Effect of vegetation cover on the hydrology of reclaimed mining soils under Mediterranean-Continental climate

Vegetation cover plays a major role in the restoration and stabilization of disturbed systems. The analysis of relationships between restored vegetation and soil hydrology has special relevance for the evaluation and operation of mining reclamation, particularly in Mediterranean-Continental environments, where climatic conditions restrict the development of continuous vegetation cover. The effect of herbaceous vegetation cover on soil hydrology was analysed by means of rainfall simulation (63 mm h^− 1; 0.24 m²) in reclaimed soils derived from opencast coal mining (a non-saline and clay-loam textured spoil) in central-eastern Spain. A total of 75 simulation experiments were conducted at three different times throughout the year (late winter, summer and autumn) to control the influence of seasonal climatic fluctuations. Sediment concentrations in runoff and the runoff coefficient decreased exponentially with vegetation cover, while increases in steady infiltration rates were obtained with vegetation cover. Additional delays in runoff responses (longer time to runoff start and stabilization) and increases in the wetting front depth were observed with vegetation cover. Seasonal variations in soil surface state and moisture strongly influenced hydrological responses; although the influence of season on the analysed hydrological responses was attenuated by vegetation cover, especially in the case of infiltration rates. We also determined a practical ground cover threshold for site restoration and evaluation of over 50% vegetation cover, which could help achieve an optimum biological control of hydrological soil responses in the studied environment.     

Native vegetation cover thresholds associated with species responses

We examined data on bird and reptile assemblages in a plantation landscape in southern New South Wales, south-eastern Australia, for evidence of threshold responses to the amount of native eucalypt vegetation in circular areas of 2000 and/or 1000 m around field survey sites. These circular areas contained varying proportions of native Eucalyptus and exotic radiata pine Pinus radiata forest thereby providing a basis for examining potential threshold effects in relation to the area of native vegetation cover. For bird species richness or the probability of detection of individual bird species we found no empirical evidence of a threshold response to the area of native vegetation cover, or any other potential explanatory variables. All relationships were characterised by considerable variability in the response data. “Broken-stick” relationships which involved sudden change points did not fit the response data better than smooth relationships obtained from generalised additive or linear models. As with birds, there was no evidence that a threshold model between lizard richness and the amount of native vegetation within 1000 m described the relationship any better than a smooth, continuous or other type of relationship. Several related factors may explain our results. An important one is that species-specific responses to landscape conditions mean that marked thresholds will not be seen for an aggregate measure like species richness at a given value for a given landscape variable. Another is that factors other than the amount of native vegetation may significantly influence underlying patterns of species occurrence. This highlights a need to be aware of the potential effects of various ecological processes, even when a substantial amount of native vegetation cover remains.Our findings do not rule out the possibility of the existence of threshold relationships. However, irrespective of the choice of measure of predictor variable (e.g., the amount of native vegetation cover), it will often be difficult to detect and estimate threshold responses due to high inherent variability - a characteristic of the vast majority of ecological datasets. Furthermore, even if it is possible to estimate functional (threshold) forms and although they might be useful from an explanatory perspective, in most instances they are likely to be of limited value in a predictive sense. This calls into question the practical significance of the threshold concept.     

