Live, Group Selection, Uphill 

LN(TT) 1.812551 

+ .000940 Distance 

.00950 Slope + 0.001721 Lateral Distance 

+ (.00001)(0.277323) (No. Logs)(Weight) 

Live, Clearcut, Uphill 

LN(TT) 1.910023 

+ .000545 Distance 

.006795 Slope + 0.002118 Lateral Distance 

.4162 (No. Logs)-1 

1 LN natural log. TT Turn time. 

25 
Table 14.--Independent variables and their contributions to R2 for each 

regression equation (equations apply to utilization level 1) 

Harvesting situation, 

regression equation 

Dependent 

variable 

Running Skyline, 

Shelterwood, 

Uphill 

_!_/ LN (TT) 

Running Skyline, 

Shelterwood, 

Downhill 

Running Skyline, 

Group Selection, 

Uphill 

Running Skyline, 

Group Selection, 

Downhill 

Running Skyline, 

Clearcut, 

Uphill 

Live Skyline, 

Group Selection, 

Uphill 

l/ LN natural log. TT 

LN(TT) 

LN(TT) 

LN(TT) 

LN(TT) 

LN(TT) 

LN(TT) 

turn time. 

Independent variable and contribution to R2 

Variable 

Distance 

Lateral Distance 

Weight 

LN (Distance) 

(Slope) (Volume) (-) 

(No. Logs) (Lateral 

Distance) 

LN (Distance) 

Lateral Distance 

(No. Logs) (Weight) 

Slope 

LN (Distance) 

Lateral Distance 

(No. Logs) (Weight) 

Distance 

(Lateral Distance) 

(Slope) 

Volume 

(Distance) 2 (-) 

No. Logs 

Distance 

Lateral Distance 

Slope (-) 

(No. Logs) (Weight) 

Distance 

(No. Logs)- 1 (-) 

Lateral Distance 

Slope (-) 

26 

Contribution to R2 

0.2957 

. 0135 

.0047 

.2134 

. 0353 

.0257 

.3787 

.0375 

.0348 

. 0121 

.1039 

.0715 

.0261 

.2176 

.0478 

.0252 

.0222 

.0160 

.2578 

.0276 

.0270 

. Oll2 

.2660 

.0476 

.0294 

.0208 

R2 for 

equation 

0.34 

.44 

.68 

. 32 

.48 

.42 

.41 
Table 15.--Turn time prediction factors, running, shelterwood, uphill 

Matrix A 

Lateral distance ft (m) 

0 10 20 30 40 50 60 70 80 90 100 

(3. 0) (6. 1) (9. 1) (12.2) (15. 2) (18. 3) (21.3) (24.4) (27.4) (30.5) 

25 4.350 4.400 4.451 4.502 4.554 4.606 4.660 4.713 4.767 4.822 4.878 

(7.6) 

125 4.567 4.620 4.673 4. 727 4.781 4.836 4.892 4.948 5.005 5.063 5.121 

(38.1) 

225 4.795 4.850 4.906 4.962 5.019 5. 077 5.136 5.195 5.255 5.315 5.376 

(68.6) 

325 5.034 5.092 5.150 5. 210 5.270 5.330 5.392 5.454 5.517 5.580 5.644 

(99. 1) 

Skyline 425 5.285 5.346 5.407 5.469 5.532 5.596 5.661 5. 726 5. 792 5.858 5.926 distance (130.0) ft 

(m) 525 5.548 5.612 5. 677 5.742 5.808 5.875 5. 943 6. 011 6.080 6. 150 6.221 

(160. 0) 

625 5.825 5.892 5.960 6.028 6.098 6.168 6.239 6. 311 6.384 6.457 6.531 

(190. 0) 

725 6.115 6.186 6.257 6.329 6.402 6.476 6.550 6.626 6. 702 6. 779 6.857 

(221. 0) 

825 6.420 6.494 6.569 6.645 6. 721 6. 798 6. 877 6.956 7.036 7. 117 7. 199 

(252. 0) 

925 6.740 6.818 6.896 6.976 7.056 7.137 7.220 7.303 7.387 7.472 7.558 

(282. 0) 

1025 7.076 7.158 7.240 7.324 7.408 7.493 7.580 7.667 7. 755 7.844 7.935 

(312. 0) 

