Agricultural Fields & Pastures
Although these areas can appear to be "blank slates", they may be the most difficult of all sites to restore to longleaf ecosystem function. The pasture grass and agricultural weed complex is aggressive and most of these sites have little or no residual seed bed from the early native forest. The first step in converting these sites to longleaf forest is to establish the trees themselves. Reforestation, of course, must be through planting. Seeding directly with longleaf seed is seldom successful. If seed is broadcast, germination is uncertain and predation on the seeds by birds and small mammals can be severe. Planting individual seeds by hand or drilling the seed into the soil is labor intensive and usually success is spotty.
Preparing the site for planting seedlings is critical. If there are pasture grasses present, they should be killed before planting is attempted. Killing grasses like Bermuda, fescue and Bahia is difficult and usually requires herbicides. An effective technique includes mowing, allowing the grass to grow back to about 6 inches in height, and then applying either 5 quarts of Roundup or Accord or 20 ounces of Arsenal per acre. The Roundup/Accord treatments can be applied anytime the grass is growing. The Arsenal approach is most effective in late spring or early summer. Follow-up spot treatments will likely be necessary to control these tough competitors, especially the Bermuda.
In both pastures and old fields, the next step is to scalp the site. Scalping peels back the top 2-3 inches in old fields and 3-4 inches in sod pastures in a furrow 24-36 inches wide. Scalping implements are available commercially or may be made from modified fire plows. There are commercial vendors in many areas that will provide scalping services. It is extremely important to rigorously follow contours when scalping. Soil movement along the scalped furrow can not only doom the planting effort, but damage water quality and ruin the productivity of the field for future generations as well.
Unless the site has been sub-soiled within the past two years, it is usually a good idea to pull a ripper bar along the furrow. Depth of the rip should be from 18 to 24 inches. If planting is to be done using a mechanical planter, it is recommended that the rip be oriented as much as a foot off center in the scalped area. This is done so that the seedlings may be planted in the center of the furrow and not in the ripped area. If trees are to be planted by hand, they should not be planted in the rip, but 6 inches or more to one side. Scalping greatly improves survival in agricultural areas. The furrow typically remains virtually weed free for much of the first growing season, reducing competition for moisture and nutrients. In addition, there is evidence that scalping reduces loss to a number of pests and diseases, including white fringed beetle grubs and charcoal root rot.
A period of several weeks should be allowed to pass after the scalping and ripping operation before planting. The soil disruption caused by the ripping should be allowed to settle as much as possible to eliminate washing and air pockets. Planting should be accomplished as soon in the fall as there is adequate moisture in the soil. All planting should be completed before Christmas if at all possible. Planting earlier in the fall gives the seedlings a chance to initiate root growth before entering dormancy and gives them a head start the following spring. It is recommended that planting be done with containerized seedlings in these situations. Recent research indicates that seedlings should be planted so that ½ to 1 inch of the plug is exposed, especially in scalped areas. Soil tends to move into these areas and seedlings with terminal buds covered by soil are not likely to survive.
In the spring following planting, an herbaceous weed control treatment might be desirable. One frequently recommended treatment is 2 - 3 ounces of Oust per acre in March or April. The addition of 10.67 ounces per acre of Velpar DF gives broader spectrum control and may extend the effectiveness of the treatment. A pre-mixed version of these chemicals, Oustar, can also be applied at a rate of 10.5 ounces per treated acre. These treatments are applied directly over the top of the seedlings and generally in a band 3-4 feet wide or in 4 foot diameter spots over each seedling. In banded treatments, total volume of spray (chemical plus water) should be at least 10 gallons per acre.
Before spraying, one or two seedlings should be excavated and checked for new root growth. If the seedlings have not begun to initiate new root growth outside the plug, delay spraying until that occurs. Also, areas where soil pH is high (greater than 6.0) should not be treated with Oust. Oust is a root growth inhibitor and high pH tends to exacerbate its effectiveness. If root growth on new seedlings is retarded by the chemical, April and May droughts may cause high mortality.
Another herbicide combination that has proven to be successful in these situations is Arsenal and Oust. However, Arsenal should not be applied over longleaf seedlings before May 15th. One treatment combines an early treatment with 2 or 3 ounces of Oust per treated acre in March or April followed by a subsequent treatment, if needed, with 5 or 6 ounces of Arsenal per treated acre after May 15th or later. The Arsenal and Oust may be applied together in one treatment after May 15th. Late germinants, such as crabgrass, can prove disastrous to old field and pasture plantings if only the early treatment is used. Appendix II contains a summary of some common herbicides, how they work, what species they are likely to control, which species are tolerant or resistant, and recommended methods of application.
Since these sites generally have no remnants of the native forest understory vegetation and little or no seedbed to draw on, the use of chemicals to control vegetation does little damage to the total restoration effort. Once the trees are established on agricultural sites, they can be burned almost immediately. In fact, it may be difficult to use fire effectively on many of these sites because there is often very little fine fuel on the ground to carry the fire. Old field weeds like dog fennel, ragweed, and goldenrod do not burn well and are not effective at carrying fire. Broomsedge or Andropogon is a better fuel and will carry a fire if there is a slight wind. The trees are fire tolerant throughout their life, but the stage when they are 6 inches to three feet tall is the most vulnerable. Trees in this size class should not be burned in the growing season when they are "candling" (when the terminal bud is elongating and is tender and white). Young longleaf may be burned successfully with strip headfires, although other types of fires may be successful as well. Mowing between rows may be helpful for access and to help carry fire, but care should be taken to avoid damaging seedlings.
Restoring the understory in these situations is extremely difficult because there is typically no seed source in place and the competition from agricultural weeds is fierce. The protocols for establishing native plants on these sites are still in the development stage and can be very expensive. Seeds of some of the legumes, like partridge pea, are readily available commercially and are relatively inexpensive. Planting is not difficult and they will re-seed following disturbance (e.g., fire or light disking) for several years after establishment. Most of the other desirable natives are not widely available (at this time) and success in re-establishing them is spotty at best. Wiregrass can be started from seed or containerized plugs. Plugs are more expensive, but more reliable. Seed is not readily available, and germination is unpredictable at this point. Other native grasses and forbs can also be planted from seed with planters like the Truax or Wildlander brands, but the species most readily available are not necessarily native to the longleaf region. Many native grass and legume species are slow colonizers, so spread from adjoining forest land or from newly established sources in the field itself is likely to be extremely slow. Continued burning of old field sites over many years can eventually restore native ground cover species. The cost in dollars is relatively low, but the time investment may be high.