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Reclaiming Surface-Mined Land
The purpose of this paper is to detail the practical, cost-effective guidelines used by the Paulownia Reforestation Project (PRP,) Farr Better Trees, and Plan-it, Plant-it, Planet for reclaiming surface-mined land to forestland.
Principles of Reforestation
The eastern deciduous hardwood forest with its hundreds of species of plants and animals is one of the most complex plant systems in North America. After mining and land reclamation, this complex forest, given enough time, will be restored to its original function and structure through a process called forest succession.
Forest succession is a natural process whereby, following disturbance, the forest regains its original composition through a slow process of species replacement and site amelioration. When land is surface mined, the entire forest including shrub layer, tree canopy, root stocks, seed pools, animals, and micro organisms, is removed. It is not possible to instantaneously restore the original forest of red oak, sugar maple, Fraser magnolia, cucumber tree and other mid to late-successional species. Mined land cannot be artificially prepared for these species. Instead, pioneer species such as leguminous trees and shrubs (black locust, autumn olive, and bicolor lespedeza) and Paulownia species that can tolerate a wide range of acidity, fertility, moisture, and temperature should be established first.
The pioneer species will eventually yield to the more site-sensitive hardwoods. In the meantime, the mine soil is being conditioned, nitrogen and organic matter are being incorporated, populations of macro and micro plants and animals are increasing, a more diverse wildlife habitat is being created, and valuable wood products are being produced. The rate at which natural forest succession proceeds depends on the nature of the reclaimed site and adjoining undisturbed sites. In any case, it would require one to two hundred years for the oaks and other mid to late successional hardwoods to dominate if forest restoration were left entirely to nature.
PRP reforestation procedures are designed to accelerate forest succession while providing for the immediate concerns of land stabilization, erosion control, bond release, and economic considerations of land owners. A combination of grasses, legumes, nurse shrubs and trees, and crop trees are established more or less simultaneously. Each plant type serves a specific reclamation function then yields to another plant type. Hydroseeded grasses emerge first to quickly stabilize the minesoil surface. Grasses will then yield to legumes when applied nitrogen is minimized. The slow-starting, ground-sprawling legumes allow trees to become established and free to grow before totally covering the site. The legumes enrich the site and eventually give way to the tree cover. Nurse trees and shrubs condition the site for the crop trees and yield to the crop trees as they close canopy. If pines are established at recommended densities, hardwood species will invade and will be poised for growth when the pines are removed for their economic value. This process of matching plant species to site conditions, matching plant species for their compatibility with each other, and managing tree stands to accomplish certain objectives as they develop over time, is called reforestation silviculture.
Forest Land Postmining Land Uses
Since about 1985, almost all reclaimed land planted with trees has been designated as "unmanaged forest land" (or non-commercial forestland) in reclamation operations permits. Although seldom used, there is another forestland post-mining land-use option referred to as "commercial forest land." Although bond release requirements specified by state regulations are similar for commercial and non-commercial forest land, there are some subtle differences. Typically, unmanaged forestland is planted with white pine and various nitrogen-fixing shrub and tree species. This species composition provides for good forestry, wildlife, and environmental benefits with little or no management input after establishment. The "commercial forest land" option provides the opportunity to use alternative tree species or reclamation practices to achieve a specific management objective. Landowners who want to establish Christmas tree farms, Paulownia plantations, or some timber species other than white pine should designate commercial forestland as the post-mining land use. As with any land-use designation, the coal company must submit a simple management plan which explains how the proposed post-mining land use is to be achieved. Additionally, a copy of the comments by the landowner concerning the proposed use must be submitted. These documents are required to verify that the landowner is committed to the proposed commercial forestland, and that it can be reasonably achieved.
Bond Release Requirements
The guidelines offered in this paper were developed to increase the probability of timely bond release for the coal operator as well as to ensure the establishment of productive forest land. Of particular importance are requirements relative to final surface grading, ground cover, and number of trees per acre required.
Final surface grading
Through the years, the establishment of smoothly-graded slopes with lush vegetation during the first year has become the standard goal for reclamationists. Unfortunately, land reclaimed in this way is often compacted by excessive grading, and the ground cover vegetation is too dense for tree establishment. Most natural forested landscapes in, for example, Southwest Virginia are uneven and many are strewn with rocks and boulders. These surface conditions are consistent with forests and forest management. Natural forest soils are rough and loose which allow deeply-rooted woody species to become established and grow unimpeded. After groundcover and tree establishment, small to medium gullies need not be filled unless they are associated with sedimentation problems. Small to medium gullies may interfere with hayland/pasture uses, but do not interfere with forestry and wildlife habitat. Mine-soil compaction resulting from gully repair is counterproductive.
Ground cover establishment
When trees are planted for "wildlife management, recreation, shelterbelts or forest uses other than commercial forest land," the success standard is 90 percent. This means that coal companies must achieve 81 percent cover for bond release, which is 90 percent of the standard. Ground cover for commercial forestland must only be adequate to control erosion and achieve the specified land use.
Number of trees per acre
The number of trees per acre and species selection differs between commercial forestland and non-commercial forestland. For commercial forestland, there must be at least 400 commercial trees/acre plus 40 wildlife trees or shrubs (a minimum of 440 trees/acre). In Virginia, white pine is the most common commercial species. Other species could be considered commercial as long as the landowner submits a letter of intent to manage alternative species for a commercial purpose, such as Paulownia. For non-commercial forest land, there must be at least 400 trees/acre of which at least 40 must be wildlife trees or shrubs. Native invading hardwoods count toward bond release as long as they are 1-ft tall.
Selection, Placement, and Grading of Mine Soil Material
Carefully-constructed mine soils can be deeper and more fertile than some of the natural soils found in mountainous terrain. Natural soil in many steeply sloping areas of the Appalachians is thin and difficult to recover, store, and replace during reclamation. "Topsoil substitutes" containing large amounts of blasted overburden materials are allowed by law and can be used successfully as plant-growth media. But in order to be as productive as natural soils, the spoil materials must have desirable physical and chemical properties conducive for good growth of deeply-rooted trees. The surface four feet of mine soil material should be easily weatherable so that most rocks and boulders decompose to fine soil materials within a few years. The soil texture of the fine-earth fraction should be loamy to sandy, and the mine-soil should be low in total salts and moderately acid. Most important, the mine-soil must also be left uncompacted to a depth of four feet.
Research studies and many observations of reclaimed sites in Virginia, West Virginia, and Kentucky show that tree survival and long-term growth is excellent on oxidized, moderately-acid, sandstone-derived mine soils.
In general, siltstone and shale that occur directly above or below coal seams should be avoided. These rock types usually have high levels of soluble salts, a high pH, and compact to greater densities w hen trafficked. Some of the blue-gray sandstones that occur further below the surface are acceptable for forest land. However, some of these spoils weather very slowly and should only be selected when brown sandstone is not available.
Reclaimed mine soils must be left loose and uncompacted to ensure successful establishment and long-term growth of trees. Prior to seeding ground covers, reclaimed sites are often cleared of large boulders, gullies are filled, and the surface is graded smooth and "tracked in" with bulldozers to create a seedbed for ground covers. This treatment may be conducive to hayland/pasture establishment, but it is very undesirable for tree establishment and long-term forest growth. Powell River Project research shows that mine soil compaction is the greatest single factor limiting the success of reforestation. When soils are excessively graded and tracked in, trees cannot be planted deeply enough. This results in poor survival rates and permanently reduces the mine soil quality. Compacted mine soils reduce water infiltration, reduce plant available water, increase sheet erosion, and restrict root growth.