Browsing by Author "Richardson, CJ"
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Item Unknown A cost-effective method for reducing soil disturbance-induced errors in static chamber measurement of wetland methane emissions(Wetlands Ecology and Management, 2016-08-01) Winton, RS; Richardson, CJ© 2015, Springer Science+Business Media Dordrecht. Static chambers used for sampling methane (CH 4 ) in wetlands are highly sensitive to soil disturbance. Temporary compression around chambers during sampling can inflate the initial chamber CH 4 headspace concentration and/or lead to generation of non-linear, unreliable flux estimates that must be discarded. In this study, we tested an often-used rubber gasket (RG)-sealed static chamber against a water-filled gutter (WFG) seal design that could be set up and sampled from a distance of 2 m with a newly designed remote rod sampling system to reduce soil disturbance. Compared to conventional RG design, our remotely sampled static chambers reduced the chance of detecting inflated initial CH 4 concentrations ( > 3.6 ppm) from 66 to 6 % and nearly doubled the proportion of robust linear regressions (r 2 > 0.9) from 45 to 86 %. Importantly, the remote rod sampling system allows for more accurate and reliable CH 4 sampling without costly boardwalk construction. This paper presents results demonstrating that the remote rod sampling system combined with WFG static chambers improves CH 4 data reliability by reducing initial gas measurement variability due to chamber disturbance when tested on a mineral soil-restored wetland in Charles City County, Virginia, USA.Item Unknown A five year study of floristic succession in a restored urban wetland(Ecological Engineering, 2013-12-01) Ho, M; Richardson, CJThe Stream and Wetland Assessment Management Park (SWAMP) project created a wetland-stream complex that encompasses a wide array of micro-environments and hydrology. These diverse habitats were designed to facilitate ecosystem diversity via enhanced pathways for ecological succession during restoration. We took an empirical approach to examine floral succession under natural processes following wetland restoration of floodplain and marsh habitats. Survey plots were set up in four forest gaps in palustrine wetlands, each containing a Low Marsh and a High Marsh. During five years of recovery from the soil disturbance and upland vegetation removal, wetland species richness gradually increased from 24 to 38 species in the Low Marshes, where waterlogged conditions precluded upland species invasions. Conversely, upland species richness quickly declined from 69 to 29 species over time in the High Marsh, now subjected to increase flooding. The species successional patterns suggest a slower turnover in the wet Low Marsh, but faster turnover in the moist High Marsh. Following the intermediate disturbance hypothesis, we observed that High Marsh species richness reached its maximum in the first year of the vegetation survey, whereas even after five years the plant diversity in the Low Marsh has yet to peak. The once widespread Ligustrum sinense (Chinese privet) was decimated following the SWAMP restoration. However, the exotic invasive species, Microstegium vimineum (Japanese stilt grass) dominated the floodplain except in the wettest Low Marsh sites. Given the successional patterns of increased wetland species following restoration, we recommend removal of woody invasive species such as L. sinense to prevent their re-establishment followed by long-term monitoring and continued removal (5-7 years) of invasive species to allow native species establishment. Our study shows that the creation of wetter floodplain habitats with increased flooding suppresses the establishment of the highly invasive M. vimineum. © 2013 Elsevier B.V.Item Unknown A multi-scale approach to prioritize wetland restoration for watershed-level water quality improvement(Wetlands Ecology and Management, 2010-12-01) Flanagan, N; Richardson, CJWetland restoration is commonly presented as an important strategy for maintaining and enhancing the water quality and ecological capital of watershed-scale ecosystems. Prioritizing restoration sites on the landscape is often a haphazard process based on widely held, though often untested, assumptions about relationships between watershed characteristics and water quality. We present a framework to target and prioritize wetland restoration locations using both regional and watershed-level screening models. The regression-tree and random forest models presented in this paper identify watershed variables with the strongest relationships to a given water quality parameter, present a clear hierarchy of variable importance, and