1125 7.429 7.515 7.601 7.689 7. 777 7.867 7.957 8.049 8.142 8.236 8.330 

(343.0) 

Matrix B 

Weight lb (kg) 

30 1510 2990 4470 5950 7430 8910 10390 11870 13350 14830 

(13.6) (685) (1356) (2028) (2699) (3370) ( 4042) (4713) (5384) (oOS6) (6729) 

1.000 1. 014 1. 027 1. 041 1. 055 1.069 1. 083 1. 098 1. 112 1. 127 1.142 

27 
Table 16.--Turn time prediction factors, running, shelterwood, downhill 

~latrix A 

Lateral distance ft (m) 

0 10 20 30 40 50 60 70 80 90 100 

(3. 0) (6.1) (9. 1) (12.2) (15. 2) (18. 3) (21. 3) (24.4) (27.4) (30.5) 

1 1.968 1. 972 1.977 1. 982 1. 987 1. 991 1.996 2.001 2.006 2.011 2.015 

2 1.968 1. 977 1. 987 1.996 2.006 2.015 2.025 2.035 2.045 2.054 2.064 

3 1.968 1.982 1.996 2.011 2.025 2.040 2.054 2.069 2.084 2.099 2.115 

Number 4 1.968 1. 987 2.006 2.025 2.045 2.064 2.084 2.104 2.125 2.145 2.166 

of 5 1.968 1.991 2.015 2.040 2.064 2.089 2.115 2.140 2.166 2.192 2.218 

logs 6 1.968 1.996 2.025 2.054 2.084 2.115 2.145 2.176 2.208 2.240 2. 272 

7 1.968 2.001 2.035 2.069 2.104 2.140 2.176 2.213 2.251 2.289 2.328 

8 1.968 2.006 2.045 2.084 2.125 2.166 2.208 2.251 2.294 2.339 2.384 

9 1.968 2. 011 2.054 2.099 2.145 2.192 2.240 2.289 2.339 2.390 2.442 

10 1.968 2.015 2.064 2.115 2.166 2.218 2.272 2.328 2.384 2.442 2.501 

Matrix B 

Volume bd.ft. (m3) 

5 30 55 80 105 130 155 180 205 230 255 

(0.02) (0.14) (0.25) (0. 36) (0.48) (0.59) (0. 70) (0.82) (0.93) (1. 04) (1.16) 

-30 1.005 1.029 1.054 1.080 1.106 1.133 1.160 1. 189 1. 218 1.247 1.277 

-25 1.004 1.024 1.045 1.066 1.088 1.110 1.132 1.155 1.178 1. 202 1.226 

-20 1.003 1. 019 1. 036 1. 053 1. 070 1. 087 1.104 1.122 1.140 1.159 1.177 

Slope -15 1.002 1.015 1.027 1.039 1.052 1.064 1.077 1.090 1.103 1.117 1.130 

(per- -10 1.002 1.010 1. 018 1.026 1.034 1. 042 1. 051 1.059 1.068 1. 076 1.085 

cent) - 5 1. 001 1.005 1.009 1.013 1. 017 1.021 1.025 1.029 1.033 1. 037 1.042 

0 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 

5 .999 .995 .991 .987 .983 .979 .976 . 972 .968 .964 .960 

10 .998 .990 .983 .975 .967 .959 .952 .944 .937 .929 .922 

15 .998 .986 .974 .962 .951 .940 .928 .917 .906 .895 .885 

20 .997 .981 .965 .950 .935 .920 .906 .891 .877 .863 .849 

Matrix c 

Distance ft (m) 

25 105 185 265 345 425 505 585 665 745 825 

(7.6) (32.0) (56.4) (80.8) (lOS) (130) (154) (178) (204) (227) (251) 

1. 531 1.851 1.995 2.093 2.167 2.228 2.279 2.324 2.364 2.399 2. 432 

28 
Table 17.--Turn time prediction factors, running, group selection, uphill 

Matrix A 

Weight lb (kg) 

200 1200 2200 3200 4200 5200 6200 7200 8200 9200 10200 

(90. 7) (544) (998) (1452) (1905) (2359) (2823) (3266) (3720) (4173) ( 4627) 

