Logging for the 21st Century: Protecting the Forest Environment Mathew Smidt and Charles R. Blinn

Copyright ©  2009  Regents of the University of Minnesota. All rights reserved.

Table of Contents

Introduction

Environmental protection is becoming an increasingly important part of timber harvesting. Landowners and foresters aim not only to prevent soil erosion, but also to protect wetlands, aesthetics, and plant and animal habitat. Loggers and foresters who want satisfied customers must respond by using harvesting techniques and equipment that protect the environment.

Minnesota's recently completed Generic Environmental Impact Statement for timber harvesting and forest management (GEIS) provides a valuable look at how we can minimize the environmental impacts of logging. This publication describes how you can apply some of these recommendations to your own operation. Although the scope of the GEIS was limited to Minnesota, its conclusions apply in many other settings as well.

An important point to remember as you consider how you can meet landowners' demands for increased environmental protection is that the way we harvest trees today is not the only way to accomplish a timber harvest. Today's technologies evolved in response to historical trends, demand by mills and consumers, societal demands, equipment costs, and forest conditions. Now technologies and techniques that reduce environmental impacts are more available than ever before. Some of these may have tradeoffs in lower productivity or increased cost. Others, however, may benefit your operation by reducing maintenance, down time, and the need for shutdowns during adverse conditions.

The main environmental impacts of concern to landowners today that relate to timber harvesting are loss of soil nutrients, soil damage, and loss of wildlife habitat, biodiversity, and aesthetics. The following sections briefly describe these impacts and some alternative techniques that can help minimize them. You may want to use more than one of these alternative strategies in some areas.

Some techniques and technologies to reduce these environmental impacts may not be locally available today. Others are being developed. Because product lines change constantly, we do not refer to specific companies or products. Nevertheless, the information that follows will provide a valuable starting point as you plan how your harvesting operations can accommodate the increased demand for environmental protection. A glossary is included at the end of the publication to define key terms.

Nutrient Depletion

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Nutrients are an important part of a healthy forest. A forest's nutrient capital — the nutrients in the plants, animals, dead matter, and soil — plays a big part in how well trees grow and reproduce. Some soils do a good job of retaining nutrients and organic particles and supporting the decomposers that make nutrients available to plants. Others are less able to do so.

Much of a forest's nutrient capital is found in living trees. Timber harvesting removes some nutrients. On many soils this amount is insignificant compared to the total nutrient capital. On soils where the nutrient supply to plants is limited, however, harvesting may remove enough nutrients to harm future forest productivity.

Different harvesting systems affect the nutrient capital differently. Tree-length and shortwood systems that harvest only the main stem or bole remove fewer nutrients than the full-tree system, which also takes leaves and bark from the site.

You can reduce nutrient loss by delimbing and debarking at the stump and leaving unmerchantable material there, and by distributing unmerchantable material generated at the landing back across the site. This allows the nutrients in the leaves, small branches, and bark to remain available for future trees.

Delimbing

Figure 1. Feller-processor head

One way to delimb at the stump is with a chain saw. Productivity is low and labor cost is high with this method. In addition, feller-bunchers and grapple skidders lose efficiency when combined with chain saw delimbing.

Some machines designed for delimbing at the landing can be used at the stump. These machines are less productive and more expensive to operate in the woods. However, mobile delimbers are increasingly being used for this purpose.

Cut-to-length (CTL) systems, pioneered in Scandinavia, are another option for delimbing at the stump. These are feller-processors that combine felling, delimbing, and bucking functions in a single in-woods machine. The feller-processor works in conjunction with a forwarder, which takes the cut-to-length shortwood pieces to a landing or a roadside.

In most CTL processors, rollers feed stems past stationary delimbing knives (Figure 1). Such machines were designed for conifers and may not work as well with hardwoods because the larger limbs and crooked stems are more difficult to feed through the rollers and delimbing knives. However, changes in head design continue to improve processing of hardwood trees. A few processors have stroke-type delimbers that can handle large-limbed hardwoods more easily (Figure 2). Machines equipped with both the stroke-type delimber and stationary delimbing knives may be appropriate for mixed hardwood and conifer forests.

