单词 | felling |
释义 | Fellingfell 1F0071600 (fĕl)fell 2F0071600 (fĕl)fell 3F0071600 (fĕl)fell 4F0071600 (fĕl)fell 5F0071600 (fĕl)Felling(ˈfɛlɪŋ)FellingFelling,town (1991 pop. 36,377), Gateshead metropolitan district, NE England. Felling is an industrial suburb of Gateshead and part of the Newcastle upon Tyne industrial concentration. Felling has various engineering works; it also produces paint and radar equipment.Fellingcutting down and removing trees from a forest to obtain timber and to renew, improve, and increase the productivity of a forest. Four principal types of felling are distinguished in forestry: main-use, maintenance, combination, and improvement. The felling of mature trees is called main-use felling. In selective felling some trees are cut down, while others are left standing. Selective felling may involve cutting down only large good-quality trees, with only the most valuable part of the trunk used for timber. Another form of selective felling involves cutting down large mature trees and immature trees of little value from time to time in forests with trees of various ages; all the wood is used for timber. In Russia, selective felling was carried out in pine forests in the northern European part of the country and in some southern forests, where timber was procured for shipbuilding. In the USSR selective felling is used to help a forest retain its protective properties. It is particularly advisable in tundra, water-conserving, and mountain forests. Another type of main-use felling, clear-cutting, involves the removal of all the trees in a given area during the logging season. Clear-cut areas are small and strictly limited or large and concentrated. Clear-cutting over large areas is widely used in heavily wooded taiga regions with mechanized logging. Successive main-use felling is the cutting down of trees in a single area at different times over a period of several years. It is used in zones of mixed and mountain forests. Maintenance felling is the periodic cutting down of some immature trees to enable the valuable species to become dominant, to improve the quality of the timber, and to increase productivity of a forest. In addition, the water-conserving, water-regulating, field-protecting, health-benefiting, and aesthetic functions of a forest are promoted. Trees are divided into three categories in maintenance felling: I—best, II—auxiliary (useful), and III—worst. In addition to category III trees and trees of undesirable species, some well-growing trees are felled in order to thin out dense stands that are comparatively homogeneous. There are four kinds of maintenance felling: (1) thinning out until the young trees make crown contact (up to ten years of age), (2) thinning out after the trees make general crown contact, (3) thinning out at the pole stage, and (4) thinning out older tree stands before maturity. Depending on the type of tree stand and on economic conditions, the trees that are thinned out are mostly from the understory (slow-growing and dying trees) or mostly from the overstory, or canopy (rapidly-growing but undesirable species that retard the dominant species, or trees of the dominant species with poorly shaped trunks and crowns that adversely affect adjacent trees). Lower maintenance methods are ordinarily used in pure single-story stands, and upper ones in mixed and complex stands. Maintenance felling entails cutting down 10 to 40 percent of the trees. The first and second kinds of maintenance felling are carried out every two or three years, the third kind every five to ten years, and the fourth kind every ten to 15 years. Maintenance felling produces commercially undersized timber that is used as industrial raw material. Combination felling includes both main-use and maintenance felling. For example, in a two-story stand of mature aspen (overstory) and young spruce (understory), main-use felling is used in the removal of the aspen, and maintenance felling in the removal of the spruce (to provide more light and weaken root competition). Improvement felling is the cutting down of young, middle-aged, mature, and overmature stands that have been damaged by fires, insects, or disease; this form of felling makes the stands healthier. REFERENCESGeorgievskii, N. P. Rubki ukhoda za lesom. Moscow-Leningrad, 1957.Melekhov, I. S. Rubki glavnogo pol’zovaniia, 2nd ed. Moscow, 1966. Melekhov, I. S. Problemy sovremennogo lesovodstva. Moscow, 1969. Iziumskii, P. P. Rubki promezhutochnogo pol’zovaniia v ravninnykh lesakh. Moscow, 1969. Davydov, A. V. Rubki ukhoda za lesom. Moscow, 1971. Ievin’, I. K., and A. Ia. Kazhemak. Problemy tekhnologii rubok ukhoda. Riga, 1973. I. S. MELEKHOV Felling |
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