The United States' use of coal results in many environmental alterations. In the Appalachian coal belt region, one widespread alteration is conversion of forest to reclaimed mineland. The goal of this study was to quantify the changes to ecosystem structure and function associated with a conversion from forest to reclaimed mine grassland by comparing a small watershed containing a 15-year-old reclaimed mine with a forested, reference watershed in western Maryland. Major differences were apparent between the two watersheds in terms of biogeochemistry. Total C, N, and P pools were all substantially lower at the mined site, mainly due to the removal of woody biomass but also, in the case of P, to reductions in soil pools. Mineral soil C, N, and P pools were 96%, 79%, and 69% of native soils, respectively. Although annual runoff from the watersheds was similar, the mined watershed exhibited taller, narrower storm peaks as a result of a higher soil bulk density and decreased infiltration rates. Stream export of N was much lower in the mined watershed due to lower net nitrification rates and nitrate concentrations in soil. However, stream export of sediment and P and summer stream temperature were much higher. Stream leaf decomposition was reduced and macroinvertebrate community structure was altered as a result of these changes to the stream environment. This land use change leads to substantial, long-term changes in ecosystem capital and function.

There is evidence that oxidation of CH4 to CO2 by methanotrophic bacteria in forest soil is a major sink for atmospheric CH4, even though growth of the bacteria on such low CH4 concentrations (<1.7 µL L−1) is perplexing. Measurements of CH4 and CO2 in a northern hardwood ecosystem in the Adirondack Park in the state of New York indicated that: (i) soil CH4 concentrations were mostly higher than the concentration of CH4 in forest air, with concentrations as high as 500 µL L−1 at the 0.1‐m depth in the early and late parts of the growing season; (ii) soil CO2 concentrations ranged from the atmospheric level to as high as 19 000 µL L−1 at the 0.2‐m depth in midsummer; (iii) net consumption of atmospheric CH4 emission by soil in midsummer averaged only 0.25 mg m−2 d−1, which is low compared with findings for most forest ecosystems; and (iv) methanogenesis occurred in soil samples throughout the profile when incubated anaerobically as well as aerobically with CH3F to inhibit methanotrophs. The prominent activity of methanogenic bacteria producing CH4 in the spring and autumn could support the growth of methanotrophic bacteria that otherwise consume atmospheric CH4 when methanogens are not active. Therefore, CH4 dynamics in this Spodosol represent the balance between CH4 production and CH4 oxidation, which is similar to the CH4 dynamics in many wetland ecosystems.

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Acid mine drainage (AMD) affects thousands of stream miles in the Appalachian region of the USA and results in elevated concentrations of iron and aluminum in the stream water and sediments and wide ranging pH values. It was hypothesized that these conditions would lead to increased P buffering capacity of the sediments which in turn would cause a decrease in dissolved reactive phosphorus (DRP) in the water column. In the lab fresh Fe, Al, and Mn oxide precipitates all adsorbed DRP strongly but over different pH ranges. Sulfate and calcium ions inhibited adsorption of DRP with Fe oxides but the effect was less apparent with Al oxides. In the field DRP concentration was reduced 54-90% just downstream of an AMD input compared to upstream of the input. In addition the sediment buffering capacity increased and equilibrium phosphate concentration decreased dramatically downstream of the AMD inputs. The strength of the effect and the widespread occurrence of AMD suggest that AMD could be altering the P dynamics of streams and rivers throughout the Appalachian region.

The objective of this study was to evaluate the nitrogen (N) biogeochemistry of an 18-22 year old forested watershed in western Maryland. We hypothesized that this watershed should not exhibit symptoms of N saturation. This watershed was a strong source of nitrate (NO 3 À ) to the stream in all years, with a mean annual export of 9.5 kg N ha À1 year À1 and a range of 4.4-18.4 kg N ha À1 year À1 . During the 2001 and 2002 water years, wet deposition of inorganic N was 9.0 kg N ha À1 year À1 and 6.3 kg N ha À1 year À1 , respectively. Watershed N export rates in 2001 and 2002 water years were 4.2 kg N ha À1 year À1 and 5.3 kg N ha À1 year À1 , respectively. During the wetter water years of 2003 and 2004, the watershed exported 15.0 kg N ha À1 year À1 and 18.4 kg N ha À1 year À1 , rates that exceeded annual wet deposition of N by a factor of two (7.5 kg N ha À1 year À1 in 2003) and three (5.5 kg N ha À1 year À1 in 2004). Consistent with the high rates of N export, were high concentrations (2.1-3.3%) of N in foliage, wood (0.3%) and fine roots, low C:N ratios in the forest floor (17-24) and mineral soil (14), high percentages (83-96%) of the amount of mineralized N that was nitrified and elevated N concentrations (up to 3 mg N l À1 ) in soil solution. Although this watershed contained a young aggrading forest, it exhibited several symptoms of N saturation commonly observed in more mature forests.