CTL systems are more expensive to operate than most common tree-length and full-tree systems. However, they also make it easier to sort higher-value products and increase the productivity of thinning operations over some equipment combinations developed for clearcutting. If you consider performance in thinnings as well as clearcutting, CTL systems may provide an average production level similar to that of full-tree systems under the same conditions. And if labor costs continue to increase, CTL harvesting may become even more competitive because it requires very little labor.

Debarking

Debarking usually occurs at the mill, where the bark is used for boiler fuel or mulch or is discarded. Debarking at the landing recently has been introduced for the production of high-quality chips from full-tree logging and chipping. However, this still removes bark from the immediate vicinity of the individual harvested trees. Debarking at the stump would keep more nutrients near the harvested tree.

Debarking at the landing. Debarking at the landing is becoming more common in full-tree chip harvesting because mills often require chips to contain less than one percent bark.

Chain flail debarking in front of the chipper is the most common technique for debarking at the landing. Portable drum and ring debarkers are also available and produce chips with lower bark content than chain flail debarkers. Portable drum and ring debarker operations typically are larger and serve larger satellite chipping mills rather than individual landings.

Debarking at the landing has the same nutrient loss drawback as full- tree harvesting unless bark and limbs are distributed evenly over the harvested area. One partial solution is for the grapple skidder to grab a pile of slash and bark and distribute it during the return trip. While this involves nearly no extra cost, it also produces small, scattered piles rather than an even distribution.

Figure 2. Stroke/roller feller-processor head

Debarking at the stump. Debarking at the stump is rare because manual methods are slow and mechanical methods are only now being developed. Manual debarking at the stump is common in other countries and was common in the United States when manual harvesting was more widespread. It works well during the growing season when the bark is easily separated from wood. However, low productivity and high labor costs make it incompatible with mechanized logging.

Mechanical systems are being developed for debarking at the stump. Because different tree species have different bark characteristics, such systems may have to be adapted to specific circumstances. If efficient systems become available, they could not only benefit the forest by leaving nutrients at the stump, but also benefit the logger by reducing hauling costs and increasing product quality However, de- barking at the stump may introduce difficulties in transportation and fiber quality not present in the current system.

Systems under development for debarking at the stump include modified delimbing knives with feed rollers and compression rollers. Delimbing knives may be modified for debarking by increasing the pressure on the knives and using feed rollers with more aggressive teeth. Compression rollers remove bark by compressing it against the stem and so loosening it.

Few commercial machines exist for either of these debarking designs. The best ones remove 60 to 70 percent of bark area with substantial reduction in overall system productivity. There is little information to indicate if the systems would work on tree species in North America or how they are affected by frozen bark. However, it is probably only a matter of time before such machines become available in the United States.

Soil Disturbance and Compaction

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Soils not disturbed by machine traffic often have pores and structure that developed over hundreds of years. This structure aids in root growth, water infiltration, and microbial activity, all of which enhance nutrient availability and tree growth.

Soil compaction and disturbance resulting from timber harvesting can disrupt soil structure, harming tree growth and regeneration. Although soil eventually recovers, it may take years or even decades depending on the severity of compaction, soil type, and climate. Soils with shrink-swell clays and moist soils subject to freezing and thawing recover much more quickly than other soils.

Soil compaction can be a serious problem in timber harvesting. Unless soils are frozen, compaction is inevitable due to felling, skidding, and/or forwarding. Landings, main skid trails, and secondary skid trails are the principal areas affected.

On susceptible soils, shallow ruts form with the first pass of a machine. Ruts can become steadily deeper with more traffic unless impeded by a hardpan or bedrock. Soil compaction severe enough to harm plant growth usually occurs after five to ten passes of a machine. Deep ruts may collect water, disrupt underground water movement, and flood surrounding areas, injuring tree growth. In some forests the skid trails and landings are still visible from harvests 60 and 70 years earlier.

To reduce compaction, evaluate the soil's susceptibility before beginning harvest. Wet soils are more easily compacted than dry soils. Clay and loam soils are more easily compacted than sandy soils. Protect susceptible soils by harvesting only when the ground is frozen or using techniques such as those described below to minimize compaction.

Skidding Patterns

If a skid trail network is not already established, machine operators often use an unrestricted number of trails to bring the wood to the landing. This can lead to trafficking of up to 70 percent of the logged area. To protect susceptible soils under such conditions, confine traffic to the smallest possible area. While this approach increases the severity of rutting within the trafficked area, it minimizes the total area affected.

