Hardwood Regeneration in Degraded Stands
Poor and Very Poor Sites
Natural regeneration of degraded hardwood stands on poor and very poor sites presents some special problems but also some opportunities. Potentially slow growth and poor tree quality argue against spending much money on these sites. However, much can be accomplished at little or no cost by appropriate harvesting. If the stand is to be regenerated, the more material harvested the better. Thousands of acres of low-quality stands on poor sites are well suited for shearing or other broad-scale operations. The resultant regeneration will be primarily of sprout origin and will contain a variety of desirable and undesirable species (McGee 1980). There will also be a few barren spots. Overall, the regeneration resulting from a heavy or complete harvest cut will usually produce a stand that will be better than the harvested degraded stand. Landowners should not expect high-quality hardwoods on these poor sites, even under the best of circumstances. Most of the regrowth will be suitable for pulpwood, fuelwood, chips, or short logs. If traditional methods are employed, the logger should use as much of the residual stand as practicable. But when culls, poles, and many small tolerant stems remain, the landowner must decide how much can be spent on natural regeneration. Such stands, may contain numerous culls or relicts, and the felling or deadening of these trees should be the highest priority. Of second priority will be the felling of nonmerchantable trees that would interfere with regeneration. These trees may be numerous and the cost of total control may be prohibitive. Despite the problems with regenerating degraded stands on poor sites, landowers should view hardwoods as the best potential crop. Unsuitable for agriculture, or even conversion to pine, these stands should be targets for controlled and opportunistic regeneration and improvement.
Medium Sites
Degraded hardwood stands growing on medium sites can be regenerated readily by clearcutting. Many stands are on terrain that can be sheared. However, some regeneration can be expected after partial cuts or even high- grading. Regeneration will develop from stump sprouts, advance regeneration, and new seedlings. The expected regeneration mix will be highly variable, depending on the size of openings, the available seed source, the size, distribution, and species of the overstory removed, the condition of advance regeneration, and the weather during the harvest and for several years thereafter. Medium sites can produce hardwood sawlogs, tie logs, pulpwood, fuelwood, and other products. However, production of veneer and better quality sawlogs will be limited. Control of competing vegetation will be more important than on poorer sites. Without effective control or utilization of culls and less desirable trees, medium sites will remain in the degraded category. While potential for volume and quality growth is fair to good, the economics of site preparation should be carefully monitored. Injection or utilization of large culls and relicts is a high priority activity on sites scheduled for regeneration. Intermediate trees also should be controlled or utilized at a somewhat higher level than on poorer sites. If trees in the 2- to 12-inch diameter class cannot be used, then expenditures should be anticipated for their control. Control can be achieved by injecting undesirable species with herbicide prior to logging and felling unmerchantable stems that will produce desirable sprouts after the logging.
Good and Very Good Sites
Regenerating low-quality hardwood stands on good and very good sites requires specific action if the sites potential is to be realized. Even though existing stands may be classed as low in quality, stumpage revenues can be substantial. Portions of this revenue should be used to prepare the site for improved future yields. Recognizing good sites among areas that may have been cutover several times and possibly burned can be difficult. Quite often, good cutover sites that need to be regenerated will contain, in addition to culls, large numbers of less desirable species, such as red maple, dogwood, sourwood, some oaks, and blackgum. If these trees are not killed or cut, they can dominate the site and stand quality will continue to be low. Grapevines, honeysuckle, and kudzu can also inhibit regeneration on good sites. Pre-harvest control of grapevines and injection of red maple should receive high priority. Culls and relicts should also be cut or deadened if not utilized. Good sites now supporting degraded hardwoods can grow high-quality saw and veneer logs. Yellow-poplar, white oak, northern red oak, white ash, black walnut, and black cherry should grow well, but past cutting practices will probably determine how well these species regenerate. While clearcutting will usually result in good regeneration, reliable inexpensive techniques are not available for controlling the species mix or for favoring one species over another in the preferred group. A frequent trend following clearcutting on good sites is for yellow-poplar, white ash, and other light-seeded species to predominate where mixed oaks may have previously dominated. This trend is a problem for owners with strong commitments to wildlife habitat or production of fine oak. If advance oak regeneration exists, shelterwoods are better options for managing oak. Cleaning or crop tree release may be advisable on some good sites but should only be considered 8 to 12 years after stand regeneration.
Encyclopedia ID: p2312
