Altered Wetland Research Articles

Spatial assemblage of shorebirds (Aves: Charadriiformes) in an altered wetland of the southern coast of Sri Lanka

Spatial assemblage of shorebirds (Aves: Charadriiformes) in an altered wetland of the southern coast of Sri Lanka

Wetland soil microbial responses to upland agricultural intensification and snail invasion

Wetland soils harbor diverse microorganisms including bacteria, archaea, and fungi, all of which play significant roles in maintaining soil health and ecosystem functions but are susceptible to influences from multiple environmental changes. Agricultural intensification and biological invasion are two fundamental drivers of environmental change for wetlands, but their interactive effects on soil microbial communities remain less well understood, particularly for seasonal subtropical wetlands. Yet such understanding is vital for wetland conservation and management. In this study, we conducted a 14-week field mesocosm experiment to investigate how agricultural intensification and invasive apple snail (Pomacea maculata) – an emerging and increasingly concerning threat to natural and agricultural systems in southeastern U.S. – altered wetland soil microbial communities and structures. We found that invasive P. maculata showed selective effects on relative abundance of specific microbial taxa (e.g., Proteobacteria, Nitrospirota), and interactive effects with upland intensification on Spirochaetota and Mortierellomycota. Upland agricultural intensification also exerted significant and consistent effects on microbial composition and diversity across microbial domains. Changes in microbial composition were partly manifested through modifications in water chemistry, such as dissolved oxygen, which acted as environmental regulators. In addition, upland intensification led to more complex but sparsely connected microbial networks, while invasive snail presence decreased network complexity and resulted in greater modularity, less edge density, and longer path length, indicative of lower molecular information exchange efficiency. Our research emphasizes the need for a comprehensive evaluation of microbial responses (i.e., composition, diversity, and co-occurrence patterns) to better understand multi-stressor impacts from human activities on wetland belowground microbial communities. By holistically characterizing microbial responses, our findings show how global change drivers may impact wetland microorganisms in subtropical biomes and infer their functional consequences. Our results have important implications for sustainable landscape management and conservation of wetlands that are experiencing escalating human-induced environmental changes.

Demography of a painted turtle intergrade (Chrysemys picta picta X C. p. marginata) population from an altered wetland

The demography of a painted turtle Chrysemys picta picta X C. p. marginata population from a eutrophic habitat was examined at a wetland site in south-central Pennsylvania (USA) during 2011–2019. Males reached sexual maturity at 90 mm carapace length (CL) in half the time taken, but at the same size, as painted turtles studied elsewhere in the north-eastern portion of the United States. Females matured at 130 mm CL at our site, which was larger and began at an earlier age than conspecifics. Our data corroborate findings of faster growth in C. picta juveniles resulting in earlier maturity at body sizes equal to or larger than slower growing juveniles. Our results also conform to previous findings linking wetlands altered by added nutrient input to increased growth patterns of their resident painted turtle population. Rapid growth rates for aquatic turtles are likely to become more common globally as urbanisation continues to expand and alter wetland habitats.

Soil Conditions Following Hydrologic Restoration in Cypress Dome Wetlands

Soil characteristics and decomposition rates were investigated in 12 geographically isolated wetlands (cypress domes) across a gradient of hydrologic alteration (altered, marginally altered and least altered sites) seven years after passive recovery from historic groundwater withdrawals. Above- and belowground decomposition rates were determined in transition (seasonally flooded) and outer deep (semi-permanently) hydrologic zones. Flood duration, frequency, redox conditions, pH, and soil organic matter were measured to potentially explain patterns across the alteration gradient. Despite the reduction in groundwater withdrawals, altered sites exhibited fewer days of inundation in transition and outer deep zones compared to marginally altered and least altered wetlands. Over a 56 week period, altered wetlands displayed greater decomposition in the aboveground outer deep zone (73.3 ± 4.0% mass remaining) and in the belowground transition zone (62.0 ± 4.5% mass remaining) compared to marginally and least altered sites. Analyses indicated that marginally altered wetlands were more comparable to least altered wetlands however differences in altered wetland soils (including decomposition) persist. Although wetland hydrology has been partially restored, additional time and/or further site augmentation may be needed for altered sites to be functionally equivalent to least altered wetlands and in some cases (e.g., excessive subsidence) the degree of past alteration may limit restoration potential.