1 1.788 1.795 1.802 1.809 1. 817 1.824 1. 831 1. 838 1.846 1. 853 1. 861 

2 1.789 1.804 1.818 1.833 1.847 1.862 1. 877 1.892 1.907 1.923 1. 938 

3 1.791 1. 812 1.834 1.856 1. 879 1. 901 1. 924 1.948 1.971 1.995 2.019 

Number 4 1. 792 1.821 1.850 1.880 1. 910 1. 941 1. 973 2.004 2.037 2. 070 2. 103 

of 5 1.793 1.830 1.867 1.904 1. 943 1. 982 2.022 2.063 2.105 2.147 2.191 

logs 6 1.795 1. 838 1. 883 1. 928 1. 976 2.024 2.073 2.123 2.175 2.228 2.282 

7 1.796 1.847 1.900 1.954 2.009 2.066 2.125 2.185 2.248 2. 311 2. 377 

8 1. 798 1.856 1. 917 1.979 2.043 2.110 2.178 2.249 2.323 2.398 2.476 

9 1.799 1.865 1. 934 2.004 2.078 2.154 2.233 2.315 2.400 2.488 2.579 

10 1. 801 1. 874 1. 951 2.030 2.113 2.199 2.289 2.383 2.480 2.581 2.687 

Matrix B 

Lateral Distance ft (m) 

0 10 20 30 40 so 60 70 80 90 100 

(3.0) (6 .1) (9. 1) (12.2) (15. 2) (18.3) (21.3) (24.4) (27.4) (30.5) 

22 .935 .953 .971 .990 1.009 1.029 1.049 1. 070 1.090 1.112 1. 133 

27 .920 .938 .956 .975 .994 1. 013 1. 033 1. 053 1. 074 1.095 1. 116 

32 .906 .924 .942 .960 .979 .998 1. 017 1. 037 1. 057 1. 078 1.099 

37 .892 .910 .928 .946 .964 .983 1.002 1.021 1. 041 1.062 1. 082 

Slope 42 .879 .896 .913 .931 .949 .968 .987 1.006 1.025 1.045 1.066 

(per- 47 .865 .882 .899 .917 .935 .953 . 972 .990 1. 010 1. 029 1.049 

cent) 52 .852 .869 .886 .903 .921 .938 .957 .975 .994 1. 014 1. 033 

57 .839 .856 .872 .889 .906 .924 .942 .960 .979 .998 1. 018 

62 .826 .842 .859 .876 .893 .910 .928 .946 .964 .983 1.002 

67 .814 .830 .846 .862 .879 .896 .914 .931 .949 .968 .987 

72 .801 .817 .833 .849 .866 . 882 .900 .917 . 935 .953 . 972 

Matrix c 

Distance ft (m) 

so 170 290 410 530 650 770 890 1010 1130 1250 

(15.2) (51.8) (88.4) (125) (162) (198) (235) (271) (308) (344) (381) 

2.118 2.678 2.967 3.171 3.331 3.464 3.579 3.679 3. 770 3.852 3. 927 

29 
Table 18.--Turn time prediction factors, running, group selection, downhill 

Matrix A 

Weight lb (kg) 

250 1150 2050 2950 3850 4 750 5650 6550 7450 8350 9250 

(113) (526) (930) (1338) (17 46) (2155) (2563) (2971) (3379) (3788) (4196) 

2 0.503 0.506 0.509 0.513 0.516 0.519 0.522 0.526 0.529 0.533 0.536 

3 .503 .508 .513 .518 .523 .528 .533 .538 .543 .549 .554 

4 .504 .510 .517 .523 .530 .537 .544 .551 .558 .565 .572 

Number 5 .504 .512 .521 .529 .537 .546 .555 .564 .573 .582 .591 

of 6 .505 .514 .524 .534 .545 .555 .566 .577 .588 .599 . 611 

logs 7 .505 .517 .528 .540 .552 .565 .577 .590 .604 .617 .631 

8 .506 .519 .532 .546 .560 .574 .589 .604 .620 .636 . 652 

9 .506 .521 .536 .551 .567 .584 .601 .618 .636 .655 .674 

10 .506 .523 .540 .557 .575 .594 .613 .633 .653 .674 .696 

11 .507 .525 .544 .563 .583 .604 .625 .648 .671 .695 . 719 

Matrix B 

Distance ft (m) 

