Here's How to Manage a Woodlot for Firewood

From the December 2004 issue of The Forestry Source

Just as the owners of large tracts of land must establish management plans to ensure that their forest land remains productive, owners of small woodlots must do the same-even if their objective is something as seemingly straightforward as firewood productions In fact, even if a landowner's goal is to meet his or her personal fuel wood needs for the year, steps must be taken to ensure that a sufficient number of trees are available for two or three cords of stacked wood to be harvested annually without depleting the supply.

Before cutting any firewood,inventory all the trees within the boundary of the landscape you have set aside for fuel wood production. The inventory should include the number and species of trees and two measurements: the total height (in feet) and the diameter (in inches) at breast height (dbh). The dbh is generally taken at 4.5 feet above the ground.

For example, using the table at the right, if the measured tree is 12 inches dbh and 60 feet tall,approximately .33 standard cords of firewood can be cut from that tree. Repeat this exercise for each tree in the woodlot to find the total number of standard cords of firewood currently available.

Keep records of the initial inventory of trees and wood volume. Record and deduct the trees and volume you remove and watch for those trees that were previously not counted but grew large enough to be measured and added to the total volume. As a rule, an acre of good hardwood land should be capable of producing about two cords of wood each year. Hardwood sites with this capacity can produce almost all of your fuel needs on a single acre. On poorer sites, several acres may be required to yield the same continuous supply.

The First Firewood Harvest 
On a well-forested site, the first firewood harvesting effort should be a thinning. Suppressed trees (i.e., trees that are tall, slender, and have compressed crowns because of overcrowding)should be removed. Leave for the time being dominant trees that have expressed a competitive advantage by producing a full, wide-spreading crown. This method of cutting, often called a "low thinning" or "thinning from below," facilitates the removal of trees that have not grown as fast as others in the stand. It also reduces unnecessary competition for the fast-growers.

Any improvements to the stand, such as taking out diseased, damaged, and defective trees, may be conducted at this time. Dead trees or decaying snags may be left as nesting cavities for birds and animals. These relics are by no means competing with the other trees, and the decaying wood is less than satisfactory for fuel. However,they may cause accidents when they fall, so watch them closely.

If possible, conduct thinning and cutting operations in the late winter/early spring of the year in which the wood will be used. This schedule gives adequate time for the wood to dry to the right moisture content for efficient burning. It is also important in regenerating the stand.

Second-Year Harvest 
Because most of the suppressed, dead, and dying trees were removed during the first year's low thinning and improvement operations, the second-year harvest must come from the larger, healthier trees in the stand.

Thus, the second year's harvest will drastically modify the stand, because trees that make up the main canopy will be removed.

Choosing the trees to cut during the second year may be based on several factors, but the most important relates to the growth rate of the individual trees. Using the inventory information from the previous year, several trees that were measured should be identified New measurements should be taken on those trees to find out how much new wood has accrued over the past year. For example, if the estimated standing volume after the first cut (the low thinning and cut) was 10 cords and the estimated standing volume before the second year's harvest is 11 cords,harvest only one cord during the second year. Make the second-year firewood cut from those trees that did not show any growth over the past year. If all the trees that were measured showed some new growth, cut from those that grew the least.

It is important to remember not to allow the harvest to exceed the amount of wood that the stand is adding through growth each year. This concept, known as "sustained yield management,"ensures a steady supply of firewood for the future. By eliminating the slow-growing species and reducing competition for sunlight, space, nutrients,and moisture, the best trees may even have higher growth rates. In fact, if handled properly, the volume of the annual harvest may increase.

Plans for conducting the third-year and subsequent harvests should be carried out in the same manner as the second year's operations.

Regenerating the Stand 
During the second year's cutting operations, known as "selective thinning" or "thinning from above,"some provision must be made for the regeneration of new trees. Keep in mind during the harvest that several young trees are already present in the general area of the one being cut. Identify some of the larger, more vigorous seedlings and protect them during the cutting operation.

Many species of hardwoods will sprout from living stumps to produce a "coppice," or sprout stand. Some species sprout more than others, and in general the younger trees sprout better than older ones. Many of the species that make excellent firewood, such as oaks, sprout abundantly. Cutting the parent tree in late winter/early spring also may increase the chances for sprouting. Because the stump already has an extensive root system and it is still alive, first-season sprouts will grow more rapidly than either planted or natural seedlings.

During the first spring,each stump may produce numerous sprouts. Select the largest stem on each stump and pull or cut the remaining ones. This concentrates the future growth into one tree rather than several small ones that would be overcrowded.

Because the stand will have large gaps left in the canopy, many species of grasses, shrubs, nettles, and briars will invade the open area in the spring. This vegetation may not over top the seedlings and sprouts that were left, but it will compete for nutrients and moisture Controlling the undesirable vegetation through chopping, raking, or chemical treatment should increase the growth rates of the favored seedlings.

Areas that are not in forest may be planted with species that are suitable for firewood.
For hardwood plantings, the land must be prepared almost as well as a field for agricultural crops. After planting, the seedlings must be protected from grazing animals and vegetative competition until they are well established.

Once the planted stands are established, they may be managed similar to the management scheme detailed previously for natural stands. The first harvest should be a low thinning to take out those trees that were suppressed. The second and all future harvests should be based on the amount of wood that grew the previous year.

This article was adapted from Managing Your Forest Landscape for Firewood (FOR-19), by D.M. Flinchum, a publication of the University of Florida, Institute of Food and Agricultural Sciences Extension Service. (Note:This document was first published as FRC-19 in 1981 and was revised in April 1998)

For more information,contact D.M. Flinchum, professor, University of Florida, Everglades Research Center, 3200 East Palm Beach Road, Belle Glade, FL 33430; (561) 753-5241; dmflinchum@ifas.ufl.edu.

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