FOREST MANAGEMENT General Determining the Cut in the Woodland. To assure a sustained yield from the woodland, have some plan for determining the amount which can be safely removed. This should be based upon the annual growth. Assuming that the woodland will be protected against fire and excessive grazing and that the best trees will be encouraged by thinnings and improvement cuttings, it is safe to say that the annual growth of most farm woodlands can be increased. This is one of many reasons why it is undesirable to attempt to establish a fixed and permanent annual crop for more than a few years at a time. Group Selection.--This method of cutting is particularly adapted to farm woodland conditions. Take as an example 40 acres covered with a normal stand of trees which may be cut into saw logs when they are 80 years old. In all probability the woods will include trees of all ages. Each year some will reach maturity. Plan to cut off the merchantable trees as rapidly as they attain the age of 80 years. Actually the owner will not reckon in terms of years, but rather according to the size to which he has decided to cut. Experience has shown that the entire area may be cut over in 40 years, or just half the number of years at which the trees reach maturity. The actual work may take the form of an annual cutting of four groups of about one-fourth acre each. If the owner feels that this is too small to bother with, he may cut the mature timber from 5 acres, or from 20 one-fourthacre plots, and then wait five years before making another large cutting. In any case the series of cuttings will be planned to carry over a period of 40 years. Such a plan presents some difficulties when applied for the first time to the average farm woods. It may have to be preceded by an improvement cutting to get rid of the large, overmature trees. If it is carried through the full 40 years, it should result in a fully stocked forest containing trees of different ages up to 80 years. "Cut and Try" Method. Another way to determine the cut from a woodland is to assume an arbitrary figure as the probable annual growth per acre and make the cuttings on that basis. Subsequent changes in this amount may be made if the woods give evidence of having been undercut or overcut. For example, on the basis of the owner's experience or observations, it may be assumed that the woods will produce half a cord of wood an acre each year. (A cord is a pile 4 by 4 by 8 feet.) One hundred acres could be expected to produce 50 cords per year. The cuttings may be made on the basis either of a full crop each year or of small crops of perhaps 15 cords of thinnings for firewood material during a period of four years, and a big crop in the fifth year. During the four years of small cuttings a surplus of 140 cords would have accumulated, which, added to the growth of 50 cords for the fifth year, would give a possible crop of 190 cords. If the trees are of saw-log size it is usually safe to assume that a cord of logs can be sawed into 500 board feet of lumber. After 10 years of this method the owner can determine from his observation whether the woods are being too heavily cut or if the growth is exceeding the crop and vary his cutting accordingly. U. S. D. A.-10-1-26 To find the number of board feet in a log according to Doyle rule, deduct 4 from the diameter (in inches) of the small end and square the remainder, This gives the contents of a 16-foot log in board feet. The number of board feet in logs of other lengths is in proportion to their lengths; for example, an 8-foot log contains half as many board feet as a 16-foot log, and so on. The above figures were obtained in this manner. |