Examining Playa Wetland Contemporary Conditions in the Rainwater Basin, Nebraska

Based on three critical criteria – soil, hydrology, and vegetation, this study examined contemporary playa wetland conditions to determine the extent of wetland degradation in the Rainwater Basin in south-central Nebraska. Geospatial statistics were used to evaluate the changes between historical hydric soil footprints and the most recent wetland survey datasets. The results indicate that the historical hydric soil footprints dominated by the Scott and Fillmore soil series have degraded 31.0% and 79.4% respectively. We also found approximately two-thirds of the footprints no longer pond water during spring migration. In fact, only 16.8% of the historical hydric soil footprints contain hydrophytes in recent surveys. Furthermore, the majority of these footprints (and the associated uplands) have been converted to cropland and no longer pond frequently or support hydrophytes. Additionally, the extensive grid road system supports commodity crop production, but in many instances this infrastructure has significantly altered wetland footprints and the associated watersheds to reduce the total water volume delivered to wetlands. The resulting situation is that conserved lands, including Waterfowl Production Areas (WPAs), Wildlife Management Areas (WMAs), and conservation easements only represent 11.3% of total historical footprints, but contribute to over 40.5% of the current total ponded water and hydrophytes.

A Case Study Examining the Efficacy of Drainage Setbacks for Limiting Effects to Wetlands in the Prairie Pothole Region, USA

Abstract The enhancement of agricultural lands through the use of artificial drainage systems is a common practice throughout the United States, and recently the use of this practice has expanded in the Prairie Pothole Region. Many wetlands are afforded protection from the direct effects of drainage through regulation or legal agreements, and drainage setback distances typically are used to provide a buffer between wetlands and drainage systems. A field study was initiated to assess the potential for subsurface drainage to affect wetland surface-water characteristics through a reduction in precipitation runoff, and to examine the efficacy of current U.S. Department of Agriculture drainage setback distances for limiting these effects. Surface-water levels, along with primary components of the catchment water balance, were monitored over 3 y at four seasonal wetland catchments situated in a high-relief terrain (7–11% slopes). During the second year of the study, subsurface drainage systems were installed in two of the catchments using drainage setbacks, and the drainage discharge volumes were monitored. A catchment water-balance model was used to assess the potential effect of subsurface drainage on wetland hydrology and to assess the efficacy of drainage setbacks for mitigating these effects. Results suggest that overland precipitation runoff can be an important component of the seasonal water balance of Prairie Pothole Region wetlands, accounting on average for 34% (19–49%) or 45% (39–49%) of the annual (includes snowmelt runoff) or seasonal (does not include snowmelt) input volumes, respectively. Seasonal (2014–2015) discharge volumes from the localized drainage systems averaged 81 m3 (31–199 m3), and were small when compared with average combined inputs of 3,745 m3 (1,214–6,993 m3) from snowmelt runoff, direct precipitation, and precipitation runoff. Model simulations of reduced precipitation runoff volumes as a result of subsurface drainage systems showed that ponded wetland surface areas were reduced by an average of 590 m2 (141–1,787 m2), or 24% (3–46%), when no setbacks were used (drainage systems located directly adjacent to wetland). Likewise, wetland surface areas were reduced by an average of 141 m2 (23–464 m2), or 7% (1–28%), when drainage setbacks (buffer) were used. In totality, the field data and model simulations suggest that the drainage setbacks should reduce, but not eliminate, impacts to the water balance of the four wetlands monitored in this study that were located in a high-relief terrain. However, further study is required to assess the validity of these conclusions outside of the limited parameters (e.g., terrain, weather, soils) of this study and to examine potential ecological effects of altered wetland hydrology.

