United States

Department of 

Agriculture

Forest Service

Northern 

Research Station

General Technical

Report NRS-91

Harvesting Systems for the 

Northern Forest Hardwoods

Chris B. LeDoux
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Abstract

This monograph is a summary of research results and environmental compliance measures for 

timber harvesting operations. Data are presented from the Northern Research Station’s forest 

inventory and analysis of 20 states in the northern forest hardwoods. Harvesting systems available 

in the region today are summarized. Equations for estimating harvesting costs are documented. 

Safety considerations are compiled along with images of safety equipment and clothing engineered 

to protect the head, ears, eyes, face, hands, and legs. Mandatory and voluntary best management 

practices (BMPs) are discussed for streamside management zones (SMZs), patch/structural 

retention, invasive plant mitigation, and soil protection. Profitability and cost control are addressed. 

The importance of keeping machines working, exploiting machines’ payload capacity, and matching 

machines to the size of wood being harvested is illustrated. The information offered in this text 

should be valuable to the harvesting industry and serve as a text for a course in timber harvesting.

Manuscript received for publication 14 March 2011

Cover Photo

The author observes a clambunk skidder transporting a load of logs to the landing. Photo courtesy 

of Andrew Whitman, Manomet Center for Conservation Sciences.

The Author

CHRIS B. LEDOUX is a supervisory research industrial engineer with the U.S. Forest Service’s 

Northern Research Station at Morgantown, WV.

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 or the Forest Service of any product 

or service to the exclusion of others that may be suitable.

Acknowledgments

The author expresses gratitude to the following persons who read the entire manuscript and 

contributed comprehensive reviews and valuable suggestions: Michael Vanderberg, postdoctoral 

fellow-environmental scientist, Appalachian Hardwood Center, West Virginia University, 

Morgantown, WV, and Edward T. Cesa, deputy director of the Wood Education and Resource 

Center, U.S. Forest Service, Northeastern Area State and Private Forestry, Princeton, WV.

The author has attempted to provide photographs of each logging machine. Most of the 

photographs used were taken by the author over a period of years. Where photographs were used 

that were not taken by the author, permission was requested in advance. It is beyond the scope of 

this text to thank everyone for information and photographs that were used; however, the author 

robustly thanks all of those that contributed.
Contents

Introduction.......................................................................................................... 1

Part I—Forest Inventory and Analysis of the Northern Forest 

Hardwood Resource............................................................................................ 2

Part II—Harvesting Systems................................................................................ 7

Production and Cost Estimation.................................................................... 19

Logs and Wood Hauling................................................................................ 26

Chippers and Chip Hauling........................................................................... 30

Part III—Safety and Environmental Compliance ............................................... 32

Safety Considerations................................................................................... 32

Best Management Practices (BMPs)............................................................ 37

BMPs for Streamside Management Zones (SMZs).................................. 37

BMPs for Patch or Structural Retention.................................................... 39

BMPs for Invasive Plant Mitigation........................................................... 41

BMPs for Soil Protection........................................................................... 44

Part IV—Considerations for Managers .............................................................. 47

Using the Harvesting System Applicability Matrix......................................... 47

Managing People and Machinery ................................................................. 47

Weather and Hauling Regulations ................................................................ 48

Profitability and Cost Control......................................................................... 49

Literature Cited .................................................................................................. 56

Index.................................................................................................................. 65
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1

Introduction

This four-part monograph has been written to help landowners, decisionmakers, and 

professional loggers understand and use the tools available today to harvest the northern 

hardwood resource. It is a collection and synthesis of numerous studies of harvesting systems 

conducted by the author over the years and by many researchers in the hardwood region 

and should serve as the basis for harvesting system selection, cost and production estimation, 

safety, environmental compliance, and on-the-ground implementation. It can also be used as a 

primary source for a course in harvesting systems.

Part I provides a basic review of important Forest Inventory and Analysis (FIA) information 

about the northern forest hardwood resource (Smith et al. 2004). The information provides a 

baseline of acreages, ownerships, terrain (percent sideslope), species, volumes, geography, and 

tree size distributions (diameter at breast height - d.b.h.). The text deals exclusively with the 

timber resource available in the FIA inventory to avoid complications caused by nonmarket 

products such as water, wildlife, nontimber products, and a wide array of other forest products 

and benefits. Transportation networks linking the timber inventory to sawmills, pulpwood, and 

other timber-consuming facilities are discussed. The current and historic timber consumption 

demands are addressed to provide the reader with some gauge of the demand versus the supply 

of northern forest hardwood resources. This type of information can help decisionmakers, 

landowners, and loggers select harvesting systems.

The harvesting systems commercially available in the region today are presented in Part II 

in terms of their applicability, cost and production, and environmental impact. The list of 

harvesting systems documented includes mechanized systems such as CTL (cut-to-length), 

feller bunchers, forwarders, and clambunk skidders. The list of nonmechanized systems 

includes traditional rubber-tired skidders, crawler and dozer tractors, small farm tractors, 

and other small systems such as horses, mules, and winches with chainsaw felling. In-woods 

chippers and chip transport are also addressed. Types of transportation including trucks and 

vans are documented. A section on how to estimate the production and cost of harvesting 

systems includes time study techniques, statistical methods, computer simulation, development 

of general cost and production equations, and development of user friendly computer software 

for the public.

Part III summarizes information on safety and environmental compliance—both safety 

concerns as well as safety equipment and its proper use. The author emphasizes chainsaw safety 

because most logging systems in use today require chainsaws and most workplace injuries 

involve chainsaws. Best Management Practices (BMPs) for riparian protection, structural 

retention, soil protection and disturbance, and invasive species mitigation are discussed. The 

section on BMPs is included in this text because various owners (including government, 

commercial industries, and private nonindustrial) require the implementation of BMPs to 

protect the numerous resources on their lands. Additionally, Sustained Forestry Initiative 

(SFI) and Certified Forestry Initiative (CFI) programs require the use of various BMPs for 

certification purposes. Loggers operating on these lands must be familiar with alternative 

BMPs; they must comply with these requirements safely and responsibly. In the case of BMPs 

for invasive plant mitigation, where the available guidelines and literature are limited, direction 
2

for future studies is provided. This section largely summarizes the safety equipment and 

regulations, BMPs available and required today, and is not intended to be the final word.

Part IV of the text provides considerations for managers, loggers, and decisionmakers who 

are involved or are considering becoming involved in the process of harvesting timber from 

the northern forest hardwood resource. The treatment is general and includes safety training, 

environmental compliance, legal issues, professional registration, and profitability and cost control. 

This section includes a discussion of timber sale appraisals and property boundary definitions.

Part I—Forest Inventory and Analysis of The 

Northern Forest Hardwood Resource

The most basic discussion of a harvesting operation begins with the definition of the tract in 

question. The tract(s) to be harvested are defined by the geography, terrain, ownership, species 

composition, volume of wood, tree size distribution, and several other variables including any 

special consideration for environmental compliance. Terrain will usually dictate the type of 

harvesting system that should be used on that site. For example, extremely steep terrain will 

require aerial systems such as helicopters or cable systems. Tracts on more gentle terrain can be 

harvested by ground-based systems such as cut-to-length machines, feller bunchers, skidders, 

dozers, and other small systems such as horses, mules, and winches. The tree size distribution 

will generally dictate the size of the machines needed to harvest the tract.

This section of the text summarizes important FIA inventory information about the northern 

forest hardwood resource (Smith et al. 2004). The FIA data summarized here provide a onetime 

snapshot of the current conditions as of the latest inventory. This summary is provided as a 

baseline example of the forest conditions that loggers, decisionmakers, and policymakers will 

encounter while planning harvesting operations in the northern forest hardwood resource. 

Special considerations of how a specific tract must be harvested or the surrounding resources 

protected may dictate the harvesting system that must be used on that specific tract. For 

example, a contract that requires that riparian areas or other resources such as shallow soil 

profiles be protected where the logs or trees to be extracted must be fully suspended as opposed 

to dragged may dictate the use of helicopters or cable systems.

The northern forest hardwood land base totals 170 million acres, includes 8 million reserve 

acres, covers 41 percent of the north, makes up 23 percent of the Nation’s total forested land 

base, and has remained relatively stable over the past 40 years (Fig. 1). The majority of the forest 

is owned by private individuals, 75 percent of the total or 128 million acres. State and local 

governments manage 28 million acres while the National Forest System cares for another 11 

million acres (Fig. 2). Family forest owners control 94 million acres (55 percent of the total), 

and most family forest land owners hold fewer than 10 acres each (Fig. 3). Hardwood forests 

predominate with 139 million acres. Maple-beech-birch and oak-hickory forests are the most 

common with more than 50 million acres each. Most of the softwood forests are spruce-fir; 

sawtimber-size stands predominate for both hardwoods and softwoods (Fig. 4). The growingstock volume on the stump is about 218 billion cubic feet, most of it hardwoods; it supplies 

17 percent of the Nation’s total harvest but almost half (47 percent) of its hardwood saw log 

harvest (Fig. 5). This vast resource supports a forest products industry that employs more than 

450,000 people and contributes more than $100 billion annually to the region’s economy. The 
3

Figure 1.—Map of the northern forest hardwood resource (Smith et al. 2004).

8%

1%

12%

4%

75%

National Forest

Other Federal

State

County and Municipal

Private

Figure 2.—Forest ownership in the northern forest hardwood resource 

(Smith et al. 2004).

region grows about twice as much wood as it harvests (Fig. 6). Figure 7 shows the percent of 

acres by stand diameter class size for the northern forest hardwood resource. The majority of 

the resource is in large trees 11 inches d.b.h. or more. Table 1 shows the acreage by state and 

percent sideslope. More than 16,508,300 acres or 9.73 percent of the total forest land is located 

on sideslopes of 30 percent or higher. Most of the forest land is located on gentle to moderate 

slopes of 29 percent or less.
4

0

10

20

30

40

50

60

70

<10 10-99 100+ 

Family Forest Ownership

(%)

Tract Size (acres)

49,879

167,751

0

20,000

40,000

60,000

80,000

100,000

120,000

140,000

160,000

180,000

Softwoods Hardwoods

Growing-stock 

Volume

(million cubic feet)

Figure 3.—Tract size of family forest ownerships in the northern forest hardwood resource (Smith 

et al. 2004).

Figure 4.—Forest species composition 

in the northern forest hardwood resource 

(Smith et al. 2004).

Figure 5.—Growing-stock volume of the major species groups in the northern forest hardwood 

resource (Smith et al. 2004).

Softwoods

18%

Hardwoods

82%
5

6%

26%

68%

small

medium

large

Figure 6.—Net annual growth, removals, and mortality of growing stock in the northern forest hardwood 

resource (Smith et al. 2004).

Figure 7.—Percent of acres by stand diameter class size for the 

northern forest hardwood resource; conditions: large-diameter 

trees >= 11 inch d.b.h.; medium-diameter trees >= 5 inch d.b.h.; 

small-diameter trees < 5 inch d.b.h. (Smith et al. 2004).

0

1,000,000

2,000,000

3,000,000

4,000,000

5,000,000

6,000,000

Growth Removals Mortality

Growing-stock Volume

(Thousand cubic feet)
6

Table 1.—Acreage by state and percent sideslope intervals for the northern forest hardwood resource (Smith et al. 2004)

Sideslope percent

Total forest land 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35+

---------------------------------------------------------------------------------------(acres)--------------------------------------------------------------------------------------

Connecticut 1,859,292 852,630 346,965 236,101 167,900 132,764 40,662 20,159 62,111Delaware 382,847 378,756 1,422 0 0 2,669 0 0 0

Illinois 4,330,770 2,050,158 796,097 507,903 382,158 208,236 121,931 125,892 138,395Indiana 4,500,748 2,106,777 740,513 587,586 387,563 224,906 167,945 106,626 178,832Iowa 2,050,200 759,200 273,300 253,000 240,200 140,300 124,000 102,200 158,000Maine 17,699,410 11,364,093 2,738,889 1,544,332 770,639 483,559 343,015 171,624 283,260Maryland 2,565,797 1,352,740 343,962 255,055 199,656 149,264 66,908 52,406 145,806Massachusetts 3,126,003 1,558,956 566,807 364,753 234,731 151,157 87,920 37,613 124,066Michigan 19,280,800 10,235,300 7,699,400 537,500 222,800 83,500 64,100 36,100 402,100Minnesota 16,680,373 10,890,050 4,430,053 435,100 280,300 144,400 72,400 51,500 376,570Missouri 13,991,968 4,372,906 3,052,274 2,454,972 1,685,480 1,051,464 685,476 327,996 361,400New Hampshire 4,818,264 1,542,759 1,031,627 786,363 544,853 321,019 241,604 96,839 253,201New Jersey 2,132,162 1,578,447 195,351 103,999 82,844 64,251 41,089 16,265 49,917New York 18,431,988 6,992,548 2,606,854 2,214,426 1,421,871 884,729 706,186 454,125 689,197Ohio 7,855,170 2,913,490 784,606 878,931 788,974 751,592 590,443 358,290 788,844Pennsylvania 16,904,653 4,893,137 2,937,700 2,380,027 1,834,496 1,275,595 1,027,980 573,029 1,982,689Rhode Island 385,364 233,816 64,433 49,814 14,647 957 11,076 0 10,620

Vermont 4,618,076 1,028,543 704,567 720,496 694,603 415,551 339,998 256,920 457,399West Virginia 12,107,993 1,058,327 569,504 771,997 892,438 1,103,318 1,159,448 1,272,127 5,280,834Wisconsin 15,963,026 10,570,757 2,268,181 1,083,391 684,786 378,033 272,508 216,535 488,835Total 169,684,903 76,733,388 32,152,505 16,165,744 11,530,939 7,967,264 6,164,689 4,276,246 12,232,077
7

Part II—Harvesting Systems

The harvesting systems currently available to log the northern forest hardwood resource range 

from highly expensive helicopters and mechanized machines such as cut-to-length systems 

and feller bunchers to less expensive systems such as horses, mules, and small winches. In 

this section of the text, we discuss and document each of these systems. We begin with the 

nonmechanized and less expensive systems and work our way to the more complicated and 

expensive ones.

Horses and other livestock have been used to 

transport logs from the stump to the landing 

for decades (Fig. 8). This approach generally 

couples chainsaw felling and bucking with 

livestock doing the skidding. The approach is 

somewhat labor intensive and requires that trees 

be felled, limbed, and bucked before skidding. 

