Longleaf Pine Silviculture

A mature longleaf pine stand

A mature longleaf pine stand

Longleaf Pine Prospects

Cornerstone of Sustainability

As “the scientific management of forests for the continuous production of goods and services, ”Silviculture is fundamental to sustaining the health and productivity of America’s longleaf pine ecosystems. Improved understanding of the basic physiology of longleaf pine and its native understory plant communities and how they interact with the environment remains a crucial need.

Decades of Progress

Since the 1930s and 1940s, U.S. Forest Service scientists have conducted studies at the Palustris and Escambia Experimental Forests. This previous work has provided information about:

  • Seed production and collection
  • Bare‐root and container seedling production
  • Field planting techniques
  • Prescribed fire use
  • Stand management

Even‐aged Management: shelterwood methods were found to be the most effective.

Uneven‐aged Management: studies begun in 1977 are evaluating selection methods.

Needed Discovery and Development

Many unanswered questions still remain. Ongoing research is focused on improving basic physiology information about longleaf pine and its understory plant communities and developing cost-effective silviculture systems that meet landowner management objectives. These objectives included timber production, quality wildlife habitat, hunting, biodiversity and income generation. Research efforts support the Region-Wide Conservation Plan and Joint MOU by the U.S. Departments of Agriculture, Defense and Interior.

Physiological Foundations

Longleaf pine is vulnerable to disease and decline when drought or fire significantly damage root systems and/or tree crowns.

Research will identify protocols for prescribed burning, which will minimize fire damage. Studies of drought impacts will lead to improved silvicultural practices that mitigate adverse effects.

Fire Ecology and Prescribed Burning

Burning longleaf pine stand

Burning longleaf pine stand

Long-term studies of fire frequency during the dormant and growing seasons have highlighted the value of burning at 2-3 year intervals, when forest fuels are sufficient but not excessive.

Prescribed burning is proving to be useful for restoring longleaf pine forests previously in poor condition (especially when combined with thinning and/or herbicide treatments).

The effects of periodic fire on restoration of native understory species are being studied.

Growth, Mortality and Yield Models

Investment by the Forest Service, in nearly 50 years of data collection, made possible last year production of the first reliable growth, mortality and yield simulation model for naturally-regenerated longleaf pine forests.

Ongoing research and data collection will produce a refined model, which includes an “Expert System for Managers” that is linked to economic, carbon balance and climate change data.

A long-term effort for longleaf pine plantations using 75 years of data to develop a similar model has so far resulted in a stand growth and yield model published in the online journal Forests.

Reproduction and Restoration

Regenerating longleaf pine stand

Regenerating longleaf pine stand

While continuous-canopy management is best achieved through irregular shelterwood and selection methods, these techniques need further study before they are widely applied in longleaf pine. We are doing a Comparative Analysis of Reproduction Techniques to evaluate these plus a new selection method, Proportional-B (Pro-B). Pro-B is an easy-to-apply, accurate, single-pass method that achieves a stable stand structure, provides regular periodic outputs of forest products and conserves biodiversity. An online Pro-B Calculator is being developed to allow the public to interactively run stand data for their own forests before selecting treatment options.

A Hurricane Recovery study is evaluating treatments for rapidly restoring the forest following damaging winds. Vulnerability to windthrow (resulting from poor root development) is being addressed by Field Testing of Copper-lined Containers, which promote greater seedling root symmetry and enhanced long-term stability. Past plantation establishment and site preparation practices on poorly-drained soils are being studied relative to their effects on maintaining native understory plants. Overstory thinning and canopy-gap creation to convert Loblolly Pine to Longleaf Pine Forests, are being studied.

Silvopasture

Combining longleaf pine timber production with livestock grazing by cattle or goats provides an attractive economic option to many landowners in the region, especially those with limited resources. Systems that use double-rows of longleaf pine separated by wide alleys of forage grasses for rotational grazing by livestock are being evaluated. Ways to incorporate some wildlife habitat benefits into these management systems will also be evaluated. These systems can contribute to stable land tenure and a sustainable environment.

References

  • Connor KF, Brockway DG, Boyer WD, Tucker RK. 2009. The Escambia Experimental Forest. In: Bowersock EP, Hermann SM, Kush JS, comps. Forestry in a Changing World: New Challenges and Opportunities. Proceedings of The Longleaf Alliance Seventh Regional Conference and Forest Guild Annual Meeting. Longleaf Alliance Report No. 14: 45-48.
  • Lugo, A.E., Swanson, F.J., Gonzalez, O.G., Adams, M.B., Palik, B.J., Thill, R.E., Brockway, D.G., Kern, C., Woodsmith, R. Musselman, R. 2006. Long-term research at the USDA Forest Service’s experimental forests and ranges. BioScience 56(1), 39-48.
  • Brockway, D.G., Lewis, C.E. 2003. Influence of deer, cattle grazing and timber harvest on plant species diversity in a longleaf pine bluestem ecosystem. Forest Ecology and Management 175(1-3), 49-69.
  • Brockway, D.G., Lewis, C.E. 1997. Long-term effects of dormant-season prescribed fire on plant community diversity, structure and productivity in a longleaf pine wiregrass ecosystem. Forest Ecology and Management 96(1,2), 167-183.
  • Boyer, W.D. 1990. Pinus palustris Mill. Longleaf pine. In: Burns, R.M., Honkala, B.H., (Tech. Coords.) Silvics of North America. Volume 1, Conifers. USDA Forest Service, Agricultural Handbook 654. Washington, DC. pp. 405-412.
  • Bohn, K.K., Chancy, C., Brockway, D.G. 2013. Structure and regrowth of longleaf pine forests following uneven-aged silviculture and hurricane disturbance at the Escambia Experimental Forest. Biennial Southern Silviculture Research Conference. Southern Research Station, USDA Forest Service, Shreveport, Louisiana. March 2013. (Abstract)
  • Loewenstein, E.F., Brockway, D.G., Samuelson, L. 2010. Comparing carbon storage in longleaf pine among various stand structures. In: Carbon Sequestration in Longleaf Pine Ecosystems: Current State of Knowledge and Information Needs. School of Forestry and Wildlife Sciences, Auburn University, Alabama. February 2010. (Abstract)
  • Estes, B.L., Gjerstad, D.H., Brockway, D.G. 2006. Spatial patterns of fuels and fire intensity in longleaf pine forests. The 6th Longleaf Alliance Conference. Tifton, Georgia. November 2006. (Abstract)

Contact Dale Brockway for more information on this topic.