Reclaimed Mine Lands Research Articles

Soil water balance dynamics on reclaimed mine land in the southwestern United States

Understanding the dynamics of soil water movement in arid and semi-arid environments is critical to successful reclamation of mined lands. Characteristics of applied topsoil impact soil water processes and long-term ecosystem health. The objective of this study was to better understand the soil water balance at a reclaimed mine in the southwestern United States through the investigation of soil hydraulic properties and subsequent one-dimensional water balance modeling. The study was conducted on a mine reclaimed using geomorphic principles. Complementary field and laboratory techniques were used to describe soil properties. Dry bulk density of topsoil at the mine sites increased with depth, while saturated hydraulic conductivity decreased with increasing bulk density. Two discrete one-dimensional models were created to investigate soil water dynamics and results indicate the importance of appropriately describing soil layering to create more accurate model predictions. In addition, results suggest that matric potentials during the study period were often too low for substantial plant growth. Models similar to those created in this study may be helpful in future assessment of seed germination on reclaimed lands as well as the implications that global climate change may have on reclamation strategies in the future.

Northern bobwhite breeding season ecology on a reclaimed surface mine

ABSTRACTSurface coal mining and subsequent reclamation of surface mines have converted large forest areas into early successional vegetative communities in the eastern United States. This reclamation can provide a novel opportunity to conserve northern bobwhite (Colinus virginianus). We evaluated the influence of habitat management activities on nest survival, nest‐site selection, and brood resource selection on managed and unmanaged units of a reclaimed surface mine, Peabody Wildlife Management Area (Peabody), in west‐central Kentucky, USA, from 2010 to 2013. We compared resource selection, using discrete‐choice analysis, and nest survival, using the nest survival model in Program MARK, between managed and unmanaged units of Peabody at 2 spatial scales: the composition and configuration of vegetation types (i.e., macrohabitat) and vegetation characteristics at nest sites and brood locations (i.e., microhabitat). On managed sites, we also investigated resource selection relative to a number of different treatments (e.g., herbicide, disking, prescribed fire). We found no evidence that nest‐site selection was influenced by macrohabitat variables, but bobwhite selected nest sites in areas with greater litter depth than was available at random sites. On managed units, bobwhite were more likely to nest where herbicide was applied to reduce sericea lespedeza (Lespedeza cuneata) compared with areas untreated with herbicide. Daily nest survival was not influenced by habitat characteristics or by habitat management but was influenced by nest age and the interaction of nest initiation date and nest age. Daily nest survival was greater for older nests occurring early in the breeding season (0.99, SE < 0.01) but was lower for older nests occurring later in the season (0.08, SE = 0.13). Brood resource selection was not influenced by macrohabitat or microhabitat variables we measured, but broods on managed units selected areas treated with herbicide to control sericea lespedeza and were located closer to firebreaks and disked native‐warm season grass stands than would be expected at random. Our results suggest the vegetation at Peabody was sufficient without manipulation to support nesting and brood‐rearing northern bobwhite at a low level, but habitat management practices improved vegetation for nesting and brood‐rearing resource selection. Reproductive rates (e.g., nest survival and re‐nesting rates) at Peabody were lower than reported in other studies, which may be related to nutritional deficiencies caused by the abundance of sericea lespedeza. On reclaimed mine lands dominated by sericea lespedeza, we suggest continuing practices such as disking and herbicide application that are targeted at reducing sericea lespedeza to improve the vegetation for nesting and brood‐rearing bobwhite. © 2016 The Wildlife Society.

Tree-Substrate Water Relations and Root Development in Tree Plantations Used for Mine Tailings Reclamation.

Tree water uptake relies on well-developed root systems. However, mine wastes can restrict root growth, in particular metalliferous mill tailings, which consist of the finely crushed ore that remains after valuable metals are removed. Thus, water stress could limit plantation success in reclaimed mine lands. This study evaluates the effect of substrates varying in quality (topsoil, overburden, compost and tailings mixture, and tailings alone) and quantity (50- or 20-cm-thick topsoil layer vs. 1-m plantation holes) on root development and water stress exposure of trees planted in low-sulfide mine tailings under boreal conditions. A field experiment was conducted over 2 yr with two tree species: basket willow ( L.) and hybrid poplar ( Moench × A. Henry). Trees developed roots in the tailings underlying the soil treatments despite tailings' low macroporosity. However, almost no root development occurred in tailings underlying a compost and tailings mixture. Because root development and associated water uptake was not limited to the soil, soil volume influenced neither short-term (water potential and instantaneous transpiration) nor long-term (δC) water stress exposure in trees. However, trees were larger and had greater total leaf area when grown in thicker topsoil. Despite a volumetric water content that always remained above permanent wilting point in the tailings colonized by tree roots, measured foliar water potentials at midday were lower than drought thresholds reported for both tested tree species.