The logs are skidded or dragged to the landing 

by a single horse or mule or by a team (Fig. 9) 

of animals depending on the size of the wood 

being harvested. One or more woods workers 

use rigging consisting of leather reins, metal 

chains, and hooks to steer and control the team 

of livestock during the extraction process. In 

many applications, a woods worker does the 

felling, steers, and controls the team as a one 

person operation. In some applications, a team of woods workers operate together, one person 

doing the felling, limbing, and bucking while the other person does the skidding, tends to the 

Figure 8.—Team of small horses with rigging attachments. Photo courtesy of North Carolina Outdoors.

Figure 9.—Operator steering a team of small horses with rubber-tired 

bunk pulling some logs. Photo courtesy of Mountain Laurel Review.
8

livestock, and takes care of the landing operations such as sorting and decking. Clearly, bigger 

logs require bigger animals or teams of animals to transport the logs to the landings. Although 

the system is associated with low productivity, it is relatively low cost, and makes minimal 

impact to the site with respect to soil disturbance, compaction, and residual tree damage. 

Horses, mules, and other livestock play a minor role in the harvesting of the hardwood resource.

Portable winches come in many forms and sizes and can be used for a variety of tasks, such as 

skidding logs, pulling trees over, loading and unloading logs, pulling rigging, bunching trees or 

logs, cleaning streams, and when coupled with blocks and additional rigging, they can be used 

to move equipment in the woods or at the landing (Fig. 10). They are relatively low cost, low 

productivity, low impact, and very labor intensive. Some winches can be powered by chainsaws 

or with small engines (LeDoux et al. 1987) that are part of the winch. Small portable winches 

play a small role in the harvest of northern forest hardwood resources.

Small farm tractors can be equipped with winches operating off the three-point hitch or 

with grapples that are attached to an arch mounted at the rear of the tractor (Figs. 11, 12). 

Small farm tractors are relatively inexpensive, low impact, low productivity, and somewhat 

labor intensive in that operators or their helpers move the rigging and hook and unhook the 

logs (Huyler et al. 1994; Huyler and LeDoux 1989, 1990). The trees in a small farm tractor 

operation are usually felled, bucked, limbed, and processed using chainsaws.

Rubber-tired skidders are the major workhorse used to log the northern forest hardwood 

resource. They come in a wide array of sizes, are articulated, four-wheel driven, with multiple 

options for tires and chains (Erickson et al. 1991b). They can be equipped with cable drum sets 

Figure 10.—Small chainsaw-powered winch. Photo courtesy of Stihl and Lewis.
9

and chokers (Fig. 13) or with grapples (Fig. 14) for skidding or dragging the trees or logs. Some 

applications require the use of wide or high flotation tires for operation in wet, soft soils, or 

swampy conditions (Fig. 15). Trees can be transported tree length or bucked into logs (LeDoux 

et al. 1993). This system requires a network of skid trails over the harvest tract so that the 

skidder can easily move within the stand or tract to build a turn of logs for transport to landings 

where the trees or logs can be further processed, sorted, and loaded onto trucks for transport 

to wood processing centers. Skidders are most applicable on gentle to moderately steep terrain, 

can create soil disturbance, and may cause several levels of soil compaction especially on skid 

trails that experience multiple passes (Wang et al. 2006, 2007). Some applications require 

Figure 11.—Small farm tractor with tire chains and blade in the front. Photo courtesy of Neil 

Huyler, U.S. Forest Service, retired.

Figure 12.—Large, rubber-tired, four-wheel drive farm tractor with rear-mounted double 

winch, remote control, and bucket in the front. Photo by Chris LeDoux, U.S. Forest Service.
10

Figure 13.—Rubber-tired skidder with drum set, arch attachment, tire chains, and wire 

rope chokers at the landing (notice slash/debris mat on heavily used skid trail). Photo by 

Chris LeDoux, U.S. Forest Service.

Figure 14.—Rubber-tired skidder 

with grapple attachment, tire 

chains, and blade in the front 

with payload. Photo by Chris 

LeDoux, U.S. Forest Service.

Figure 15.—Rubber-tired skidder equipped with grapple and high flotation tires. Photo 

courtesy of Tigercat.
11

preplanned skid trails and roads where the skidder stays on the trail and the winch line is pulled 

to the trees or logs and hooked or choked, then winched back to the skidder and transported 

to landings (Erickson et al. 1991a). This approach is used primarily when the objective is to 

minimize soil disturbance and compaction. Logging operators are advised to match the machine 

size to the size of wood being extracted to minimize soil 

disturbance and compaction, keep residual stand damage to 

acceptable levels, and to minimize skidding costs (LeDoux 

2000). Skidders can be equipped with a small blade in the 

front that can be used to push logs when building a turn or 

hitch or for maneuvering logs at the landing or for decking. 

Trees are generally felled, bucked, limbed, and processed 

using chainsaws in most cable-skidder applications but may 

be felled, bunched, and processed by feller bunchers when 

skidders equipped with grapples are used to transport the 

wood.

Crawler tractors and bull dozers are also used to extract 

logs or trees that are chainsaw or feller buncher processed. 

Generally, if the trees are cut by a feller buncher and 

bunched, the dozer will be equipped with a grapple to 

maximize payload. These are generally track mounted and can 

be configured with winch drum sets and chokers (Fig. 16) 

or with grapples (Fig. 17). Many crawler systems also have a 

blade attachment in the front that can be used to excavate, 

build truck roads and skid trails, push logs, and sort and 

deck logs at the landing; it can be equipped with a trailing 

arch (Fig. 18). The additional advantage of the blade is that 

it can be used to stabilize the machine while winching logs 

on steep terrain. Dozers are generally slower than skidders, 

but they can be used for multiple purposes such as skidding, 

road building, clearing landings, and general road, deck, 

Figure 16.—Small, track-mounted crawler dozer with 

winch in back and blade in front working a log deck. 

Courtesy of Montgomery County Community College, PA.

Figure 17.—Medium, track-mounted crawler dozer with 

grapple in back and blade in front skidding a turn of logs. 

Photo courtesy of Caterpillar.

Figure 18.—Small, track-mounted crawler dozer with winch in back, blade in front, pulling a 

track-mounted arched bunk. Photo courtesy of International Tractor Co..
12

and landing maintenance. Dozers and crawlers are generally used in gentle to moderately steep 

terrain but can be used in steeper terrain applications than skidders because they are track 

mounted and have a lower center of gravity than most rubber-tired skidders. They create about 

the same levels of soil disturbance and compaction as rubber-tired skidders, but in some cases 

may cause less soil compaction depending on the width of the track they are equipped with. 

Generally, with all factors equal (size of skidder versus crawler, length of skid distance, payload 

size, and terrain), rubber-tired skidders will outproduce crawler tractors simply because rubbertired skidders can travel the same distance faster. Dozers and crawlers usually require a network 

of skid roads and trails like rubber-tired skidders, but because they can use the blade to move 

obstacles out of their path and because they are track mounted, they may in some cases require 

a less dense network of trails than rubber-tired skidders.

Mechanized systems such as cut-to-length and feller bunchers are also used to harvest the 

hardwood resource (Figs. 19, 20). These machines come in various sizes and can be configured 

with various choices for the felling, delimbing, and debarking heads (Figs. 21, 22) (Huyler 

and LeDoux 1996, 1997a, 1997b, 1997c, 1998, 1999; LeDoux and Huyler 1999, 2000, 

Figure 19.—Large, self-leveling, trackmounted cut-to-length machine with 

felling and delimbing head. Photo 

courtesy of Andrew Whitman, Manomet 

Center for Conservation Sciences.

Figure 20.—Large, selfleveling, track-mounted 

feller buncher with 

accumulating felling head. 

Photo courtesy of John 

Umstead, West Virginia 

University.
13

Figure 21.—Medium, track-mounted cut-to-length machine with felling, delimbing, 

and debarking head (notice log bundles behind and brush/debris mat in front). Photo 

courtesy of Kurt Gottschalk, U.S. Forest Service.

Figure 22.—Medium, track-mounted cut-to-length machine with felling, delimbing, 

and debarking head (notice log piles behind the machine). Photo courtesy of Kurt 

Gottschalk, U.S. Forest Service.

2001). These systems are generally coupled with rubber-tired skidders with grapples, dozers 

and crawlers with grapples, clambunk skidders, or forwarders to transport the logs or trees to 

landings or central processing areas (LeDoux 2010). These systems are best applied on gentle 

to moderately steep terrain, are expensive, and have high production rates. The cut-to-length 

system fells the tree, delimbs, bucks the trees into logs, debarks the stem, can sort the wood 
14

Figure 23.—Small, track-mounted feller buncher with accumulating felling head. 

Photo courtesy of John Umstead, West Virginia University.

Figure 24.—Medium, rubber tire-mounted feller buncher with accumulating felling 

head felling a tree. Photo courtesy of John Deere.

as desired, and can build bunches according to the capacity of the machine that is going to 

be used for skidding. The feller buncher system fells the trees, can accumulate multiple stems 

in the head (Figs. 23, 24, 25), can be used to sort the wood as required, and builds bunches 

for future transport by the skidding machines. These machines are generally track mounted, 

with self-leveling cab, and are equipped with a boom that can extend the felling head a 

substantial distance beyond the machine itself. They are generally very ergonomic and highly 
15

maneuverable. They are low impact with respect to soil disturbance and compaction, residual 

stand damage, and overall impact to the site (LeDoux and Huyler 1999, Wang et al. 2005b). 

The cut-to-length system can use the limbs from the delimbing process to form a mat to travel 

on that further mitigates soil disturbance and compaction. These machines have an additional 

advantage in that both can fell the tree, eliminating a person on the ground with a chainsaw. 

Use of chainsaw felling is the most popular method for felling trees but can be very dangerous. 

Felling trees with these mechanized systems 

minimizes or eliminates most of the hazards 

and risks associated with manual chainsaw 

felling (Bell 2002). For example, manual felling 

of snow- or ice-ladened trees is extremely 

dangerous, if not impossible. However, such 

trees are no obstacle for mechanized systems such 

as feller bunchers or cut-to-length systems.

Clambunk skidders are commonly used in 

association with mechanized systems such as 

cut-to-length and feller bunchers (Fig. 26). They 

are generally track mounted and are equipped 

with a bunk and large grapple or clam attached 

to the back of the skidder. Some applications 

of this machine also have a boom that can be 

used to build loads, sort logs, build decks, and 

Figure 26.—Track-mounted clambunk skidder with boom attachment 

working on log deck. Photo courtesy of Andrew Whitman, Manomet 

Center for Conservation Sciences.

Figure 25.—Medium, rubber tire-mounted feller buncher with accumulating head in travel 

mode. Photo courtesy of John Deere.
16

maintain landings. Generally, clambunk skidders are used to move the bunched logs created by 

the cut-to-length machine or feller buncher to landings or central log processing areas. They are 

moderately expensive, relatively low impact, and very productive. The major trails used to travel 

to and from the landing and log processing areas can be severely impacted. They can move large 

volumes of wood in a very short time period. They are suited for gentle to moderately steep 

terrain and can be used to transport logs long distances. They are limited somewhat in their 

ability to maneuver because of their size. One end of the log rests on the bunk and is held there 

during the skidding process while the other end of the log is dragged on the ground.

Forwarders are generally used to transport logs or trees in association with mechanized and 

non-mechanized systems (Fig. 27) when the logs or trees to be extracted have been prebunched 

in the woods. Forwarders come in various sizes with a range of payloads (Figs. 28, 29, 30). 

Forwarders can be equipped with rubber tires (Figs. 30, 31) and chains or track mounted and 

are usually equipped with a boom with a grapple attachment for self loading and unloading. 

Figure 27.—Small forwarder with tracks 

in the rear, rubber tires in the front with 

chains, and boom, loading in the woods. 

Photo courtesy of Neil Huyler, U.S. 

Forest Service, retired.

Figure 28.—Very small, self-propelled, 

track-mounted forwarder with operator 

and steering bar with control. Photo by 

Chris LeDoux, U.S. Forest Service.
17

Figure 29.—Small forwarder with 

rubber tires front and rear, boom, 

blade in the front, loading in the 

woods. Photo courtesy of Neil Huyler, 

U.S. Forest Service, retired.

Figure 30.—Large forwarder with 

rubber tires and boom, loading in the 

woods. Photo by Chris LeDoux, U.S. 

Forest Service.

Figure 31.—Small forwarder with 

rubber tires and chains in the front, 

tracks in the rear, boom, blade in 

the front, unloading and sorting at 

the landing. Photo courtesy of Neil 

Huyler, U.S. Forest Service, retired.
18

They are a good alternative to rubber-tired 

or dozer skidding when the skid distances 

are very long and the terrain is gentle to 

moderately steep (Erickson et al. 1992). 

They can sort logs or trees by species or 

product type in the woods while loading or 

at the landing while unloading (Fig. 31). 

They are slower than rubber-tired skidders, 

but they can transport bigger payloads than 

skidders or dozers. The wood is carried on 

bunks and not dragged on the ground as 

by horses, rubber-tired skidders, crawler 

tractors, or clambunk skidders. They range 

in cost from moderate to expensive, have 

relatively low impact on the site, but do 

create significant soil disturbance and 

compaction on the most heavily traveled 

skid roads and trails.

Cable systems are generally used on steep 

terrain where ground-based systems would 

not be 

appropriate 

or where 

road construction is constrained by environmental or other 

concerns (LeDoux 1983; LeDoux and Butler 1981a, b). For 

example, contract requirements that require logs or trees to 

be fully suspended during the extraction process may dictate 

the use of cable systems (Baumgras and LeDoux 1985, 1995; 

Baumgras et al 1994; Huyler and LeDoux 1995; LeDoux 2006; 

LeDoux and Baumgras 1990; LeDoux and Whitman 2006, 

2007, 2008; LeDoux et al 1990; Peters and LeDoux 1984, 

1990). Cable yarders come in various sizes (Huyler and LeDoux 

1997a, b; LeDoux 1984a, b, LeDoux 1985a, b; LeDoux 

1986a, b; LeDoux 1987a, b; LeDoux 1989; LeDoux and Peters 

1985; LeDoux and Starnes 1986; LeDoux et al. 1986, 1991, 

1994, 1995a; Olsen et al. 1983; Sherar and LeDoux 1989;) 

with a range of payload capacities, yarding distances that can 

be achieved, and tower heights, and they can be mounted 

on rubber tires, tracks, on the bed of trucks, or on platforms 

that rest on sleds that can be moved from landing to landing 

(Figs. 32, 33). The machine generally rests on a landing area 

located on a road, and the wood is yarded uphill or downhill 

to these landings. The machine is generally accompanied by a 

shovel loader located at the landing that removes the yarded 

logs or trees from underneath the skyline; sorts, decks the wood; 

Figure 32.—Medium cable yarder with 30-foot tower 

mounted on rear-drive flatbed truck. Photo by Chris 

LeDoux, U.S. Forest Service.