The impact of ornithogenic inputs on phosphorous transport from altered wetland soils to waterways in East Mediterranean ecosystem

Large flocks of Eurasian crane (Grus grus, >35,000) have begun wintering in an altered wetland agro-ecosystem located in Northern Israel, a phenomenon that attracts more than 400,000 eco-tourists a year. A 100-ha plot has been used to feed the cranes in order to protect nearby fields. The objective of this study was to evaluate the influence of this bird's feeding practice on the P status of the altered wetland soils and waterways. We installed a series of wells at two depths (40 and 90cm) between two major waterways in the feeding area and monitored the hydraulic heads and collected groundwater samples for elemental analyses. We collected six soil cores and four sediment samples from the waterways and conducted sequential P extraction. We found significant increase in groundwater soluble reactive P (SRP) (>0.5mgl−1) compared with much lower concentrations (~0.06mgl−1) collected in the period prior to the feeding. We found significant decrease in Fe(II), Ca, and SO4 concentrations in the shallow groundwater (33, 208, and 213mgl−1, respectively) compared with the period prior to the feeding (47, 460, and 370mgl−1 respectively). An increase in the more labile P fraction was observed in soils and sediments compared with the period before the feeding. The P input by bird excrement to the feeding area was estimated around 700kg P per season, while P removal by plant harvesting was estimated around 640kgPyr−1. This finding supports the current eco-tourism practices in the middle of intensive farming area, suggesting little impact on waterways.

Catastrophic Dieback of Cyperus Papyrus in Response to Geochemical Changes in an East Mediterranean Altered Wetland

Catastrophic vegetation dieback is a common phenomenon that has occurred in many wetland habitats worldwide. Different mechanisms have been proposed to explain these occurrences. We tested two published models proposed as potential mechanisms for the catastrophic dieback of Cyperus papyrus in the Hula Nature Reserve (HNR), Israel. Sulfide toxicity and P limitation models were tested using lysimeters. The sulfide toxicity was tested by redox-suppression simulation, while the P deficiency was evaluated using N/P ratio index. The sulfide toxicity model was not accepted as a viable mechanism because papyrus stands did not show any sign of stress, even when growing with sulfide concentration threefold that reported during the cattail dieback in a nearby wetland or values reported in the literature. The P limitation model was not supported by the N/P index that indicated N limitation rather than P limitation. Next, we tested two alternative mechanisms that link the dieback to N cycles and depletion in the HNR system or to a sequential stressor cascade that caused major N limitation. We concluded that the N deficiency hypothesis is a better explanation for the observed dieback and the current health status of C. papyrus in this East Mediterranean ecosystem.

Assessment of phosphorus fertilizer practices in altered wetland soils using uncertainty analysis

AbstractIntensive P fertilizer application is widely practised in East Mediterranean altered wetland soils, even when results from the Olsen‐P extract indicate sufficiency (>10 mg P/kg). To reduce or even eliminate this practice we conducted a large field study to test the feasibility of a major reduction in the use of P fertilizers. A total of 90 sample sites were evenly spaced with respect to their parent material (deep peat, shallow peat, marl). Soils were analysed for Olsen‐P, bulk density, pH, electrical conductivity, and nitrate, chloride and sulphate in saturated paste extracts. We determined variograms and estimated the spatial structure of Olsen‐P data by ordinary kriging. We then used a sequential Gaussian model to produce 100 alternative simulations to measure the joint spatial uncertainty of P concentrations in the study area (ca. 1500 ha). Finally, we post‐processed the simulation results to compute the probability of exceeding the threshold Olsen‐P value of 10 mg/kg. The simulation results indicate a high probability of exceeding the 10 mg/kg threshold in most peat soils supporting an earlier recommendation to reduce or even eliminate P fertilizer application in these fields. On the other hand, a very low probability of exceeding this threshold was observed in most marl soils justifying continued fertilizer application. However, the added P is likely to affect adjacent waterways and increase potential downstream eutrophication due to high conductance and flow continuity between the marl soils and adjacent waterways.

Chemical evolution and vegetation response in an altered wetland ecosystem, Hula Valley, Israel (1988–2004)

The Hula Nature Reserve (HNR) (0.3 km2) in northern Israel is a semiarid wetland ecosystem within the greater Hula Valley. In the 1950s, approximately 60 km2 of wetlands were drained and converted to farmland. The HNR was established during this time to preserve some of the native flora and fauna. Agricultural runoff and a reflooding of the area with peat water in 1999 resulted in high sulfate (SO4 2−) concentrations of 66.67 ± 4.00 mg/L. We identified the existence of SO4 2−, nitrate (NO3 −), and ammonium (NH4 +) nutrient gradients as well as related mechanisms affecting the growth and dieback of Cyperus papyrus. The observed changes in the C. papyrus populations were caused primarily by fluctuations in SO4 2−. After two key events that affected levels of SO4 2− in the HNR, C. papyrus coverage was altered by more than 80%.