Identifying the Presence of AMD-Derived Soil CO2 in Field Investigations Using Isotope Ratios

Recent incidents of hazardous accumulations of CO2 in homes on or adjacent to reclaimed mine land have been shown to be linked to neutralization reactions between acidic mine drainage and carbonate material. An efficient and economic method is necessary to identify the presence of acid mine drainage- (AMD-) derived CO2 on reclaimed mine land, prior to construction. One approach to identify the presence of AMD-derived CO2 is to characterize stable carbon isotope ratios of soil CO2. To do so, a viable method is necessary to acquire soil gas samples for isotope ratio analysis. This paper presents preliminary investigations of the effectiveness of two methods of acquiring gas samples (sampling during soil flux measurements and using slam bar) for isotope analysis. The results indicate that direct soil gas sampling is cheaper and provides better results. Neither method is adequate without accounting for temporal effects due to changing gas transport mechanisms. These results have significant implications for safe post-mining land uses and future investigations of leakages from geologic carbon sequestration sites.

Life-history and phenotypic traits of insectivorous songbirds breeding on reclaimed mine land reveal ecological constraints

Studies assessing impacts of industrial activities on wildlife typically examine population- or community-level responses. However, changes in measures such as species abundance or diversity are driven by cumulative responses of individuals to disturbance, and may take time to detect. Quantifying individual responses could allow us to foresee and mitigate future population declines resulting from industrial activities, while providing ecologically informative indices to assess quality of reclaimed land. We examined life-history and phenotypic traits of mountain bluebirds (Sialia currucoides) and tree swallows (Tachycineta bicolor) breeding on reclaimed copper mine lands in Canada over two years in comparison to a nearby undisturbed reference area. Bluebirds feed on terrestrial invertebrates, whereas swallows feed on adult forms of insects with aquatic larvae, allowing us to assess quality of both reclaimed terrestrial and aquatic systems as habitat for insectivorous birds. Supplemental feeding of bluebirds also was used to experimentally assess nutritional limitation of birds feeding on terrestrial invertebrates. Bluebirds on reclaimed land initiated clutches later, and in one year had lower fledging success compared to birds on the reference area. Tree swallows also bred later in the season on reclaimed land, but were otherwise comparable to or exceeded performance of birds on the reference area. Annual differences in responses of nestling bluebirds on the mine to supplemental feeding revealed an apparent switch in life-history strategy of parents between years, from brood reduction to brood survival, suggesting greater annual fluctuations in ecological conditions within terrestrial systems on reclaimed land. Sex differences in response of nestling bluebirds to food supplementation additionally suggested high within-brood competition for food on reclaimed land. We suggest that measures of avian life-history and phenotypic traits, particularly when assessed over multiple years using experimental approaches such as food supplementation, are informative and sensitive indices of the health of reclaimed terrestrial and aquatic systems.

Delineating hazardous CO2 fluxes from acid mine drainage

Incidents of hazardous accumulations of CO2 in homes built on or near reclaimed mine land, in the last decade, have been shown to be linked to neutralization reactions between acidic mine drainage and carbonate material. Recent research has shown that CO2 fluxes on reclaimed mine land with this hazard are, sometimes, spatially autocorrelated (i.e., the spatial variability is not random). This result implies geostatistics can be used to delineate hazardous areas where fluxes are likely to exceed established thresholds. This study applies sequential Gaussian simulation to delineate this emerging hazard on a site in southwestern Indiana, USA. Due to lack of regulatory threshold limits for CO2 flux at the current time, the authors conduct a sensitivity analysis of the threshold limit using the 75th, 90th and 95th percentiles of the measured fluxes for the first day of monitoring. These limits are used to produce hazard maps, which are validated with the known hazard at the site. This work further shows the potential of surface CO2 flux monitoring as a cheap and effective strategy to monitor and delineate such hazards to avoid residential and commercial real estate development in high risk zones.

