This method retains mature trees on a site to provide a source of seed and shelter to encourage natural pine regeneration. The shelterwood system involves several steps: control of competing understory vegetation, the shelterwood selection and final harvest cut. The first requirement is control of understory vegetation. Prescribed burning is the cheapest method to control the understory. Periodic burns every three to four years should keep the understory vegetation under control. Where prescribed burning has never taken place, burn for two consecutive years before the shelterwood selection to help reduce the understory competition. Large hardwoods not killed by burning may require chemical control. Do not be reluctant to burn before shelterwood selection when small pines are in the understory. Most of these small pines are suppressed and will not respond to release.
The second step is selecting the shelterwood trees about five years before final harvest is planned. Selecting the very best quality, straight, disease free seed producing trees is important. This will provide some measure of upgrading the future stand. Mark these ``leave'' trees with paint. Make sure they are well distributed over the area to provide uniform seed dispersal. Remove the rest of the trees in your first timber sale. Be sure not to damage the ``leave'' trees as they will be adding growth as sawtimber while they are reseeding the site. The number of ``leave'' trees is dependent on size (Table 2). Longleaf pine requires more ``leave'' trees per acre than slash, loblolly and shortleaf due to the limited dispersal of the large heavy longleaf seed. The shelterwood method differs from the ``seed tree'' method by leaving more trees per acre which can entice buyers to a second timber sale. ``Seed tree'' methods often leave only six to eight trees per acre which are not attractive to timber buyers due to the limited volume of material. The few ``leave'' trees retained in a ``seed tree'' operation may only bring pulpwood prices despite being sawtimber size.
| Diamater (inches) | Leave Trees Per Acre |
| 12 | 30-50 |
| 14 | 20-40 |
| 16 | 18-30 |
| 18 | 15-25 |
The final step is the harvest of the ``leave'' trees once the area has been adequately stocked and before the developing seedlings get too large. An adequately stocked stand should have several thousand seedlings established per acre before shelterwood removal. This allows for natural seedling mortality associated with the harvest of the ``leave'' trees. It is not uncommon to have over 10,000 seedlings per acre. When this occurs, bushhog or harrow strips through the area after the shelterwood harvest to achieve the desired stocking rate. Reducing stocking to 600 to 750 pine stems per acre will promote best growth and volume gains.