Coppice methods use vegetative means to regenerate species; tree crops originate mainly from shoots and suckers, and are grown in relatively short rotations (Helms 1998, Society of American Foresters 1989). Coppice methods are applicable only to the species and individual trees that have a capacity to sprout or sucker. That requirement limits coppice systems mainly to stands of broadleaved species, and to trees of young to moderate ages.

The coppice method involves clearfelling all trees in the original stand in blocks, strips, or patches. Clearfelling allocates total space to the new age class, and makes maximum resources available to the sprouts and suckers. Because the new shoots live off well-established and large root systems of the parent trees, with many absorbing and actively growing tips, new coppice grows rapidly and forms a closed canopy sooner than in even-aged seedling stands (Nyland 1996).

Two variants of coppice methods are distinguished by whether they include trees of seed origin. Simple coppice methods retain only trees of sprout origin, while the coppice-with-standards method rentains both sprout- and seed-origin trees (Nyland 1996).

Simple coppice methods retain only trees of sprout origin, and vary according to the location of sprouts (from stumps or roots) and the length of rotation (Nyland 1996).

Coppice Methods Based on Stump Sprouting

There are several considerations in using coppice systems with stump sprouts. Sprouts that emerge close to the ground or from the root collar are less likely to develop decay than sprouts off the tops or upper parts of tall stumps. Sprouts attached to a large mass of decaying stump also are more likely to develop rot. Perhaps for that reason alone, sprouts from younger trees (less than 35-40 years old) do not develop decay as readily as sprouts from older trees. Foresters can control these problems by having the logging crews cut the trees close to the ground, and by limiting the rotation length (Nyland 1996).

Stools repeatedly coppiced decrease in sprouting capacity after several generations, so that after about three rotations landowners must replace the old stools. In studies, average shoot height and diameter from surviving stools decreased with each successive cycle. With sycamore, trials have shown that annual coppicing reduces the number of sprouts, their basal diameter, their total height, and their green weight compared with rotations of 3-4 years (Kennedy 1975, Schmeckpeper and Belanger 1985). Additionally, as many as 15 percent of the stumps may not sprout due to logging damage (Zobel and others 1987). With alder and locust, only stools with moderate to heavy damage decline in sucker productivity (Nyland 1996).

While coppicing via stump sprouts normally produces a multistem clump, the weaker sprouts die as a clump develops. Numbers per clump decline fairly rapidly during early stages of stand development, leaving only one or two by large pole or sawtimber sized stems (Stroempl 1984). With long rotations, this self-thinning leads to a normal-looking community of trees that pose no particular problems during eventual harvesting. In short rotations, logging crews must use equipment suited to cutting multistem stumps close to the ground. Otherwise they leave tall stumps that give rise to poor-quality sprouts (Nyland 1996).

Short-Rotation Coppice Systems

Interest in using wood as an energy source led to several innovative coppicing systems. Generally, species that reproduce vegetatively by stump sprouts were used in plantations. Short- and mini-rotation coppice crops appeared to offer considerable potential for producing high volumes of wood fiber on a relatively limited land area. These schemes usually include production of woody biomass in rotations of 1 to a few years. Species of Alnus, Platanus, Populus, and Salix have shown great promise for short-term fiber crops in temperate regions. One early scheme tested in the Southeast became known as silage sycamore. Sycamore planted at 1- by 4- to 4- by 4-foot spacing on 3-year rotations yielded 13-14 green tons/acre/year (32.1-34.6 green tons/hectare/year) (Nyland 1996).

With short rotation coppice systems, managers must manage soil nutrients to maintain high levels of fertility over repeated cutting cycles. Since nutrients are concentrated in living tissues, harvesting on short cycles eventually reduces available nutrients below the levels required for continued vigorous growth. Unless managers lengthen the rotation or supplement the nutrient losses by applying fertilizer, productivity will decline (Nyland 1996).

Coppice Methods Based on Root Suckers

Coppice systems based on root suckers differ in several ways from coppice based on stump sprout. Compared with stump sprouts, suckers come up singly, develop independent root systems, fill the area more evenly, and do not develop decay from the parent tree. Furthermore, suckering potential does not decline over repeated rotations. The new age class usually has a greater stem density than the parent stand, and the spatial distribution resembles that of a well-stocked seed-origin community (Nyland 1996).

Although treatments, such as disking, that sever or break root systems will reduce suckering, small injuries that break the bark and promote callus formation may enhance sprouting in some species (Jones and Raynal 1986). Prescribed burning has promoted suckering at sites with a fairly thick organic layer, and in clearfelled and burned areas suckers are produced from deeper roots, perhaps due to added heat absorption by the blackened surface (Nyland 1996). Aspen and American beech are two tree species that lend themselves well to coppice methods based on root suckers.

Setting Rotation Length in Coppice Systems

In sucker- and sprout-origin stands, the crop should be harvested when mean annual increment peaks. Because landowners use coppice systems primarily to produce fiber products, they do not thin the stand. Intermediate treatments may include a release cutting to eliminate undesirable tree or shrub species, and protection measures to ensure stand health and safety. Harvesting is done by clearfelling (Nyland 1996).