Habitat manipulation influences northern bobwhite resource selection on a reclaimed surface mine

ABSTRACTMore than 600,000 ha of mine land have been reclaimed in the eastern United States, providing large contiguous tracts of early successional vegetation that can be managed for northern bobwhite (Colinus virginianus). However, habitat quality on reclaimed mine land can be limited by extensive coverage of non‐native invasive species, which are commonly planted during reclamation. We used discrete‐choice analysis to investigate bobwhite resource selection throughout the year on Peabody Wildlife Management Area, a 3,330‐ha reclaimed surface mine in western Kentucky. We used a treatment‐control design to study resource selection at 2 spatial scales to identify important aspects of mine land vegetation and whether resource selection differed between areas with habitat management (i.e., burning, disking, herbicide; treatment) and unmanaged units (control). Our objectives were to estimate bobwhite resource selection on reclaimed mine land and to estimate the influence of habitat management practices on resource selection. We used locations from 283 individuals during the breeding season (1 Apr–30 Sep) and 136 coveys during the non‐breeding season (1 Oct–Mar 31) from August 2009 to March 2014. Individuals were located closer to shrub cover than would be expected at random throughout the year. During the breeding season, individuals on treatment units used areas with smaller contagion index values (i.e., greater interspersion) compared with individuals on control units. During the non‐breeding season, birds selected areas with greater shrub‐open edge density compared with random. At the microhabitat scale, individuals selected areas with increased visual obstruction >1 m aboveground. During the breeding season, birds were closer to disked areas (linear and non‐linear) than would be expected at random. Individuals selected non‐linear disked areas during winter but did not select linear disked areas (firebreaks) because they were planted to winter wheat each fall and lacked cover during the non‐breeding season. Individuals also selected areas treated with herbicide to control sericea lespedeza (Lespedeza cuneata) throughout the year. During the breeding season, bobwhites avoided areas burned during the previous dormant season. Habitat quality of reclaimed mine lands may be limited by a lack of shrub cover and extensive coverage of non‐native herbaceous vegetation. Managers aiming to increase bobwhite abundance should focus on increasing interspersion of shrub cover, with no area >100 m from shrub cover. We suggest disking and herbicide application to control invasive species and improve the structure and composition of vegetation for bobwhites. © 2015 The Wildlife Society.

Restoration of Riparian Buffer Function in Reclaimed Surface Mine Soils

Ecosystem processes such as water infiltration and denitrification largely determine how riparian buffers function to protect surface water quality. Reclaimed mine areas offer a unique opportunity to study the restoration of riparian function without the confounding influence of past land use. Between 1980 and 2000 in southern Illinois, agricultural fields with forest buffers were established along three restored stream reaches in reclaimed mine land. Our research objective was to compare common indicators of soil quality (infiltration, soil C and N, bulk density, and soil moisture) between forest and cultivated riparian zones to determine if riparian function was being restored. Soil bulk density was significantly lower in the forest buffers compared to the agricultural fields. The forest buffers had greater soil total C, total N, and moisture levels than agricultural fields likely due to greater organic matter inputs. Soil total C and N levels in forest buffers were positively related to age of restoration, indicating soil quality is gradually being restored in the buffers. Restoration success of riparian buffers should not be estimated by the return of structure alone; it also includes reestablishment of functions such as nutrient cycling and water retention that largely determine water quality benefits. Watershed planning efforts can expect a lag time on the order of decades between riparian restoration activities and surface water quality improvement.

Spatial autocorrelation of soil CO2 fluxes on reclaimed mine land

Recent evidence has shown that CO2 emissions from reclaimed mine soil with acid mine drainage and carbonate material is an emerging geohazard. Surface CO2 flux measurements can be a cheap and effective way to delineate such hazards and avoid residential and commercial real-estate development on high-risk zones. Very little work has been done to ascertain whether or not such fluxes are spatially correlated, which has significant implications on the choice of statistical methods for analysis. The objective of this study was to understand the extent to which CO2 fluxes on a reclaimed mine spoil, with CO2 from carbonate neutralization of acidic drainage, are spatially autocorrelated. CO2 fluxes from three reclaimed surface coal mine sites were measured and used in statistical analysis to test the research hypothesis. The results show that the spatial variability of fluxes is not always random but can show significant (p < 0.0001) spatial autocorrelation. This result implies that classical statistical analysis of CO2 fluxes from reclaimed mine land may lead to wrong inferences, since such analysis ignores the spatial correlation. It appears spatial autocorrelation in CO2 fluxes may be related to spatial autocorrelation in soil temperatures, suggesting a common underlying phenomenon. Significant contribution of CO2 from exothermic acid mine drainage to soil CO2 flux is suggested as a possible explanation.