An even better way to reduce soil compaction is to limit skidders or forwarders to designated trails. Plan trails before you start logging and stick to them. Be sure to consider the lay of the trail network when felling so that you can reach trees from the trail with minimal maneuvering.

Trail designs often follow specific patterns. In the most common, main trails parallel one another, with one trail channeling the rest to a centralized landing (Figure 3). The lowest trail density can be achieved with widely placed parallel trails. The distance between main trails can be expanded if short secondary trails are made at angles, usually 45 degrees, to the main trail (Figure 4). This design is called a herringbone. In a third design, known as dendritic, main trails branch into other trails that access the remainder of the area (Figure 5). Dendritic patterns lead to higher trail density than other patterns but are sometimes the best option for irregularly shaped areas with a single landing or for hilly terrain.

Figure 3. Parallel trail design

Figure 4. Herringbone trail design

Figure 5. Dendritic trail design

You can also minimize the trafficked area if you start harvesting at the back of the site and use designated trails throughout. Designated skid trails only slightly increase average turn distance and time because there is less wandering and bunch placements by the feller are more reliable.

High Flotation

A second way to protect susceptible soils from compaction is to reduce the pressure on them from machinery by increasing flotation. Tires and tracks apply two main forces to soils (Figure 6). The vertical force, which relates to the soil's ability to support the machine, is called flotation. The horizontal force, which moves the machine forward, is known as traction. Soil texture and moisture influence both forces.

Figure 6. Flotation and traction Wider tires and duals increase the soil contact area and increase traction and flotation on moist and wet soils.

Machines are normally equipped so they move easily and provide adequate traction under most soil conditions. When soils are dry or frozen, machines without high flotation are most efficient because high flotation tires or tracks make the machine heavier and more cumbersome. On soils that are susceptible to compaction, however, high-flotation equipment is needed to minimize soil damage. Such equipment can reduce rut depth on main trails and reduce compaction elsewhere. This allows greater use of trails that might otherwise become impassable, eliminating the need to expand the trail system and controlling the area of soil compaction.

You can increase flotation (and usually traction, too) by increasing the size of tires or tracks to spread the machine weight over more surface area. Ground pressures of less than 5 or 6 pounds per square inch (psi) are often considered high flotation. Ground pressures lower than 4 psi may be needed to operate on swamps without difficulty.

You can compare the flotation of various machine-tire combinations without loads if you know the weight of the machine and the footprint area, or the contact area between the tire or tracks and the soil (see formulae below). Once you know the ground pressure of your existing machine-tire combination, you can estimate how changing tire sizes would change your ground pressure. After you calculate the ground pressure of the machine, evaluate the soil to determine whether you need high flotation (see Figure 7).

Estimating ground pressure of machinery

For wheeled machines, ground pressure in pounds per square inch (psi) without load is approximated as: [Formula 1]

machine weight —————————————— tire footprint x number of tires

Machine weight can be determined from information provided by the dealer. You can approximate tire footprint if you know the tire size. Tire sizes are commonly given as a series of three numbers such as 66 x 43.00 – 26, where the first number is the tire diameter in inches, the second is the tire width in inches, and the third is the rim diameter in inches. The approximate tire footprint in square inches equals: [Formula 2]

tire diameter ———————— 2

x tire width

To calculate ground pressure for tracked vehicles without a load, first convert all dimensions to inches or pounds. Ground pressure then equals: [Formula 3]

machine weight —————————————— track length x track width x 2

Example: 110 hp skidder; weight 27,000 lbs, with tires 73 x 44.00 – 32 Tire footprint = (tire diameter/2) x tire width = (73/2) x 44 = 1,606 square inches Ground pressure = weight / (tire footprint x number of tires) = 27,000 / (1,606 x 4) = 4.20 psi (pounds per square inch) without load

Figure 7. Method for determining the need for high flotation machines.

First determine the soil texture. Then determine the soil moisture by using the characteristics listed for that texture. Castes are made by pressing the thumb into a small amount of soil held in the palm of the hand.

If you know the soil moisture and texture, you can determine what ground pressure is needed to minimize rutting and compaction on different soil conditions (determine psi as shown in the formulae section above.)