present approximate thresholds in watershed area where these variables express the greatest impact on water quality. The proportion of watersheds classified as prior-converted agricultural land was an important predictor of both ortho and total phosphorus. Fortunately because prior-converted agricultural lands were historically wetlands, they are often very suitable for wetland restoration. These sites often have poorly-drained soils requiring artificial drainage to be suitable for agriculture. These drainage systems become conduits for transporting phosphorus from agricultural field and to area streams and rivers. Maintaining natural land-cover within stream buffers is identified as another important predictor of water quality. This seems to be especially true with regard to NO 3 -NO 2 concentrations. Our model results support specific management recommendations including: (a) exclusion of agricultural land-uses from riparian buffers, (b) maintaining or increasing watershed-level wetland-cover and (c) reducing wetland fragmentation. © 2010 Springer Science+Business Media B.V.Item Unknown Coastal freshwater wetland plant community response to seasonal drought and flooding in Northwestern Costa Rica(Wetlands, 2011-08-01) Osland, MJ; González, E; Richardson, CJWetlands in tropical wet-dry climates are governed by distinct and extreme seasonal hydrologic fluctuations. In this study, we investigated the plant community response to seasonal flooding and drought in Palo Verde Marsh, Costa Rica. Climate change models for the region predict reduced rainfall and a drier wet season which would likely alter seasonal hydrologic cycles and prompt vegetation change.We quantified compositional change following disturbance emphasizing seasonal differences in plant life-form abundance across life history stages via standing vegetation, seed bank, and seedling recruitment measurements. Whereas the dry season standing vegetation was dominated by emergent species, aquatic species (floating-rooted, free-floating, and submerged life forms) were more dominant during the wet season. Seed bank and seedling recruitment measurements indicated that many species are resilient with life history traits that enable them to respond rapidly to extreme hydrologic filters. Interestingly, species richness was highest during seasonal flooding. Our results highlight the importance of early-wet season rainfall for plant regeneration and community change. Our findings also indicate that a drier future would likely have a large impact upon wetland plant communities with a decrease in species richness and an increase in the abundance of drought-tolerant emergent species. © Society of Wetland Scientists 2011.Item Unknown Different plant traits affect two pathways of riparian nitrogen removal in a restored freshwater wetland(Plant and Soil, 2013) Sutton Grier, AE; Wright, JP; Richardson, CJBackground & aims: Plants may have dissimilar effects on ecosystem processes because they possess different attributes. Given increasing biodiversity losses, it is important to understand which plant traits are key drivers of ecosystem functions. To address this question, we studied the response of two ecosystem functions that remove nitrogen (N) from wetland soils, the accumulation of N in plant biomass and denitrification potential (DNP), to variation in plant trait composition. Methods: Our experiment manipulated plant composition in a riparian wetland. We determined relative importance of plant traits and environmental variables as predictors of each ecosystem function. Results: We demonstrate that Water Use Efficiency (WUE) had a strong negative effect on biomass N. Root porosity and belowground biomass were negatively correlated with DNP. Trait ordination indicated that WUE was largely orthogonal to traits that maximized DNP. Conclusions: These results indicate that plant species with different trait values are required to maintain multiple ecosystem functions, and provide a more mechanistic, trait-based link between the recent findings that higher biodiversity is necessary for multi-functionality. While we selected plant traits based on ecological theory, several of the plant traits were not good predictors of each ecosystem function suggesting the ecological theory linking traits to function is incomplete and requires strengthening. © 2012 Springer Science+Business Media B.V.Item Unknown Does an ‘iron gate’ carbon preservation mechanism exist in organic–rich wetlands?