Figure 33.—Medium cable yarder with 30-foot tower 

mounted on flatbed six-wheel-drive truck with remote 

control umbilical cord. Photo by Chris LeDoux, U.S. 

Forest Service.
19

and loads trucks that are headed to sawmills, pulp mills, or other wood processing centers. On 

some very narrow roadbeds where landings are too small to accommodate a shovel loader, a 

skidder or crawler is used to swing the yarded logs or trees from underneath the skyline to an 

alternative processing area. Cable logging systems are generally expensive, moderately to highly 

productive, and result in little to no impact to the site. Cable systems require a goodly amount 

of preplanning of roads, landings, corridors, guyline, and skyline anchors before any actual 

yarding of logs takes place. Trees are usually pre-felled and bucked before yarding operations.

Helicopters are generally used where 

road building or related disturbance is 

simply not acceptable and where the 

timber to be extracted is of high volume 

and value (LeDoux 1975, Wang et al. 

2005c). For example, on very steep 

slopes or on sites where the soils are 

fragile or swampy, and where these 

conditions are matched by large volumes 

of wood of high value, it sometimes 

becomes economically feasible to extract 

the timber with helicopters. Helicopters 

are sometimes used where typical road 

building operations would impact the 

visual resource or where large volumes 

of wood must be extracted to prevent 

additional loss due to stain or decay. For example, following a major weather event such as a 

tornado or hurricane that blows down large volumes of valuable timber, helicopters are often 

used to extract the wood before stain or other value degrading agents move in before any road 

building can be accomplished. Helicopters come in a variety of sizes with alternative payloads 

(Fig. 34). They can transport high volumes of trees or logs quickly so it is crucial to plan 

landing operations so that logs or trees are handled as quickly as they arrive at the landing to 

avoid congesting the landing area and causing costly delays. The felling and hooking crews have 

to work closely together so that logs or trees are bucked and hooked to avoid exceeding the 

capacity of the helicopter being used. It is common practice to pre-fell and buck the timber and 

pre-choke several loads at the hooking site ahead of extraction operations. Helicopters are very 

expensive to own and operate, are highly productive operations, and result in little to no impact 

to the logging site. Helicopter operations require a substantial amount of planning prior to any 

on-the-ground event.

Production and Cost Estimation

Clearly, loggers and logging contractors must know what their logging machines can produce 

and at what cost if they are to compete in the timber harvesting environment for logging 

chances and make a profitable return on their investments. Having a good handle on what 

machines are capable of producing and what the related cost is per unit produced for the range 

of on-the-ground operating conditions allows loggers to bid on logging sales, make a profit, 

and stay in business. Many operators rely on their experience over time to develop estimates of 

Figure 34.—Helicopter with large payload capacity. Photo by Chris 

LeDoux, U.S. Forest Service.
20

production and cost for their machines. Many operators only work on tracts with large valuable 

saw logs or veneer type timber products, pulpwood, firewood, or fiber products exclusively, 

while others work on tracts where the product mix ranges from low value firewood to high 

value prime and veneer logs. In any case, loggers must have a good idea of what their machines 

are capable of producing and at what cost.

An excellent method for estimating production and cost is to conduct time studies of the 

respective machine(s) and operating(s) conditions. Time study techniques are well developed 

and have been used in many industrial settings for years to develop estimates of production and 

cost. The basic procedure involves defining the work elements that are involved in the process 

and then simply observing and using a stopwatch to record the time it takes to complete a 

given task. For example, the process of forwarding logs from the stump to the landing may 

be segmented into the following discrete components: traveling out unloaded, sorting in the 

woods, loading, traveling back loaded, unloading, decking, and sorting at the landing. Delays 

may be segmented, observed, and timed as desired. For example, the forwarder may need to 

move obstacles such as trees out of the travel path on its way to the landing or on its way to 

the woods. The forwarder may need to wait at the landing for other machines to move out of 

its way before it can proceed to unload or return to the woods. Then there is always an array 

of mechanical delays such as a failure of a hydraulic hose or the need for the operator to take 

a break. Once the element components and delays are defined, it may be useful to define 

variables that are independent of the respective component but that may influence or affect 

the time consumed in that segment. For example, the time required to complete the travel 

loaded task may be influenced by the distance that the loaded machine must travel between 

the loading point and the landing, the size of the load being transported, the conditions of the 

skid trail, the slope of skid trail, and the other traffic using the same trail. Although many time 

studies have been conducted and numerous variables have been investigated, several variables 

have proven to have a direct statistical correlation to the time required to complete a given task. 

These variables include the distance traveled, lateral distance traveled, logs per turn, volume 

per turn, volume per log, percent sideslope, volume per tree, average d.b.h. of the material cut, 

and volume per acre removed. Distance traveled is simply the distance that a machine must 

travel empty or loaded during the extraction process. For ground-based systems, this distance is 

measured along the skid trails traveled to and from the landing. For cable systems, this distance 

is measured along the skyline corridor being used as the extraction path. The lateral distance 

can be the distance the boom must reach out to cut a tree as in the case of feller bunchers and 

cut-to-length harvesters. In the case of cable systems, this distance is measured as the distance 

that chokers and mainline must be pulled laterally from the skyline or carriage to hook a turn 

of logs. Logs per turn are defined as the number of logs that form a given turn/hitch/load for 

both ground-based and cable systems. The volume per turn is defined as the sum total of the 

board-foot or cubic-foot volume of the logs that form that turn. Volume per log is defined 

as the average volume of the logs that form a turn. Volume per tree or piece size is defined as 

the volume of the tree being processed. The d.b.h. is the average diameter of the trees being 

harvested. The volume per acre is the board-foot or cubic-foot volume that is being removed 

per unit area.
21

For a forwarder, this series of events and the variables involved can be expressed as a 

mathematical relationship (LeDoux and Huyler 1992). This relationship could be expressed 

as the travel loaded time being the dependent variable and distance, load size, trail condition, 

and trail slope being the independent variables. In other words, the time to travel loaded 

is dependent on the randomly occurring distance, load, trail slope, trail and condition. In 

mathematical terms, these relationships may be expressed as y = ƒ(x1, x2, x3, x4) where y= the 

time it takes to travel loaded, x1= distance traveled, x2= load, x3= trail slope, and x4= condition 

of the skid trail. After many cycles are observed and timed, we have a database of times and 

causal variables that lend themselves to modeling using statistical techniques such as regression 

theory. Generally, a regression equation is fit to the data and we are then able to predict or 

estimate the time or production for the set of modeled conditions.

It is virtually impossible to time study or sample every combination of machine and operating 

condition. Operating on-the-ground conditions are extremely variable and subject to change as 

the terrain, tree size, and other variables vary from site to site. Computer simulation becomes 

a valuable tool that allows us to simulate conditions that are beyond the limited sample size 

(Baumgras and LeDoux 1992a, b, c; Baumgras et al. 1993; LeDoux 1983, 2002; LeDoux 

and Baumgras 1989; LeDoux and Butler 1981a; Wang and LeDoux 2001; Wang et al. 2003, 

2005a). For example, time study data may be available for a limited set of terrain, stand 

conditions, and log sizes. Simulation techniques may be used to explore, simulate, and develop 

production and cost estimates for sets of conditions that are outside the available data sets of 

terrain, stand conditions, and log sizes. Simulation has been used for many years to develop 

estimates/estimators for a wide range of machine(s) and stand combination(s).

Each simulated result is generally considered an individual data point and as such the results 

from multiple simulation runs can be expressed mathematically in equation form and used to 

predict production and cost for a wide range of machines and operating conditions. Time study 

data blended with simulation techniques become a powerful tool that can be used to estimate 

production and cost for multiple combinations of machines and operating conditions. Tables 2 

to 9 summarize the results of such equations for estimating the stump-to-mill cost of harvesting 

for multiple sets of conditions and machines. Table 2 contains equations for estimating costs 

for chainsaw felling, bucking, limbing, hauling, forwarding, and loading. The hauling cost can 

Table 2.—Equations for loading, hauling, forwarding, and chainsaw felling, bucking, and 

limbing components

Variable Equation Variable Limits

Loading $/ft3 = -0.04282 + 1.02238 * (1 /DBH) DBH: 6-22 

Hauling $/ft3 = (-0.71667 + 0.08333 * TCa + 0.37629 * RCb) / 100 * Mileage

Forwarding $/ft3 = 110 / (408.9482 + 0.00241 * TPc * SYD - 0.0006 * SYD2 )

Felling, 

Bucking, & 

Limbing

$/ft3 = 0.43744 - 0.11407 * LN(DBH) DBH: 6-24

aTC = Truck Class, see Table 4

bRC = Road Class, see Table 3

cTP = turn payload (ft3) = 400

DBH = average diameter at breast height (in.)

SYD = slope yarding distance (ft)
22

be estimated for several road class (Table 3) and truck type (Table 4) combinations. Table 

5 contains equations for estimating the cost of ground-based skidding with several different 

skidders and small farm tractors. The skidders range in horsepower from 60 to 120. The farm 

tractors include small tractors such as the Pasquali 993, medium tractors such as Holder A60F, 

and large tractors such as the Massey Ferguson. Table 6 contains an equation for estimating 

the cost of a grapple skidder. Table 7 contains equations for estimating the cost of felling and 

bunching for a small and large feller buncher. Table 8 contains equations for estimating the 

cost of a small and large cut-to-length machine. Table 9 contains equations for estimating the 

yarding cost for several cable yarders. The choice of yarders includes some very large machines 

such as the Skylok 78 and some very small machines such as the Bitterroot with a range of 

machines in between. The limits of the variable equations should be observed religiously or the 

equations may produce estimates that are mathematically sound but unreliable from a practical 

standpoint. The results from these time studies, statistical analysis, computer simulation, and 

development of production and cost estimators can be packaged in user friendly computer 

software programs for mass distribution and use such as WCOST (Fight et al. 1984) and 

ECOST (Baumgras and LeDoux 1992a, b, c; LeDoux 1985b, 1986a, 1987a, 1988, 1989; 

LeDoux and Baumgras 1989; LeDoux and Kosir 1989; LeDoux et al. 1986; Wang and 

LeDoux 2003). For users who wish to develop their own algorithms, the equations in this 

text may be incorporated into spreadsheet software or other methods as desired. In either 

case the variable limits must be observed for the equations to produce reliable results. These 

programs can be run on just about any type of computer and can be linked with other software 

programs to develop integrated software that can be used for forest planning and optimization 

of integrated decisions such as MANAGEPC (LeDoux 1986c), PROFITPC (LeDoux et al. 

1989), FOREX ( LeDoux et al. 1995b), and THINEX ( LeDoux et al. 1998, 2003). The 

programs MANAGEPC, PROFITPC, FOREX, and THINEX were developed primarily 

Table 3.—Road class by design speed

Class Design speed

(miles/hour)

2 35+

3 25

4 16

5 8

6 4

Table 4.—Truck class by body type

Class Body Type

5 Flat bed, 4x2, single axle

4 Flat bed, 6x4, tandem axle

3 Truck tractor, 4x2, single axle with tandem trailer

2 Truck tractor, 6x4, tandem axle with tandem trailer

1 Truck tractor, 6x4, tandem axle with tandem 30- to 35-foot trailer w/additional 15- to 

20- foot trailer
23

Table 5.—Simulated, delay-free, ground-based, skidding cost equations by skidder/tractor

Skidder/Tractor Equation Variable Limits

Pasquali 993 $/ft3 = 0.1804113 + 0.0146528 * DBH + 0.000001948 * VOAC

 - 0.0021978 * VPL + 0.0000635 * SYD - 0.0058381 * VPT

 + 0.0073219 * LPT

DBH: 7 to 24

SYD: 446.4 to 1511.5

VOAC: 334 to 4121

VPL: 5.82 to 20.01

VPT: 25.4 to 38.2

LPT: 2.05 to 5.04

Holder A60F $/ft3 = 0.4067681 – 0.0103927 * DBH 

 + 0.0000008024 * VOAC + 0.0022703 * VPL

 + 0.0000577 * SYD - 0.0058798 * VPT 

 + 0.006546 * LPT

DBH: 5 to 29

SYD: 494.2 to 1554.2

VOAC: 334 to 5160

VPL: 5.82 to 30.8

VPT: 29.1 to 65.3

LPT: 1.93 to 6.71

Massey Ferguson $/ft3 = 0.2210557 + 0.0002437 * DBH

 + 0.0000002598 * VOAC+ 0.0001181 * VPL

 + 0.0000438 * SYD- 0.0024174 * VPT

 + 0.0039977 * LPT

DBH: 5 to 32

SYD: 494 to 1554.3

VOAC: 334 to 10599

VPL: 5.82 to 75.07

VPT: 29.9 to 75.1

LPT: 1.0 to 6.69

Samé Minitaurus $/ft3 = 0.2757052 – 0.0010672 * DBH 

 - 0.0000006278 * VOAC - 0.0002746 * VPL 

 + 0.00003963 * SYD - 0.0028276 * VPT 

 - 0.0040634 * LPT 

DBH: 5 to 32

SYD: 493.9 to 1603.3

VOAC: 334 to 10599

VPL: 5.82 to 76.16

VPT: 29.7 to 78.1

LPT: 1.0 to 6.69

JD 440C $/ft3 = 0.1654157 + 0.0137012 * DBH 

 + 0.0000008906 * VOAC - 0.001362 * VPL

 + 0.00004815 *.SYD - 0.0027067 * VPT 

 + 0.0024094 * LPT

DBH: 5 to 32

SYD: 486.9 to 1612

VOAC: 334 to 10600

VPL: 5.82 to 113.98

VPT: 28.9 to 128.2

LPT: 1.08 to 6.64

JD 540B $/ft3 = 0.43486 – 0.0201429 * DBH 

 + 0.0000005772 * VOAC + 0.002606 * VPL 

 + 0.00004743 * SYD - 0.0015778 * VPT 

 - 0.0145491 * LPT 

DBH: 5 to 32

SYD: 480.4 to 1616.3

VOAC: 334 to 10599

VPL: 5.82 to 127.77

VPT: 29.4 to 168.1

LPT: 1.27 to 6.64

JD 640D $/ft3 = 0.3415523 – 0.0072889 * DBH + 0.000001086 

 * VOAC + 0.0012704 * VPL + 0.0000495 

 * SYD - 0.001875 * VPT - 0.0058284 * LPT 

DBH: 5 to 32

SYD: 457.7 to 1627.4

VOAC: 334 to 10599

VPL: 5.82 to 127.77

VPT: 29.44 to 186.6

LPT: 1.27 to 7.82

DBH = average diameter at breast height (in.) VPL = volume per log (ft3)