Wet organic soils High floatation machines (ground pressure no more than 4 psi unloaded) are needed to minimize rutting.	Moist clay and loam soils Moist sandy soils High flotation machines (ground pressure no more than 5 psi unloaded) are optional to reduce compaction and rutting.
Moist organic soils Wet clay and loam soils Wet sandy soils High flotation machines (ground pressure no more than 5 psi unloaded) are needed to minimize compaction and rutting.	Dry clay and loam soils Dry sandy soils No high flotation machines are needed because there is little concern for compaction or rutting.

For forwarders, you could add load weight to machine weight in Formula 1 (see above) to determine total ground pressure. This doesn't work for skidders, however, because the proportion of the load weight transferred to the skidder varies. Once the machine is equipped with high-flotation tires, it is important that you not increase the load over what you would put on conventional machines and that you decrease the load as soil conditions worsen. Otherwise the benefits that are provided to the site by high flotation will be reduced or lost.

Forwarders typically have higher ground pressure than skidders but skidders require more power to counteract friction from dragging. As a result, a skidder must be more powerful and heavier than a forwarder to move a given load. Since forwarders can carry larger loads than skidders of the same horsepower, it's more practical for forwarders to decrease load size to maintain flotation when soils are wet and easily rutted. Operating on wet soils that force skidders to decrease load size leads to very poor productivity and high production costs.

Most tracked machines are high flotation. Many are available with wider tracks to handle extreme conditions. In such conditions tracked vehicles are often superior to wheeled vehicles because they provide not only more flotation but also more traction. However, tracked vehicles typically are slower than wheeled machines. They also are less suitable for forwarding and skidding in highly mechanized systems, especially where skid distances are long. Tracked machines are preferred when loads are very large or where the terrain is very steep or very swampy.

Tracked skidders have been developed that are much faster than commonly available crawler tractors, but they have not been widely used because of their high initial cost.

Figure 8. Clambunk skidder Clambunk skidders with bogeys are an example of machines with high payloads that maintain low ground pressure. Bogeys act like tracks to spread the machine and load weight over a greater surface area.

You can decrease ground pressure in three ways:

• Increase tire diameter and width. Tall, narrow tires make machines more maneuverable than short, wide tires. However, it's hard to increase footprint substantially just with increases in tire diameter.

• Increase the number of wheels. Some skidders and forwarders are limited by chassis design to two axles. Others, notably clambunk skidders with a grapple that opens upward (Figure 8), have three or four axles. These machines can be equipped with bogeys over pairs of axles, making them similar to tracks. Dual tires also decrease ground pressure. However, they also make the machine extremely wide and harder to maneuver.

• Use smaller machines. The largest skidders or forwarders may weigh more than 35,000 pounds while small machines may weigh less than 15,000 pounds. Large machines allow greater hauling distances and less labor. However, it is also harder to reduce ground pressure by increasing tire size on such machines.

Cable Logging

Figure 9. Skyline cable system

Figure 10. Highlead cable system

Cable logging is another technique for reducing soil compaction. In this method, a yarder pulls logs into the landing with cables. This eliminates the need for skid trails and machine traffic.

There are two common cable configurations. In skyline systems (Figure 9), a cable lifts most or all of the load off the ground during transport to the landing by another cable. In highlead systems (Figure 10), the yarder pulls logs to the landing and the only lift is provided by the height of the tower.

Cable logging is most common on steep mountain slopes. It also has been used in the swamps of the southeastern United States. It is practical on gentle slopes and flat land, especially in the skyline configuration. On flat land or slopes that have irregular shapes or ridges, intermediate supports are used.

Cable logging is more expensive than skidding and forwarding. However, it may have a place in salvage harvests or in harvesting valuable wood where skidders and forwarders cannot operate safely or would cause too much disturbance. The limits of ground-based logging with skidders and forwarders have often been considered to be at 30 percent to 40 percent slope. However, where the timber values support it, the use of cable logging in low-slope areas is increasing because of concerns about soil disturbance.

Habitat, Biodiversity, and Aesthetics

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There is a lot of potential in forest management to protect biodiversity and enhance wildlife habitat. Protecting biodiversity includes managing rare habitats such as old growth more carefully. But there is clearly a role for logging and forest management in protecting biodiversity and enhancing wildlife habitat.

