ECOLOGICAL SIGNIFICANCE OF WETLANDS ON MINED LANDS

Fred J. Brenner

Grove City College
Grove City, PA 16127

Wetland evaluation and mitigation criteria based on ecological principles is proposed as a guide to both regulatory agencies and the mining industry. These criteria may include Habitat Evaluation Procedures (HEP) developed by the U.S. Fish and wildlife Service and/or other operational variables concerned with the severity of impact and the cost and technical aspects of mitigation. Regional numerical indices should be developed for established wetlands that impacted wetlands can be compared with on a regional basis. Mitigated wetlands should be concerned not only with the principal species being impacted by mining but also the ecology of the region. Wetlands may also be constructed for mine drainage abatement and also slurry pond reclamation. whenever possible, wetland developments should be encouraged to increase the diversity and productivity of mined lands.

Concern over the decline in the number and size of wetlands has resulted in a revised federal regulatory strategy adopted in 1982. These revised regulations expanded the interpretation of normal or routine agricultural, mining, timber, and oil production activities so that regulatory agencies must evaluate the impact of these activities on wetlands prior to the issuance of a permit. Unless a variance is received, current regulations require that mining cannot occur within 90m (300 ft) of a wetland and cannot impact on the hydrologic or ecological balance of the wetland. In Pennsylvania for example, all wetlands, regardless of size or quality, are evaluated by at least two regulatory agencies, usually three or four, prior to the issuance of a mining permit. This current strategy of wetland protection will impact on mining activities in the glaciated and possibly other regions of the United States.

In some regions however, there is a strategy to relax the protection of wetlands associated with isolated water bodies, wetlands above the headwaters of tributaries to navigable streams and wetlands where designated activities are presumed to have only minor individual or cumulative adverse effects.¹ Unfortunately, this may not be the policy of individual state regulatory agencies, nor does it account for differences in the natural values of wetlands or their vulnerability to developmental pressure. The question is not whether the rationale should be an easing or strengthening of the regulations but that the regulations and resultant policies be based on sound ecological principles that enable wetlands to be evaluated in view of the ecology of the region as well as their potential for mitigation. The wetland impact and mitigation policy adapted by the U.S. Fish and Wildlife Service ranks the relative threat to wetlands according to their regional scarcity and their value to key wildlife species.² Many state and local regulatory agencies and private conservation organizations ignore these distinctions. Wetlands may be constructed on mined lands to: (1) enhance reclamation, (2) mitigate existing wetlands, (3) mine pollution abatement and (4) slurry pond reclamation. In the following discussions, a wetland evaluation and mitigation policy based on ecological principles is proposed as a guide to the mining industry that at the same time protect and enhance our wetland resources.

Wetland evaluation procedures must be specifically concerned with the effects of major disturbances, such as mining on wetland areas and, in addition, be able to evaluate a single wetland independently of others for its own intrinsic worth as a wildlife habitat or other functional value.³ The Habitat Evaluation Procedure (HEP) developed by the U.S. Fish and Wildlife Service is applicable for determining habitat value as well as the development of a mitigation policy. The guidelines for evaluation and mitigation of wetlands are based on the following for resource categories:⁴

1. High value unique wetland. Wetland is of high value and irreplaceable on a national or regional basis. No loss of existing habitat will be allowed.
2. High value scarce wetland. Wetland is of high value for evaluating species and is scarce or becoming scarce on a national or regional basis. No loss of existing habitat value will be allowed, unless compensated for by replacement with the same type of wetland having the same habitat value.
3. High to medium value wetland. Wetland is of high or medium value for evaluation of species and is relatively abundant on a national basis. No loss of existing habitat value will be allowed, unless compensated for by replacement with wetland of comparable habitat (may not be same type) and every effort made to reduce impact or loss of existing wetland types.
4. Medium to low value wetland. Wetland is of medium to low value for evaluation of species (regardless of scarcity). If losses cannot be minimized, compensation with replacement or enhanced habitat may be recommended, depending on the significance of the potential loss.  

These guidelines are applicable for the evaluation of wetlands as wildlife habitats but they should be based on developing habitat values for one or more key species.