(Soil Biology and Biochemistry, 2019-08-01) Wang, H; River, M; Richardson, CJ© 2019 Recent research suggested that iron oxidation may protect carbon from drought-accelerated decomposition in wetlands by promoting the sorption of lignin derivatives and decreasing phenolic oxidase activities. Here we examined whether this mechanism exists in organic-rich peatlands, which store over 30% of the world's soil carbon, by simulating drought and flooded conditions in peat soil with and without the addition of reduced iron. Our results suggest that iron does not protect carbon from decomposition in organic-rich peatlands, and in fact iron may exacerbate carbon decomposition via precipitation of phenolic compounds, which otherwise have been shown to inhibit microbial activity. In addition, scanning electron microscopy analyses of different types of peat soil from Minnesota to Peru showed evidence of iron-sulfide minerals (pyrite), indicating that some portion of the reduced iron in peatlands is effectively immobilized and therefore does not interact with the carbon cycle.Item Open Access Dual controls on carbon loss during drought in peatlands(Nature Climate Change, 2015-01-01) Wang, H; Richardson, CJ; Ho, M© 2015 Macmillan Publishers Limited. Peatlands store one-third of global soil carbon. Drought/drainage coupled with climate warming present the main threat to these stores. Hence, understanding drought effects and inherent feedbacks related to peat decomposition has been a primary global challenge. However, widely divergent results concerning drought in recent studies challenge the accepted paradigm that waterlogging and associated anoxia are the overarching controls locking up carbon stored in peat. Here, by linking field and microcosm experiments, we show how previously unrecognized mechanisms regulate the build-up of phenolics, which protects stored carbon directly by reducing phenol oxidase activity during short-term drought and, indirectly, through a shift from low-phenolic Sphagnum/herbs to high-phenolic shrubs after long-term moderate drought. We demonstrate that shrub expansion induced by drought/warming in boreal peatlands might be a long-term self-adaptive mechanism not only increasing carbon sequestration but also potentially protecting historic soil carbon. We therefore propose that the projected 'positive feedback loop'between carbon emission and drought in peatlands may not occur in the long term.Item Unknown Effects of exotic Spartina alterniflora on vertical soil organic carbon distribution and storage amount in coastal salt marshes in Jiangsu, China(Ecological Engineering, 2017-09-01) Liu, JE; Han, RM; Su, HR; Wu, YP; Zhang, LM; Richardson, CJ; Wang, GX© 2017 Elsevier B.V. Coastal wetlands soil organic carbon (SOC) plays an important role in global carbon sequestration, and exotic S. alterniflora affects the coastal ecosystem's functions including SOC storage (SOCS). We investigated the vertical deep soil SOC distribution (0–300 cm) in Jiangsu salt marsh and estimated its changes. The results show that (1) exotic S. alterniflora increases the SOC, with higher densities (g kg −1 ) in both topsoil and deep soil in its colonized area, and subsequently increases the SOCS vertical depth (cm) distribution. Such influences become more prominent with time since the introduction of S. alterniflora. The deepest SOC distribution (180 cm) and the highest SOC content (2.14 ± 0.19 g kg −1 ) in the deep layer (50–300 cm) were found in the zones where S. salsa – S. alterniflora co-exist (SSI). The vertical SOC distribution in zones where multi-species co-exists is deeper than that in mono-species dominated zones; (2) The deep soil (100–300 cm) SOC accounts more than 50% of 0–300 cm SOC in Jiangsu salt marsh, suggesting that SOC content of deep soil should not be ignored when calculating the global soil carbon stock; (3) Total SOCS within 0–300 cm in Jiangsu salt marshes (107.84 × 10 6 m 2 ) is 84.90 × 10 10 g, of which 0–100 cm, 100–200 cm and 200–300 cm layer accounts for 38.25%, 30.72% and 31.03%, respectively. The size of the SOCS (0–300 cm) in the Jiangsu salt marshes relatively to the global biome (0.36 × 10 −6 ) is in a lower proportion of the range of salt marsh area to global biome area (0.89 × 10 −6 ). The S. alterniflora salt marsh contributes most of the SOCS in the 0–300 cm and 0–100 cm soils.Item Open Access Erratum to: The Effects of Organic Matter Amendments on Greenhouse Gas Emissions from a Mitigation Wetland in Virginia’s Coastal Plain [Wetlands, DOI 10.1007/s13157-015-0674-y](Wetlands, 2015-10-14) Winton, RS; Richardson, CJItem Open Access Errors in greenhouse forcing and soil carbon sequestration estimates in freshwater wetlands: a comment on Mitsch et al. (2013)(Landscape Ecology, 2014-01-01) Bridgham, SD; Moore, TR; Richardson, CJ; Roulet, NT© 2014, Springer Science+Business Media Dordrecht. Radiative forcing feedbacks from wetlands have been