There is considerable concern about the common use of clearcutting. Clearcutting provides valuable habitat for many types of wildlife and plants, but it might be overused as a logging technique. Partial cuts are appropriate for regeneration and management of many types of forests. They retain many qualities of intact forest while allowing timber to be harvested. Partial cutting helps to retain valuable microhabitats for shade-loving plants. The presence of trees and shrubs of different ages and heights in close proximity makes the habitat more productive for many wildlife species.

Clearcuts also have become a rallying point for opposition to timber harvesting activity because the change in the landscape is so dramatic. While clearcuts are valuable for forest management and many ecological objectives, they may need to be limited in areas that are very visible to the public in order to protect aesthetic values.

Alternative Harvesting Technologies

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Increased use of partial cutting may mean increased demand for machines that work well in partial cutting situations. Most machines used today are fast and can manage large loads, making them most suitable for clearcutting. Machines that operate in partial cuts must be smaller and more maneuverable.

You can use tree-length and full-tree systems for partial cuttings and thinnings. However, you will need to use smaller fellers and skidders and to apply special techniques. Such limitations raise production costs above those for clearcutting. However, if there is sufficient demand for thinning and partial cutting, the change to smaller equipment may be well justified.

Changes in felling machine design and equipment to facilitate partial cutting have included:

• Using CTL systems which include both delimbing and bucking mechanisms on felling machines, making it easier to transport logs through small openings in partial cuttings;

• Decreasing the width and lowering the profile and center of gravity of fellers and using narrower and lighter skidders and forwarders to provide efficient maneuvering and minimize damage to the residual stand; and

• Improving maneuverability by forwarding rather than skidding wood from stump to landing.

Conventional machines such as rubber-tired or tracked feller-bunchers can be used in partial cut operations. However, other machines have been developed with the special needs of partial cutting in mind. Some are very sophisticated. Others are simpler and do the job without frills. Following are descriptions of some machines that were developed with partial cutting in mind. As you consider how well they would fit into your operation, be sure to consider your requirements for productivity, operating conditions, and cost.

Feller-Processors

Many new feller-processor designs have appeared in the past decade. The combinations of features available are numerous. Some general categories are identified here.

Figure 11. Single grip feller-processor on six-wheeled chassis

Single grip feller-processors on six- or eight-wheeled chassis (Figure 11). These CTL machines typically have extended chassis with articulated steering and rubber tires. Felling booms are located on one end. The felling head does the felling, bucking, and delimbing. The felling or processor head is hydraulically operated and typically consists of a chain saw that fells and bucks the log, rollers that advance the log through the head, and knives and/or stroke delimbers that remove limbs. These machines come in many brands and sizes. Differences among machines include hydraulic control of the head, speed, design of the rollers, and design of the boom.

Figure 12. Two-grip feller-processor on six-wheeled chassis

Two-grip feller-processors on a six- or eight-wheeled chassis (Figure 12). These CTL machines are similar to the single-grip design except that a separate device mounted on the machine does the delimbing and bucking. The tree is felled and then handed to the processor. This design may be slower than the single grip but can handle large trees more easily.

Figure 13. Single grip feller-processor on excavator chassis

Single grip feller-processors on excavator chassis (Figure 13). Excavator chassis have a rigid undercarriage. Most have tracks. In some, the vehicle cab and boom rotate and tilt. Excavator chassis come in a variety of sizes. Some allow operation in areas of extreme slope or difficult obstacles. The increase in working radius and low ground pressure these machines provide can help decrease site trafficking and soil compaction and make it easier to cut trees up to about 25 feet away from the machine.

Figure 14. Tricycle chassis feller-buncher

Feller-bunchers on a tricycle chassis (Figure 14). Tricycle fellers have a drive axle in front and a stabilizing wheel at the rear. These machines are very maneuverable and quick. However, they lack booms and must approach every tree. This increases site trafficking and makes it harder to guide felling direction and to create piles for skidding.

Skidders and Forwarders

Figure 15. Bumper trees Bumper, or rub, trees prevent damage to trees that are to be reserved. Use low-quality trees or trees scheduled for removal as bumper trees. In most cases damaged bumper trees, especially conifers, should be removed at the end of the harvest.

Skidders over 120 horsepower are common in clearcut operations. However, because of their size they can be very confined in partial cut operations. Skidders are more likely to injure trees and are slower and less maneuverable than forwarders in partial cuts. Damage can be minimized when skidding in partial cuttings by using cable skidders, in-woods delimbing or bucking, designated skid trails, directional felling, and bumper or rub trees to protect the residual stand (Figure 15).