Influence of elevation, soil temperature and soil moisture content on reclaimed mine land soil CO2 fluxes

Recently, incidents of hazardous accumulations of CO2 in homes built on or near reclaimed mine land have been shown to be linked to neutralization reactions between acidic mine drainage and carbonate material. Surface CO2 flux measurements have been proposed as a potentially cheap and effective strategy to monitor and delineate such hazards to avoid residential and commercial real-estate development on high risk zones. For this strategy to work, more work is needed to understand the strength of association between CO2 fluxes on reclaimed mine land and relevant covariates (e.g. sample elevation, soil temperature and soil moisture) to ensure comprehensive monitoring. The objective of this study was to understand the extent to which CO2 fluxes on reclaimed spoil are affected by sample elevation, soil temperature and soil moisture. Specifically, the work tested the hypothesis that CO2 fluxes are correlated to elevation, soil temperature and soil moisture. Carbon dioxide fluxes from three study sites were measured and used in statistical analysis to test the research hypothesis. The results show statistically significant (p < 0.05) positive but monotonic correlation between CO2 fluxes and soil temperature, while fluxes and elevation are negatively correlated, monotonically in a similar manner. Where significant, correlation between fluxes and soil moisture was observed to be negative. This result implies that flux surveys on reclaimed mine land need to measure elevation, soil temperature and soil moisture at survey points.

Growth performance and chestnut blight incidence (Cryphonectria parasitica) of backcrossed chestnut seedlings in surface mine restoration

Anthropogenic disturbances such as mining for coal have caused significant disturbance to the Appalachian forests of North America. Recovery of these disturbances is highly dependent on restoration methods that encourage natural succession. Unfortunately, current reclamation protocols have resulted in soil compaction and aggressive herbaceous groundcovers that impede the recovery of native trees. To overcome this, methods such as deep ripping and plow and disking were applied to a reclaimed mine land in Ohio, USA Plantings of pure American chestnut (Castanea dentata) and two seedling types (BC1F3 and BC2F3) bred for resistance to chestnut blight fungus (Cryphonectria parasitica) were assessed among different soil preparation treatments over five field seasons. Seedling mortality due to natural infection by chestnut blight was recorded and related to the disease resistance potential of the BC1F3 and BC2F3 seedlings. The growth and survival of chestnuts in plots that employed either ripping, plow disking, or the combination of the two methods were significantly greater than the control plots. After five seasons, differences existed among the soil treatments; plots that applied deep ripping had the highest survival and growth. When chestnut types were compared, pure American chestnut was the tallest. However, BC2F3 chestnut seedlings had the highest survival and lower disease incidence. Results suggest that employing deep ripping with backcrossed chestnut seedlings provides a method for establishing hardwood seedlings in soils impacted by surface mining. Planting methods that promote vigorous growth can be applied more broadly to other regions where anthropogenic disturbances create soil conditions that hinder seedling establishment.