Nelson and Weller proposed a rationale for the impact of development on wetlands which also applicable to mining. These authors suggest five orders of magnitude based on the extent of the impact and the cost of difficulty of mitigation.¹

1. Immediate, total, and essentially irreversible impact due to draining, filling, or displacement of flooding, etc. which may be technically but not economically feasible to reverse.
2. Permanent, often far reaching and practically irreversible adverse change to the hydrology of the system resulting in loss of wetland vegetation and wet or dry cycles.
3. Enduring, often economically irreversible but gradual and relatively confined changes to wetland soils and substrate from erosion, sedimentation and chemical contamination.
4. Chronic, sometimes persistent and widespread, but usually low level water quality deterioration from nutrient enrichment or toxic compounds.
5. Temporary, usually localized damage to soils, water quality, vegetation, and environmental aspects due to increased turbidity or similar phenomena.

As with any evaluation criteria, there are numerous factors which may modify the severity of impact at any order of magnitude and these factors may vary from one geographic area to another. Nelson and Weller, therefore, developed four general categories as a guide for evaluating the impact on wetland systems.

1. Operations variables. Distribution, scale, and types of activity, frequency, duration and season of activity, location of activity within an ecosystem.
2. Physical and chemical variables. Hydrological regime and water dynamics, particulate composition of soils and sediments, chemical composition of water and sediments.

3. Biological and -ecological variables. Habitat diversity and carrying capacity, Population abundance, diversity, and productivity, ecosystem stability, resistance and resilience, presence of key species important to the ecosystem.

4. Public interest variables. Regional scarcity of affected habitat types, abundance of sport and commercial populations, presence of endangered or threatened species.

These five orders of impact and operational variables provide criteria for determining the severity of impact as well as a framework for mitigation. The five orders of impact are concerned with the cost of technical aspects of mitigation, whereas the modifying factors introduce ecological and public interest variables into the evaluation process. Cardamone et al. suggested that a numerical index be assigned to wetlands on the basis of a comparative analysis of wetlands in the region.⁴ This index should be based on the biological, ecological, and hydrological features in conjunction with aesthetic values and uniqueness to the area. For example, a wetland that contains endangered species and a carrying capacity of 20 waterfowl/ha and was the only wetland in the region would have a higher numerical index than a wetland without endangered species, a carrying capacity of 5 waterfowl/ha and was one of several in the region. However, the total size and carrying capacity must be taken into account as well. Once a wetland has been evaluated as to the impact of mining, a determination must be made as to whether or not to mine the site in a manner that would not impact on the system or to mitigate the wetland in a manner that would be compatible with the ecology of the region.

Wetlands, in recent years, have been shown to be effective in reducing the impact of acid mine discharges on stream systems. This reduction may be a result of the precipitation of metal ions due to an increase in pH and retention time and/or the uptake of metallic ions by the plants themselves. Although the exact mechanisms are not understood, wetland plants take up and concentrate ferric ions and, to some degree, manganese oxidizing bacteria present in the soil, on the roots (rhizomes) of wetland plants or on the plant itself (algae). Preliminary data suggest that a significant relationship exists between the number of bacteria in the soil surrounding the root (rhizomes) of wetland plants and the concentration of iron (r2 = 0.61 1 P >0.05) and manganese (r2 0.93, P> 0.01) concentrations in the tissues. Further research on the ecology and physiology of these systems will be necessary before we fully understand the physical, chemical and biological processes involved in the abatement of acid mine discharges. At present, they appear to be a promising alternative to the chemical treatment of acid mine drainage.

Table 1. Iron, manganese and aluminum concentrations in four plants growing in wetland receiving acid mine drainage in Butler County, Pennsylvania.

Wetland Development From Slurry Ponds.

At several mine sites in the midwest, slurry ponds have been reclaimed as productive wildlife areas. 14,15 Slurry consists of a mixture of water and the fines that remain after the coal has been cleaned, this mixture is then discharged into a depression for storage. Because of its pyritic sulfur content and acid producing potential, slurry is considered a potentially toxic substance by OSM and must be disposed of in a prescribed manner. Current regulations require that slurry be covered with at least 1.2m (4 ft.) of non-toxic material and revegetated. This procedure is not only costly to the mine operator but also generally results in land that has limited potential for secondary reclamation.