an important component of past climate change and will likely be so in the future, so accurately assessing the carbon (C) and radiative balances of wetlands remains an important research priority. This commentary shows that the paper by Mitsch et al. (Landscape Ecol 28:583–597, 2013) seriously underestimated the radiative forcing effect of methane (CH < inf > 4 < /inf > ) emissions and overestimated soil C sequestration in freshwater wetlands. The model that they used is flawed in double counting the atmospheric decay of CH < inf > 4 < /inf > and incorporating a single 100 year CH < inf > 4 < /inf > global warming potential. They also used a small number of sites and short-term soil dating that resulted in unrealistically high soil C sequestration rates, ignoring decay of the entire soil C pool and allochthonous inputs of C. They calculated the radiative balance instead of the radiative forcing of natural wetlands, making their calculations irrelevant to anthropogenic climate change. Irrespective of the radiative forcing of wetlands, they provide essential ecosystem services that are important to protect.Item Open Access Human-soil relations are changing rapidly: Proposals from SSSA's cross-divisional soil change working group(Soil Science Society of America Journal, 2011-11-01) Richter, DDB; Bacon, AR; Megan, LM; Richardson, CJ; Andrews, SS; West, L; Wills, S; Billings, S; Cambardella, CA; Cavallaro, N; DeMeester, JE; Franzluebbers, AJ; Grandy, AS; Grunwald, S; Gruver, J; Hartshorn, AS; Janzen, H; Kramer, MG; Ladha, JK; Lajtha, K; Liles, GC; Markewitz, D; Megonigal, PJ; Mermut, AR; Rasmussen, C; Robinson, DA; Smith, P; Stiles, CA; Tate, RL; Thompson, A; Tugel, AJ; Es, HV; Yaalon, D; Zobeck, TMA number of scientists have named our age the Anthropocene because humanity is globally affecting Earth systems, including the soil. Global soil change raises important questions about the future of soil, the environment, and human society. Although many soil scientists strive to understand human forcings as integral to soil genesis, there remains an explicit need for a science of anthropedology to detail how humanity is a fully fledged soil-forming factor and to understand how soil change affects human well being. The development and maturation of anthropedology is critical to achieving land-use sustainability and needs to be nurtured by all soil disciplines, with inputs from allied sciences and the humanities,. The Soil Science Society of America (SSSA) has recently approved a cross-divisional Working Group on Soil Change, which aims to advance the basic and applied science of anthropedology, to facilitate networks of scientists, long-term soil field studies, and regional databases and modeling, and to engage in new modes of communications about human-soil relations. We challenge all interested parties, especially young scientists and students, to contribute to these activities and help grow soil science in the Anthropocene. © Soil Science Society of America, 5585 Guilford Rd., Madison WI 53711 USA. All rights reserved.Item Open Access Influences of Coal Ash Leachates and Emergent Macrophytes on Water Quality in Wetland Microcosms(Water, Air, and Soil Pollution, 2017-09-01) Olson, LH; Misehnheimer, JC; Nelson, CM; Bradham, KD; Richardson, CJ© 2017, Springer International Publishing AG. The storage of coal combustion residue (CCR) in surface water impoundments may have an impact on nearby water quality and aquatic ecosystems. CCR contains leachable trace elements that can enter nearby waters through spills and monitored discharge. It is important, therefore, to understand their environmental fate in affected systems. This experiment examined trace element leachability into freshwater from fly ash (FA), the most common form of CCR. The effects on water quality of FA derived from both high and low sulfur coal sources as well as the influences of two different emergent macrophytes, Juncus effusus and Eleocharis quadrangulata, were evaluated in wetland microcosms. FA leachate dosings increased water electric conductivity (EC), altered pH, and, most notably, elevated the concentrations of boron (B), molybdenum (Mo), and manganese (Mn). The presence of either macrophyte species helped reduce elevated EC, and B, Mo, and Mn concentrations over time, relative to microcosms containing no plants. B and Mo appeared to bioaccumulate in the plant tissue from the water when elevated by FA dosing, while Mn was not higher in plants dosed with FA leachates. The results of this study indicate that emergent macrophytes could help ameliorate downstream water contamination from CCR storage facilities and could potentially be utilized in wetland filtration systems to treat