Lesson 7: Reproducing the Forest
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Lesson 7: Reproducing the Forest TEACHER: SCHOOL: GRADE LEVEL: 9-12 TASKS/COMPETENCIES SOL CORRELATIONS ANR8006.130 Plant forest seedlings. Biology BIO.5 (life functions of monerans, protists, fungi, ANR8008.074 Plant forest seedlings. plants, and animals) BIO.8 (change in populations) ANR8040.112 Describe methods of forest BIO.9 (dynamic equilibria within populations) regeneration. Earth Science ANR8040.113 Identify new tree care practices. ES.7 (renewable and nonrenewable resources) ANR8040.114 Demonstrate knowledge of tree English fertilization. 9.2 (oral presentations) 9.3 (variety of literature) 9.6 (technical writing) OBJECTIVES AND GOALS 10.1 (small group learning activities) 10.4 (consumer materials) • The student will list and describe the methods of 11.4 (variety of print material) site preparation for tree reproduction. 12.1 (oral presentations) 12.4 (variety of print material) • The student will list and describe natural methods of tree reproduction. EQUIPMENT, SUPPLIES, AND • The student will identify the advantages and MATERIALS NEEDED disadvantages of natural methods of tree reproduction. • Instructor-provided forest management guidelines • Instructor-prepared test on tree regeneration • The student will explain factors that affect the techniques quality of the seed source. • Seedlings and seed • Hand seeding machine (cyclone seeder) • The student will list and describe the artificial methods of tree reproduction. • The student will explain the purpose of the Virginia Seed Act. 51 ACTIVITIES Preparation Lesson approach • One of the keys to continuing success in forest management is the ability to reproduce desirable forest stands when needed. • Many ingenious schemes are found in nature to accomplish reproduction of the various tree species; however, often the low-value species will reproduce most efficiently and successfully. • It is sometimes necessary to apply certain techniques to assist or guide natural reproduction. • Often it is impossible to secure desirable tree reproduction naturally; in this case, direct seeding or planting is used to begin a new stand. General situation • There are over one-half million acres of idle agricultural land in Virginia. • There are approximately one-half million acres within the commercial forest areas that are non-stocked and can be planted without site preparation. • There are several million acres of forest land that are poorly stocked and need to be planted following site preparation. Local situation The instructor should determine local practices relative to renewing the forest, establishing forest on land previously used for another purpose, and removing undesirable trees and brush from the forest area. Application • Arrange field trips to several sites where students can observe site preparation methods. • Have students examine an area which has been reforested and interview the owner to determine how the reforesting was done and what results are expected. • Have students visit a nursery or seed orchard. • Have students participate in planting of seeds or seedlings at selected sites. 52 Presentation: Forest Reproduction Site preparation Regeneration or reproduction of forest trees is accomplished naturally in many ingenious ways. Edible fruits and nuts are distributed by animals and birds. Papery wings and silken parachute attachments carry seeds in the wind, while hook devices fasten to fur or clothes for transport. Most of these methods are effective, providing the spot where the seed finally lands is favorable for the germination and growth of the particular tree species involved. As we learned in Lesson 4, these specific site requirements are often quite complex, but since they undoubtedly determine the success or failure of this vital phase of our efforts to manage the forest, we must understand at least the basic requirements of the more valuable tree species. This knowledge can then be used to make certain that conditions in our stand are suitable for the reproduction on the tree species we desire to establish. Methods Most hardwood forests reproduce quite abundantly and with a wide variety of species if protected from grazing and fire. Numerous hardwood species are able to reproduce by sprouting from stumps and underground rootstocks, as well as from seed. Therefore, site preparation measures usually are limited to making certain that the openings in the forest stand are large enough to ensure sufficient light for growth of high-value species. For example, yellow poplar must have full sunlight and exposed mineral soil to germinate and develop. Since pure pine stands are not naturally a part of the permanent forest types in Virginia, and since they reproduce successfully only under favorable conditions, it is often necessary to use certain methods of site preparation, described as follows, to create these conditions. Occasionally, these same methods are suitable for use with some high-value hardwood stands. On Logging On Undisturbed On Disturbed Surface — Residue Surface Logged, Disked, Drum Chopped 83 Seeds per 29 Seeds per 7 Seeds per Seedling Seedling