180 240 300 360 420 480 540 600 660 720 780 

(54. 9) (73.2) (91.4) (llO) (128) (146) (165) (183) (201) (219) (238) 

10 5.934 6.540 7.052 7.499 7.900 8.265 8.600 8.912 9.204 9.478 9. 738 

(3.0) 

20 6.093 6.715 7.241 7. 701 8.ll2 8.487 8.831 9.151 9.450 9. 732 9.999 

(6. 1) 

30 6.257 6.895 7.435 7.907 8.330 8. 714 9.068 9.396 9. 704 9.993 10.267 

(9 .1) 

Lateral 40 6.424 7.080 7.634 8.ll9 8.553 8.948 9. 3ll 9.649 9.964 10.261 10.543 distance 

ft (12.2) 

(m) so 6.597 7. 270 7.839 8.337 8. 783 9.188 9.561 9.907 10.232 10.537 10.826 

(15.2) 

60 6. 774 7.465 8.049 8.561 9.018 9.434 9.817 10.173 10.506 10.819 ll.ll6 

(18.3) 

70 6.955 7.665 8.265 8.790 9.260 9.688 10.081 10.446 10.788 ll.llO 11.414 

(21. 3) 

80 7.142 7.871 8.487 9.026 9.509 9.947 10.351 10.726 11. 077 11.408 11. 720 

(24. 4) 

90 7.333 8.082 8.715 9.268 9. 764 10.214 10.629 11. 014 11. 374 11. 714 12.035 

(27. 4) 

100 7.530 8.299 8.948 9.517 10.026 10.488 10.914 11. 309 11.679 12.028 12.357 

(30.5) 

30 
Table 19.--Turn time prediction factors, running, clearcut, uphill 

Matrix A 

Volume bd.ft. (m3) 

5 25 45 65 85 105 125 145 165 185 205 

(0. 02) (0.11) (0.20) (0.29) (0.38) (0.48) (0.57) (0.66) (0.75) (0.84) (0.93) 

60 3.172 3.212 3.252 3.293 3.334 3.375 3.417 3.460 3.503 3.579 3.591 

(18.3) 

145 3.440 3.483 3.527 3. 571 3.615 3.660 3.706 3.752 3.799 3.846 3.894 

(44.2) 

230 3.701 3. 74 7 3.794 3.842 3.889 3.938 3.987 4.037 4.087 4.138 4.190 

(70.1) 

315 3.951 4.000 4.050 4.101 4.152 4.204 4.256 4.309 4.363 4.417 4.473 

(96.0) 

Distance 400 4.184 4.237 4.289 4.343 4.397 4.452 4.508 4.564 4.621 4.678 4.737 

ft (122) 

(m) 485 4.397 4.452 4.507 4.563 4.620 4.678 4.736 4.796 4.855 4.916 4. 977 

(148) 

570 4.584 4.641 4.699 4. 758 4.817 4. 877 4.938 4.999 5.062 5.125 5. 189 

(174) 

655 4.741 4.800 4.860 4.921 4.982 5.045 5.108 5.171 5.236 5.301 5.367 

(200) 

740 4.866 4.926 4.988 5.050 5.113 5.177 5.242 5.307 5.373 5.440 5.508 

(226) 

825 4.954 5.016 5.079 5.142 5.206 5. 271 5.337 5.403 5.471 5.539 5.608 

(251) 

910 5.005 5.067 5.130 5.194 5.259 5.325 5.391 5.459 5.527 5.596 5.665 

(277) 

Matrix B 

Lateral distance ft (m) 

0 10 20 30 40 50 60 70 80 90 100 

(3.0) c 6. 1) (9. 1) (12.2) (15.2) (18. 3) (21. 3) (24.4) (27.4) (30.5) 

