Thinning for Firewood
Fuelwood production from thinnings of woodlands can not only provide fuelwood, but should be done to improve the woodland by allowing desirable trees more growing space. Care must be exercised in harvesting to ensure that the quality of the woodland is not reduced.
The goal of fuelwood harvests should be to make the woodland better after the harvest than before. Concentrate this timber stand improvement practice on young stands (6-10 inches in diameter) because their growth increase will be greater.
First, identify the "Crop Trees". Start at any location in the forest stand and on the average of every 20 feet, identify and mark with a non damaging marker such as plactic or cloth flagging the best trees. The best trees are generally of high value species and trees with the best form and potential to develop into high quality sawlogs when they are mature.
A species priority list from high to low might include black walnut, red oak, white oak, black oak, bur oak, ash, maple, basswood and hickory. Crop trees must also have good form; the taller, trees that are tall, straight and have a clear trunk should be selected over less desirable forms.
When working with Iowa woodlands, work with what is in the forest. You will generally mark a variety of tree species, some with excellent form and some with less desirable form, but always the best in that growing space. Crop tree spacing will vary from less than 10 feet to more than 30 feet, but always try to select the best 100 trees per acre.
After the crop trees have been identified, mark the trees which should be removed for firewood. Work with each individual crop tree and looking at its crown or foliage with respect to its competitors. The goal of thinning is removal of competiting trees on 3 to 4 sides of the crop tree if they are crowding or overtopping the crop tree.
Allow the crop trees some room for expansion or growth, but do remove all competition. If the crowns of competiting trees are 3 to 4 feet away from the crop tree, it is not interfering with growth at this time, although as they grow larger, it may have to be removed in future thinnings. Follow this procedure for all crop trees in your stand.
Over thinning around crop trees may result in reduced quality because of epicormic branches which are formed by buds beneath the bark that begin to grow in response to too much sunlight. Never remove trees if their crowns are below the crowns of the crop trees because they will continue to promote self pruning of the crop trees.