SYD = slope yarding distance (ft) VPT = volume per turn (ft3)

VOAC = volume per acre (ft3) LPT = logs per turn

for research purposes. ECOST, a computer program developed by the author for estimating 

stump-to-mill costs of cable logging, conventional ground-based skidding, cut-to-length, fellerbuncher systems, forwarding, and several small farm tractors for logging a wide range of eastern 

hardwoods, incorporates the results from Tables 2 to 9 and is now available for downloading at: 

http://www.nrs.fs.fed.us/tools/software/.
24

Here is an example of how these equations can be used to estimate costs. Suppose a logger 

wishes to estimate the cost of using CTL + Forwarding to harvest a tract. The tract attributes 

are average tree d.b.h. (DBH) = 12 in., volume cut/acre (VOAC) = 2,000 ft3, slope yarding 

distance (SYD) = 1,200 ft. Using the equation from Table 8 for the JD 988 and the forwarding 

equation from Table 2, we have:

For the JD 988

$/ft3 = 115.0 / (-440.25 + 201.74 * DBH - 1.85 * DBH * HT)

$/ft3 = 115.0 / (-440.25 + 201.74 * 12 - 1.85 * 12 * 67.02)

$/ft3 = 0.23

Table 6.—Simulated, delay-free, grapple skidding equation (LeDoux and Wang, in review)

Machine Equation Variable Limits

Timberjack 460 $/ft3 = 0.65 * ((82.17 / (466.49 – (0.13*SYDa) + (3.76*Plb) – 

(0.003*Pl2) – (0.36*BSc) + (0.003*BS2))))

SYD: 400 to 1800

Pl: 50 to 250

BS: 30 to 270

aSYD = slope yarding distance (ft)

bPl = pay load (ft3) cBS = bunch size (ft3)

Table 7.—Simulated, delay-free, felling and bunching cost equations by feller buncher 

(LeDoux and Wang, in review)

Machine Equation Variable Limits

Timbco 425 $/ft3 = 119.17

 / (1087.1828 + 38.0275 * TreeVola

 + 0.1865 * VOAC)

DBH: 4 to 30

VOAC: 334 to 10600

Timbco 445 $/ft3 = 138.33 

 / (633.3737 + 63.9942 * TreeVol

 + 352162.052 * (1 / VOAC))

DBH: 4 to 30

VOAC: 334 to 10600

aTreeVol = tree volume (ft3) 

If DBH = 4 then TreeVol = 1.76; If DBH = 5 then TreeVol = 2.37; If DBH = 6 then TreeVol = 4.72 Else 

TreeVol = -32.0924 + 5.529*DBH

VOAC = volume per acre (ft3)

Table 8.—Simulated, delay-free, cut-to-length cost equations by harvester

Machine Equation Variable Limits

Timbco T425 $/ft3 = 146.7 / (7830 + 270.77 * DBH

 - 1.88 * DBH * HTa

 - 642.51 * DCb

 + 11.44 * DC * DC)

DBH: 5 to 20

JD 988 $/ft3 = 115.0 / (-440.25 

 + 201.74 * DBH 

 - 1.85 * DBH * HT)

DBH: 5 to 14

aHT = total height (ft) = 34.95428248+2.672088601*DBH bDC = ground travel distance of harvester/cycle (ft) = 22

DBH = average diameter at breast height (in.)
25

For the Forwarder

$/ft3 = 110 / (408.9482 + 0.00241 * TP * SYD - 0.0006 * SYD2)

$/ft3 = 110 / (408.9482 + 0.00241 * 400 * 1200 - 0.0006 * 12002)

$/ft3 = 0.16

Combined total $/ft3 for the JD 988 and forwarder = .39 or about $34.81/cord; $42.45/cord 

adjusted for 18-percent delay/down time; $55.19/cord adjusted for 18-percent down time and 

30 percent profit and risk.

Table 9.—Simulated, delay-free, cable yarding cost equations by yarder

Yarder Equation Variable Limits

Skylok 78 $/ft3 = 0.090775 + 0.594844 * (1 / DBH)

 + 0.000071 * SYD 

 + 739.473795 * (1 / (VOAC * DBH)) 

DBH: 7 to 24

SYD: 50 to 950

VOAC: 780 to 6871

Urus 1000-3 $/ft3 = 0.203908 - 0.000387 * DBH2

 + 0.000144 * SYD

 + 13.160361 * (1 / VOAC) 

DBH: 7 to 24

SYD: 50 to 950

VOAC: 780 to 6871

Koller-K300 $/ft3 = 0.167004 - 0.000343 * DBH2

 + 0.000146 * SYD 

DBH: 7 to 16

SYD: 50 to 950

VOAC: 780 to 6871

RadioHorse 9 $/ft3 = -0.1264 + 1.1965 * (1 / DBH)

 + 0.00023 * SYD

 + 235.30853 * (1 / (VOAC * DBH) )

DBH: 4 to 12

SYD: 50 to 150

VOAC: 334 to 700

Berger 25Y $/ft3 = 0.09587038 + 0.00007867 * SYD

 + 458.98997156 * (1 / (VOAC * DBH)) 

DBH: 6 to 24

SYD: 50 to 1500

VOAC: 780 to 6871

Appalachian Thinner $/ft3 = -0.089289 + 1.535553 * (1 / DBH)

 + 0.000269 * SYD

 + 81.991053 * (1 / VOAC)

 - 496.820821 * (1 / (VOAC * DBH))

DBH: 7 to 24

SYD: 50 to 950

VOAC: 780 to 6871

Bitterroot $/ft3 = 0.161995 - 0.000783 * DBH2

 + 0.000172 * SYD

DBH: 7 to 9

SYD: 50 to 950

VOAC: 780 to 6871

Ecologger I $/ft3 = 0.707187 - 0.050285 * DBH 

 + 0.001089 * DBH2

 - 2.095831 * (1 /DBH)

 + 0.000168 * SYD

 + 33.101018 * (1 /VOAC) 

DBH: 7 to 24

SYD: 50 to 950

VOAC: 780 to 6871

Clearwater $/ft3 = 0.12577 - 0.00328 * DBH

 + 0.000048 * SYD 

 + 623.08404 * (1 / (VOAC * DBH))

DBH: 4 to 16

SYD: 50 to 950

VOAC: 780 to 6871

DBH = average diameter at breast height (in.)

SYD = slope yarding distance (ft)

VOAC = volume per acre (ft3)
26

Logs and Wood Hauling

In this text, the process of moving logs or wood from the stump to the landing is defined as 

primary transportation. The process of moving logs or wood from the landing to sawmills, 

pulpwood mills, sort yards, or other processing facilities is defined as secondary transportation 

and is generally done by large trucks (Figs. 35a, b, 36). Although logs or wood can be 

transported by railroad, barge, airline, or floated as a raft down a river, they are generally 

transported by truck. Trucks of various sizes are used to haul logs sometimes configured with 

one or more trailers (Figs. 37, 38) that are loaded at landings or log decks with a log loader 

(Figs. 39a, b). Other applications call for log trucks with multiple rear axles that are equipped 

with a self-loading mechanism on board (Figs. 40, 41, 42). Where trucking weights are 

relaxed such as on private haul roads, trucks may be equipped with as many as four trailers. 

Figure 35.—Large log truck with (a) continuous flatbed trailer with logs loaded across the bed, equipped with a 

moose bumper; and (b) large log truck with second trailer loaded piggyback. Courtesy of Forestry Equipment Sales 

in Minnesota.

Figure 36.—Large log truck with trailer loaded piggyback. Courtesy of Whit-Log Trailers in Oregon.
27

Secondary transportation networks are well established and usually consist of well-developed 

and heavily traveled public rural and freeway and interstate roads. These roads experience heavy 

traffic volumes and generally have very well defined haul load limits, loads must be secured 

and covered, and load weights and speeds must be observed. It is not unusual to be traveling 

down the interstate and to be passed by or encounter log trucks hauling a wide array of raw 

logs as they travel to sawmills, pulp mills, sort yards, or other wood-processing facilities. High 

quality veneer logs, prime saw logs, and select species peeler logs may be transported by truck 

in excess of 100 miles to their final destination. In some regions, where winter conditions lend 

themselves to such, loggers will take advantage of frozen lake surfaces to form ice bridges they 

can travel on, often saving 2 or 3 hours of travel time. Generally speaking, log trucks equipped 

with trailers designed for hauling saw logs or pulpwood will be able to negotiate even the 

Figure 37.—Small single-axle log 

truck with cab protector. Courtesy of 

Truck Paper.

Figure 38.—Pup pole trailer. Courtesy 

of Forestry Equipment Sales in 

Minnesota.
28

narrowest, tightest horizontal and vertical curves, with just about any type of road surface. Mud, 

snow, and ice present a totally different set of challenges, but these trucks with good aggressive 

tires and skilled drivers can usually keep the wood flowing. Although equations and procedures 

are presented in this text in the stump-to-mill cost estimation section, the author’s principal 

emphasis is on the primary transportation process because the secondary transportation process, 

networks, and trucks are well established and defined. The haul mileage is the primary cost and 

limiting factor involved in transporting logs or wood with trucks.

Figure 39.—Large log truck with (a) two trailers at landing 

ready to be loaded; and (b) large log truck with Douglas-fir logs 

in two-trailer mule train. Courtesy of Vannatta Forestry and 

Logging, Oregon.
29

Figure 40.—Dual rear-axle log 

truck with self loader in the rear. 

Courtesy of Truck Paper.

Figure 41.—Medium multiple 

rear-axle log truck with self loader 

in the rear. Courtesy of Forestry 

Equipment Sales in Minnesota.

Figure 42.—Large log truck with 

one-piece continuous trailer and 

self loader in the middle. Courtesy 

of Forestry Equipment Sales in 

Minnesota.
30

Chippers and Chip Hauling

Some operations call for the trees or stems to be chipped in the woods and transported via 

chip vans to their final destinations. Here the logs or trees are extracted to roadside, processing 

area, or landings by skidders, dozers, clambunk skidders, or forwarders and then processed by 

portable chippers. Chippers come in many sizes and capacities (Figs. 43, 44) in their ability to 

chip trees of alternate sizes, production rates, and costs to operate. Clearly, bigger horsepower 

chippers cost more to purchase and operate, but they also have the capacity to handle bigger 

dimension stems and produce more chips per unit time than smaller machines. These portable 

chippers are generally stationed at landings or near log decks where the flow of wood coming 

into the chipper and the flow of chip van traffic arriving to load and turn around do not create 

congestion or delays. A smooth well-planned operation is desirable where the amount of idle 

Figure 43.—Large portable chipper. Photo courtesy of Mainka Enterprises, WI.

Figure 44.—Medium portable chipper. Photo courtesy of Mainka Enterprises, WI.
31

time is eliminated primarily around the chipper. In other words, 

the chipper ideally should not have to wait for wood being brought 

in to feed it and should not have to wait for chip vans to blow the 

chips into. Chip transport vehicles or vans come in various sizes 

with alternate payloads (Figs. 45, 46). The transportation network 

becomes more critical for large chip vans than for trucks hauling 

saw logs and pulpwood. Chip vans generally ride low to the ground 

and have solid walls to hold the chips in. Roads with sharp vertical 

curves or low dipping drainage structures can become problematic 

for chip vans in that the low belly of the van can scrape the bottom 

of the vertical curve or dip damaging the trailer. Vans can literally 

get hung up on some vertical curves. The vans may have difficulty 

negotiating sharp horizontal curves. The road network should also 

be cleared of large overhanging branches 

that may come in contact with the van 

walls damaging the van sides. Trucks 

hauling saw logs that would come in 

contact with these overhanging branches 

would simply push the branches out 

of the way, but a chip van cannot do 

this without damaging the sides. The 

road network must be ergonomic to 

large chip van traffic, or smaller vans 

that can negotiate the road must be 

used for in-woods chipping operations 

to work. Another option would be 

to truck the materials to be chipped 

to a central processing area where the 

chipper and large van traffic would be 

accommodated, but this adds more cost 

to the operation than may be justified. Limiting chipping operations 

to small vans that can negotiate the road network sharply reduces 

the amount of payload that can be transported, cutting the profit 

margins. Another variable for large chip vans is the combination 

of road grade and the surface finish on the road. For example, on 

road segments with steep uphill pulls and adverse grades that are 

surfaced with loose gravel, the truck may spin out and never get up 

the hill. Trucks equipped for hauling saw logs usually get around 

this challenge by redistributing the trailer load or having the trailer 

ride piggyback on the front trailer (Figs. 35b, 36). In some small 

operations and in an urban setting, it is desirable to have a small 

chip truck that also tows the chipper (Fig. 47). The author directs 

readers to search the published literature for their region for studies 

on production and cost for alternate chippers and transport vehicles 

that may match their conditions. Users may wish to conduct their own 

studies to determine such information.

Figure 45.—Small chip truck with dumping 

capability. Photo courtesy of Mainka 

Enterprises, WI.

Figure 46.—Large chip van trailer with open top. Courtesy of Pinnacle Trailers, NC.

Figure 47.—Small chip truck with dumping 

capability and medium chipper in tow. Photo 

courtesy of Mainka Enterprises, WI.
32

Part III—Safety and Environmental Compliance

Safety Considerations

Harvesting or logging of timber products is one of the most hazardous occupations with more 

frequent and serious injuries and fatalities than many other industries. Most time-consuming 

and expensive logging accidents occur when woods workers are struck by a falling or flying 

object or get tangled or caught and crushed or killed between objects or machines. Woods 

workers such as loggers (including fellers, buckers, rigging slingers, hook tenders, delimbers, 

choker setters, and chasers), general laborers, machine operators, truck drivers, and landing 

personnel are injured or killed most often. Woods workers have to be alert to ever changing 

conditions being created by the activities during the harvesting operation and must also be 

aware of changing conditions brought on by weather events such as rain, snow, ice, and wind. 