20 1.000 1.009 1.017 1.026 1.035 1.044 1. 053 1.062 1. 071 1.080 1. 090 

25 1. 000 1. 011 1. 022 1. 033 1. 044 1. 055 1. 067 1.078 1.090 1. 102 1.113 

30 1.000 1.013 1.026 1.039 1. 053 1. 067 1. 080 1.095 1.109 1.123 1.138 

Slope 35 1.000 1. 015 1. 031 1.046 1. 062 1.078 1.095 1.111 1.128 1.145 1. 162 

(per- 40 1.000 1. 017 1.035 1. 053 1. 071 1.090 1.109 1.128 1.148 1.167 1. 188 

cent) 45 1.000 1. 020 1. 039 1.060 1.080 1.102 1.123 1. 145 1.167 1.190 1.213 

50 1.000 1. 022 1.044 1.067 1. 090 1.113 1.138 1.162 1. 188 1. 213 1. 240 

55 1.000 1. 024 1. 048 1. 074 1.099 1.126 1.152 1.180 1. 208 1. 237 1. 267 

60 1.000 1. 026 1. 053 1.080 1.109 1.138 1.167 1.198 1. 229 1. 261 1.294 

Matrix c 

Number of logs 

2 3 4 5 6 7 8 9 10 

1.020 1.040 1. 060 1. 081 1.103 1.125 1. 14 7 1.169 1.193 1. 261 

31 
Table 20.--Turn time prediction factors, live, group selection, uphill 

~-latrix A 

Lateral distance ft (m) 

0 10 20 30 40 50 60 70 80 90 100 

(3.0) (6.1) (9 .1) (12.2) (15. 2) (18. 3) (21.3) (24.4) (27.4) (30.5) 

40 4.189 4.262 4.336 4. 411 4.488 4.566 4.645 4. 726 4.808 4.891 4.976 

45 3.995 4.064 4.135 4.207 4.280 4.354 4.430 4.506 4.585 4.664 4.745 

Slope 50 3.810 3.876 3.943 4.012 4.081 4.152 4.224 4.297 4. 372 4.448 4.525 

(per- 55 3.633 3.696 3.760 3.825 3.892 3.959 4.028 4.098 4.169 4.242 4.315 

cent) 60 3.464 3.525 3.586 3.648 3. 711 3. 776 3.841 3.908 3.976 4.045 4.115 

65 3.304 3.361 3.419 3.479 3.539 3.601 3.663 3.727 3.791 3.857 3.924 

70 3.150 3.205 3.261 3.317 3.375 3.434 3.493 3.554 3.615 3. 678 3.742 

~1atrix B 

Weight lb (kg) 

75 875 1675 2475 3275 4075 4875 5675 6475 7275 8075 

(34. 0) (397) (760) (1123) (1486) (1848) (2211) (2574) (2937) (3300) (3663) 

1 1. 000 1.002 1.005 1.007 1.009 1.011 1. 014 1. 016 1. 018 1. 020 1. 023 

2 1.000 1.005 1.009 1.014 1. 018 1. 023 1. 027 1.032 1. 037 1. 041 1.046 

3 1.001 1.007 1. 014 1. 021 1. 028 1.034 1. 041 1.048 1.055 1.062 1.069 

4 1.001 1. 010 1. 019 1. 028 1. 037 1.046 1.056 1.065 1. 074 1.084 1.094 

Number 5 1.001 1. 012 1. 023 1.035 1.046 1. 058 1. 070 1.082 1.094 1. 106 1.118 

of 6 1. 001 1.015 1.028 1.042 1.056 1.070 1.084 1.099 1.114 1.129 1. 144 

logs 7 1.001 1. 017 1.033 1.049 1.066 1. 082 1.099 1.116 1. 134 1. 152 1. 170 

8 1.002 1.020 1. 038 1.056 1. 075 1. 095 1.114 1.134 1.154 1.175 1.196 

9 1.002 1. 022 1. 043 1.064 1.085 1.107 1. 129 1. 152 1. 175 1.199 1. 223 

10 1. 002 1. 025 1. 048 1. 071 1. 095 1.120 1.145 1.170 1. 197 1. 224 1. 251 

11 1.002 1. 027 1. 052 1. 078 1.105 1.132 1.160 1.189 1. 218 1. 248 1.279 

12 1.002 1.030 1.057 1.086 1.115 1.145 1.176 1. 208 1.240 1. 274 1. 308 

Matrix c 

.. Distance ft (m) 

50 125 200 275 350 425 500 575 650 725 800 

(15.2) (38.1) (61. 0) (83.8) (107) (130) (152) (175) (198) (2 21) (244) 

1.048 1.125 1. 207 1.295 1.390 1. 491 1.600 1. 717 l. 842 1. 977 2.121 

32 
Table 21.--Turn time prediction factors, live, clearcut, uphill 

fvlatrix A 

Lateral distance ft (rn) 

