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West Virginia University
Table 1.Forage plants and seeding rates for groundcover where trees will be planted
Table 2.Tree species for reforestation of surface mined lands in West Virginia.
Statement of the Problem
Coal mining has disturbed approximately 2.4 million ha (6 million ac) since 1930 in the United States. In Appalachia where much of the surface coal mining had occurred in the U.S. prior to 1975, the majority of land mined for coal was originally forest land. Laws were passed in Ohio, Pennsylvania, and West Virginia during the late 1930s and 1940s requiring mine operators to register with the state and pay bonds to ensure some reclamation would take place. Reclamation prescribed in these early laws directed soil, subsoil, and overburden (the geologic material overlying the coal) be used to refill the excavated area. Backfilling and leveling the land was specified, and then trees and shrubs were to be planted in the regraded areas.
Studies of surface mine revegetation with trees began in the 1940s. Black locust was the most extensively studied and successful species (see author for list of references). Other species such as autumn olive (Elaeagnus umbellata Thumb.), Virginia pine (Pinus virginiana Mill.), red pine (P. resinosa Ait.), and white pine grew well in many of those early studies. Hardwoods like oaks (Quercus spp.) and cherry (Prunus spp.) failed to grow usually because the trees sustained rodent damage.
During ensuing decades, laws and regulations governing surface mine reclamation in the eastern U.S. evolved into seeding grasses and legumes rather than establishing trees. The rationale for this change was that forage species controlled erosion, provided a quick economic return to land owners through haying or grazing of livestock, and was aethetically pleasing.
These laws have hindered tree planting because they permit partial release of reclamation bonds as soon as the ground cover requirement is met. The cover requirement is achieved by herbaceous plants, and planting of woody plants is an added reclamation expense to mining companies.
Under management, most mined areas in the eastern U.S. produced sufficient quantities of forage for these systems. However without management, hayland and pasture in West Virginia, either by design or as continued management decreases, will ultimately return to forest. Woody species will often become established by natural secondary succession if given the opportunity and sufficient time, especially where the reclaimed site is surrounded by native forest. Establishment of a forest of commercial value is extremely slow by natural succession.
Most of the land mined for coal in West Virginia was forested before mining. Therefore, post-mining reclaimed land should be largely returned to forestland, particularly those with steep slopes found in the southern West Virginia coal fields. Small areas after reclamation may have gentle slopes and may be better suited to haying or grazing land, or some areas may be capable of supporting crops. But the majority of land disturbed for coal mining should be returned to forestland.
Forestland as the post-mining land use has a
number of advantages. First, long-term stabilization of the site
is accomplished (even though during initial stages some erosion
may occur). Second, establishing desirable tree species which are
capable of maintaining the site will slow or prohibit invasion of
less desirable, weedy species. Third, trees will eventually
provide economic returns although several decades must generally
pass before harvesting can take place. Fourth, tree planting aids
in the development of wildlife habitat and also promotes
hydrologic balance in the watershed.
Recommendations (based on Torbert and Burger in 1992)
Reclamation procedures for restoring forestland on surface mined sites are different that procedures for establishing pasture. Five keys are critical to successful establishment of trees on mined lands.
1. Spoil Selection
Four feet of good-quality overburden material should be placed at the surface to maximize the rooting of trees. This overburden material should be material from the oxidized zone, and the brown sandstones often found in southern West Virginia overburdens weather rapidly into a good soil medium for trees. Textures can range from sandy loams to loams, and should be somewhat coarse-textured and may contain rocks. The paste pH of these materials should be from 5.0 to 6.5, but not over 7.5. These materials should also not contain high levels of soluble salts. Place topsoil on the surface where it can be saved.
2. Grading and Compaction
Minimizing compaction on sites where trees are to be planted cannot be over-emphasized. Simple leveling of the dumped spoil materials with small bulldozers is recommended. Do not track level areas or slopes where trees will be planted. Rough grading is adequate.
3. Forage Groundcover
Successful tree planting requires a slow-growing, low groundcover that controls erosion but does not hinder tree growth. Forage species used in revegetation of surface mines are commonly aggressive, fast-growing grasses and legumes which monopolize a site's resources thereby allowing no other plants to establish or grow. K-31 tall fescue and most clovers should not be seeded where trees are to be established. See table 1 for recommended forage species and seeding rates for groundcover where trees are to be planted.
4. Tree Species Selection
Trees such as pines and nitrogen-fixing plants are best suited to minesoils. Native hardwoods will eventually invade and establish on these sites when compatible grasses and legumes have been seeded. See table 2 for trees recommended for surface mine planting.
5. Hydroseeding and Seedling Planting
A few tree species have shown good establishment with hydroseeding (black locust, bristly locust, black alder, autumn olive, redbud, etc.). Black locust seeding rates should range from one-half to one pound per acre.
The most widely-planted tree on surface mines in the Appalachian Coal Region is white pine. Yellow-poplar, oaks, white ash, and Virginia and loblolly pines have also been successfully planted and show good growth on many reclaimed sites. Planting of trees should be done on 10 x 10 or 12 x 12 foot spacings (300-400 trees/acre). In 30 to 50 years, good stands can produce pulpwood and merchantable timber. Procedures for purchasing, handling, and transplanting tree seedlings are available to maximize seedling survival.
Test plantings can be conducted on 10- to 30-acre sections where a single tree species is planted into compatible groundcovers. Based on survival of the specific trees, a selection of the most-suitable tree or trees for the site can be made. It may be desirable to have one or two sections planted with a mixture of trees to evaluate survival in a mixed stand.
|Table 1. Forage plants and seeding rates for groundcover where trees will be planted. Before seeding, about 200 pounds/acre of 16-26-14 fertilizer should be applied.|
|Foxtail Millet||5 (Use foxtail millet for spring seeding only)|
|Rye||30 (Use rye for fall seeding only)|
Table 2. Tree species for reforestation of surface mined lands in West Virginia.