Silviculture similar to vegetable gardening By JAMES C. FINLEY Area Forest Resource Agent tire Extension Service Penn State University J PARK • Silviculture is the art and growing trees. An analogy can easily be drawn silviculture and a vegetable garden. When a ilanted, weeded, and thinned, one can expect to ;ood crop, provided the plants receive adequate 1 are protected from disease and insects. But planted in the wrong site, forced to compete i, or left in crowded rows will not produce crops. like'gardens, need to be weeded and thinned in iroduce good crops of timber and water. In time, . do the weeding and thinning, but often we do the time or patience to wait, the years foresters have learned how in* , and other organisms interact to influence s growth. They have studied tree species and specific requirements for growth. This study •equirements is called “silvics.” Silvics has several needs which influence a plant’s ability and grow. Light, water, and nutrients are •gulaton of a species’ competitive ability. id nutrients are primary regulators of a species’ ! ve ability. observation reveals that certain species are -ticular locations within a stand. For instance, mently occurs on north fadng slopes or along ' in coves, but is seldom seen on south facing temlock grows best on these sites because of moisture. It does not grow well on dry areas, has a wide-spreading shallow root system toisture near the soil surface. . frequently occurs in nearly pure stands ir areas that contain essentially nothing but Hemlock’s tolerance to shading is the reason characteristic. Hemlock forms a very dense and allows very little light to reach a forest floor, ues that can grow under very heavy shade will and hemlock can survive in heavy shade. Con- U BUY.> MMER I LEE IN BUSINESS TO STAY! SEE YOUR l0(M - agri-builder m -stahlman tam agri ’ksh Valley Road CORPORATION "fd, Md. 21502 R.O. 11 , Mountain Road e3 «l 777-0512 Disburf, Pa. 17019 Rhone 717-432-3376 mead sales tap enterprises inc. OaifiSi R. 0.13,.13, Box 2S6A iftSSJJ Fleehwod.Pa. 19522 LET YOUR AGRI-BUILDER HELP YOU DESIGN AN EFFICIENT SYSTEM FOR YOUR GRAIN sequently, hemlock seedlings willbecome established in the shade of the parent tree. They will survive, grow, and replace older hemlocks (when the older hemlocks die). Hemlock is classified as a climax species because once it fully occupies a site, it will continue to dominate the site and exclude other species. Species composition of a climax forest will persist until either a natural distur bance or man alters the stand. Another example of a species influenced by moisture is chestnut oak (rock oak). This species is most often found on dry ridge sites. It grows on more moist sites, but is unable to compete successfully for light against species such as hemlock. As a result, chestnut oak grows where other species cannot find sufficient moisture. It soon becomes evident that light and moisture can limit successful growth of any species. Foresters have studied the natural occurrence and growth rates of species and have constructed charts of relative tolerance to shade. These charts are used to explain why trees occur where they do within a forest and to understand their vigor. A list of relative tolerance to shade follows: Very Tolerant - Eastern Hemlock, Beech, Sugar Maple, Basswood, Hop Hornbeam. Tolerant - Red Maple, Silver Maples, Yellow Birch. Intermediate - E. White Pine, Elm, Amer. Hornbeam. Intolerant - Black Cherry, White Ash, Yellow Poplar, White Oak, Red Oak, Hickory. Very Intolerant - Paper Birch, Black Locust, Aspen, Larch. Tolerance within a species is recognized by a number of characteristics. Tolerant species such as hemlock or beech persist in a forest understory. They respond to release from competition for light and moisture with accelerated growth and improved vigor, even after being suppressed for many years. Under the same competitive conditions, lower branches of intolerant species usually die and break off many years earlier than those of tolerant species. This natural process is called self-pruning. Crowns of shade tolerant species have a denser appearance, and more leaf layers than do r NEW FINANCE PLAN 1*15% DOWN PAYMENT |*s YEARS ON BALANCE 1*7% INTEREST TEMCO PARTS CO. INC. C.H. WALTZ SONS INC. Route 213 and 544 Cofan Station, Pa. 17728 Cheslertown.Md. 21620 Phone 717-435-2921 Phone 301-771-4454 TRI-STATE MARINE DIST.INC. Root! 256 Dealt, Md. 20751 Phone 301-567-1447 BUTLER MARK ANTHONY &SONS R. 0.11 Rochester Mfe, Pa. 15771 Phone 412-216-9250 Lancaster Farming, Saturday. JuneZS. 1977—2 intolerant species, because lower branches remain alive much longer than those of intolerant trees. As a result, tolerant species frequently are slow to self-prune. They also tend to have more taper in the sawlog portion of their boles (trunks) in order to support their crowns. Within mixed stands, tolerant trees persist and compete very well with species of equal size. Consequently, they tend to form stands that are dense, with more stems per acre than stands of intolerant species. In even-age situations, such as occur after fires or clear cuts, tolerant species are quickly overtopped by faster growing intolerant species. The tolerant trees will persist until the intolerant species is removed. Hie tolerants will then dominate the stand. However, in a situation where both tolerant and in tolerant trees are being established under an existing canopy, tolerant trees will dominate from the start. Because tolerant species prosper under shaded conditions they eventually become a major stand component, regardless of circumstances leading to stand regeneration. The chart of relative tolerances shows that some of our more valuable species are found among intolerant species (black cherry, yellow poplar, white oak). These intolerant species have growth characteristics that make their wood valuable. Stands of intolerant species often have widely spaced stems, thus promoting rapid growth in height and diameter of each tree. Crowns on intolerant trees will be small, resulting in relatively little log taper. Intolerant species in properly stocked stands will self-prune quickly, yielding high quality lumber with few knots. Various species compete for a position within a developing stand. Left to nature, this competition can leave a lot to chance. Timber Stand Improvement (TSI) Practices shorten the time required to develop desirable forests. One common set of TSI practices is intermediate harvest cuttings. TSI practices include weedings (of inferior trees and tree species), thinning (so that growth within the stand (Continued on Page 381 GRAIN [®nM@ DRYER IfiJUUM® “ASCS Financing” P. E. Hess, Butler Mfg. Co. Box 337, Oxford, PA 19363 I’m interested in more information on Butler products. □ BuiMinjs □ Bins □ Dryers □ Bulk-O-Matics Name Address County. AGRI-BUILDER State. 1 |
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