CCR wastewater before discharge. Additionally, measuring elevated B and Mo in aquatic plants may have potential as a monitoring tool for downstream CCR contamination.Item Open Access Integrated stream and wetland restoration: A watershed approach to improved water quality on the landscape(Ecological Engineering, 2011-01-01) Richardson, CJ; Flanagan, N; Ho, M; Pahl, JWater quality in Upper Sandy Creek, a headwater stream for the Cape Fear River in the North Carolina Piedmont, is impaired due to high N and P concentrations, sediment load, and coliform bacteria. The creek and floodplain ecosystem had become dysfunctional due to the effects of altered storm water delivery following urban watershed development where the impervious surface reached nearly 30% in some sub-watersheds. At Duke University, an 8-ha Stream and Wetland Assessment Management Park (SWAMP) was created in the lower portion of the watershed to assess the cumulative effect of restoring multiple portions of stream and former adjacent wetlands, with specific goals of quantifying water quality improvements. To accomplish these goals, a three-phase stream/riparian floodplain restoration (600m), storm water reservoir/wetland complex (1.6ha) along with a surface flow treatment wetland (0.5ha) was ecologically designed to increase the stream wetland connection, and restore groundwater wetland hydrology. The multi-phased restoration of Sandy Creek and adjacent wetlands resulted in functioning riparian hydrology, which reduced downstream water pulses, nutrients, coliform bacteria, sediment, and stream erosion. Storm water event nutrient budgets indicated a substantial attenuation of N and P within the SWAMP project. Most notably, (NO 2 - +NO 3 - )-N loads were reduced by 64% and P loads were reduced by 28%. Sediment retention in the stormwater reservoir and riparian wetlands showed accretion rates of 1.8cmyear -1 and 1.1cmyear -1 , respectively. Sediment retention totaled nearly 500MTyear -1 . © 2010 Elsevier B.V.Item Open Access Long-term transformation and fate of manufactured ag nanoparticles in a simulated large scale freshwater emergent wetland.(Environ Sci Technol, 2012-07-03) Lowry, GV; Espinasse, BP; Badireddy, AR; Richardson, CJ; Reinsch, BC; Bryant, LD; Bone, AJ; Deonarine, A; Chae, S; Therezien, M; Colman, BP; Hsu Kim, H; Bernhardt, ES; Matson, CW; Wiesner, MRTransformations and long-term fate of engineered nanomaterials must be measured in realistic complex natural systems to accurately assess the risks that they may pose. Here, we determine the long-term behavior of poly(vinylpyrrolidone)-coated silver nanoparticles (AgNPs) in freshwater mesocosms simulating an emergent wetland environment. AgNPs were either applied to the water column or to the terrestrial soils. The distribution of silver among water, solids, and biota, and Ag speciation in soils and sediment was determined 18 months after dosing. Most (70 wt %) of the added Ag resided in the soils and sediments, and largely remained in the compartment in which they were dosed. However, some movement between soil and sediment was observed. Movement of AgNPs from terrestrial soils to sediments was more facile than from sediments to soils, suggesting that erosion and runoff is a potential pathway for AgNPs to enter waterways. The AgNPs in terrestrial soils were transformed to Ag(2)S (~52%), whereas AgNPs in the subaquatic sediment were present as Ag(2)S (55%) and Ag-sulfhydryl compounds (27%). Despite significant sulfidation of the AgNPs, a fraction of the added Ag resided in the terrestrial plant biomass (~3 wt % for the terrestrially dosed mesocosm), and relatively high body burdens of Ag (0.5-3.3 μg Ag/g wet weight) were found in mosquito fish and chironomids in both mesocosms. Thus, Ag from the NPs remained bioavailable even after partial sulfidation and when water column total Ag concentrations are low (<0.002 mg/L).Item Open Access Quantification of Peat Thickness and Stored Carbon at the Landscape Scale in Tropical Peatlands: A Comparison of Airborne Geophysics and an Empirical Topographic Method(Journal of Geophysical Research: Earth Surface, 2019-12-01) Silvestri, S; Knight, R; Viezzoli, A; Richardson, CJ; Anshari, GZ; Dewar, N; Flanagan, N; Comas, X©2019. The Authors. Peatlands play a key role in the global carbon cycle, sequestering and releasing large amounts of carbon. Despite their importance, a reliable method for the quantification of peatland thickness and volume is still missing, particularly for peat deposits located in the tropics given their limited accessibility, and for scales of measurement representative of peatland environments (i.e., of hundreds of km2). This limitation also prevents the accurate