Carbon Life Cycle Assessment for Prairie as a Crop in Reclaimed Mine Land

ABSTRACTA life cycle assessment with carbon (C) as the reference unit was used to balance the benefits of land preparation practices of establishing tall‐grass prairies as a crop for reclaimed mine land with reduced environmental damage. Land preparation and management practices included disking with sub‐soiling (DK‐S), disking only (DK), no tillage (NT), and no tillage with grazing (NT‐G). To evaluate the C balance and energy use of each of the land preparations, an index of sustainability (Is = CO/CI, Where: CO is the sum of all outputs and CI is the sum of all inputs) was used to assess temporal changes in C.Of the four land preparation and management practices, DK had the highest Is at 8·53. This was due to it having the least degradation of soil organic carbon (SOC) during land‐use change (−730 kg ha−1 y−1) and second highest aboveground biomass production (9,881 kg ha−1). The highest aboveground biomass production occurred with NT (11,130 kg ha−1), although SOC losses were similar to DK‐S, which on average was 2,899 kg ha−1 y−1. The Is values for NT and DK‐S were 2·50 and 1·44, respectively. Grazing from bison reduced the aboveground biomass to 8,971 kg ha−1 compared with NT with no grazing, although stocking density was low enough that Is was still 1·94. This study has shown that converting from cool‐season forage grasses to tall‐grass prairie results in a significant net sink for atmospheric CO2 3 years after establishment in reclaimed mine land, because of high biomass yields compensating for SOC losses from land‐use change. Copyright © 2014 John Wiley &amp; Sons, Ltd.

Ripping Improves Tree Survival and Growth on Unused Reclaimed Mined Lands

There is renewed interest in re-establishing trees on 0.6 million ha of mining-disturbed lands in the Appalachian mountains of Eastern United States. Many coal-mined lands reclaimed to meet requirements of US federal law have thick herbaceous vegetation and compacted soils which impede tree establishment. Mitigation practices were applied on three mine sites and evaluated for success in enabling planted trees to become established. Eastern white pine (Pinus strobus), hybrid poplar (Populus deltoids × Populus trichocarpa), and mixed Appalachian hardwoods were established using weed control only and weed control with subsoil ripping. Trees were measured in October of 2008 after 5 years of growth. Subsoil ripping increased mixed hardwood survival from 43 to 71%, hybrid poplar biomass index from 1.51 to 8.97 Mg ha(-1), and Eastern white pine biomass index from 0.10 to 0.32 Mg ha(-1). When restoring trees to unused mined sites, subsoil ripping can aid survival and growth to an extent that will result in a valuable forest.

Soil quality index as a tool for Scots pine (Pinus sylvestris) monoculture conversion planning on afforested, reclaimed mine land

In Central Europe, a large portion of post-mining sites were afforested with Scots pine, which is characterized by good adaptability and a tolerance for poor habitat at the beginning of forest ecosystem development. Conversion of monoculture on mine sites into more biodiverse mixed hardwood forests, especially on more fertile deposits, can be an emerging need in this part of Europe in next decades. The ability to classify the forests at these post-mining sites will facilitate proper species selection as well as the management and formation of the developed ecosystem’s stability. This work describes the guidelines that can be followed to assess reclaimed mine soil (RMS) quality, using the mine soil quality index (MSQI) and a classification of developed forest sites as a basis of tree-stand species selection and conversion of pine monocultures. The research was conducted on four post-mining facilities (lignite, hard coal, sulphur, and sand pit mining areas) on different RMS substrates dominant in Central Europe. Soil quality assessment takes into account the following features of the soil: texture soil nutrients (Ca, Mg, K, Na, P); acidity (pH KCl); and Corg-to-Nt ratio in the initial organic horizon. An analysis was conducted of classification systems using the MSQI validation correlation (at p =0.05) with vegetation features affected by succession: aboveground biomass of forest floor and ecological indicators of vascular plants (calculated on the basis of Ellenberg’s (2009) system). Eventually, in the analysed data set, the MSQI ranged from 0.270 for soils on quaternary sands to 0.720 for a mix of quaternary loamy sands with neogene clays. Potential forest habitat types and the role of the pine in the next generation of tree stands on different RMS parent rock substrate were proposed.

Erodibility of low‐compaction steep‐sloped reclaimed surface mine lands in the southern Appalachian region, USA

