Northern Prairie Wildlife Research Center
Along with disturbance from surface mining in the early 1970's, the Ollis Creek watershed, Campbell County, Tennessee, has been impacted by active logging for many years, barren lands because of acid spoil conditions, and old deep mines with acid mine drainage potential (Starnes et al. 1978). Due to pyritic materials associated with coal seams mixed with overburden material, efforts in the early 1970's to plant over a half million trees and to seed approximately nine tons of grass generally failed to provide the necessary cover. When the soil weathered, sulfuric acid formed, causing spoil pH to decrease (4.7-3.0). Water quality in receiving streams began to deteriorate. Silt carried by the streams was reaching a downstream reservoir, thus reducing its storage capacity.
To remedy these problems, the Tennessee Valley Authority used various combinations of soil treatments, regrading, and applying topsoil to the most critical areas. Treatments initiated during fall 1974 included spreading and disking-in agricultural limestone to raise spoil pH, fertilizing, seeding with grasses and legumes to provide a protective ground cover, and planting trees and shrubs the following planting season. Three years later, treatment sites contained 39% to 76% herbaceous cover and 1,727 to 4,868 woody plants/ha. Incorporation of lime and fertilizer into spoils was essential for successful revegetation of the acid sites. In addition, stream pH increased and other water quality parameters improved (e.g., turbidity, sulfates, and certain metals). Aquatic invertebrate fauna responded slowly to remedial treatments, but did appear to show trends toward recovery. No permanent fish populations were present, but fish periodically used the Ollis Creek tributaries.
Numerous attempts have been made to rehabilitate wetlands of the phosphate mine region of central Florida (Clewell 1983). Restoration of forested wetlands has been generally less successful than marsh restoration. Restoration of forested wetlands has focused on techniques of tree planting and not on introduction of understory plants. Various techniques for planting trees have been attempted. Successful restoration appears to be dependent on using a combination of techniques, including mulching with riverine forest topsoil. Irrigation is necessary for the first few years, unless near-saturated soils can be maintained during dry seasons. Several reforestation methods should be attempted to ensure a dense initial growth of trees. If these trees grow quickly, a canopy will begin to close within 4-5 years, protecting preferred undergrowth species transferred in the mulch.
Sandrik and Crabill (1983) found that transplanting organic mulch to restoration sites at the Amax Big Four Mine in west-central Florida provided a diverse seed and plant source and a quick start for marsh revegetation. In addition, this technique appeared to help control rapid cattail (Typha spp.) invasion on unvegetated wetland sites, which created undesirable monocultures.
Sink Branch, a perennial stream located in the phosphate mine region of central Florida, was diverted from its original course into a channel excavated on mined land reclaimed with a complex mixture of overburden and clay (Robertson 1984). Other restoration techniques included planting nine species of native tree seedlings, planting of emergent vegetation in the stream, and fencing to exclude cattle. Soil treatments incorporated into the experimental design were: (1) addition of fertilizer to holes in which trees were planted, (2) application of a 15-cm layer of organic topsoil, (3) application of a 30-cm layer, and (4) the control site (no treatment). Soil amendments incorporated into the reclamation plan at the mined site had no effect on growth or survival of trees planted over a 3-year period. However, overall survival differed greatly between species: Florida elm (Ulmus floridana), 94%; bald cypress Taxodium distichum), 1%; sweetbay (Magnolia virginiana), 6%; and dogwood (Cornus foemina), 6%.
Physical water quality data after 6 months was similar between treated and control sites. Water flowing out of the channel was slightly lower in nitrogen and orthophosphate than water entering the channel, indicating that the channel had a slight positive effect on water quality by reducing the nutrient content of the water. After 1 year, density and diversity of aquatic invertebrates were similar between treated and control sites; however, the two sites supported different groups of species (e.g., isopods, amphipods, and snails from the treated channel; mosquitoes and predaceous diving beetles from the control site). Species richness was greater in the reclaimed channel than in the undisturbed control site.