Rapidly quantifying reference conditions in modified landscapes

Reference conditions remain widely used as a benchmark for ecosystem management, but there remains conjecture about the definition of the reference state. Many techniques used to predict reference conditions are difficult to apply operationally because they are resource-intensive, subjective, or applicable for a limited suite of environmental variables or over a narrow range of environmental variation. We defined the reference state as variation in native vegetation exhibiting relatively little evidence of modification by humans since European settlement. Using data from 462 sites supporting native vegetation in a fragmented landscape in south-eastern Australia, we demonstrated a relatively quick and cost-effective way of objectively predicting reference conditions for various surrogates of biodiversity. We predicted reference values for several variables that are used as biodiversity surrogates (i.e., tree densities by diameter class, trees with hollows, tree regeneration, trees with mistletoe, fallen timber, vegetation cover by vertical stratum, litter cover, cryptogam cover and native plant species richness) using generalized additive models (GAMs) fitted with predictors representing measures of human modification since European settlement (exotic plant cover, number of stumps, evidence of firewood collection, evidence of rabbits, evidence of recent grazing by stock, surrounding land use) and measures of environmental variation (floristic composition, mean annual precipitation, mean annual temperature, solar insolation, aspect, slope). Reference values for each response variable were predicted from these models by holding the significant explanatory variables representing modification since European settlement at their minimum observed values, that is, our definition of the reference state. We demonstrated the importance of independently evaluating predictions of this type using generic ecological models and estimates of reference conditions derived from other sources.     

Large-scale reclamation of barren lands in Iceland by aerial seeding

Catastrophic soil erosion has resulted in the desertification of vast areas in Iceland. Barren lands are revegetated on a large scale by aerial broadcasting of commercial grass seed of Festuca rubra cv. Leik (red fescue) and subsequent regular fertilizer application for five years. Vegetation cover following aerial seeding of F. rubra was recorded in three reclaimed sites, which were two, ten and 25 years old, in an inland area in southern Iceland. As a comparison, vegetation cover was also recorded on barren land. Plant succession was inferred from these records. Vegetation cover was recorded using the point-intercept method. Spores of arbuscular mycorrhizae fungi (AMF) were recorded from each site. Barren lands have characteristically low (<5%) vegetation cover. The highest cover of F. rubra was found two years after revegetation was initiated. Non-dependent AMF forbs also colonized and increased their cover rapidly in the second year due to fertilizer application, but after a decade their cover declined. Ten years after the aerial seeding, F. rubra disappeared and the area was dominated by the native grass Agrostis stolonifera (creeping bent grass). A cover of mosses and plant litter was also recorded on the ten-year-old site. AMF spores were low in all studied sites, and colonization of AMF was only found in the roots of A. stolonifera. After 25 years, it appeared that the cover of native forbs started to increase again and salix bushes were established. Aerial seeding of F. rubra failed to create a long-lasting cover to facilitate natural rapid succession. Alternative revegetation practices, taking into consideration the dynamics of the mutualistic microorganisms (Rhizobium and AMF)/plant association, are suggested for a better and more economic management of reclamation strategies. Copyright © 1999 John Wiley & Sons, Ltd.     

Assessing Impacts of Crested Wheatgrass AND Native Species Establishment on Soil Characteristics in Reclaimed LAND Using Bayesian Posterior Predictive Distributions

We examined the interacting effects of drastic disturbance and re‐vegetation communities on the development of soil properties over time. We compared soil characteristics from an undisturbed reference site with reclaimed mine sites that differed by vegetation type and time since reclamation: Three sites were seeded solely with crested wheatgrass (Agropyron cristatum) (11, 16, and 29 years old), and two were seeded with native cool‐season grass mixes (14 and 26 years old). We sampled soil at two depths (0–5 and 5–15 cm) for soil macroaggregate and microaggregate weights, aggregate carbon to nitrogen (C : N) ratios, and microbial abundance. We employed a Bayesian bivariate model to account for potential correlations in soil properties across depths and compared soil properties across sites using posterior predictive distributions. We found that all reclaimed soils, regardless of vegetation type, had total aggregate weights that were similar to the undisturbed reference soil but had a larger proportion of macroaggregates than the reference soil. Aggregate C : N ratios were similar between the undisturbed reference and crested wheatgrass soils, while the reclaimed native cool‐season grass soils had lower C : N ratios in the top 5 cm. Total microbial abundance in soils seeded with crested wheatgrass was an order of magnitude lower than that in soils occupied by native species (both reclaimed and undisturbed). The presence of crested wheatgrass on the reclaimed sites alone did not differentiate all soil properties across our reclamation sites, but seeding this single, aggressive species may have contributed to maintaining different belowground characteristics on reclaimed soils. Copyright © 2015 John Wiley & Sons, Ltd.     