Work areas, whether for felling, bucking, delimbing, skidding, unloading, sorting, loading, or 

related tasks, must constantly be evaluated for hazards. Retreat zones must be identified, and 

workers must be trained in first aid and must be prepared to evacuate themselves or injured 

workers quickly. Accordingly, OSHA and other safety organizations have developed guidelines, 

rules, and laws for each phase of the logging operation to help prevent accidents and to protect 

woods workers. Loggers who manually fell trees with chainsaws are exposed to the most 

frequent and greatest logging risks. OSHA requirements that remedy some of these risks are 

presented for the following categories (www.osha.gov):

1. Required Training and Qualifications for Loggers

2. Personal Protection Equipment

3. Head Protection

4. Hearing Protection

5. Eye and Face Protection

6. Leg Protection

7. Foot Protection

8. Hand Protection

9. Chainsaw

10. Other Hand Tools and Equipment

It is beyond the scope of this monograph to capture all of the guidelines, rules, and laws 

available; however, the author finds it useful to summarize some of the most important 

ones. Proper training gives loggers the tools and skills necessary to perform their work safely 

and efficiently. Employers are required to properly train their employees and to ensure that 

they are performing their jobs in a safe manner. Properly trained workers should be able to 

anticipate, recognize, and mitigate job hazards as they develop or are encountered. Training 

must be provided without cost to all employees on their initial tasks and assignments and when 

new work tasks, tools, equipment or vehicles are assigned. This training must include work 

procedures, practices, and requirements of the work site, to include recognition, prevention, 

and control of general safety and health hazards encountered in logging and to perform assigned 

work tasks safely, including safe use, operation, and maintenance of tools. All training must be 

conducted by a knowledgeable person and must be presented in a manner that all employees 
33

can comprehend. Employees that require training must be closely 

supervised until they demonstrate mastery of their training, and 

monthly meetings must be held to alert workers of the hazards and 

safety considerations of the job. Additionally, a written certification 

record must be maintained by the employer with the names of the 

employees trained, the dates of the training, the signature of the 

trainer, and the date when the employer determined that the training 

given the employee was adequate.

Personal protection equipment for the head, ears, eyes, face, hands, 

and legs is designed to prevent or lessen the severity of injuries. 

All personal protection equipment must be inspected before each 

work shift, and except for foot protection, must be provided by the 

employer at no cost to the employee. Hardhats must meet safety 

standards and be worn when overhead hazards are present. Most 

commercially available hardhats offer adequate protection. Hearing 

protection must be worn when noise levels are 

at a point where hearing damage may result. 

Most chainsaw hard hat and mesh screen 

and ear muff combination protection devices 

available on the market will provide adequate 

hearing protection (Fig. 48). Additionally, ear 

plugs may be used. Eye and face protection 

must be worn when there is potential for injury 

to the eyes or face. Logger type mesh screens are 

considered adequate eye and face protection for 

chainsaw operators. Leg protection is required 

primarily for chainsaw operators and should 

extend from the upper thigh down to the top of 

the shoe. Leg protection is available in a variety 

of forms, including chaps (Fig. 49a), logger 

pants, and leggings (Fig. 49b). The protective 

matter must contain cut resistant material and 

can include ballistic nylon, protective Kevlar®, 

Engtek®, or other cut-resistant materials. Foot 

protection must ensure that heavy duty boots 

are waterproof, cover the ankle, and offer some 

type of anti-slip sole. If the boots are going 

to be worn by chainsaw operators, it may be 

necessary to require steel toes and cut-resistant 

material to protect from contact with running 

chain. Hand protection may be required by 

employees who handle wire rope and other 

abrasive materials where there is a potential 

hazard for cuts, scrapes, and puncture wounds 

such as from jaggers from wire rope. A wide 

Figure 48.—Hardhat combination that 

protects head, face, eyes, and ears. Photo 

courtesy of Makita.

Figure 49.—Chaps (a) and leggings (b) with varying types and 

layers of protection against running chain. Photos courtesy of Ben 

Meadows and Clark Engineering.

(a)

(b)
34

array of hand protection is available on the market including gloves with built-in ballistic nylon 

(Fig. 50a), heavy leather palm and knuckles (Fig. 50b), heavy duty cloth for handling wire rope 

or setting chokers (Fig. 50c), and special vibration-absorbing gloves for timber fallers or users of 

chainsaws (Fig. 50d).

Chainsaws are extremely powerful tools for felling, bucking, limbing, and additional processing 

of trees into wood products. Table 10 shows that the majority of the harvesting systems dealt 

with in this text require a chainsaw to be fully operational. When used properly, chainsaws can 

be very productive and useful in many applications including brush clearing and general cutting 

jobs. Chainsaws can also be extremely dangerous tools when used carelessly. More people are 

killed when felling trees than any other logging activity. Most of these fatalities can be avoided. 

(a)

(b)

(c) (d)

Figure 50.—Gloves offering different types of hand protection: 

(a) protection from running chain and vibration absorbing 

capacity; (b) protection for fingers, palm, knuckles; (c) protection 

for handling wire rope; (d) vibration absorbing capacity. Photos 

courtesy of Amick’s Superstore, Clark Engineering, North Star 

Gloves, and Ben Meadows.
35

Table 10.—Harvesting system applicability matrixHarvesting system Chainsaw 

required

Terrain Initial cost Productivity Labor 

intensity

Environmental 

impact

Ease of moving 

in/out

Setup time 

required

Horses/Livestock Yes Gentle Low Low High Low High Low

Portable Winches Yes Gentle-steep Low Low High Low High Low

Small Farm Tractors Yes Gentlemoderate Low Low High Medium to high Medium Medium

Cable/Grapple Skidders

Yes Gentlemoderate Medium Medium Medium Medium to high Medium Medium

Bulldozers/Crawler Tractors

Yes Gentlemoderate Medium Medium Medium Medium to high Medium Medium

Feller Bunchers No Gentle-steep High High Low Low Low Medium

Cut-to-LengthSystems

No Gentlemoderate High High Low Low Low Medium

Forwarders No Gentlemoderate High High Low Medium to high Medium Medium

ClambunkSkidders

No Gentlemoderate High High Low Medium to high Medium Medium

Cable Yarding Systems

Yes Gentle-very 

steep

High Medium Medium Low Low High

Helicopters Yes Gentle-very 

steep

High High Medium Low Medium High
36

Many guidelines, rules, and laws exist to help operators minimize, eliminate, or reduce the 

hazards involved. Chainsaws come in many sizes, configurations, and safety and ergonomic 

features. For example, chainsaws can be equipped with chain brakes and anti-kickback chains 

to help mitigate kickback and to stop the running chain should the operator lose control of the 

saw. Some saws are equipped with a chain-catching device that catches the chains if it is thrown 

off the bar during operation. As mentioned above, chainsaw operators can use protective gear 

from head to toe to protect themselves from some of the hazards associated with running a 

chainsaw. Figure 51 illustrates where most of the chainsaw injuries occur on the human body. 

Clearly most of the injuries occur in the hand, arm, and leg area. These areas can be protected 

by using hand and leg protection devices such as gloves and chaps, logger pants, or leggings. 

Careful attention should be directed to chainsaw use, maintenance, safety, and the protective 

equipment available to mitigate injuries because so many of the harvesting systems in use today 

to harvest the northern hardwood resource require the use of chainsaws (Table 10). Several 

independent organizations and contractors offer a wide array of chainsaw safety training as well 

as the Game of Logging series.

Other hand tools and equipment that timber fallers may require include axes, wedges, winches, 

gas and oil containers, saw files, screw drivers, jacks, and a variety of other useful items. As with 

all devices, safety must be a major consideration in the transport, storage, and use of these tools. 

Again, many guidelines exist for the proper use, storage, and transport of these items.

OSHA generally divides safety considerations into those for manual and mechanical operations. 

In this text, all safety is considered as being equally important regardless of the type of 

operation. However, manual operations where there is a person on the ground performing a 

function clearly have more safety hazards than a machine performing the same function (Bell 

2002, National Institute for Occupational Safety and Health 2005).

Figure 51.—Accident location and frequency due to chainsaw injuries. 

Diagram courtesy of OSHA.
37

Best Management Practices (BMPs)

The idea of best management practice (BMP) asserts that there is one technique, method, 

process, activity, incentive, or reward that is more effective at delivering a particular outcome 

than any other technique, method, process, etc. The idea is that with proper processes, 

checks, and testing, a desired outcome can be delivered with fewer problems and unforeseen 

complications. In this text, the author will consider best management practices for protecting 

riparian areas and streamside management zones (SMZs), for retaining structural and patch 

retention, for protecting soil erosion and soil properties, and for mitigating the invasion of 

undesirable plants following harvesting disturbances. This section will include summaries of 

BMPs by subject category as available in the contemporary literature and a dusting of the 

author’s personal experiences from working in this field for many years.

BMPs for Streamside Management Zones (SMZs)

The discussion of SMZs will focus on specific areas associated with a stream, lake, wetland, 

or other body of water that is designated and maintained during silviculture or harvesting 

operations. The purpose of the SMZ is to protect water quality and riparian functions by 

reducing or eliminating forestry or harvesting related outputs of sediment, nutrients, logging 

debris, chemicals, and water temperature fluctuations that could adversely affect aquatic 

communities. SMZs provide shade, stream bank stability and erosion control, as well as 

detritus and woody debris that benefit the aquatic ecosystem in general (Fig. 52). The SMZ is 

also designed to maintain certain forest attributes that provide specific wildlife habitat values 

such as snags, den and cavity trees as well as mast-producing trees required by several species of 

wildlife. SMZs provide habitat for many species of wildlife for resting, breeding, raising their 

Figure 52.—Stream with riparian protection on both banks with complement of woody 

component on banks and in the stream. Photo courtesy of Karen Sykes, U.S. Forest Service.
38

young, being safe, protection from predators, roosting, and for feeding. The SMZs can have 

variable widths, definitions of size and length, and operational restrictions with respect to the 

harvest of timber and traffic ability by harvesting machines. SMZs are generally implemented 

on both sides of a stream or wetland. The width of any one SMZ that is necessary to protect a 

given area is largely determined by general guidelines or based on judgment that relies on local 

experience. Some SMZ guidelines are based on the slope of the land adjacent to the stream, 

soil erodibility, precipitation, and sensitivity of the stream. The following table is an example 

of guidelines that consider soil type and slope of the adjacent land for Hawaiian forests, see 

Table 11 (www.state.hi.us/dlnr/dofaw/wmp/bmps.htm). In this set of guidelines partial harvest 

is acceptable where 50 percent of the original forest crown cover or 50 ft2 of basal area, evenly 

distributed, must be retained in the SMZ. Clearcutting is prohibited within the SMZ. Although 

this text is largely about the northern forest hardwood resource, the author found the Hawaiian 

SMZ guidelines useful because they are based on percent sideslope and soil erodibility only.

The State of West Virginia, for example, passed a logging sediment control act in 1992 that 

has stipulations for logger licensing, logger certification, timber operation notification, logging 

operation posting, enforcement for activities causing erosion, and/or sediment, and reclamation 

to be completed within 7 days of the planned completion of the logging job. This act also 

provides guidelines for SMZs so that buffer zones should be at least 100 feet wide on each 

side of perennial or intermittent streams and 25 feet wide on each side of ephemeral streams. 

Perennial streams flow year round, intermittent streams flow only a portion of the year, and 

ephemeral streams flow only during wet periods when the surrounding ground is saturated. 

Equipment operation in these zones should be limited; however, cutting and pulling trees from 

within the area is permitted (West Virginia Division of Forestry 2005).

Recommendations also vary among national forests; for example, the Mark Twain uses riparian 

management zones (RMZs) and watershed protection zones (WPZs). The WPZ extends 100 

feet (horizontal distance) on either side of the channel. Some activities are prohibited in the 

WPZ such as log landings, road and skid trail construction, and construction of wildlife ponds. 

Timber harvesting is allowed, but trees cannot be cut within 25 feet of the stream channel 

unless necessary to move the area toward the desired condition or to facilitate designated 

crossings. By contrast, the Green Mountain and Finger Lakes National Forests use 25-foot 

equipment-free zones on either side of the channel where logging equipment is prohibited. 

However, trees may be cut in this 25-foot strip but must be winched out (LeDoux and 

Table 11.—Recommended widths, in feet, for streamside management 

zone (www.state.hi.us/dlnr/dofaw/wmp/bmps.htm)

Soil type Percent slope SMZ width (each side)

Slightly erodible 0-5 35

Slightly erodible 5-20 35-50

Slightly erodible 20+ 50-160

Erodible 0-5 35-50

Erodible 5-20 80 minimum

Erodible 20+ 160 minimum
39

Wilkerson 2008). LeDoux and Wilkerson (2006) developed a methodology that simultaneously 

considers the protection of multiple riparian functions and computes the opportunity costs 

involved with implementing SMZs of alternative widths. They applied the methodology to 

a case study for northern forest hardwood resource conditions for SMZ widths of 50, 100, 

and 150 feet. Their study concluded that 150-foot SMZs were required to fully protect 

the following riparian functions: coarse woody debris recruitment, shade and temperature 

maintenance, sediment filtering, aquatic communities (macroinvertebrates and periphyton), 

and riparian bird communities (riparian associated passerines). The study also quantified the 

capital recovery costs associated with alternative SMZ widths. Clearly, the use of SMZs to 

protect riparian functions is important, can be 

expensive, and requires vast variability in the 

widths required depending on the immediate 

conditions to be protected. It is beyond the 

scope of this text to deal with the vast array 

of combinations of conditions and SMZ 

widths needed; however, managers, loggers, 

landowners, policymakers, and decisionmakers 

need to consult their local laws and guidelines 

to arrive at SMZ widths that best accomplish 

their objectives. The methodology provided by 

LeDoux and Wilkerson (2006) can be used to 

compute the opportunity and capital recovery 

costs involved with implementing alternative 

SMZ widths.

BMPs for Patch or Structural Retention

Patch or structural retention harvesting 

can be used as a habitat or biodiversity 

management strategy (LeDoux and 

Whitman 2006). Patch retention calls 

for retaining about 5 to 20 percent of 

a harvest unit in discrete patches or 

islands of mature or immature trees 

(Forest Sciences 1994) (Fig. 53). These 

patches of standing timber are retained 

to provide post-harvest habitat for many 

plants, wildlife, insects, microorganisms, 

biological and ecological processes, and in 

some cases to protect the visual resource 

(Fig. 54). Managers need to plan for 

unharvested patches within harvest units 

and loggers must be careful to protect 

the patch from disturbance and do so in 

a safe manner. For example, many safety 

regulations prohibit workers from operating in the danger zone of snags that might be left in 

patches. Larger patches can incorporate snags in the center and thus allow workers to safely 

Figure 54.—One-fourth-acre patch retention with vernal pool. Photo courtesy 

of Andrew Whitman, Manomet Center for Conservation Sciences.

Figure 53.—Multiple patches of variable size and shape. Photo courtesy 

of Forest Science, Prince Rupert Forest Region, British Columbia.
40

operate on the periphery of the patch, or “no work zones” can be established around smaller 

patches or where individual trees are retained. Mechanized systems such as feller bunchers or 

cut-to-length harvesters work very effectively and safely to create patches. The British Columbia 

Forest Service (Forest Sciences 1994) lists some useful criteria for selecting patches and stands 

for retention (Table 12). It also provides a formula and table for determining the minimum area 

(percent) that should be retained as a function of the percent area that is available for harvest 

and the percent of available area that has been harvested for a grid size of 248 acres (Table 13). 