Evaluation of phosphorus management practices in East Mediterranean altered wetland soils

AbstractIn this study, we re‐examined the common practice of intensive P fertilization in altered wetland soils even when soil test (Olsen‐P) indicates sufficient P levels (>10 mg/kg). We tested the effects of P fertilization on crop performance and P leaching in 36 lysimeters (1.5 m3) filled with peat, marl or alluvial materials and compared a new bone‐char‐based fertilizer to the common superphosphate. The lysimeter experiment consisted of the two fertilizer types, two application rates and a typical crop rotation of setaria (Setaria italica), pea (Pisum sativum) and tomatoes (Lycopersicon esculentum). By the end of each crop rotation, the yield was evaluated relative to P‐fertilization rates and soil‐test P. P fertilization resulted in increased Olsen‐P, soil‐solution P and P loss through leachates and a slight quality yield advantage in pea and tomato with no increase in yield of any crop. P budget calculations showed that plant uptake was not affected by the amount or type of applied P. We concluded that P fertilizer application should be significantly reduced because of limited crop response and increased P concentrations in leachates that may increase P loss to waterways especially in the marl soils. The ABC Protector exhibited slow P release, but its environmental implications should be further studied.

Evaluation of groundwater and phosphorus transport in fractured altered wetland soils

Nutrient loss from altered wetlands to waterways may influence the water quality of downstream water resources. To test potential nutrient transport from a highly fractured agricultural field of altered wetland to waterways, we computed water and solute budgets in a large field (320 ha) experiment. The water level was raised in a drainage canal for 28 days (raising stage) to generate water flow to the field and then lowered (drainage stage) to generate back flow to the canal. Differential sampling stations (DISS) equipped with an Eh-pH measuring system were installed to monitor and sample crack and matrix water separately. Water flowing in cracks exhibited Eh > 250 mV and EC < 1.5 dS m ―1 while in the matrix, the Eh was <100 mV and EC exceeded 3.0 dS m ―1 . High similarity was found between crack water measured in the DISS and water that drained directly into the drainage canal. We proposed a conceptual model for water and solute transport by a dual-domain system. Most of the water flow occurs in the cracks and most of the solute reaches the cracks by advection and diffusive flow mechanisms in the soil matrix. The conceptual model is based on the assumption that the crack and matrix domains are in chemical disequilibrium because of low transport rate from the matrix to the cracks relative to water flow rate in the cracks. Using this conceptual model, we calculated that during the drainage stage, only 0.64 kg P, compared with 3700 kg of the non-sorptive sulfate ion, were transported from the field to the canal. The oxidized conditions in the crack walls lead to Fe-hydroxide precipitation. These fresh precipitate amorphous iron hydroxides serve as an adsorption sink to P and other potential adsorbates.

Hydrogeological characterization of an altered wetland

Summary Spatiotemporal changes in the hydrogeology of the Hula altered wetland may influence the water quality of Lake Kinneret, which provides up to 30% of the potable water for the state of Israel. The main objectives of this work were to study the groundwater-flow characteristics in this wetland and assess the potential impact on downstream water quality. We constructed variograms of hydraulic heads, computed decision-tree models of major ions, and determined the hydraulic conductivity ( K ) and δ 2 H/δ 18 O ratios, to ascertain the spatial and vertical distribution of hydrogeological parameters. We also performed large-scale field experiments (⩾1 km 2 ) to assess the connectivity between the waterways and the wetland’s aquifer. The aquifer is fragmented by three parent materials: deep peat, shallow peat/marl complex and marl. The decision-tree-based model, the isotopic ratios and K determinations suggest that the deep peat subaquifer is composed of one homogeneous layer characterized by low K (0.001 m d −1 ). The two other subaquifers consist of three hydrostratigraphic layers: (i) the vadose zone, (ii) a layer with well-developed macropores at a depth of 1.5–4 m and (iii) an aquitard layer at a depth of 4–15 m. The temporal head fluctuations, the high K values of the second layer (>170 m d −1 ), and the large volume of water flowing into and out of the two subaquifers during large-scale field experiments all attest to excellent connectivity with the waterways. These results support the concept of critical source area which claims that most of the P loss in a catchment derives from small areas in which specific P release and transport mechanisms coincide with high connectivity. We conclude that the high connectivity of this Mediterranean altered wetland to waterways, coupled with the high P release that has occurred in recent years following soil flooding, provides the loading mechanism that partially explains the observed P increase in the Jordan River.