Measuring soil disturbance effects and assessing soil restoration success by examining distributions of soil properties

Successful restoration of an ecosystem following disturbance is typically assessed according to similarity between the restored site and a relatively undisturbed reference area. While most comparisons use the average or mean parameter to represent measured properties, other aspects of the distribution, including the variance of the properties may assist in a more robust assessment of site recovery. Our purpose was to compare soil properties in different ages of reclaimed soils with those in reference areas by incorporating the potentially different distributions according to areas. On two sampling dates, in consecutive years, we examined soil properties on a chronosequence of reclaimed natural gas pipelines spanning recovery ages of <1–54 years, obtaining data on soil moisture, organic carbon, nitrogen, electrical conductivity, pH, and microbial abundance. To make the comparisons, we analyzed our data with a Bayesian hierarchical linear mixed model and obtained posterior predictive distributions for the soil properties. This allowed us to probabilistically quantify the extent to which a soil property from a reclaimed treatment was similar to that from an undisturbed reference. We found that the posterior predictive variance of most soil properties was particularly sensitive to disturbance and reclamation, especially, within the first few years of recovery. Response of this variance to disturbance, reclamation, and recovery was not necessarily accompanied by a shift in the posterior predictive mean value of the property. Patterns for all soil properties changed over time, with posterior predictive distributions of soil properties generally becoming more similar to those of the undisturbed reference sites as recovery time increased. We suspect these trends in altered variability coincide with the degree of spatial heterogeneity in soil properties that results following disturbance and reclamation, which is also coupled to patterns of vegetation recovery.     

Accumulation of carbon,nitrogen and phosphorus during soil formation on alder spoil heaps after brown-coal mining,near Sokolov (Czech Republic)

The accumulation of carbon (C), nitrogen (N) and phosphorus (P) and their vertical distribution in the soil profile in relation to site age were studied in a chronosequence of 19 sites on reclaimed spoil heaps from open-cast coal mining, near Sokolov (Czech Republic) and compared to a semi-natural alder forest in the vicinity of the mining area. The reclaimed sites were located on tertiary clay or quaternary gravel–sand spoil material and afforested with alder species (Alnus glutinosa, A. incana) 4–65 years ago.Rapid accumulation of C and N in the soil profile was registered within 15 years after reclamation. The rate of increase in C and N contents in the whole profile and the thickness of the litter and fermentation layers was slower in 25-year-old and older reclaimed sites. The soil of the semi-natural alder forest was richer in C and N in the 5–10-cm layer compared with 40-year-old (clays) and even with 65-year-old (gravel–sand) reclaimed soils. N accumulated more slowly in comparison with C, especially in deeper (5–10 cm) parts of the profile. Accumulation of organic C resulted in a decrease in substrate pH from alkaline, which was characteristic of young sites, to slightly acidic on older sites. The pH decreased gradually with increasing site age in all soil layers but increased with depth in the soil profile. In contrast to C and N, P content did not significantly change with site age in any layer of the soil profile. The highest amount of P was found in the fermentation layer, but there was no difference to the other layers. The soil profile of the semi-natural sites was richer in P in comparison to 40-year-old reclaimed ones.     