As an alternative to the prescribed method of slurry pond reclamation, researchers at Southern Illinois University and AMAX Coal Company are developing viable wetlands on slurry disposable sites. The company received an Experimental Practices Permit under Section 711 of SMCRA which allows them to develop an alternative for slurry pond reclamation. Briefly, the procedure involves the determination of highly toxic materials and covering them with top soil according to OSM regulations; then the remainer of the pond are re-vegetated with wetland species. Species are selected and planted according to the water depth and available moisture in each zone (Appendix Table 1). This alternative to slurry pond reclamation enabled the development of a viable wetland with the pH of both the slurry and water returning to acceptable pH ranges. Reclaimed slurry ponds are currently being used by migrating and nesting Canada Geese (Branta canadenesis), blue and green-winged teal (Anas discors, A. carolinensis), great blue herons (Ardea herodias) and a variety of shore birds. The deep water portions are supporting a viable sport fishery (Thompson 1984). In addition to developing a valuable wildlife habitat, the company was able to reduce their reclamation costs by approximately 80 percent.¹⁵  These procedures should be given serious consideration by regulatory agencies and the coal industry as an alternative to slurry pond reclamation.

For over four decades, wetlands have been left as an aftermath of surface mining and many of these areas have been shown to be beneficial for fish and wildlife,^5,6 especially waterfowl.^7,8,9  However, when wetlands have to be mitigated, prime consideration should be given the principal species affected by the disturbance of the natural system. For example, if the disturbed wetlands contained nesting and feeding areas for woodcock (Philohela minor), then habitat suitable for this species should be developed during mitigation. In the future, the development of woodcock habitat should be given prime consideration during reclamation regardless of whether mining impacted on woodcock habitat since breeding populations of this species has been declining in the northeast for several years.

In both the northeast and midwest, waterfowl and shorebirds nest on reclaimed mined lands as well as use these man-made wetlands for nesting and feeding during mitigation. Waterfowl and shorebird habitat developments on mined lands should include shallow areas for feeding along with nesting islands and appropriate nesting cover along the shore. Shorelines should be constructed as irregularly as possible, thereby providing sufficient edges for feeding and nesting by waterfowl. In some areas, it may be desirable to develo wetlands for specific species including those that may be threatened or endangered. 10,1 In other areas, it might be beneficial to the ecology of the region to provide diversity of habitats suitable for a variety of species. In general, a variety of species should be planted according to hydrologic regimes of the reclaimed wetland (Appendix Table 1), thereby developing a diverse and productive ecosystem which according to theoretical studies on ecosystem dynamics suggest that diversity and productivity are indicative of ecosystem stability. 12,13 In order to achieve diversity and reconstruct natural systems, studies are currently underway in Pennsylvania involving removing wetland vegetation and bottom sediments from natural wetlands and transporting them to a mitigated wetland on mined lands.

To evaluate the success of this program, the diversity and productivity of these wetlands are being compared with mitigated wetlands revegetated with wetland species and natural systems in the same region. Three or four hedgerows of wildlife tree and shrub species separated by 6-7 m grass-legume strips should be planted around each wetland on the site.

Regardless of whether mine operators are required to mitigate wetlands, the development of these habitats should be encouraged whenever water conditions and terraine are suitable and the landowner(s) approves of their construction. In addition, it may be desireable to plant wetland species in sediment and treat slurry ponds once mining has been completed, thereby developing these areas as fish and wildlife habitats.^14,15 All wetland systems should be planned to be as resilient as possible: That is, developed to a successional stage suitable for the desired species as quickly as possible. As with all ecosystems, wetlands on mined lands will have to be managed so that they will remain in the successional stage(s) most advantageous to the principal species of concern.¹¹ Brooks and Hi11¹⁶ reported that there were 18 percent more Palustrine wetlands on mined lands than on unmined lands in Pennsylvania and these authors as well as Brenner 10111 indicated that wetlands should be encouraged on mined lands and managed for either diverse communities or for individual or groups of species.

Criteria used to evaluate wetlands should include their value as wildlife habitat, hydrologic features, and their importance in the overall ecology of the region. Whenever possible, a numerical index should be assigned to wetlands on the basis of a comparative analysis of wetlands in the region. The criteria used in the evaluation should include a determination of the severity of impact and a framework for mitigation. Whenever wetlands are developed on mined lands, they may be either designed for specific species or contain a diversity of habitats suitable for a variety of species. wetlands should be encouraged on all mined lands regardless of whether wetlands were impacted by mining in order to increase the diversity and productivity of mined lands.