0 10 20 30 40 50 60 70 80 90 100 

(3. 0) (6 .1) (9. l) (12.2) (15.2) (18.3) (21. 3) (24. 4) (27.4) (30.5) 

10 6.790 6.935 7.084 7.236 7.390 7.549 7. 710 7.875 8.044 8.216 8.392 

(3. 0) 

90 7.093 7.245 7.400 7.558 7. 720 7.885 8.054 8.226 8.402 8.582 8. 766 

(27.4) 

170 7.409 7.567 7. 729 7.895 8.064 8.236 8.413 8.593 8. 777 8.965 9.157 

(51.8) 

250 7.739 7.905 8.074 8.247 8.423 8.604 8. 788 8.976 9.168 9.364 9.565 

(76. 2) 

330 8.084 8.257 8.434 8.614 8. 799 8.987 9.179 9.376 9. 577 9. 781 9.991 

(101) 

410 8.444 8.625 8.810 8.998 9.191 9.387 9.588 9.794 10.003 10.217 10.436 

(125) 

Distance 490 8.820 9.009 9.202 9.399 9.600 9.806 10.016 10.230 10.449 10.637 10.901 ft 

(rn) (149) 

570 9.214 9.411 9.612 9.818 10.028 10.243 10.462 10.686 10.915 11. 148 11.387 

(174) 

650 9.624 9.830 10.041 10.255 10.475 10.699 10.928 11.162 11.401 11. 645 11.894 

(198) 

730 10.053 10.268 10.488 10.713 10.942 11. 176 11.415 11.660 11.908 12.164 12.425 

(223) 

810 10.501 10.726 10.955 11.190 11.429 11.674 11. 924 12.179 12.440 12.706 12.978 

(24 7) 

890 10.969 11.204 11.444 11.689 11.939 12.194 12.455 12.722 12.994 13.272 13.557 

(271) 

970 11.458 11. 703 11.954 12.209 12.471 12.738 13.010 13.289 13.573 13.864 14.161 

(296) 

Matrix B 

Number of logs 

2 3 4 5 6 7 8 9 10 

45 0.486 0.598 0.641 0.664 0.678 0.687 0.694 0.699 0. 703 0. 707 

Slope so .470 .578 .620 .642 .655 .664 .671 .676 .680 .683 

(per- 55 .454 .559 .599 .620 .633 . 642 .648 .653 .657 . 660 

cent) 60 .439 .540 .579 .599 .612 .621 .627 .631 .635 .638 

65 .424 .522 .560 .579 .592 .600 .606 .610 .614 .617 

70 .410 .505 .541 .560 .572 .580 .586 .590 .593 .596 

33 
Table 22.--Total foreign element statistics. (Foreign elements are 

delays attributed to machines, manpower, material, and environmental factors) 

System 

Running Skyline 

Shelterwood 

Uphill 

Running Skyline 

Shelterwood 

Downhill 

Running Skyline 

Group Selection 

Uphill 

Running Skyline 

Group Selection 

Downhill 

Running Skyline 

Clearcut 

Uphill 

Live Skyline 

Group Selection 

Uphill 

Live Skyline 

Clearcut 

Uphill 

Turns with 

foreign elements 

Percent 

30.6 

27.7 

40.7 

14.7 

15.7 

20.0 

19.6 

34 

Av. total foreign 

element time in 

turns with foreign 

elements 

Minutes 

28.0 

3.8 

2.5 

2.2 

3.0 

11.0 

3.2 

Av. foreign 

element time 

for all turns 

Percent 

14.4 

23.7 

26.3 

6.4 

8.2 

27.8 

10.8 
Turn 

time 

(min) 

3.0 

.2 

. 4 

.6 

.8 

4.0 

.2 

.4 

.6 

. 8 

5.0 

. 2 

.4 

.6 

. 8 

6.0 

.2 

. 4 

.6 

.8 

7.0 

.2 

.4 

.6 

. 8 

8.0 

Table 23.--Cubic foot (m 3 ) volume per hour for turn times given piece size and number of logs 

4.0 Log/Load 

10 12 14 16 18 20 

(0.24) (0.29) (0.33) (0.38) (0.43) (0.48) 

800 960 1120 1280 1440 1600 

(22.6) (27.2) (31.7) (36.2) (40.8) (45.3) 