For example, if 60 percent of the landscape is available for harvest, and only 10 percent of the 

available area has been harvested, the minimum retention objective in a 248-acre grid would 

be 7 percent. In contrast, if 60 percent of the landscape is available for harvest and 90 percent 

has been harvested, then the objective would be to retain 15 percent of the remaining area. 

The authors suggest these figures as BMPs and guidelines of what should be retained when 

considering structural retention.

Table 12.—Some criteria for selecting patches and stands for retention

Biodiversity/Wildlife Considerations

1. adjacent to wetlands and riparian areas

2. rock outcrops/bluffs

3. diverse tree species and canopy layers

4. less common tree species

5. large snags, or potential snags

6. evidence of present wildlife use (e.g., nests, 

feeding activity)

7. unusual or rare plant communities

Silvicultural/Operational Considerations

1. advanced regeneration or trees suitable 

for release and further growth

2. suitable seed trees for natural 

regeneration

3. gullies or other difficult terrain

4. deciduous and/or brush patches

5. wind firmness of residual trees

6. visual screening is desired

7. low disease/pest spread potential

8. broadcast burning not prescribed

Table 13.—Patch retention objective for each landscape cell

% Landscape Available for Harvest

% Harvested 100 90 80 70 60 50 40 30 20 10

10 11 10 09 08 07 06 05 04 03 02

20 12 11 10 09 08 07 06 05 04 03

30 13 12 11 10 09 08 07 06 05 04

40 14 13 12 11 10 09 08 07 06 05

50 15 14 13 12 11 10 09 08 07 06

60 16 15 14 13 12 11 10 09 08 07

70 17 16 15 14 13 12 11 10 09 08

80 18 17 16 15 14 13 12 11 10 09

90 19 18 17 16 15 14 13 12 11 10

100 20 19 18 17 16 15 14 13 12 11
41

BMPs for Invasive Plant Mitigation

There is no question that invasive native and nonnative plant and other organism species are a 

major threat to forested ecosystems and the general balance of nature. It is beyond the scope of 

this text to go into any detail on individual species, threats, or consequences of any one invasion 

or invader or the spread of such. The author’s intent is to present state-of-the-art voluntary 

BMPs that may mitigate the spread of invasive plant species that are particularly associated with 

logging and forest operations that create the type of disturbance suitable for invasion or spread 

of certain plants. The focus is on the types of disturbance associated with logging and forest 

operations only as opposed to disturbance caused by recreational activities, moving of wood 

products, or other types of events. Forest operations such as road and skid trail construction, 

removal of trees during harvest, landing construction, skidding of logs, and movement of 

machinery in and out of different operating sites create conditions and opportunities for 

invasive plants to invade or spread within or from site to site. For example, the removal of trees 

during a harvest creates conditions where more sunlight is reaching the forest floor—conditions 

favorable for invaders to get established or spread. The construction of roads, skid trails, 

landings, along with the skidding of logs, creates soil disturbance where mineral soil is exposed, 

creating conditions favorable for invaders. Moving equipment from one logging site to another 

or moving equipment that has operated in areas that have invasive plants established within a 

single logging chance provides a vehicle where seeds or other plant parts can be transported into 

areas that were void of invaders. Currently, there are no mandatory BMPs for logging and forest 

operations that are designed to mitigate the spread or invasion of invasive plants.

Loggers protect themselves by disclosing what they see to the landowner, and this information 

could become part of the contract. An invasive species inspection by the landowner or by the 

logger would document what the circumstances are, and both parties would sign and date this 

document. This text provides proposed voluntary scientific guidelines on what loggers and 

landowners could do to mitigate “invasion” or spread during harvesting operations (Fig. 55). 

The Invasive Plant Council of British Columbia lists additional T.I.P.S. for Forestry Operations 

(Table 14).

The voluntary BMPs described in this text are general and state of the art. They are grounded 

in scientific principles but may not be substantiated in rigorous studies in the literature. As 

such, they should be viewed and used as a starting place for developing more rigorous BMPs 

for invasive species mitigation. However, a logger would be prudent to follow these guidelines 

and share this information with the landowner to further mitigate any actions taken against 

the logger by the landowner to account for any invasive plants or conditions created by the 

logging operation. The logger would be wise to survey, document, and inform the landowner 

of any invasive plant infestations or communities of invasive plants within the proposed harvest 

tract before any harvesting operations. The logger would also be wise to follow these voluntary 

BMPs, document them, and disclose them to the landowner. This approach would inform the 

landowner and establish a record of prior conditions and precautions the logger took to avoid 

aggravating the situation.
42

Figure 55.—Flow diagram of proposed voluntary BMPs for invasive species mitigation during harvest operations. (aInvasive Plant Council of BC 2007; bKearns and Chapin 2008).

Operate in areas that are free of invasives first, then move toward areas that are infested so as not to transport seeds or plant parts from contaminated areasaTrain staff to identify, monitor for, report, control, and map new/old infestationsa,bInspect and clean equipment of soil, seeds, plantsa,b

Minimize the length of time that bare ground is exposed – reseed/vegetate bare ground as quickly as possiblea,b

Landings, roads, recent disturbance – reseed/ 

Pre

revegetate disturbed areas 

-treat infested areas 

prior to logging/silvicultural operations. Identify and treat existing invasive plants prior to logging, skid trail constructiona,b

Wash off equipment before moving from site to sitea,b

Demonstrate that logger exercised reasonable Mow at best time to reduce seed set and to minimize spread of seedprecautions/procedures in his practices

a,b

Follow the documented guielines in the published literaturea,b

Where possible, keep the clearing limits for roads, skid trails, and landing construction to the minimal widths acceptable for safety to minimize the amount of sunlight that could reach the forest floor

Document, date, and sign what events occurreda

Create equipment staging areas where seeds won’t get picked up. Mow or spray staging areas before bringing equipment in. Clean up staging area afterwardsb

Acquire clean construction materials, fill dirt, gravel, sand, and mulcha,b
43

Table 14.—Targeted Invasive Plant Solutions for forestry operations (Invasive Plant Council of BC 2007)

T.I.P.S. for Forestry Operations

OPERATION TARGETED INVASIVE PLANT SOLUTIONS General

These practices are always applicable, regardless of the operation, and are not limited to specific 

operations listed here.

1. Determine priority invasive plant species within your operating area.

2. Stay informed through collaborations with regional experts, and assist staff and contractors 

to identify and minimize spread of invasive plant species within your operating area.

3. Carry out regular detection surveys and record the locations of invasive plants in your 

operating area.

4. Keep equipment out of areas infested by invasive plants and keep equipment yards and 

storage areas free of invasive plants.

5. Regularly inspect the undercarriages of vehicles and remove any plant material found.

6. Dispose of plant material at the site of the infestation (if no flowers are present), or bag the 

plant material and dispose of it (locally) in the garbage (if flowers are present).

7. Wash plant seeds and propagules from personal gear, equipment, vehicles and machinery 

at designated cleaning stations before leaving infested sites. Ensure soil that is being moved 

does not contain invasive plant seeds or propagules.

8. Minimize unnecessary soil disturbance during road, landing, skid trail and site preparation. 

Ensure soil that is being moved does not contain invasive plant seeds or propagules.

9. Re-vegetate disturbed areas as soon after disturbance as possible using an appropriate 

combination of scarification, seeding, fertilizing and/or mulching. Ensure that seed used to 

re-vegetate will meet site objectives. Use Canada Common #1 Forage Mixture or better.

10. Treat infestations of invasive plants prior to disturbance (pre-treatment).

11. Monitor treatment sites for several years to ensure efficacy. Re-treat as necessary to ensure 

spread does not continue.

Silviculture & 

Reconnaissance 

Surveys

1. Consult the Invasive Alien Plant Program (IAPP) Application database to determine locations 

of high-risk infestations.

2. Incorporate IAPP spatial data into planning maps (www.nric.ca/).

3. Incorporate detection surveys into existing survey procedures.

4. When an invasive plant is encountered: record the species, date of observation, location 

(UTM coordinates), and estimated area of infestation (ha or m2). IAPP field cards are 

available for use. Provide this information to the regional invasive plant committee 

coordinator or MFR invasive plant specialist, or enter the data independently.

Road Building & 

Maintenance

1. Inspect gravel pits and material sources for invasive plants, and remove invasive plant seeds 

and materials prior to use.

2. Where possible, begin work in un-infested areas and move toward infested areas.

3. Promptly re-vegetate disturbed areas along roadsides, landings, and cleaned culverts.

4. All machinery and equipment capable of carrying invasive plant propagules should be 

cleaned prior to moving on and off site.

5. Grade roads in directions that do not encourage spread of seeds away from known, priority 

invasive plant sites.

Harvesting

 & Site 

Preparation

1. Re-vegetate all harvested openings by re-establishing an appropriate stand of trees following 

the stocking standards prescribed in the Forest Stewardship Plan.

2. Minimize disturbance and the duration of time the site is left un-vegetated. Consider seeding 

if there is a delay in re-vegetation.

3. All machinery and equipment capable of carrying invasive plant propagules should be 

cleaned prior to moving on and off site.
44

BMPs for Soil Protection

There is no question that silvicultural practices and machinery used in the process of harvesting 

trees or achieving future desired forest conditions can result in various degrees of soil 

disturbance and compaction. Some silvicultural prescriptions require machines to be on the 

site and to travel throughout the tract in question to achieve the stated objective. Clearly, most 

harvesting operations require some type of machinery to be used in felling and extracting trees. 

These machines and processes can result in soil disturbance, soil erosion, sedimentation, rutting, 

and compaction. These soil impacts can have a cascading effect. For example, soil disturbance 

can lead to soil erosion; soil erosion can lead to loss of valuable topsoil and nutrients. Soil 

erosion can also lead to sedimentation in streams and riparian areas, impacting fisheries, animal 

and plant diversity, and it may change ecosystems. Heavy machinery in combination with 

wet saturated soils can lead to severe rutting. Rutting is caused when soil is displaced from 

underneath the machine tire or track and moved sideways, allowing the tire or track to sink into 

the subsoil. Rutting can also have a cascading effect in that ruts can channel water, accelerating 

erosion or soil movement. Rutting can also result in ponding where water is captured and held 

within the rut. Ponding of water may be undesirable for tree and root growth and may in some 

cases create microsites altering the ecosystem. Soil compaction may impact the infiltration rate 

of water, alter soil properties, reduce soil porosity, and impede root growth. For example, heavy 

harvesting equipment can harm existing trees and future regeneration by compacting soils. 

Good soil should contain about 50-percent pore space for aeration and moisture retention. 

Tree roots need oxygen to function. Heavy equipment can compact soil, reducing oxygen 

and inhibiting root growth. Multiple loaded and unloaded machine passes over the same skid 

trail can severely compact the soil in the skid trail. Not too much can be done to minimize or 

mitigate soil disturbance and compaction on the most heavily used skid trails. Several things 

can be done, however, to minimize soil disturbance and compaction by following some wellestablished BMPs. Controlling soil erosion protects and maintains water quality. Table 15 lists 

some commonly accepted BMPs that can be used to mitigate soil disturbance and compaction 

during harvesting operations.

Preplanned skid trails require the skidding machines to remain on the trail, and operators must 

pull the bull or winching line to the trees or logs. The logs or trees are then winched back to the 

machine. Tracked vehicles spread the weight of the machine over a wider footprint and have 

better traction, leading to less spin and churning of the soil. Skyline, cable, and aerial systems 

Table 15.—Commonly accepted BMPs for protecting soil during harvesting 

operations

1. Require the use of preplanned skid trails

2. Require the use of tracked vehicles

3. Require the use of cable or aerial systems

4. Restrict operations on wet/saturated soils

5. Require skidding on frozen ground

6. Require skidding on deep snow pack

7. Use mats of limbs and branches to travel on 

8. Require skidding/winching across the slope as opposed to up and down the slope

9. Require the use of wide/high flotation tires
45

such as helicopters fully suspend some or all of the log or tree during the extraction process. 

Restricting operations when soils are wet and saturated prevents compaction and rutting. 

Skidding on frozen ground or on deep snow pack also prevents compaction and rutting. Use 

of limbs, branches, and vegetation on the skid trails during the extraction process also helps 

reduce compaction, disturbance, and rutting. Using a heavy layer of tree limbs, branches, and 

vegetation along the most heavily used skid trails, especially where the trails meet the landing 

area along with frozen ground or deep snow packs, can greatly reduce the impact of multiple 

machine passes on skid trails (Fig. 13). For machines such as feller bunchers and cut-to-length 

processors, the limbs and branches from the trees being processed can be used ahead of the 

machine as a mat to travel on thus protecting soil properties (Fig. 21). Winching across the 

slope when practical and safe as opposed to skidding or winching straight up and down the 

slope can also be effective in reducing soil disturbance and rutting. Wide and high flotation tires 

may be used to extend the operating season in wet and saturated or flooded areas. Such use may 

not actually protect soil properties but in fact may actually harm soils by churning and mixing 

soil into soup-like consistencies. These soupy and churned up soils may take decades to recover 

to their original conditions, if ever. In some applications, wide and high flotation tires may 

spread out the weight of the machine’s footprint in a desirable way. The author’s focus in this 

discussion has been on the BMPs that can be used to mitigate soil impacts on the site and on 

the lesser used skid trails.

Multiple objectives may be accomplished by selectively using one or more of the BMP 

guidelines. For example, leaving wide buffer zones adjacent to a stream may protect the stream 

and associated ecological functions; serve as a filter to minimize erosion, sedimentation, and 

nutrient movement; serve as a form of patch or structural retention; and, by not allowing 

harvesting or equipment traffic within the zone, may eliminate or minimize the spread or 

invasion of native and nonnative plant species. Many states have used these BMP guidelines 

successfully in the past (Vermont Department of Forests, Parks & Recreation 1999), and some 

foreign countries have developed their BMP practices based on what many states use here in 

the U.S. (Warkotsch et al. 1994). These BMP guidelines are based in science and they work 

when properly applied. Many states have logger and landowner training programs such as LEAP 

(Logger Education to Advance Professionalism) and PLP (Professional Loggers Program) where 

the methods are communicated to landowners and loggers. It is beyond the author’s capacity 

in this document to list every example and reference for use of these techniques. However, 

many of these methods have been around for a long time, training programs abound, and the 

procedures have been proven to work. The challenge to the logger and landowner is to become 

familiar with these methods and to successfully implement them. Successful implementation of 

these principles will pay dividends in healthy forest lands, water resources, and ecosystems for 

future generations.

