Natural and Artificial Regeneration
Regeneration is Crucial
Although longleaf pine was known in the past for erratic seed production and poor seedling survival, knowledge gained through research in recent decades has greatly increased regeneration success. Periodic regeneration, preferably by natural means and if necessary by artificial approaches, is essential for the sustainable management of longleaf pine forests.
Artificial Regeneration
When a natural seed source is absent, sites can be regenerated by planting longleaf pine seedlings. These are produced in tree nurseries and grown as either bare-root or container planting stock. Woody plant competition should be controlled by mechanical, herbicide and/or fire treatments for site preparation. Container-grown seedlings can then be planted anytime from July to March, while bare-root seedlings are best planted from November to February, when soil moisture is adequate. To obtain 300 well-established seedlings per acre, 500 or more seedlings may be planted as a hedge against mortality, which can sometimes be as high as 40 percent but is often lower.
Longleaf pine seedlings planted on sandhills.
Natural Regeneration
When a natural seed source is present, natural regeneration allows managers to forgo the expense of planting. Although exceptional seed crops do not occur each year, some “seed rain” falls from the longleaf pine overstory every year. This modest seed input is adequate to support regeneration for uneven-aged management. Even-aged management, on the other hand, depends greatly on infrequently-occurring heavy seed crops for successful regeneration.
Longleaf cones and seedlings on forest floor.
Even-Aged Management
Even-aged management for longleaf pine is most often performed using the Shelterwood Method in combination with a natural overstory seed source. This method is far superior to the Seed-tree Method, which produces insufficient seed for regeneration and needle-cast to carry essential periodic surface fires. The clearcutting Method is seldom used, since it additionally requires the costly steps of mechanical and herbicide treatments for site preparation plus planting longleaf pine seedlings.
Longleaf pine stand
Uneven-Aged Management
Single-tree Selection and Group Selection may be successfully applied in longleaf pine forests and woodlands. These selection methods maintain a continuous canopy cover while providing a sustained output of forest products. The key to successful uneven-aged management is to maintain each stand at a basal area that allows the pine trees to effectively regenerate while remaining free to grow. Traditional forest regulation approaches for uneven-aged management, like BDq and VGDL, have proven to be complicated to apply in the field and have not been widely adopted. Therefore, work on developing more practical and effective methods has proceeded.
References
- Dyson, D.S., Loewenstein, E.F., Jack, S.B., Brockway, D.G. 2012. Influence of light and moisture on longleaf pine seedling growth in selection silviculture. In: Butnor, J.R. (Ed.) Proceedings of the Biennial Southern Silviculture Research Conference. Southern Research Station, USDA Forest Service, General Technical Report SRS-156. Asheville, North Carolina. pp. 100-106.
- Brockway, D.G., Outcalt, K.W., Boyer, W.D. 2006. Longleaf pine regeneration ecology and methods. In: Jose, S., Jokela, E.J., Miller, D.L. (Eds.), Longleaf Pine Ecosystems: Ecology, Silviculture and Restoration. Springer Science, New York. pp. 95-133.
- Brockway, D.G., Outcalt, K.W., Guildin, J.M., Boyer, W.D., Walker, J.L., Rudolph, D.C., Rummer, R.B., Barnett, J.P., Jose, S., Nowak, J. 2005. Uneven-aged management of longleaf pine forests: a scientist and manager dialogue. USDA Forest Service, Southern Research Station, General Technical Report GTR-SRS-78. Asheville, North Carolina. 38 pp.
- Brockway, D.G., Outcalt, K.W. 1998. Gap-phase regeneration in longleaf pine wiregrass ecosystems. Forest Ecology and Management 106(2, 3), 125-139.
Contact Dale Brockway for more information on this topic.