750 900 1050 1200 1350 1500 

(21.2) (25.5) (29.7) (34.0) (38.2) (42.5) 

706 847 988 1129 1271 1412 

(20.0) (24.0) (27.9) (32.0) (36.0) (40.0) 

667 800 933 1067 1200 1333 

(18.9) (22.6) (26.4) (30.2) (34.0) (37.8) 

637 756 884 1010 1137 1263 

(18.0) (21.4) (25.0) (28.6) (.)2.2) (35.8) 

600 720 840 960 1080 1200 

(17.0) (20.4) (23.8) (27.2) (30.6) (34.0) 

571 686 800 914 1029 1143 

(16.2) (19.4) (22.6) (25.9) (29.1) (32.4) 

546 655 764 873 982 1091 

(15.5) (18.5) (21.6) (24.7) (27.8) (30.9) 

522 626 730 835 939 1043 

(14.8) (17.7) (20.7) (23.6) (26.6) (29.5) 

500 600 700 800 900 1000 

(14.2) (17.0) (19.8) (22.6) (25.5) (28.3) 

480 576 672 768 864 960 

(13.6) (16.3) (19.0) (21.7) (24.5) (27.2) 

462 554 646 738 831 923 

(13.1) (15.7) (18.3) (20.9) (23.5) (26.1) 

444 533 622 711 800 889 

(12.6) (15.1) (17.6) (20.1) (22.6) (25.2) 

429 514 600 686 771 857 

(12.1) (14.6) (17.0) (19.4) (21.8) (24.3) 

414 497 579 662 745 828 

(11.7) (14.1) (16.4) (18.7) (21.1) (23.4) 

400 480 560 640 720 800 

(11.3) (13.6) (15.9) (18.1) (20.4) (22.6) 

387 464 542 619 697 774 

(ll.O) (13.1) (15.3) (17.5) (19.7) (21.9) 

375 450 525 600 675 750 

(10.6) (12.7) (14.9) (17.0) (19.1) (21.2) 

364 436 509 582 655 727 

(10.3) (12.3) (14.4) (16.5) (18.5) (20.6) 

353 423 494 565 635 706 

(10.0) (12.0) (14.0) (16.0) (18.0) (20.0) 

343 411 480 549 617 686 

(9.7) (11.6) (13.6) (15.5) (17.5) (19.4) 

333 400 467 533 600 667 

(9.4) (11.3) (13.2) (15.1) (17.0) (18.9) 

324 389 454 519 584 649 

(9.2) (11.0) (12.9) (14.7) (16.5) (18.4) 

316 379 442 505 568 632 

(8.9) (10.7) (12.5) (14.3) (16.1) (17.9) 

308 369 431 492 554 615 

(8.7) (10.5) (12.2) (13.9) (15.7) (17.4) 

300 360 420 480 540 600 

(8.5) (10.2) (11.9) (13.6) (15.3) (17.0) 

35 

5.0 Log/Load 

10 12 14 16 18 20 

(0.24) (0.29) (0.33) (0.38) (0.43) (0.48) 

1000 1200 1400 1600 1800 2000 

(28.3) (34.0) (39.7) (45.3) (51.0) (56.6) 

938 1125 1312 1500 1688 1875 

(26.6) (31.9) (37.2) (42.5) (47.8) (53.1) 

882 1059 1235 1412 1588 1765 

(25.0) (30.0) (35.0) (40.0) (45.0) (50.0) 

833 1000 1167 1333 1500 1667 

(23.6) (28.3) (33.1) (27.8) (42.5) (47.2) 

789 947 1105 1263 1421 1579 

(22.3) (26.8) (31.3) (35.8) (40.2) (44.7) 

750 900 1050 1200 1350 1500 

(21.2) (25.5) (29.7) (34.0) (38.2) (42.5) 

714 857 1000 1143 1286 1429 

(20.2) (24.3) (28.3) (32.4) (36.4) (40.5) 

682 818 955 1091 1228 1364 

(19.3) (23.2) (27.0) (30.9) (34.9) (38.6) 

652 782 913 1043 1174 1304 

(18.5) (22.1) (25.9) (29.5) (33.2) (36.9) 

625 750 875 1000 1125 1250 

(17.7) (21.2) (24.9) (28.3) (31.9) (35.4) 