References

1. R.W. Nelson, and E.C. Weller, "A Better Rationale for Wetland Management", Environmental Management, Vol. 8, Springer-Verlag, NY, pp. 295-308, 1984.
2. Federal Register, "U.S. Fish and Wildlife Service Mitigation Policy", Vol. 46, pp. 7644-7663, 1981.
3. M.A. Cardamone, J.R. Taylor, and W.J. Mitsch, "Wetland and Coal Surface Mining: A Management Handbook with Particular Reference to the Illinois Basin of the Eastern Interior Coal Region", Center for Environmental Science and Management, University of Louisville, Louisville, KY. 1984.
4. P.R. Adamus and L.T. Stockwell, "A Method for wetlands Functional Assessment", Vol. 1, Critical Review and Evaluation Concepts, Vol. II, FHWA Assessment Method, U.S. Department of Transportation, Federal Highway Administration, FHWA-1P-82-23 and FHWA-IP-82-24, Washington, D.C. 1983.
5. F.J. Brenner and J. Kelly, "Characteristics of Bird Communities on Surface Mined Lands in Pennsylvania", Environmental Management, Vol. 5, Springer-Verlag, NY) pp. 441-449, 1981.
6. RP Brooks, J.B. Hill, F.J. Brenner, S. Capets, "Wildlife Use of Wetlands on Coal Surface Mines in Western Pennsylvania", Wetlands and Water Management on Mined Lands Proceedings, Pennsylvania State University, University Park, PA., pp. 327-352, 1985.
7. F.J. Brenner, "Evaluation of Abandoned Strip Mines as Fish and Wildlife Habitat", Transactions of the Northeast Wildlife Conference, Vol. 34, pp. 205-229, 1973.
8. F.J. Brenner and J.J. Mondok, "Waterfowl Nesting Rafts Designed for Fluctuating Water Levels", Journal Wildlife Management, Vol. 43, pp. 978-982, 1978.
9. J.E. Sandusky, "The Potential for Management of Waterfowl Nesting Habitats on Reclaimed Mined Lands", Surface Mining and Fish/Wildlife Needs in the Eastern United States, Fish and Wildlife Service Office of Biological Services, Washington, D.C., pp. 325-327, 1978.
10. F.J. Brenner, "Aquatic and Terrestrial Habitats in Pennsylvania", Species of Special Concern in Pennsylvania, Carnegie Museum of Natural History, Pittsburgh, pp. 7-17, 1985.
11. F.J. Brenner, "Habitat Preservation and Development for Rare and Endangered species", Endangered and Threatened Species Programs in Pennsylvania and other States: Causes, Issues and Management, Pennsylvania Academy of Science, Easton, PA, pp. 37-52, 1986.
12. J. Waide, "Methods for Investigating Stability of wetlands", Analysis of Selected Wetland Functions and Values, U.S. Army Corps of Engineers, Institute for Water Resources, Unpublished, 198T.
13. J.R. Webster, J.B. Waide, and B.C. Patten, "Nutrient Recycling and the Stability of Ecosystems", Proceedings of a Symposium on Mineral Cycling in Southeastern Ecosystem, Augusta, GA., U. S. Energy Research and Development Administration (NTIS-CONF-740513), pp. 1-27, 1975.
14. J.R. Nawrot and S.C. Yaich, "Slurry Discharge Management for Wetland Soil Development", Symposium on Surface, Mining Hydrology, Sedimentation and Reclamation, University of Kentucky, Lexington, KY, pp. 11-18, 1982.
15. C.S. Thompson, "Experimental Practices in Surface Coal Mining - Creating Wetland Habitat", Wetlands Newsletter, 1984.
16. R.P. Brooks and J. B. Hill, "Status and Trends of Freshwater wetlands in the coal Mining Region of Pennsylvania", Environmental Management, Vol. 11, Springer and Verlag, NY, pp. 29-34, 1987.

APPENDIX

Table 1. Wetland species recommended for planting on mitigated wetlands in the eastern and midwestern United States.