AbstractThe use of loose spoils on steep slopes for surface coal mining reclamation sites has been promoted by the US Department of Interior, Office of Surface Mining for the establishment of native forest, as prescribed by the Forest Reclamation Approach (FRA). Although low‐compaction spoils improve tree survival and growth, erodibility on steep slopes was suspected to increase. This study quantified a combined KC factor (combining the effects of the soil erodibility K factor and cover management C) for low compaction, steep‐sloped (&gt;20°) reclaimed mine lands in the Appalachian region, USA. The combined KC factor was used because standard Unit Plot conditions required to separate these factors, per Revised Universal Soil Loss Equation (RUSLE) experimental protocols, were not followed explicitly. Three active coal mining sites in the Appalachian region of East Tennessee, each containing four replicate field plots, were monitored for rainfall and sediment yields during a 14‐month period beginning June 2009. Average cumulative erosivity for the study sites during the monitoring period was measured as 5248.9 MJ·mm·ha−1·h−1. The KC ranged between 0.001 and 0.05 t·ha·h·ha−1·MJ−1·mm−1, with the highest values occurring immediately following reclamation site construction as rills developed (June – August 2009). The KC for two study sites with about an 18–20 mm spoil D84 were above 0.01 t·ha·h·ha−1·MJ−1·mm−1 during rill development, and below 0.003 t·ha·h·ha−1·MJ−1·mm−1 after August 2009 for the post‐rill development period. The KC values for one site with a 40 mm spoil D84 were never above 0.008 t·ha·h·ha−1·MJ−1·mm−1 and also on average were lower, being more similar to the other two sites after the rill development period. Based on an initial KC factor (Ke) measured during the first few storm events, the average C factor (Ce) was estimated as 0.58 for the rill development period and 0.13 for the post‐rill development period. It appears that larger size fractions of spoils influence KC and Ce factors on low‐compaction steep slopes reclamation sites. Copyright © 2013 John Wiley &amp; Sons, Ltd.

Approximate Solution to the Sokolovskiĭ Concave Slope at Limiting Equilibrium

AbstractThe growth of precision autoguidance systems on construction equipment suggests that nonplanar slopes and landforms now can be constructed readily. Slopes with concave cross sections not only appear more like natural slopes, but can also have superior stability and erosion resistance. Thus, it is desirable to have the description of concave slopes that provide mechanical stability for a given set of soil properties. In this paper, an approximate solution that defines the geometry of critical concave slopes (factor of safety ≈1) in a frictional medium is developed, based on the slip-line field method. The approximate solution is compared with previous numerical results and validated via limit-equilibrium method and FEM analyses. The proposed solution is simple in form, and, when implemented with precision construction equipment, will allow the construction of embankments and reclaimed mine lands that appear more like those in nature and yet are more resistant to erosion.

English

Use of biomass to supplement the nation's energy needs for ethanol production and green fuel for power plants has created a demand for growing reliable feedstocks. Switchgrass (Panicum virgatum L.), miscanthus (Miscanthus x giganteus), and giant cane (Arundo donax L.) are possible biofuel crops because they produce large amounts of biomass over a wide range of growing conditions, including marginal and reclaimed land. West Virginia's climate and large acreage of available reclaimed mine land provide a land base to generate high amounts of biomass for a biofuel industry. The purpose of this study was to determine the yield of three biomass crops on reclaimed mined land in central West Virginia. A 25-year-old reclaimed site near Alton, WV was prepared using herbicides to eliminate all existing cool-season vegetation on a 5-ha area. Twenty-three plots of 0.4-ha in size were established. Mine soil samples showed an average pH of 7.5 and adequate supplies of plant nutrients. Two switchgrass varieties (Kanlow and BoMaster) were randomly assigned to 10 plots (five replications) and seeds were drilled into the killed sod at a rate of 11 kg ha -1 . Two types of miscanthus (sterile public and private varieties) were randomly assigned to 10 plots and planted with seedling plugs on 0.8-m centers. Giant cane was assigned to three plots and rhizomes were planted on 1.5-m centers. Yield measurements were taken in September the second and third years after planting. Yields for Kanlow switchgrass varied from an average of 4,000 kg ha -1 in 2011 to 4,900 kg ha -1 in 2012. BoMaster switchgrass was lower at 2,750 kg ha -1 in 2011 and 3,981 kg ha -1 in 2012. The public variety of miscanthus showed yields 7,500 kg ha -1 in 2011, but decreased to an average of 4,900 kg ha -1 in 2012. The private miscanthus variety was much greater at 21,880 kg ha -1 in 2011 and 15,500 kg ha -1 in 2012. Giant cane yields were low with an average yield of 515 kg ha -1 in 2012. Survival and growth of giant cane was hindered by weed competition and poor establishment. Target yields for reclaimed lands, as established by the WV Department of Environmental Protection of 5,000 kg ha -1 for switchgrass and 15,000 kg ha -1 for miscanthus were not attained with switchgrass and the public variety of miscanthus, but was achieved with the private variety of miscanthus. More time may be needed for these yield goals to be achieved as stands continue to develop over time.