600 720 840 960 1080 1200 

(17.0) (20.4) (23.8) (27.2) (30.6) (34.0) 

577 692 808 923 1038 1154 

(16.3) (19.6) (22.9) (26.1) (29.4) (32.7) 

556 667 778 889 1000 1111 

(15.7) (18.8) (22.0) (25.2) (28.3) (31.5) 

536 643 750 857 964 1071 

(15.2) (18.2) (21.2) (24.3) (27.3) (30.3) 

517 621 724 828 931 1034 

(14.6) (17.6) (20.5) (23.4) (26.4) (29.3) 

500 600 700 800 900 1000 

(14.2) (17.0) (19.8) (22.6) (25.5) (28.3) 

484 

(13. 7) 

581 677 774 871 968 

(16.5) (19.2) (21.9) (24.7) (27.4) 

469 562 656 750 844 938 

(13.3) (15.9) (18.6) (21.2) (23.9) (26.6) 

455 545 636 728 819 909 

(12.9) (15.4) (18.0) (20.6) (23.2) (25.7) 

441 529 618 706 794 882 

(12.5) (15.0) (17.5) (20.0) (22.5) (25.0) 

429 514 600 686 771 857 

(12.1) (14.6) (17.0) (19.4) (21.8) (25.3) 

417 500 583 667 750 833 

(11.8) (14.2) (16.5) (18.9) (22.1) (23.6) 

405 486 568 649 730 811 

(11.5) (13.8) (16.1) (18.4) (20. 7) (23.0) 

395 474 553 632 711 790 

(11.2) (13.4) (15.7) (17.9) (20.1) (22.4) 

385 461 538 616 692 769 

(10.9) (13.1) (15.2) (17.4) (19.6) (21.8) 

375 450 525 600 675 750 

(10.6) (12.7) (14.9) (17.0) (19.1) (21.2) 

Gardner, Rulon B. 

1980. Skyline logging productivity under alternative 

harvesting prescriptions and levels of utilization 

in larch-fir stands. USDA For. Serv. Res. Pap. 

INT-247, 35 p. Intermt. For. and Range Exp. Stn., 

Ogden, Utah 84401. 

Larch-fir stands in northwest Montana were experimentally 

logged to determine the influence of increasingly intensive levels 

of utilization upon rates of yarding production, under three 

different silvicultural prescriptions. Variables influencing 

rate of production were also identified. 

KEYWORDS: Skyline yarding, productivity, utilization. 

Gardner, Rulon B. 

1980. Skyline logging productivity under alternative 

harvesting prescriptions and levels of utilization 

in larch-fir stands. USDA For. Serv. Res. Pap. 

INT- 247, 35 p. Intermt. For. and Range Exp. Stn., 

Ogden, Utah 84401. 

Larch-fir stands in northwest Montana were experimentally 

logged to determine the influence of increasingly intensive levels 

of utilization upon rates of yarding production, under three 

different silvicultural prescriptions. Variables influencing 

rate of production were also identified. 

KEYWORDS: Skyline yarding, productivity, utilization. 


The Intermountain Station, headquartered in Ogden, 

Utah, is one of eight regional experiment stations charged 

with providing scientific knowledge to help resource 

managers meet human needs and protect forest and range 

ecosystems. 

The Intermountain Station includes the States of 

Montana, Idaho, Utah, Nevada, and western Wyoming. 

About 231 million acres, or 85 percent, of the land area in the 

Station territory are classified as forest and rangeland. These 

lands include grasslands, deserts, shrublands, alpine areas, 

and well-stocked forest~. They supply fiber for forest industries; minerals for energy and industrial development; and 

water for domestic and industrial consumption. They also 

provide recreation opportunities for millions of visitors each 

year. 

Field programs and research work units of th~ Station 

are maintained in: 

Boise, Idaho 

Bozeman, Montana (in cooperation with Montana 

State University) 

Logan, Utah (in cooperation with Utah State 

University) 

Missoula, Montana (in cooperation with the 

University of Montana) 

Moscow, Idaho (in cooperation with the University of Idaho) 

Provo, Utah (in cooperation with Brigham Young 

University) 

Reno, Nevada (in cooperation with the University 

of Nevada) 

FOREST RESIDUES UTILIZATION 

RESEARCH AND DEVELOPMENT PROGRAM