Mixed Hardwood-Pine or
Pine-Hardwood Forests
Many historical longleaf pine sites have become occupied today by forests composed of loblolly and/or shortleaf pine and mixed hardwoods. In much of the natural longleaf range, this is the typical forest condition following a total harvest if no attempt was made to reforest. These forests can produce valuable timber, excellent wildlife habitat, and are often aesthetically pleasing. Still, they occupy sites that once supported longleaf pine ecosystems and are well suited to that forest type. In order to restore the longleaf pine ecosystem to these sites, planting longleaf seedlings will be necessary.
One technique that has been applied successfully begins with the commercial harvest of the hardwood component, followed by a growing season fire, preferably in late March through mid-May. Clearing logging slash away from the boles of the residual pines manually or mechanically is a wise precaution. The intense heat these piles or tops can generate can damage or kill the roots and cambium layer and scorch the crowns of nearby trees. Continuing to burn on a two or three year rotation, using growing season and dormant season burns, should control the hardwood sprouting and most of the pine regeneration.
When the woody understory is under control, the next step is to remove the pine component in a final harvest. Following the harvest and prior to replanting, site preparation is typically needed to remove un-merchantable hardwoods and pines. The method of site preparation should be chosen with the level of residual competition and the presence or absence of desired groundcover species in mind. If the fire has done its job well, the woody competition should be minimal and any residual groundcover should have begun to express itself. Fire should be a part of the site preparation process to also control the Pales weevils.
Post-planting control of hardwood sprouts might be desirable and can be achieved by directed spray with foliar active herbicides or spot treatments with hexazinone products. Appendix II contains a summary of appropriate forest herbicides and recommendations for their use. Restoration of understory vegetation is likely achievable through repeated use of fire, particularly growing season fire, throughout the rotation unless the site was in cultivation for an extended period prior too becoming reforested. If, after several years, the understory has not recovered, it may be necessary to artificially supplement it with seed or seedlings.
Another approach, less often employed, is to leave a portion (no more than 10 square feet per acre of basal area (BA)) of the loblolly or shortleaf pine stand intact after the pine harvest and under-plant with longleaf seedlings. This would create a two-aged stand and would help provide fuel for subsequent fires. There are several cautions, however. There is evidence that even as little as 10 ft 2 /Acre BA can significantly retard growth of the new stand. More importantly, there may not be adequate pine fuel to carry sufficiently hot fires to control the prolific loblolly or shortleaf seedlings sure to result from this technique. These seedlings can be important competitors for the longleaf and choke out desirable understory vegetation if not controlled. The more likely outcome of this approach is the creation of a mixed species pine stand.