Overestimation of Phosphorus Adsorption Capacity in Reduced Soils: An Artifact of Typical Batch Adsorption Experiments

Although soil reduction often results in P release to soil solutions, many researchers have observed an increased maximum P adsorption (Smax) following soil reduction. We hypothesized that this result is an experimental artifact caused by exposure of the reduced soils to aerobic conditions and by the use of high P additions, which may result in precipitation. Four semiarid altered wetland soils were incubated under reduced conditions, followed by reoxidation, and their P‐adsorption characteristics were measured under atmospheric and N2–atmosphere conditions. During the reductive incubation, soluble P and Fe concentrations increased. In one of the soils, P and Fe were monitored after reoxidation and both were found to decrease. The reduction–reoxidation cycle has led to increased Smax values. Under an N2 atmosphere, the equilibrium P concentrations at zero adsorption (EPC0) of all soils were higher than those determined under atmospheric conditions, whereas no significant changes were observed in Smax values. Oversaturation of the equilibrating solutions with respect to P minerals suggested P precipitation and overestimation of Smax at high added P concentrations under both aerobic and N2–atmosphere conditions. We conclude that aerobic batch experiments of reduced soils are affected by P adsorption to newly in‐tube‐formed ferric oxides. In accordance, we stress the importance of the EPC0 rather than the Smax as an informative measure of P adsorption, and the need for using low‐P experiments and maintaining anaerobic conditions in evaluating P adsorption of reduced soils.

Hydrological Control of Phosphorus Mobility in Altered Wetland Soils

Ground water transport of P from the altered wetland soils of the Hula Valley may influence the water quality of Lake Kinneret, which provides up to 30% of the potable water for the state of Israel. We hypothesized that land use change in these altered wetland soils is the cause for the reported increase in particulate P loading to the Jordan River, which empties to Lake Kinneret. To test this hypothesis we evaluated the P mobility from the Hula's wetland soils to waterways under various hydrological conditions using a field‐scale experiment (0.8 km2) with well‐monitored boundary conditions. The spatiotemporal changes in hydraulic head across the study area were measured using automated monitoring stations installed in eight observation wells. The hydraulic conductivity (K) of the near‐surface peat/marl layers (179 m d−1) was significantly larger than the K values (0.001 to 0.03 m d−1) measured in the marl layers at 5 to 15 m below surface. The large K values of the near‐surface layers result from the drainage of this wetland in the late 1950s followed by the oxidation of the peat layers and dissection of the lower peat and upper silt‐clayey marl layers. Using a simple water‐budget approach, the large field experiment yielded a discharge of 0.27 Mm3 and a loading of 306 kg P transported from the altered peat soils to the waterways, in just 7 wk. Most of the P loading was in the form of particulate P (&gt;0.45 μm) rather than dissolved P.

Hydrological controls on soil redox dynamics in a peat-based, restored wetland

Increasing areas of altered wetland are being restored by re-flooding the soil. Evidence in the literature indicates that this practice can induce the redox-mediated release of soil nutrients, thereby increasing the risk of diffuse water pollution. However, for the sake of improving wetland management decisions, there is a need for more detailed studies of the underlying relationship between the hydrological and redox dynamics that explain this risk; this is particularly the case in agricultural peatlands that are commonly targeted for the creation of lowland wet grassland. A 12-month field study was conducted to evaluate the relationship between hydrological fluctuations and soil redox potential (Eh) in a nutrient-rich peat field (32 g N kg − 1 and 1100 mg P kg − 1 in the surface 0–30 cm soil) that had been restored as lowland wet grassland from intensive arable production. Field tensiometers were installed at the 30-, 60- and 90-cm soil depths, and Pt electrodes at the 10-, 30-, 60- and 90-cm depths, for daily logging of soil water tension and Eh, respectively. The values for soil water tension displayed a strong negative relationship ( P < 0.001) with monthly dip well observations of water table height. Calculations of soil water potential from the logged tension values were used, therefore, to provide a detailed profile of field water level and, together with precipitation data, explained some of the variation in Eh. For example, during the summer, alternating periods of aerobism (Eh > 330 mV) in the surface, 0–10 cm layer of peat coincided with intense precipitation events. Redox potential throughout the 30–100 cm profile also fluctuated seasonally; indeed, at all depths Eh displayed a strong, negative relationship ( P < 0.001) with water table height over the 12-month study period. However, Eh throughout the 30–100 cm profile remained relatively low (< 230 mV), indicating permanently reduced conditions that are associated with denitrification and reductive dissolution of Fe-bound P. The implications of these processes in the N- and P-rich peat for wetland plant diversity and water quality are discussed.