Curve Numbers for Low-Compaction Steep-Sloped Reclaimed Mine Lands in the Southern Appalachians

In the coal-mining region of the Appalachians, the Forestry Reclamation Approach (FRA) is currently promoted by the U.S. Dept. of Interior, Office of Surface Mining (OSM). FRA’s goal in establishing native forest cover on reclamation sites requires the use of loose spoils rather than traditionally compacted spoils during hillslope reconstruction. Loose spoils improve tree planting survival and enhance overall forest growth. Although FRA has been shown to be successful on low-gradient slopes without excessive runoff leading to erosion, rainfall-runoff relationships have not been studied on steep slopes (>20°) where most surface-mine reclamation typically occurs. A curve number (CN) range representing low-compaction steep-sloped conditions was needed for Appalachian FRA sites. Three active surface-mine sites in East Tennessee were monitored during a 1-year period (June 2009–July 2010) for rainfall (5-min intervals) and runoff hydrology (discharge volume, peak discharge) using a unique Pinson-type collection system. CNs were estimated by the traditional NEH-4 (Part 630) method and two asymptotic, frequency-matching techniques. It was found that an initial abstraction (λ) of 0.2 best fits the data. CNs generated by the NEH-4 method among all three mining sites were not significantly different suggesting common shale-based loose spoils on steep slopes have similar runoff behavior. The CN determined by the asymptotic method provided an estimate with a practical range between 58.5 and 60. This CN range is lower than one would expect from surface-mine sites, suggesting infiltration influenced the measured rainfall-runoff relationships. Further research is needed to investigate the influence of slope and infiltration on runoff behavior at surface-mine sites applying FRA.

Effect of soil depth and topographic position on plant productivity and community development on 28-year-old reclaimed mine lands

Reclamation research has shifted from short- to long-term assessment of mine land reclamation management strategies, wherein previously established study sites are revisited. In this study, we assessed long-term (28 y) relations among reestablished plant communities (production and diversity), replaced soil depth following mining (0.2 to 1.4 m [0.7 to 4.6 ft]), and restored slope position (5% north slope, 2% south) for three different subsoil types (A, B, C; characterized by 43%, 23%, and 14% clay, respectively) on a previously established soil wedge experiment in North Dakota (Merrill et al. 1998). Nonnative seeded species such as crested wheatgrass (Agropyron cristatum) and smooth brome (Bromus inermus) had close to 50% persistence after 28 y, while less aggressive seeded species, such as Russian wildrye (Psathyrostachys juncea) and alfalfa (Medicago sativa), were more susceptible to invasion by other species leading to greater plant community diversity (Shannon9s Diversity Index [H′ = 1.348 and 1.717, respectively]). The most significant plant productivity response to soil depth/topographic position was observed for subsoil C on the south facing 2% slope (r2 = 0.43; p = 0.03). The two soil parameters measured in this study (electrical conductivity and pH) indicated mine soil profile development through time for both slope position and subsoil type. Specific relations observed in this long-term study were somewhat more difficult to identify compared to earlier short-term studies conducted on this site, providing strong evidence that replaced soil depths should be determined based on soil stabilization and initial establishment of diverse, sustainable plant communities to reduce invasion of undesirable plant species.

Assessing Hydrologic Change in Surface-Mined Watersheds Using the Curve Number Method

The U.S. Surface Mining Control and Reclamation Act of 1977 requires that mine operators minimize disturbances to the prevailing hydrologic balance of surface-mined sites and associated off-site areas through land reclamation. The hydrologic evaluation to support this requirement is often performed using the curve number (CN) rainfall-runoff method. Accurate application is limited by a scarcity of tabulated CN values for reclaimed mine lands, and assumptions regarding the hydrologic behavior of reclaimed mine lands may be inaccurate. Four watersheds (three reclaimed surface coal mines and one forested reference) in the Georges Creek basin of western Maryland were instrumented for rainfall and runoff. CNs calculated for the reclaimed mine land watersheds using rainfall and runoff data (range=68–92) were generally higher than CNs estimated by prevailing engineering methods (range=65–79). The general agreement of these results with other studies indicates that a more conservative hydrologic approach may be w...