Selection silviculture can be well-suited to longleaf pine forests
Longleaf pine grows best where it has little competition for sunlight. Traditionally, longleaf pine has been managed with even-aged silviculture. However, interest in techniques for uneven-aged management is growing, with a substantial emphasis recently placed on restoring and managing longleaf for multiple resource values. In one study, Forest Service scientists compared shelterwood (even-aged) methods with group selection and single-tree selection (uneven-aged) systems for regenerating longleaf pine on sites with contrasting environmental conditions such as mesic uplands and hydric flatwoods. Although stand density and volume initially decreased, growth rates were normal in all stands. Growth rates ranged from 1 to 5 percent, and basal area and tree density increased. Despite a continuing abundance of saw-palmetto during post-treatment years, pine regeneration increased in all treated stands on flatwoods. Multi-year drought on uplands decreased pine seedlings, no matter which reproduction approach was used. Although seedling numbers eventually began to recover, they were again depressed by a wildfire in 2013. Even with such losses, sufficient pine seedlings remained in each treatment to foster successful stand regeneration. Single-tree selection produced less overall change in forest ecosystems than group selection, which caused less alteration than the shelterwood treatment. In a second study, stands at the Escambia Experimental Forest in southwestern Alabama were cut using the Proportional Basal Area method to residual basal areas ranging from 40 square foot per acre to 80 square foot per acre. Measurements of light, seedling survival, and seedling size indicated that there was an inverse relationship between the residual basal area and the number of new germinants, but their mortality was not influenced by the residual basal area. Growth of germinants was also inversely related to the residual basal area. Most plots contained more than enough seedlings to sustain the target diameter structure for the forest. Current data suggest that uneven-aged systems may be a viable alternative to the use of even-aged methods for sustainably managing longleaf pine ecosystems.
Forest Service Partners