quantification of the stored carbon as well as future greenhouse gas emissions due to ongoing peat degradation. Here we present the results obtained using the airborne electromagnetic (AEM) method, a geophysical surveying tool, for peat thickness detection at the landscape scale. Based on a large amount of data collected on an Indonesian peatland, our results show that the AEM method provides a reliable and accurate 3-D model of peatlands, allowing the quantification of their volume and carbon storage. A comparison with the often used empirical topographic approach, which is based on an assumed correlation between peat thickness and surface topography, revealed larger errors across the landscape associated with the empirical approach than the AEM method when predicting the peat thickness. As a result, the AEM method provides higher estimates (22%) of organic carbon pools than the empirical method. We show how in our case study the empirical method tends to underestimate the peat thickness due to its inability to accurately detect the large variability in the elevation of the peat/mineral substrate interface, which is better quantified by the AEM method.Item Open Access Response of fungal communities to fire in a subtropical peatland(Plant and Soil, 2021-09-01) Tian, J; Wang, H; Vilgalys, R; Ho, M; Flanagan, N; Richardson, CJPurpose: Wildfire, an increasing disturbance in peatlands, could dramatically change carbon stocks and reshape plant/microbial communities, with long-lasting effects on peatland functions. Soil fungi are important in controlling the belowground carbon and nutrient cycling in peatlands; however, the impact of altered fire regimes on these fungi is still unclear. Methods: We assessed fungal abundance, composition, and diversity across four soil depths (0–5 cm, 6–10 cm, 11–15 cm, 16–20 cm) under low-severity and high-severity fire in a subtropical peatland in the southeastern USA. Results: Low-severity fire significantly increased fungal Shannon diversity and saprotrophic fungi in the 0–5 cm soil layer immediately after fire and then retracted within 2 years. This pattern was not observed below 5 cm soils. The dominant fungal class − Archaeorhizomycetes declined initially and then returned to pre-low-severity fires levels at 0–5 cm depths. Time since low-severity fire was a primary driver of fungal composition in the 0–10 cm soil depth, while spatial distance among sites affected the deeper soils (11–20 cm). The fungal Shannon diversity failed to recover in the unburned state even 30 years after high-severity fire, especially in 6–20 cm soil layers. Stratification patterns of the fungal community were diminished by high-severity fire. Soil properties (either phenolics or carbon) were the primary drivers in shaping fungal community reassembly after high-severity fire across all soil depths. Conclusion: Collectively, the fungal communities seem to be highly resilient to low-severity fire, but not to high-severity fire in the shrub-dominated coastal peatlands.Item Open Access Riparian Habitat Dissimilarities in Restored and Reference Streams are Associated with Differences in Turtle Communities in the Southeastern Piedmont(Wetlands, 2014-01-01) Dudley, MP; Ho, M; Richardson, CJ© 2014, Society of Wetland Scientists. Few studies have assessed whether restored streams and riparian floodplains support reference communities of certain groups of freshwater organisms, such as turtles. This exploratory study compared turtle assemblages in six reference and six restored streams in the North Carolina Piedmont, which were assessed using standard trapping practices with baited hoop nets. We also quantified turtle-relevant habitat characteristics (structure, water quality, vegetation) through reach-scale surveys to assess potential differences in turtle composition. Turtle abundance at restored sites was more than twice that of references sites and trends existed in the distribution of turtle species, but neither abundance nor composition was found to be statistically different. Habitat characteristics that affect turtle communities were not equivalent between sites, with reference streams having higher canopy cover, and lower total phosphorus, dissolved oxygen and total suspended solids than restored streams. Mantel’s test and non-metric multidimensional scaling plots indicated that turtle composition was significantly correlated with habitat and vegetation, and that turtle communities were generally separated between restored and reference streams. These findings suggest a pattern that restored streams with riparian wetlands may provide more suitable habitat than reference streams for most southeastern Piedmont turtle species, but