Seedling Number of Seeds Needed to Establish One Pine Seedling on Different Classes of Seedbed • Drum chopping In this operation an implement known as a rolling drum chopper is pulled through the cutover area by a large crawler tractor. The chopper consists of a heavy metal cylinder with large knives attached at intervals. The tractor and cylinder mash and flatten unwanted weed trees to the ground, while the knives serve to cut and tear the tree stems and to expose mineral soil. Under certain conditions this operation may be sufficient to create a satisfactory site for planting or seeding without additional treatment. Usually, however, it is necessary to follow drum chopping with prescribed burning after an interval, to allow the leaves and woody fuel to dry. This equipment has, to a large extent, replaced the use of a disk on recently logged areas and also on areas occupied by sprouts and small trees of unwanted tree species. • Disking This involves pulling a large, heavy, disk-type harrow through the woodland either before or after cutting. This usually accomplishes two purposes: first, the destruction of the unwanted hardwood undergrowth, and second, the disturbance of the forest floor to expose mineral soil and encourage germination of desired seed. If done prior to cutting, disking creates a favorable seedbed for all the seed from the stand and normally gives assurance of abundant reproduction. If the disking follows cutting operations, it is considerably less efficient due to stumps, tops, and lesser amount of seed; nevertheless, if an ample seed source is available, reproduction is usually secured. The most 53 advantageous time to disk is from midsummer to the time of seed fall, but it has been found effective when applied at almost any season. • Bulldozing In this method a medium to heavy crawler-type tractor is used with a straight or toothed-type blade to scrape off the upper layer of the forest floor. This eliminates the undesirable hardwood undergrowth and also exposes mineral soil. Usually bulldozing is done after logging to reclaim or to convert areas to pine that have been invaded by unwanted hardwoods. Material pushed up is either dumped in scattered piles or in windrows and is left to decompose naturally. Some advantages of this method over disking are immediately apparent. It more completely eliminates the hardwood brush and exposes a larger percentage of mineral soil, thus creating a longer lasting seedbed. However, it has some serious disadvantages in that a certain amount of topsoil is unavoidably removed, and the soil conditions therefore become less favorable. The method is unsuited to areas subject to any considerable erosion, and in addition, it is more time-consuming and consequently more costly than disking. It is definitely unsuited to heavy- type soils that are compacted by heavy equipment. • Prescribed burning The use of carefully controlled fire to prepare a site for planting or direct seeding has become an accepted practice in Virginia. Used either by itself or in connection with drum chopping or chemical spraying, fire has proven to be an effective and economically practical method for eliminating logging debris and reducing weed/tree species competition. There are certain factors involved with the use of fire that must be understood before finally deciding on its use. Fuel conditions and weather factors can determine the success or failure of any burning effort. Plans for control and assessment of the risks involved should be thoroughly considered. Seeking professional recommendations and guidance is strongly urged. Fire can be effective and comparatively economical if wisely used, or completely ineffectual and extremely costly if used without planning. • Use of tree poisons (silvicides) The primary use of chemicals is to kill the unwanted vegetation so that desirable trees have room to grow. There are several good silvicides on the market and more are being developed and tested. Because of new developments in the chemical field, it is not practical to list the currently accepted silvicides. Up-to-date information should be obtained from local professionals. Silvicides must be used according to the directions on the label. Improper use can cause damage to the environment and the person using the chemical. • Girdling This is effective on most trees 12 inches in diameter and larger. Girdling is accomplished by cutting a band 3 to 6 inches wide entirely around the tree, making certain that the axe cuts sever the cambium and penetrate well into the wood. Seed source It is an accepted fact in agricultural research that the quality of a seed directly determines the quality of the plant it will produce. Like the breeding of farm animals, the quality of an offspring depends upon the characteristics of both parents that produce it. These characteristics are inherited qualities that may result in good or bad tendencies. Trees and their offspring are governed by the same laws of inheritance as corn, tobacco, or hogs. It follows then, that not only is an ample seed source important, but also more attention must be paid to the quality of tree seed if we are to improve our woodland.