草原区露天煤矿植被覆盖度时空演变与驱动因素分析

采用多时相Landsat TM遥感数据,借助于植被指数与植被覆盖度,基于不同时序植被覆盖度格点回归斜率、标准差和基末年等级转换矩阵等,分析了研究区植被覆盖度空间异质性及其驱动机制,剖析了采复联动下研究区、开采区和复垦区植被覆盖度变化趋势和波动程度,进而揭示随着时间变化采复活动与植被覆盖度间的响应。研究结果表明：不同年份研究区植被覆盖度及其等级空间分布整体上具有一定相似性,矿山采复活动在一定程度上打破了区域植被覆盖度时空演变格局;研究区植被覆盖度以中（Ⅳ等）、中低（Ⅲ等）为主,按多年均值计算,两者之和占研究区总面积的80%以上;植被覆被度呈增加和减少的区域面积比为2∶3,相关系数在?0.9266～0.4805之间,斜率正值范围内相关性并不显著,而负值范围的?0.9266～?0.895呈现不同程度显著性相关;露天采区、排土场及其周边1.5 km范围内的植被覆盖度呈显著下降趋势,且趋于一致。矿区植被恢复经历了一个“高—低—高”的周期循环,半干旱草原区复垦管护期限尽量保证在6 a以上。70%以上区域在研究时段内植被覆盖度发生转换,转换较为频繁,Ⅰ等植被覆盖度中的90%是由采矿活动转入的。露天煤矿区植被覆盖的提升有赖于矿区社会压力减少和生态恢复力提高两方面。研究成果将为露天煤矿及其所在区域生态环境科学保护与决策、恢复和治理提供信息支撑。     

黄土区露天煤矿排土场复垦后土壤与植被的演变规律

恢复受损的土壤和植被是矿区生态恢复的关键,植被恢复过程的实质是植被-土壤复合生态系统相互作用的过程。该文通过典型小区调查的方法,选择山西平朔州安太堡露天煤矿复垦排土场为研究区,分析了不同复垦年限（3、5、10、12和17 a）土壤环境因子和乔木林地植被生物量的动态演变规律,建立了黄土区露天煤矿排土场复垦土壤环境因子和乔木林地植被生物量Logistic演替模型,并构建了土壤-植被交互影响的偏微分方程组。相关系数及显著性检验表明所建立的土壤各环境因子演变模型和乔木林复垦地的植被生物量演变模型有效,能够很好地反映排土场的土壤因子和植被生物量的动态演变过程;随着复垦年限的增加,研究区土壤环境因子质量不断提升并逐渐接近原地貌,土壤因子和植被生物量都呈S型变化,符合Logistic生长演替模型;土壤环境因子与植被生物量二者交互作用明显,符合Kolmogorov捕食模型。该研究可为黄土区露天矿排土场土地复垦与生态恢复提供理论依据。     

Humus accumulation, humification, and humic acid composition in soils of two post-mining chronosequences after coal mining

Purpose

To assess how the rates of humus formation and humification are affected by land use and age of ecosystems, this study investigated soil development in two post-mining chronosequences (spoil heaps formed from open-cast coal mining near Sokolov, Czech Republic). The following characteristics were measured: content, composition, and properties of humic acids; organic carbon (C) and total nitrogen (N) contents; pH; and amorphous iron content.

Materials and methods

Two chronosequences were studied. One consisted of unreclaimed spontaneously revegetated spoils (3, 12, 20, and 40 years old). The other consisted of heaps that were reclaimed by planting alder in graded heaps (7, 15, 20, 30, and 40 years old). Humus and iron contents as well as pH were determined, and humic acids were extracted for detailed chemical analyses (C, H, N, ¹³C-NMR, and pyrolysis mass-spectrometry).

Results and discussion

C and N accumulated faster in the reclaimed sites than in the unreclaimed sites; organic matter accumulation results in the decrease of pH in all soils and in spontaneous sites also increase of amorphous iron content. Humic acids (HA) and fulvic acids (FA) increased with the site age in both chronosequences. The CHA/CFA was higher in the reclaimed soils than in the unreclaimed soils, and the CHA/CFA ratio increased with age in the unreclaimed soils. Humic acid aromaticity was higher in the reclaimed site than in the unreclaimed sites but increased with the age of unreclaimed sites. H and O content decreased with age of reclaimed soils. Humification led to an increase in HA caloricity in the reclaimed sites but not in unreclaimed sites because of the influence of residual wax-type substances in the unreclaimed sites. Degree of HA oxidation (ω) for the reclaimed plots was similar to that in typical zonal soils but was highly variable in unreclaimed soils.