Forwarders are available in a variety of sizes. The larger loads possible with forwarders often justify long hauling distances and the slower loading times. Use designated trails with forwarders to minimize soil compaction and residual tree damage.

Conclusions

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There are many techniques and technologies available or under development that help reduce the environmental impacts of timber harvesting. However, it is hard to compare productivity, costs, and environmental effects of various options because they vary with operating condition and operator.

If you are trying to compare alternatives, start by talking with people who are already using them. If you can't find anyone, you may need to rely on equipment demonstrations, manufacturers, and reports of equipment performance. Be sure to look carefully at the operating conditions in published studies to make sure they are similar to the ones in which you normally operate.

Some USDA Forest Service Experiment Stations publish results of studies of forest harvesting techniques and equipment. Stations active in forest engineering research are listed at the end of this paper. The Forest Engineering Research Institute of Canada (FERIC) publishes equipment reports. So do forestry and forest products journals. Trade organizations and magazines also are good sources for this type of information. Contact the library of a college or university with a forestry program for more information about logging publications. Your natural resource extension educator, public forest management agency, or private forestry consultant also may have valuable information concerning logging publications and research.

Glossary

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Biodiversity – The variety of living organisms.

Bumper or rub tree – A tree in a partial cut whose position next to the skid trail will protect the residual trees from damage.

Clearcut – Timber harvest that removes nearly all the merchantable trees and sometimes unmerchantable trees from an area usually greater than two acres.

Cut-to-length system (CTL) – A feller-processor that combines felling with delimbing and bucking at the tree stump.

Feller-processor – A machine that combines felling with one or more other functions, typically delimbing and bucking.

Forwarder – A machine commonly used with a short-wood system that transports wood in the forest while completely supporting it.

Full-tree system – A harvesting system in which the entire tree is hauled to the landing (usually by a skidder) after felling.

High flotation – Equipment that has a ground pressure of less than five or six pounds per square inch (psi). Less than four psi may be needed to operate on swamps without difficulty.

Highlead – A cable yarding system in which lead blocks are hung on a spar or tower to provide lift to the front end of the logs.

Landing – Area on a harvested site where wood is transferred from the skidders or forwarders to trucks for road transport. In some operations the trees are processed or stored on the landing before transport.

Nutrient capital – The total supply of nutrients in the organic matter and the soil.

Partial cutting – Any harvest in which not all of the trees are removed.

Residual tree – Any tree not harvested within a harvest area.

Rut or rutting – Depressions in the soil caused by repeated machine traffic.

Shortwood system – A harvesting system in which the tree is felled, delimbed, and cut into short lengths before it is hauled to the landing (usually by a forwarder).

Skidder – A machine that transports wood in the forest by supporting it at one end and dragging the other across the ground.

Skyline – A cable logging method in which a block or carriage rides on a wire rope called a skyline.

Soil compaction – Increase in the soil density that reduces soil drainage and soil aeration, often leading to decreased plant growth.

Soil disturbance – Any impact on the soil surface, including the litter and humus layers at the soil surface. Soil disturbance can be very slight (removal of the litter layer) or very heavy (rutting and soil compaction).

Tree-length system – A harvesting system in which the tree is felled and delimbed in the woods, and hauled to the landing (usually by a skidder).

Resources

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United States Department of Agriculture, Forest Service

Intermountain Forest and Range Experiment Station
Forest Science Laboratory
1221 South Main
Moscow, ID 83843

North Central Forest Experiment Station
Forest Science Laboratory
410 MacInnes Dr.
Houghton, MI 49931

Southern Forest Experiment Station
Andrews Forest Sciences Laboratory
Devall Street
Auburn University
Auburn, AL 36849

Northeastern Forest Experiment Station
Forest Sciences Laboratory
180 Canfield St.
Morgantown, WV 26505

Canada

Forest Engineering Research Institute of Canada (FERIC)
143 Place Frontenac
Pointe Claire, Quebec
Canada H9R 4Z7

Mathew Smidt graduate research assistant	Charles R. Blinn associate professor extension specialist
Department of Forest Resources University of Minnesota, St. Paul, MN 55108. The authors' Internet address is: cblinn@forestry.umn.edu.
Product manager: Karen Burke	Editor: Mary Hoff	Design, graphics: Jim Kiehne

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