Figure 56 is a decision flowchart that can be used to identify the respective BMP guidelines 

needed for specific applications.
46

Figure 56.—BMP compliance decision flow diagram.

Yes

Yes

Yes

Yes

No

No

No

No

Go to Table 11 

and LeDoux and 

Wilkerson 2006

Is Riparian 

Zone/Water 

Protection a 

Concern?

Is Soil 

Protection & 

Disturbance a 

Concern?

Is Patch/ 

Structural 

Retention a 

Concern?

Is Invasive 

Plant Species 

Mitigation a 

Concern?

Go to Table 12 

Go to Table 15 

Go to Table 14 

and Figure 55

End

Start
47

Part IV—Considerations for Managers

Using the Harvesting System Applicability Matrix

Table 10 shows a harvesting system applicability matrix with respect to chainsaw requirement, 

terrain, initial cost, productivity, labor intensity, and environmental impact, ease of moving 

in and out, and setup time and planning required. The rankings are in general range terms 

as opposed to exact numerical rankings. Chainsaw required means that for that system to 

operate chainsaws are required on site. The terrain column suggests the terrain the system is 

best suited for, considering safety and productivity. The initial cost column simply ranks the 

initial investment needed to purchase that system new. The productivity column ranks the 

systems by their net hourly production rate. The labor intensity column ranks the harvesting 

system by the amount of labor required to make that system work. The environmental impact 

column ranks the system by its soil disturbance, soil compaction, and residual stand damage. 

The ease of moving in and out column ranks the harvesting system by the degree of difficulty 

encountered in moving that system from one site to another. The setup time and planning 

required column ranks the system by the amount of time and difficulty in setting up and the 

planning required prior to any operations. For example, the portable winches are ranked gentlesteep in the terrain column. This implies that portable winches can be used safely on gentle 

terrain but can also be used on steep terrain. In contrast, small farm tractors have a gentlemoderate ranking in the terrain column, suggesting that small farm tractors would not be safe 

or very productive on steep terrain. Small farm tractors are low production (see productivity 

column) anyway, and trying to use them on steep or very steep terrain would simply not be safe 

or practical. The environmental impact column attempts to capture the impact to the logging 

site from the perspective of soil disturbance and compaction and residual stand damage. For 

example, a ranking of low would suggest the system application results in low levels of residual 

stand damage, little soil disturbance, and minimal soil compaction. In contrast, medium to 

high level rankings for the clambunk skidder and the forwarders would imply such levels of soil 

disturbance and compaction primarily on the most heavily traveled skid trails that experience 

multiple passes loaded and unloaded. The clambunk and forwarders may experience low levels 

of residual stand damage because they largely stay on the skid trails, yet the overall impact to the 

soil environment would be medium to high. The applicability matrix blends information from 

the literature and personal experience from the author’s many years in harvesting research and 

application on the ground. As such, the matrix is based on science and observation, but users 

may encounter difficulty in finding results from well-designed experimental long-term scientific 

studies to match or substantiate all that is captured in the matrix. The author’s intent is to 

provide managers, decisionmakers, policy formers, and loggers with a starting point on selecting 

harvesting systems for logging the northern hardwood resource. As more and new knowledge is 

obtained, the matrix should be updated.

Managing People and Machinery

Logging managers must manage their machinery and production quotas or goals, but they also 

must be people and employee managers. There is no substitute for hiring and retaining the best 

qualified and hardest working employees. A well-balanced team approach where employees 

are paid well, safety is stressed daily, and crews maintain a positive outlook and strive to 

communicate among themselves and with landowners will pay dividends in the long run. Being 
48

honest with landowners and treating them with respect goes hand in hand with operating in an 

environmentally friendly manner. Taking that extra time to satisfy landowner objectives and 

to simultaneously protect the environment will pay dividends for generations to come. With 

respect to the laws and rules, if hauling permits are required to move oversized equipment 

from job site to job site, obtain them and follow the procedures during moves. Some delays 

and expenses can be avoided by scouting the routes to be followed before any move. For 

example, getting stuck in a bridge crossing that is too narrow or low for the oversized load 

may result in unnecessary delays, fines, and expenses. Not recognizing that a sharp horizontal 

curve cannot be negotiated by the tracking mule trailer that is hauling the oversized equipment 

and result in lost time and costly adjustments. Trying to negotiate a steep vertical curve with 

a lowboy mule train trailer can result in the mule train getting hung up literally and lead to 

delays, breakdowns, and headaches. Wiping out a row of mailboxes or someone’s prize yard 

tree while negotiating a tight horizontal curve with the lowboy and the oversized load with the 

feller buncher or skidder in tow can be expensive and create a lot of ill feelings about loggers in 

general. Alternate routes may be necessary or the moving of equipment during non-peak traffic 

hours could solve the challenge of getting from one job site to another. Sometimes equipment 

must be dismantled and hauled in separate loads to satisfy legal haul limits and tricky road 

conditions. Accidents cannot be totally eliminated, but many can be avoided by a little 

preplanning and pre-scouting.

Weather and Hauling Regulations

If job site or individual registration is required for a particular job or employee, by all means 

loggers should comply. Training in job task and safety should be a top priority for all involved. 

Loggers and landowners should make property boundary definition a major objective to be 

met before any logging crews or machinery is allowed on job site. Environmental compliance 

required by the law or the landowner should be understood, communicated, and followed. 

Special considerations to protect water resources, wildlife habitat, visual resources, and future 

crop trees must be understood and communicated to all involved. Figure 57 is an example of 

a Timber Sale Agreement/Contract that could be used to capture what needs to be done and 

how. A well-written contract protects the landowner and the logger both. Provisions E, H, I, 

J, K, and L are examples of how special considerations can be incorporated into the contract. 

Although Figure 57 spells out special considerations that need to be observed, it is only an 

example of what a contract might look like. Daily or timely inspections by the side rod or 

supervisor in charge should be conducted and any modifications or shortcomings should be 

communicated, corrected immediately, and/or the contract modified. To some extent, the 

logging manager must be a bit of a weather forecaster to anticipate and deal with ever changing 

weather events. Certain weather events can affect productivity and safety, and they can create 

undesirable environmental impact. For example, although frozen roads and frozen ground 

are generally desirable for trucking and skidding (Stone 2002), too much snow or too much 

ice can create all kinds of problems that can impact trucking and skidding productivity when 

log trucks simply cannot negotiate deep snow or where skidding and cutting crews either 

cannot see the base of trees to fell them or skidding crews cannot find the logs to choke them 

or grapple them. For example, trees heavily ladened with snow or ice are extremely dangerous 

if not impossible for manual felling crews to deal with. However, they are no obstacle for 

mechanized systems such as feller bunchers or cut-to-length systems. Muddy conditions 
49

can create loss of traction in hauling, skidding, and maneuvering equipment in general, can 

lead to severe or unacceptable rutting, can alter soil properties if soil is churned and mixed 

or compacted, and can result in equipment getting stuck or hung up. Excess rain can lead to 

muddy conditions, soft spongy ground, poor visibility, flooding, and runoff leading to erosion 

where debris and rocks are washed out on the roadbed. Ice storms and freezing rains can be 

extremely dangerous to operate in. The ice accumulation on trees along haul roads and skid 

trails can lead to trees and limbs leaning into the running surface of the road and skid trail and 

can come in contact with chip vans, log trucks, and skidding machines, resulting in damage to 

equipment or posing a safety hazard to wood workers. The ice load on standing trees can create 

an explosive situation where tree tops are snapping and breaking and trees are uprooting or 

where freezing rain makes road conditions so treacherous that the roads are literally impassable 

even with the best drivers operating with the best combination of chains and tire tread. The 

secret to dealing with snow, ice, mud, and rain is to try and keep the roads open and operable. 

In some of these cases, the logging crews may need to stay out of the woods and off the roads 

and simply wait this out. Most of the time, these events can be dealt with by simply being aware 

of potential changing weather conditions and making adjustments as required. In some cases 

the woods are shut down to operations for the time required until conditions are favorable for 

logging. To the extent possible, all members of the team or crew should meet daily and discuss 

near misses and success stories; alert each other to existing and newly created safety hazards, 

changing weather conditions; discuss problems with equipment or with meeting production 

quotas; and reassure each other they are doing a good job and are looking out for each other’s 

backs. Loggers would be miles ahead to invest in a set of portable scales because most of the 

haul regulations deal with weight limits.

Profitability and Cost Control

Controlling costs and ensuring that operations are profitable are major objectives of any logging 

venture. Operating costs can spiral out of control quickly and can lead to huge losses. For 

example, excessive idle and down time (nonproductive time) can result in low production levels 

that may literally shut down a business. There are cost factors that the logger or contractor has 

some control over, and there are some cost factors that are beyond the control of the operator. 

The generation of profit is imperative to any operation for the operator to remain in business. 

Profit is defined as any net return above and beyond all operating and fixed costs. In this section 

the author will address some of the cost factors and variables that the operator has some control 

over and provide some elementary concepts on profitability.

Machine availability and utilization is one of the primary cost factors that can be controlled 

by the logger and that have the greatest impact on productivity and costs. The best way to 

illustrate the impact of utilization rate on production costs is by the following example. Using 

the equation for the Timbco T425 CTL from Table 8, with DC=22, DBH=13, HT=69.69, 

and utilization rates of 100 percent, 90 percent, 80 percent, and 60 percent, we developed 

Figure 58. We have values of $12.46, $13.79, $15.58, and $20.74/cord for the utilization rates 

mentioned above, respectively. The difference between an achievable 90-percent rate ($13.79/

cord) and a 60-percent rate ($20.74/cord) is $6.95/cord. Figure 58 tells us that the cost/ft3

has leveled off at 13 inches d.b.h. In fact, $/ft3 starts to level off at about 9 inches d.b.h. for all 

utilization rates. A utilization rate of 90 percent and higher is a reasonable goal. According to 
50

TIMBER SALE AGREEMENT

This agreement is entered into on this the _________________ day of _________________, 

19___ between Joe Bag of Donuts Logging of 543 Wiseman Road, Morgantown, WV 26505 hereinafter 

called the Buyer and _________________________________________________________________ of 

__________________________________________________________________________________ 

phone number (___) ___________________ hereinafter called the Seller.

Witnesseth:

1. The Seller does hereby sell all the trees described as follows: _________________________ 

____________________________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

2. The timber to be cut is located on the property as shown on the map attached hereto and 

made a part hereof and described as follows: ______________________________________________ 

____________________________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

3. The Seller covenants to and with the Buyer that: Seller is the lawful owner of the land and 

timber; they are free from all encumbrances: Seller has good right to sell the same as afore said; and 

Seller will warrant and defend the sale of said property, goods and chattels as hereby made unto the 

Buyer against the claims and demands of all persons whomsoever.

4. The Seller agrees to allow the Buyer to have ingress, egress, and regress upon said premises 

as described on the attached map to remove the designated timber and to perform other operations 

that are necessary in conjunction with the removal of said timber, which includes the right to establish 

clearings for log landings and loading operations and to establish access and skid roads necessary for 

the removal of said timber.

5. The Buyer agrees to cut and remove said timber in accordance with the following provisions:

(A.) Young trees shall be protected against unnecessary injury.

(B.) No cut, broken or uprooted trees shall be left hanging in standing trees.

(C.) The Buyer shall use due care to prevent fire.

(D.) Stream courses will be kept free of tops, boundary lines will be kept open, roads will be 

free and open at the completion, and mechanized cut-to-length with forwarder logging 

practices will be used to harvest said timber.

(E.) 25 foot buffer zones will be left on both sides of streams. No timber will be harvested 

from these buffer zones.

(F.) Upon completion of the harvesting, the Buyer will smooth the ruts of the main haul skid 

road, truck roads, and landings where necessary. Also diversion ditches will be built 

where necessary on steep skid trails.

(G.)All stumps will be cut to within twelve (12) inches of the ground, measured on the uphill 

side.
51

Figure 57.—Example of a Timber Sale Agreement. Courtesy of Chris LeDoux.

(H.) The landings will be seeded at the completion of harvesting as follows: 

_________________________________________________________________________

_________________________________________________________________________

(I.) An invasive species plant inventory will be conducted by the logger and landowner prior 

to any logging operations.

(J.) The logger will follow voluntary BMPs for invasive species mitigation as outlined by 

LeDoux 2011 in the publication “Harvesting Systems for the Northern Forest Hardwoods” 

(K.) One quarter acre patches of timber will be retained and protected as marked by the 

landowner.

(L.) The logger and landowner will jointly survey the subject property for safety hazards and 

will flag such.

(M.) The Buyer will have until ____________________, 19__, within which to harvest the 

timber hereby conveyed.

6. The Buyer agrees to furnish the Seller with a Certificate of Insurance evidencing his having 

General Liability Insurance, in force, with submission of this contract.

7. The Seller shall be relieved of all claims, damages, or suits arising from the actions of the 

Buyer, his agents, servants, or employees during the period of this agreement. Likewise, the Buyer shall 

be relieved of all claims, damages, or suits arising from the actions of the Seller, his agents, servants, or 

employees during the period of this agreement.

8. The Buyer agrees to pay for said timber as follows: ___________________________________ 

____________________________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

9. This agreement and all terms, provisions, and conditions shall be binding on both parties, 

their legal representatives, heirs, and successors.

IN WITNESS WHEREOF, Seller and Buyer have set their hands and seals to these presents this 

the _____________day of _________________________________________, 19___.

Signed, sealed and delivered in the presence of:

(seal)

Witness Owner

 

 (seal)

Witness Owner

 

 

Signed, sealed and delivered in the presence of:

 

 (seal)

Witness Buyer, Joe Bag of Donuts Logging
52

the author’s observation, many operators achieve utilization rates that exceed 80 percent. Figure 

58 can also be used to further explain the impact of utilization rate on the type (size) of stands 

that an operator would break even in if the CTL cost was constrained at $0.20/ft3 ($17.80/

cord). The logger should operate in 9-inch d.b.h. stands at 100-percent utilization, 10-inch 

d.b.h. stands at 90 percent, 11-inch d.b.h. stands at 80 percent, and 15-inch d.b.h. stands at 60 

percent. Although 100-percent utilization rates are not practical, 80- to 90-percent utilization 

rates are achievable. Utilization rate is something we have control over. Machines must be 

kept in good operating condition so that idle time due to breakdown and repairs is minimized. 