Conclusions

Relative to spontaneous revegetation in the unreclaimed sites, reclamation increased the rates of humus accumulation, humification, and humus acid transformations. The differences between reclaimed and unreclaimed sites, however, decreased with site age and were very small in 40-year-old sites. These differences correspond to the rapid colonization of the reclaimed sites and the slow colonization of the unreclaimed sites by soil biota.     

Growth and selenium uptake of range plants propagated in uranium mine soils

High soil selenium (Se) levels have been found in association with uranium deposits in Texas. A concern that high Se concentrations may be found in forages grown on reclaimed mine lands prompted this investigation. A native soil sampled near the mining area, and overburden materials sampled from two Se enriched uranium mine spoil sites were compared in a plant growth study in the greenhouse. Shoot yields and shoot Se concentration in each of ten grasses common to the region were determined from plants harvested three weeks after germination and from shoot regrowth harvested four weeks after the first harvest. Shoot weights were reduced for 5 of the 10 species growing in soils with medium and high Se status. Total shoot weights of Cynodon dactylon and Panicum coloratum from two harvests were consistently highest in all soil materials and are highly recommended for use as a stabilizing cover crop for lands disturbed from uranium mining. Generally, no correlation was observed between shoot weight and plant Se concentration or uptake in the 10 species. However, plant tissue Se concentrations in all species for at least one of the two harvest dates were above the 5 mg kg^‐1 concentration considered potentially harmful to grazing livestock. Therefore, none of these species would be a suitable forage for livestock grazing on reclaimed Se‐enriched uranium mining overburden.     

矿区复垦土壤与植被交互影响的研究进展

土壤与植被作为煤矿区土地复垦主要成员,在生态恢复与重建方面扮演着重要角色。同时,土壤与植被之间存在着密切的交互影响关系,认识土壤与植被恢复间的交互影响关系及其作用规律与机理对土地复垦与生态恢复具有重要意义。本文系统梳理了复垦土壤与植被演替规律、交互影响研究方法以及交互影响机理。发现研究方法多为缺乏创新性的线性方法,且未能做到对植被与土壤交互影响的连续、动态研究和全面综合分析。在此基础上,提出了深入研究方向:创新植被与土壤交互影响的方法,加强植被与土壤交互影响的动态分析,强化交互影响机理的综合研究,以期为土地复垦与生态恢复研究提供新的视角。     

Use of grain-size and elemental normalization in the interpretation of trace metal concentrations in soils of the reclaimed area adjoining Port Jackson, Sydney, Australia

Cobalt, Cr, Cu, Fe, Mn, Ni, Pb, Zn and As concentrations in the grain size and elemental normalization using Fe in gravel-free total soil ((X_m/Fe)_{total sample}; X_m = Cu, Pb, Zn, etc.) were used to determine the influence of variable grain size on the concentration of anthropogenic trace metal contaminants in the reclaimed area adjacent to Port Jackson, Sydney, Australia. Trace metal concentrations in soils in reclaimed area are greatly influenced by the heterogeneous nature of the waste materials buried at the site. The confounding effects of variable grain size in soils can be reduced by analyzing the contaminant concentration of the material after removing > 2 mm size in sample. An example from Sydney Harbour is used to demonstrate the comparability between grain size normalized data and elemental normalized data using Fe in soils from reclaimed areas. Results from the current study reveal that the vertical distribution of trace metal concentrations in soils is remarkably similar between the grain size and elemental normalization, using Fe. Normalization methods might be beneficial in overcoming texturally driven variations of contaminant concentrations in soils in the reclaimed or infilled land area.     