Conversion from Coppice to High-Forest Systems

Conversion from coppice to high-forest systems usually takes a long time. This transition will include: (1) holding the coppice growth to an advanced age to weaken its sprouting capacity and reduce its crown density, (2) increasing the numbers of trees of desired species and growing them to seed-bearing age to serve as parents for seed-origin trees and to increasingly shade the coppice undergrowth, (3) thinning the coppice growth to maintain its vigor to an extended age, and (4) gradually removing the sprout-origin trees to make space for seedlings to develop (Nyland 1996).

See: Advantages and Disadvantages of Simple Coppice Systems

Coppicing offers some general advantages over high-forest methods (Nyland 1996):

1. It involves relatively simple harvesting methods (clearfelling), and provides prompt and certain regeneration.
2. It effectively regenerates areas of any size and shape without concern for advance regeneration or seed source.
3. It produces abundant coppice shoots that grow rapidly in height and diameter, with high annual production per unit of area.
4. It allows landowners to produce high volumes of fiber crops, fuel wood, and forage over relatively short rotations.
5. It minimizes the health and disease problems associated with long rotations and old trees.
6. It produces stands of great uniformity, well suited to mechanized harvesting.
7. It provides the potential for maintaining a variety of developmental stages between adjacent stands, thereby diversifying the habitats for wildlife and herbs.

Coppice methods have some distinct shortcomings as well (Nyland 1996):

1. Financial success depends upon access to markets for small-diameter pieces and wood chips rather than saw logs.
2. Coppice systems serve a limited set of management goals, and landowners have traditionally used them with only a few species.
3. Frequent entry for harvesting requires extra caution to minimize soil disturbance on slopes, and soil nutrients may be lost after repeated rotations.
4. Succulent coppice shoots suffer damage from early- or late- growing-season freezing temperatures, and from browsing by wild animals.
5. To maintain sprouting capacity, landowners must eventually replace the old stools with new rootstocks or seedling-origin trees.
6. Replacing existing coppice stands with new trees often proves difficult and costly.
7. Coppice stands have limited amenity and other nonmarket values due to the small trees, and the uniformity of size classes.

A coppice-with-standards method maintains seed-origin trees at wide spacings for long periods interspersed with coppice crops managed on short rotations. The standards serve as parents for seedlings to renew the coppice growth as sprouting vigor declines, and to produce large-diameter sawtimber. Foresters can use coppice-with-standards systems to grow mixed-species communities, and maintain species that do not reproduce vegetatively. Most landowners use a coppice-with-standards system where markets take both small- and large-diameter products. This system may also enhance recreational uses, maintain a more favorable habitat for some wild creatures, or have some other special value to a landowner. Foresters may also use a system called "compound coppice," in which some old standards are harvested and the remainder are left to grow for additional rotations (Nyland 1996).

See: Advantages and Disadvantages of Coppice-with-Standards

A coppice-with-standards system offers some distinct advantages over simple coppice systems (Nyland 1996):

1. It yields materials of several different sizes, with some large-diameter trees of high value.
2. It provides regular returns from each stand at short intervals.
3. It retains only a relatively low residual value per unit of area, benefitting landowners who require high compound rates of return and who also wish to grow large and high-value trees.
4. The standards grow rapidly, and increase in volume and value at above-average rates.
5. The standards eventually produce viable seeds, allowing landowners to establish a seed-origin stand, or to maintain both vegetative and seed-origin growing stock.
6. The continuous partial cover of tall trees and dense understory of coppice growth protect the soil better than simple coppice systems.
7. The dense coppice between the standards prevents site occupancy by undesirable trees and other woody growth.
8. The standards enhance the appearance of a stand, both immediately after a felling and during the interim between successive entries.
9. Landowners can maintain a more diverse array of species and age classes, and provide habitat for a broader community of wildlife.

A coppice-with-standards also system has some important limitations (Nyland 1996):

1. Its complexity makes the system difficult to apply. It is particularly difficult to maintain an appropriate balance of growing space between the coppice growth and the standards.
2. The dense growth of coppice often obscures crowns of the taller trees, making reserve tree selection difficult during marking.
3. Foresters must develop regular markets for large volumes of small-diameter pieces from the coppice growth, as well as for saw logs.
4. Exposure increases the likelihood of epicormic branching and sunscald on the standards, potentially degrading their main trunks.
5. Shading by the standards may suppress coppice growth beneath reducing its development and yield, particularly in stands with multiple age classes.
6. With compound coppice systems, shading may inhibit most shade-intolerant species in the coppice growth.
7. The large machines and high-production logging systems that offer the greatest cost effectiveness for harvesting fiber crops may injure the standards.
8. Standards freed by heavy cutting may suffer wind and snow damage on exposed sites, and blowdown in areas with shallow soils.
9. When harvested, the standards may not sprout, necessitating replacement by planting or regeneration from seed.
10. Young trees intended as future standards require early release (cleaning) to ensure adequate rates of development.
11. Landowners may need to prune the lower boles of the standards to produce high-quality saw logs.
12. Standards often develop poor form and heavy branching, making them more susceptible to ice and snow loading, breakage, and blowdown.