A broken machine will simply not be able to produce any wood. Downtime due to machine 

failure and repairs should be kept to a minimum. Repairs and maintenance should be scheduled 

during non-working shifts, if possible. Equipment operators should get to know their machines 

and detect when components need repair or maintenance and do that immediately instead 

of waiting until a major component fails. Equally important is controlling and minimizing 

idle time due to machines having to wait on each other or on woods workers for wood. For 

example, ideally, chippers should be fed wood at a rate to keep them busy as opposed to having 

to wait on the arrival of wood for chipping. The helicopter should not have to hover and wait 

for the hooker to choke a turn of logs. The logs should be pre-choked and turns or loads should 

be pre-selected in advance of the hook and tag line being lowered. The grapple skidder should 

not have to wait on the feller buncher for wood. Clearly, some machine and component failures 

cannot be anticipated, but keeping a sharp eye on periodic maintenance and scheduling repairs 

at the first sign of need can go a long way toward keeping machines at the highest availability 

and utilization levels.

Machine operators should exploit the capacity of their machines whenever possible. For 

example, the skidder, forwarder, clambunk, helicopter, yarder, etc., should be loaded to safe 

working payloads every trip. Notice in Figure 59 how the load is configured on the clambunk 

skidder. The bottom layer of stems lies 2 to 3 feet behind the middle layer and the middle layer 

lies 2 to 3 feet behind the upper layer in the load. In other words, a grapple skidder running 

Figure 58.—Delay-free $/ft3 by DBH for a Timbco 425 cut-to-length machine. Conditions: DC=22, 

utilization rates = 100, 90, 80, and 60 percent.

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

$/ft3

DBH (inches)

1

0.9

0.8

0.6
53

back to the landing with one-fourth or one-half of its load capacity is only losing the contractor 

money. The best way to illustrate the impact of payload on costs is by using an example. Using 

the equation for the grapple skidder (Table 6), we developed Figure 60. Cost/ft3 decreases 

as payload increases. A 300-percent increase in payload (going from 50 ft3 to 200 ft3) results 

in a 47-percent decrease in cost (going from $.105/ft3 to $.05/ft3). Although the concept of 

exploiting a machine’s capacity cannot be stressed enough, it is not always possible to maximize 

payload. In some cases it is relatively easy to fill forwarder bunks to capacity. Similarly the 

Figure 59.—Clambunk skidder with multiple axles, dual tires on each side, and a balanced 

payload. Photo courtesy of Tigercat.

Figure 60.—Delay-free $/ft3 by payload for the Timberjack 460 grapple skidder. Conditions: 

ASD = 740, BZ = 135.

0.10

0.07

0.06

0.05

0.04

0

0.02

0.04

0.06

0.08

0.1

0.12

50 100 150 200 250

$/ft3

Pay Load (ft3)
54

grapple on the skidder, clambunk, or dozer can usually be loaded to capacity especially if 

the wood has been prebunched. In the case of loading a helicopter’s hook, hooking a turn of 

logs for a cable system, or building turns for tractors and skidders, reaching capacity is more 

challenging. The machine operator may have to hook and winch logs, moving them about the 

stand in the process of collecting enough logs to reach the capacity of the machine. Many times 

when the log population is scattered within a harvest block, the operator does best by taking 

what is available versus spending excessive time and energy trying to hook a bigger turn.

When we studied the impact of log population and distribution in Douglas-fir cable thinning 

(LeDoux 1981), we found that the number of chokers to fly depended on the log population 

distribution. We also studied when to prebunch wood in cable thinning (LeDoux and Butler 

1981b). We found that prebunching logs to decks within a stand using a small winch was more 

effective than yarding alone. Prebunching, directional felling, and loading machines to capacity 

really work and are things that the operator has some control over.

There is a fine line between exploiting the load capacity of the machines and abusing the 

machine to where it fails. For example, hooking too heavy a load on a helicopter may result in 

the pilot having to abort the load (resulting in delays to rehook the turn); hook failure, load or 

tag line failure may “pull” the helicopter into the surrounding trees or to the ground or cause 

machine and engine or component failure. Feller bunching machines with accumulating felling 

heads should be exploited to accumulate the maximum number of stems per cycle to maximize 

production. Notice in Figure 25 how multiple stems are accumulated in the felling head. 

Machine operators should always accumulate as many stems as safely possible to maximize the 

productivity of the machine without having to move to alternate locations. Figure 61 shows 

how a large forwarder can be loaded to its maximum safe operating capacity. Skyline carriages 

should be loaded to capacity by choking the maximum number of logs per cycle. Log and chip 

vans or trucks should be loaded to their safe and legal working limits. Wood or logs or stems 

should always be prebunched or bundled in the woods before any extraction operations. Equally 

Figure 61.—High capacity forwarder with a payload. Photo courtesy of Tigercat.
55

important is the practice of matching the machine size and capacity to the size of wood they 

will be operating in (Fight et al. 1984; LeDoux 1985a, 2000). For example, in the first entries 

into a young stand, a small machine may be required, while in final entries or final harvests 

of older stands, larger machines would be the way to go (LeDoux 1986c, LeDoux and Brodie 

1982, LeDoux and Butler 1981b). Suppose a logger plans to add a skidder to his equipment 

fleet. The skidder will operate in tracts where: average DBH = 12 in., volume cut/acre = 2,500 

ft3, slope yarding distance = 800 ft, volume/log = 20 ft3, logs/turn = 4, and the volume/turn = 

80 ft3. Because the numerical values of the stand attributes are within the variable limits (Table 

5), the JD 440C, JD 540B, and the JD 640D could all be selected to harvest these tracts. The 

logger could use the equations in Table 5 for the three machines as follows:

JD 440C

$/ft3 = 0.1654157 + 0.0137012 * DBH + 0.0000008906 * VOAC - 0.001362 * VPL+ 

 0.00004815 * SYD - 0.0027067 * VPT + 0.0024094 * LPT

$/ft3 = 0.1654157 + 0.0137012 * 12 + 0.0000008906 * 2500- 0.001362 * 20+ 

 0.00004815 * 800 - 0.0027067 * 80 + 0.0024094 * 4

$/ft3 = .1364

JD 540B

$/ft3 = 0.43486 – 0.0201429 * DBH + 0.0000005772 * VOAC + 0.002606 * VPL + 

 0.00004743 * SYD - 0.0015778 * VPT - 0.0145491 * LPT 

$/ft3 = 0.43486 – 0.0201429 * 12 + 0.0000005772 * 2500 + 0.002606 * 20+ 

 0.00004743 * 800 – 0.0015778 * 80- 0.0145491 * 4 

$/ft3 = .1002

JD 640D

$/ft3 = 0.3415523 – 0.0072889 * DBH + 0.000001086 * VOAC + 0.0012704 * 

VPL + 0.0000495 * SYD - 0.001875 * VPT - 0.0058284 * LPT

$/ft3 = 0.3415523 – 0.0072889 * 12 + 0.000001086 * 2500 + 0.0012704 * 20 + 

 0.0000495 * 800 - 0.001875 * 80 - 0.0058284 * 4

$/ft3 = .1485

Based on these estimates, the selection would be the JD 540B or something in the same 

capacity. The JD 440C is likely reaching its maximum capacity range with the logs from 

a 12-inch stand (LeDoux 2000). The JD 640D may have too much capacity for the stand 

conditions. Too large or small a machine for the operating conditions required will only result 

in unused capacity, delays, and machine or component failure. Obviously, operators cannot 

always exploit the capacity of the machine or exactly match the machine to the operating wood 

size, but some attention to these principles can go a long way toward controlling costs and 

increasing productivity.

To run a profitable operation, contactors or loggers must not only attempt to control the cost 

factors they can, but also understand and account for the costs involved and allow for a profit 

and risk margin. For example, the cost to fell, buck, limb, skid, load, and haul the products 

must be summed along with the road and landing construction expenses. Any expenses for 
56

special environmental compliance such as protection of SMZs or survey and procedures to 

mitigate the control and spread of invasive plant species must be factored in. The author cannot 

stress enough the need to keep accurate and detailed records of all costs, production, repairs, 

etc. A good accurate and detailed paper trail not only serves as a benchmark for identifying 

bottlenecks or areas where changes or improvements must be made but also comes in handy 

in case of audits or litigation. Costs involved with contract preparation, site visits and cruises 

or surveys, and/or post harvest treatments such as seeding, renovating roads and landings, or 

putting skid trails to bed must also be summed. After all costs are accounted for, the author’s 

guidance to students and practitioners is that the contractor should adjust the sum of all costs 

by a margin for profit and risk (this is the net return to the logger or contractor). For example, 

if the sum of all costs comes to $45/cord and the loggers’ or contractors’ margin for profit and 

risk is 30 percent, then the final bid price should reflect $58.50/cord. Clearly, many costs need 

to be considered in the process and each logging chance has its own set of operating conditions. 

The author’s treatment of this subject is not exhaustive but should provide an elementary 

introduction into profitability and cost control.

The author cannot stress enough the importance of having a solid relationship with good 

reliable repair and maintenance support that respond quickly when needed. Although most 

loggers and crews become very proficient at repairing and maintaining their equipment, many 

tasks can be handled only by the repair shop.

In closing, simply stated, do a good job, keep good employees, pay them well, work hard, stay 

positive, be environmentally friendly, be safe, be honest, treat landowners with respect, follow 

the rules and laws, and you will succeed.

Many of the papers cited are available for downloading at: http://nrs.fs.fed.us/people/cledoux

Literature Cited

Baumgras, J.E.; LeDoux, C.B. 1985. Costs of harvesting forest biomass on steep slopes 

with a small cable yarder: results from field trials and simulations. In: Smith, W.H., 

ed. Proceedings, third southern biomass energy research conference; 1985 March 12-15; 

Gainesville, FL. New York: Plenum Publishing Corporation: 133-142.

Baumgras, J.E.; LeDoux, C.B. 1992a. Computer software to estimate timber harvesting 

system production, cost, and revenue. In: FORS ninth annual computer conference; 1992 

August 25-26; East Lansing, MI. St. Paul, MN: U.S. Department of Agriculture, Forest 

Service, North Central Forest Experiment Station. 5 p.

Baumgras, J.E.; LeDoux, C.B. 1992b. Computer software to estimate timber harvesting 

system production, cost, and revenue. The Compiler. 10(4): 28-32.

Baumgras, J.E.; LeDoux, C.B. 1992c. Software to estimate timber harvesting cost and 

revenue for eastern hardwoods. In: 1992 Society of American Foresters national 

convention; 1992 October 25-28; Richmond, VA. Bethesda, MD: Society of American 

Foresters: 573-574.
57

Baumgras, J.E.; LeDoux, C.B. 1995. Hardwood silviculture and skyline yarding on steep 

slopes: economic and environmental impacts. In: Gottschalk, K.W.; Fosbroke, S., eds. 

Proceedings, 10th central hardwood forest conference; 1995 March 5-8, Morgantown, WV. 

Gen. Tech. Rep. NE-197. Radnor, PA: U.S. Department of Agriculture, Forest Service, 

Northeastern Research Station: 463-473.

Baumgras, J.E.; Hassler, C.C.; LeDoux, C.B. 1993. Estimating and validating harvesting 

system production through computer simulation. Forest Products Journal. 43(11/12): 

65-71.

Baumgras, J.E.; LeDoux, C.B.; Sherar, J.R. 1994. Harvesting costs and environmental 

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65

Index

mechanized 1, 7, 15, 16, 48, 64

operating conditions 19, 21, 55, 56

OSHA 32, 36

patch retention 37, 57, 61

payloads 16, 19, 31, 52

personal protection equipment 33

ponding 44

primary transportation 26

production and cost 1, 20, 21, 31, 61

profitable 19, 49, 55

riparian 1, 2, 37, 38, 44, 61

rubber-tired skidders 1, 12, 13

safety 1, 2, 32, 33, 36, 39, 47, 48

secondary transportation 26

simulation 1, 21, 57, 59, 60, 63

skidding 7, 8, 9, 11, 14, 16, 18, 22, 32, 41, 44, 48, 57, 

63

skid roads 12, 18, 57

skid trails 9, 11, 20, 41, 44, 47, 49, 56, 63

soil disturbance 8, 9, 12, 15, 18, 41, 43, 44, 45, 47, 63

streamside management zones 37, 61

structural retention 1, 39, 45

stump-to-mill 21, 28, 59, 60

winches 1, 2, 7, 8, 36, 47

yarders 18, 22, 63

best management practices 37, 64

bucking 7, 21, 32, 34

buffer zones 38, 45

bunching 8, 22, 54, 62

cable systems 2, 18, 20

chainsaw 1, 7, 11, 15, 21, 33, 34, 47

chipping 31, 52

clambunk skidders 1, 13, 16, 30

compaction 8, 9, 12, 15, 18, 44, 45, 47, 64

crawler 1, 11, 18, 19

cut-to-length 1, 2, 7, 12, 15, 20, 22, 40, 45, 48, 58, 

60, 61, 64

ecosystems 41, 44, 45

environmental compliance 1, 2, 56

estimating production and cost 20

feller bunchers 1, 2, 7, 11, 12, 15, 20, 40, 45, 48

felling 1, 7, 12, 19, 21, 32, 34, 44, 48, 54

forest products 1, 2

forwarders 1, 13, 30, 47

grapples 8, 9, 11, 13

harvesting systems 1, 7, 34, 47, 61, 63, 64

horses 1, 2, 7, 18

invasive species 1, 41, 59

logging 1, 19, 23, 32, 34, 37, 38, 41, 47, 48, 49, 56, 

57, 58, 59, 60, 61, 62, 63, 64
Printed on Recycled Paper

LeDoux, Chris B. 2011. Harvesting systems for the northern forest hardwoods.

Gen. Tech. Rep. NRS-91. Newtown Square, PA: U.S. Department of Agriculture, 

Forest Service, Northern Research Station. 65 p.

This monograph is a summary of research results and environmental compliance 

measures for timber harvesting operations. Data are presented from the Northern 

Research Station’s forest inventory and analysis of 20 states in the northern forest 

hardwoods. Harvesting systems available in the region today are summarized. 

Equations for estimating harvesting costs are documented. Safety considerations are 

compiled along with images of safety equipment and clothing engineered to protect the 

head, ears, eyes, face, hands, and legs. Mandatory and voluntary best management 

practices (BMPs) are discussed for streamside management zones (SMZs), patch/

structural retention, invasive plant mitigation, and soil protection. Profitability and 

cost control are addressed. The importance of keeping machines working, exploiting 

machines’ payload capacity, and matching machines to the size of wood being 

harvested is illustrated. The information offered in this text should be valuable to the 

harvesting industry and serve as a text for a course in timber harvesting.

KEY WORDS: BMPs, timber harvesting, cost, safety, logging systems, simulation

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