特大型露天煤矿土地损毁生态风险评价

露天矿在"剥－采－运－排－复"生产活动中的土地损毁对矿区生态系统产生直接和间接的危害或影响。该文以山西安太堡露天煤矿为例,将土地损毁过程作为矿区的风险源,通过构建黄土区特大型露天煤矿生态风险因果链,建立其综合生态风险的评价模型。根据露天煤矿不同土地损毁类型及矿区生态系统状态,利用生态遥感指数、实测数据与GIS空间分析方法进行风险源与风险受体评价,应用综合评价模型得出矿区综合风险值。结果表明：1）矿区土地损毁高生态风险区主要集中在未复垦的排土场,本身极不稳定,主要存在的风险为扬尘污染、水土流失、地质灾害等;2）已复垦排土场和工业场地由于多年实施复垦及管护措施,逐步恢复稳定性,而部分外排土场在早期排土过程中,由于排土工艺不合理以及后期管护不当,导致土壤和植被退化,风险相对较高;3）露天采区的生态风险性较小,其生态敏感度属于中值区,受土地损毁影响较大,人类活动对其产生剧烈扰动。该研究将矿区生态风险进行量化,实现了风险值的空间化和可视化,有利于制定基于不同风险值的分级分区防范措施。     

Post-reclamation Age Effects on Soil Physical Properties and Microbial Activity Under Forest and Pasture Ecosystems

During surface mining and subsequent reclamation efforts, physical, chemical, and biological properties of soils are disturbed. A study was conducted to evaluate the effects of age chronosequence on soil physical property and microbial activity in chronosequence reclaimed sites covering successional ages in the ranges 1, 4, 8, 11, and 13 years under forest and pasture ecosystems. The adjacent normal and unmined pasture and forest were used as a control for comparison purposes. The study site was located at the Red Hill Mine in east central Mississippi (approximately 33.3 N latitude and 89 W longitude), which is used by the North America Mining Company, LLC. Soil samples were collected from the reclaimed and unmined sites at 0–15- and 15–30-cm depth and analyzed for selected soil quality indicators. Results indicated that water stable aggregate and infiltration were increased, but soil bulk density and compaction decreased with increasing reclamation age. Soil penetration resistance was greater in the pasture than forest ecosystem. All reclaimed soils had less microbial enzyme activity than an unmined forest ecosystem; however, bacteria population level after 11 years since reclamation was similar to that of unmined forest soils. Soil organic carbon increased with increasing reclamation age strongly correlated with soil physical indicators and appears to be the main driving force during the development of soil physical and biological properties in the humid southeast.     

Decomposition and soil biota after reclamation of coal mine spoils in an arid region

Summary We compared soil biota and buried wheat straw decomposition on sites subject to topsoiling plus straw mulch reclamation procedures 1–4 years prior to our study and on an unmined site. Rates of straw decomposition were highest on the unmined site. Decomposition rates were higher on the 1- and 2-year-old sites than on the 3- and 4-year-old reclaimed spoil. Microarthropod population densities and number of taxa were greater from decomposing straw on the unmined site and lowest from straw on the 1- and 2-year-old areas. Soil bacteria, fungi, and protozoan populations on buried straw on the oldest reclaimed sites were generally equal to those on the unmined area. Nematode populations on buried straw in the unmined site and 1- and 2-year-old reclaimed sites were similar. Populations of denitrifying bacteria were larger on recently reclaimed sites than on 3- and 4-year-old sites. Decomposition and nitrogen mineralization varied as a function of the diversity and abundance of soil microarthropods. Soil microfauna can serve as an index of soil development in a disturbed arid soil.     

Soil and vegetation inter-relationships on reclaimed coal mine sites

Abstract. A spoil and vegetation survey was conducted of five fields reclaimed from coal mine spoils seeded in different years at the Whitewood mines of south-central Alberta, Canada. It aimed to understand the causes of visibly wide variations in ground cover of the seeded species which was mainly alfalfa. Sites were initially stratified into productivity classes: A (high), B (medium), and C (low) based on the seeded species, and then sampled. Cover and dry weight declined linearly with age of reclaimed field. The spoil at class-A sites contained more clay than that of class-C sites. It also contained more moisture and a better cover. Electrical conductivity (EC) and the concentrations of soluble B, Mg, Na, and K in the spoil were significantly greater at class-C sites. Cover and dry weight of the seeded species were negatively correlated with EC, B, Mg, and Na in the spoil, thus implicating these factors in poor vegetative productivity, particularly in the dry conditions that typify this part of Alberta.     

