James S. Meadows

Silvicultural systems for southern bottomland hardwood forests

Abstract Silvicultural systems integrate both regeneration and intermediate operations in an orderly process for managing forest stands. The clearcutting method of regeneration favors the development of species that are moderately intolerant to intolerant of shade. In fact, clearcutting is the most proven and widely used method of successfully regenerating bottomland oak species in the South. The seed-tree method of regeneration favors the establishment of light-seeded species. Mechanical soil scarification may be necessary if the desired species requires bare mineral soil for establishment. The shelterwood method of regeneration can provide for the development of heavy-seeded species, but has produced highly variable results with southern bottomland oaks. The single-tree selection method of regeneration favors the development of shade-tolerant species. When single-tree selection is applied repeatedly to stands containing commercially valuable shade-intolerant species, composition will gradually shift to less-valuable, more-tolerant species. Consequently, the single-tree selection method of regeneration is not recommended for any commercially valuable bottomland hardwood tree species. Group selection, in its strictest application, creates only small openings that usually fail to allow sufficient light to the forest floor for satisfactory establishment and development of shade-intolerant bottomland species. Patch cutting, a combination of uneven-aged (group selection) and even-aged (clearcutting) silviculture, designed to create larger openings, has been successfully used to produce an uneven-aged stand that consists of many small, irregularly shaped, even-aged groups. Silvicultural systems should include a planned program of intermediate operations designed to enhance the growth and development of those species favored during the regeneration process. Improvement cutting and commercial thinning are increasingly common in southern bottomland hardwood forests. Other partial cuttings employed today in bottomland hardwood forests typically involve some form of crop-tree release. Specific recommendations for the selection of silvicultural systems are presented for the eight most important species groups found in southern bottomland hardwood forests.

Influences of harvesting on functions of floodplain forests associated with low-order, blackwater streams

Abstract The influence of both aerial and ground-based harvesting on functions of forested floodplains of low-order streams was studied during a two-year period. The study sites were associated with low-order, blackwater streams with infertile and primarily organic soils. Responses to harvesting were assessed in relation to water quality, denitrification, hydrology, regeneration, and decomposition. Water quality indices included nitrate, phosphate, total and dissolved solids, and biological oxygen demand (BOD). All were unaffected by harvesting with the exception of BOD which rose once to undesirable levels. Denitrification was highly variable and also showed no significant harvest effect. Hydrologic parameters included groundwater table depths which, unexpectedly, indicated lowered water tables within harvested areas during the first growing season. Early regeneration responses were strongly linked to harvest system with primarily seed-origin species favored by ground-based activity whereas sprout-origin species dominated on aerial system plots. Owing to inherent soil wetness, decomposition responded slowly to harvest disturbance. However, after one year, decomposition was more rapid on harvested plots than in undisturbed areas.

Biotic Agents of Stress in the South

Biotic agents affect millions of hectares of forests throughout the world each year. Of all the environmental stresses affecting trees, insects and diseases are by far the most widespread and most studied but, perhaps, the least understood. Their influence on forest productivity may be relatively small, as during low-level infestations that produce nagging drains on growth, or catastrophic, as during epidemic outbreaks that may destroy thousands of hectares in a short period of time. In contrast to air pollutants, whose effects are primarily regional in nature, biotic pests permeate nearly every forest in all parts of the world and constantly pose a threat to the health of these ecosystems. Biotic pests commonly interact with other agents of stress, both natural and anthropogenic, to produce complex problems for forest managers throughout the world. These complex interactions between biotic pests and other agents of stress are beyond the scope of this chapter and are discussed elsewhere in this book (Chapter 7). This chapter addresses the relationships between susceptible hosts and the major biotic pests in the southern United States.