further studies are required to fully examine these patterns.Item Open Access Spatial Impacts of Stream and Wetland Restoration on Riparian Soil Properties in the North Carolina Piedmont(Restoration Ecology, 2011-11-01) Unghire, JM; Sutton Grier, AE; Flanagan, NE; Richardson, CJHydric soil development of riparian wetlands is primarily influenced by the hydrologic connection between the floodplains and the stream channel. Often, the goal of riparian restoration is to revitalize this connectivity through a restructuring of the stream channel and the floodplain; however, the effects of this restructuring on the physical and spatial characteristics of soil properties are rarely considered. The objective of this study was to quantify the impacts of restoration efforts on the spatial characteristics of soil properties by means of a pre- and post-restoration comparison. We determined that the spatial patterns of soil organic matter (SOM) and exchangeable phosphorus (P ex ) appeared less variable in the years following restoration than in the years before restoration. Mean SOM significantly decreased after restoration, whereas mean P ex significantly increased. The spatial characteristics and mean concentrations of NO 2 -NO 3 did not differ much between sampling dates. The loss of this spatial patterning in SOM and P ex and the decrease in SOM pools may represent negative impacts of restoration on important ecosystem characteristics. This study demonstrates that soil properties and spatial patterns can be negatively affected by restoration activities potentially hindering ecosystem development and function. © 2010 Society for Ecological Restoration International.Item Open Access Suspended Sediment Mineralogy and the Nature of Suspended Sediment Particles in Stormflow of the Southern Piedmont of the USA(Water Resources Research, 2019-01-01) River, M; Richardson, CJThe majority of annual sediment flux is transported during storm events in many watersheds across the world. Using X-ray diffraction, we analyzed the mineralogy of grab samples of suspended sediment during different stages of storm hydrographs in the Southern Piedmont. Mineralogy of suspended sediment changes drastically from quartz-dominated during the rising limb to clay dominated during the late falling limb/baseflow. Changes in mineralogy can shed insight into turbidity relationships, suspended sediment sources, energy versus supply-limited sediment transport, and other suspended sediment parameters such as anion exchange capacity and trace element chemistry. An unexpected key finding, confirmed by X-ray diffraction and electron microscopy, is that both kaolinite and quartz are primarily transported as discrete crystalline minerals of different size classes in our watersheds; this contrasts with existing scientific literature stating that in most fluvial systems suspended sediment is transported primarily as composite particles composed of a heterogeneous mix of all particle sizes. Our findings also support existing literature that turbidity can be a good proxy for elements such as P, which are preferentially adsorbed onto iron oxide coatings thus in situ turbidity probes have great potential to provide relatively inexpensive estimates of P flux when calibrated for specific watersheds.Item Open Access The Effects of Organic Matter Amendments on Greenhouse Gas Emissions from a Mitigation Wetland in Virginia’s Coastal Plain(Wetlands, 2015-10-14) Winton, RS; Richardson, CJ© 2015, Society of Wetland Scientists. There is concern that widespread restoration and/or creation of freshwater wetlands may present a radiative forcing hazard because of the potential for methane (CH 4 ) emissions. Yet data on greenhouse gas (GHG) emissions from restored wetlands are sparse and there has been little investigation into the GHG effects of amending wetland soils with organic matter (OM), a practice used to improve function of mitigation wetlands in the Eastern United States. In this study we measure GHG emissions across an OM gradient at the Charles City Wetland (CCW) in Charles City County, Virginia. We found soils heavily loaded with OM emit significantly more CO 2 than those that have received little or no OM. CH 4 emissions from CCW are low compared to reference wetlands and show no relationship with the loading rate of added OM or total soil carbon. We conclude that adding moderate amounts ( < ~150 kg m −2 ) of OM to the CCW does not greatly increase GHG emissions, while the addition of high amounts of OM produces additional CO 2 , but not CH 4 . CH 4 flux is highest under flooded conditions during warmer months but it still a modest contribution to global warming potential compared to soil CO 2 flux.