基于时序NDVI的露天煤矿区土地损毁与复垦过程特征分析

露天煤矿区是人类活动强扰动地区之一。该文以阿巴拉契亚煤田区韦恩县为研究区域,应用遥感时序分析法分析了像元尺度的土地损毁和复垦过程特征。得出结论:1984-2010年间,韦兹县露天开采扰动区域占采矿权范围的45.80%,其中植被恢复区域占开采范围的66.45%,开采时间越早,植被恢复像元比例越高;开采造成的地表无植被覆盖期时长中位数为6 a,均值为7 a;已充分复垦的区域,NDVI值恢复至采前水平的加权平均时长为12 a。基于像元变化轨迹的研究,除揭示土地损毁-复垦过程特征外,能较好地反映空间异质性,可以为土地复垦管理和相关政策决策提供科学依据。     

Root Distributions of Planted Boreal Mixedwood Species on Reclaimed Saline–Sodic Overburden

Alberta’s oil sands are located in the boreal forest where surface mining requires reconstruction of these landscapes using waste saline and sodic overburden (SSOB) piles. The impact of these SSOB materials, however, on root development of planted boreal species is unknown. The objective of this study was to examine the effect of SSOB material on the root distributions of planted boreal species. Root distributions for planted mixedwood stands were measured using soil cores and compared with soil physical and chemical properties on three reclaimed sites. Soil pH ranged from 6.1 to 7.5 across all three reclaimed sites. Sodium adsorption ratio ranged from <30 in the SSOB at the youngest site to <4 at the oldest site while soil electrical conductivity ranged from <12 and <4 dS m⁻¹ in the SSOB at the youngest and oldest site, respectively. Root length distributions were concentrated in the upper 30 cm of the soil profile and ranged from 0.96 to 7.99 cm cm⁻³. The roots were observed in the SSOB and accounted for 1.3% to 2.2% of the total root length in the profile. The root length density was also negatively correlated with Na and EC at all sites. The root distributions on these young reclaimed sites were similar to those from undisturbed boreal forest stands overlying saline soils, suggesting that root distributions on these reclaimed sites appear to be unaffected by the SSOB; however, further monitoring will be required as the stand matures to determine future impacts of the SSOB on forest productivity.     

Infiltration Rates in Reclaimed Surface Coal Mines

Reclamation of land disturbed due to mining in arid and semiarid environments occurs across the globe. Large-scale surface mines provide unique opportunities to examine the reclamation process across a landscape. The objectives of this research were to (1) measure infiltration rates in reclaimed surface coal mines and (2) determine the effects of soil properties on ground cover on infiltration rates of surface coal mines. In this study, reclaimed land 10?C15 and 20?C25?years old, and native reference site (undisturbed) were investigated at two large surface coal mines in Wyoming, USA. Infiltration rates were measured using double-ring infiltrometer method. The soil properties including bulk density, pH, carbonate content, organic carbon content, aggregate stability, electrical conductivity, and soil texture were analyzed using standard methods. The ground cover was estimated visually. Statistical analysis was conducted to determine if any correlations between infiltration rate and soil properties and ground cover exist. Results suggest that at Mine 1, infiltration rates on reclaimed land were found to be significantly higher in the 20?C25-year-old reclamation than the 10?C15-year-old reclamation and the native site. At Mine 2, the native site had significantly higher infiltration than 20?C25-year-old reclamation, which in turn had significantly higher infiltration rates than the 10?C15-year-old reclaimed site. Along with infiltration, soil characteristics were examined. Overall, the findings of this study suggest soil texture and plant cover play an important role in controlling infiltration rates in reclaimed surface coal mines.