When forested riparian zones are cleared for agriculture or development, major changes can occur in the stream temperature regime and consequently in ecosystem structure and function. Our main objective was to compare the summer temperature regimes of streams with and without forest canopy cover at multiple sites. The secondary objective was to identify the components of the stream heat budget that had the greatest influence on the stream temperature regime. Paired stream reaches (one forested and one non-forested or 'open') were identified at 11 sites distributed across the USA and Canada. Stream temperature was monitored at the upstream and downstream ends of 80 to 130-m-long reaches during summer, and five variables were calculated to describe the stream temperature regime. Overall, compared with forested reaches, open reaches tended to have significantly higher daily mean (mean difference = 0.33 ± 1.1°C) and daily maximum (mean difference = 1.0 ± 1.7°C) temperatures and wider daily ranges (mean difference = 1.1 ± 1.7°C). Mean and maximum daily net heat fluxes in open reaches tended to be greater (or less negative) than those in forested reaches. However, certain sites showed the opposite trends in some variables because of the following: (i) Daily mean and maximum temperatures were biased by differences in inflow temperature between paired reaches and (ii) inputs of cold groundwater exerted a strong influence on temperature. Modelling and regression results suggested that within sites, differences in direct solar radiation were mainly responsible for the observed differences in stream temperature variables at the daily scale.

We studied the effects of acid mine drainage (AMD) on three key stream properties and functions. Four streams from each of three categories (AMD, treated AMD, and reference) were selected randomly from within the Tygart Valley River watershed in West Virginia. Analysis of stream water verified that the three stream types had very distinct chemical characteristics. Periphyton biomass was significantly reduced in AMD streams; however, treated AMD streams were no different from reference streams. Leaf decomposition was significantly slower in treated streams than in reference streams. Compared to reference streams AMD streams exhibited significantly lower macroinvertebrate density and diversity, whereas treated AMD streams had lower diversity. Thus, although treated AMD is much less toxic than raw AMD, it still has substantial impacts on macroinvertebrate diversity and leaf decomposition which could lead to ecosystem-wide impacts. INTRODUCTIONOne of the environmental impacts of coal mining in the Appalachian region is the production of acid mine drainage (AMD), which is characterized by extremely low pH and high sulfate and metal ion concentrations. Biota in streams receiving AMD is negatively affected by the acidic conditions and metal toxicity as well as the precipitation of an orange or gray floc, consisting of iron, aluminum, and manganese oxides, that coats the stream bed and inhibits oxygen diffusion into sediment. The effects of AMD in this region are widespread. Approximately 27% of the stream miles within the coal mining region of West Virginia are impacted by AMD (Herlihy et al. 1990).Mines that were closed before the Surface Mining Control and Reclamation Act of 1977 are called "abandoned" and often discharge untreated AMD into surface waters. Other coal mines have been required to treat AMD before discharging it into streams. Treatment options include additions of alkali, such as lime, sodium hydroxide, or ammonium hydroxide and passive treatment by anoxic limestone drains or constructed wetlands (Skousen and Ziemkiewicz 1995, DeNicola and Stapleton 2000). The main goal of most treatment systems is to raise the pH of the AMD so as to trigger precipitation and settling of metal hydroxides in settling ponds or wetlands. With these methods a large fraction, but not all, of the toxic metals is removed from the water before it is discharged.Treatment systems are designed to produce effluent that does not exceed the permitted levels of acid or metals. These chemical criteria, which are established by state and federal agencies, ensure that concentrations of pollutants do not exceed a specified level. This regulatory approach assumes that streams receiving treated AMD are not impaired. However, the ecosystem hnction and biological integrity of receiving streams have not been studied extensively. Streams receiving treated AMD often exhibit metal

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