Redox reactions and phosphorus release in re‐flooded soils of an altered wetland

SummaryPhosphorus loss from land can be a major factor affecting surface water quality. We studied P‐release mechanisms in wetland soils that had been drained and cultivated for four decades and then re‐flooded. We measured redox, pH and solution composition in two sites in the field and in four peat and calcareous soils incubated in biogeochemical microcosms. The redox and pH measurements during the 120 days of incubation and the resulting soil solution composition indicated that the main process leading to P release is reductive dissolution of ferric hydroxides on which P was adsorbed and in which P was occluded. The molar Fe:P ratio increased with period of reduction from below 1 in the first week of re‐flooding to 15–60 after 120 days. This suggests an increased P‐retention capacity upon reoxidation of the soil solution, whether within the soil profile or in the drainage canals. Prolonged flooding of the calcite‐poor, gypsum‐rich peat soils increased the oversaturation of soil solutions with respect to hydroxyapatite and occasionally β‐Ca3(PO4)2(c), indicating that in spite of the large Ca concentration, the rate of Ca‐P precipitation was insufficient to maintain the saturation status of the Ca‐P system. In the calcareous soils the Ca‐P system effectively controlled the P activity in soil solution throughout the incubation period. In both cases the precipitation of Ca‐P minerals could be an important P‐retention mechanism.

The Geochemistry of Phosphorus in Peat Soils of a Semiarid Altered Wetland

An understanding of P transformations in altered wetlands has mainly developed from temperate and humid regions with neutral to acidic soils. Little is known regarding downstream water quality impact of P transformations in semiarid wetlands that undergone repeated cycles of drying and rewetting. The P geochemistry was studied using the Hedley fractionation scheme in the altered peat soils of the Hula Valley, Israel. The peat soils were sampled according to the peat depth and redox potential characteristics. The mean total P concentration (Pt) in the surface peat horizons (1190 ± 300 mg kg−1) was significantly higher than in the anaerobic (EH &lt; −220 mV) peat layers (650 ± 260 mg kg−1). The concentrations of P in all fractions except the most labile P were significantly higher in the aerobic (EH = 400 mV) peat layers. The predominant extractable fractions in the surface peat horizons were Ca‐P extracted by 1 M HCl (21–60% of Pt), Iron‐P extracted by 0.5 M NaOH (11–41% of Pt), and residual P extracted by H2SO4 (20–40% of Pt). The source of the Ca in the Ca‐P fraction was mainly from gypsum dissolution following the rewetting cycles. The results clearly showed that the drainage of these wetlands facilitated rapid organic matter (OM) oxidation, release of organically bound metals and P followed by sesquioxides and gypsum precipitation. These geochemical transformations enhanced the Pt concentration per mass of altered peat soil and changed the P distribution among the different pools. Most of the P is currently associated with Fe oxides and hydroxides and/or coprecipitated with Ca.

Spatial analysis of phosphorus sorption capacity in a semiarid altered wetland.

The observed increase in phosphorus (P) loading into the Jordan River could increase eutrophication processes in Lake Kinneret, the only freshwater lake in Israel, which provides 25% of the country's drinking water. The P may originate from the peat soils of the highly altered Hula Valley's semiarid wetland ecosystem through which the Jordan River runs. The objectives of this research were to ascertain the sorption capacity of these soils and to identify areas with high potential for P release from soils to ground water. We extracted 80 soil samples collected across the valley with ammonium oxalate and determined the ratio of extractable P to Fe and Al, from which we derived the degree of phosphorus saturation (DPS). A relatively low DPS (<15%) was observed in Histosols compared with the high DPS (>30%) observed in many of the hydromorphic organo-mineral soils. We used a sequential Gaussian simulation technique to assess the spatial pattern of the DPS and found that the Histosols have a low probability (<10%) of exceeding the widely used environmental DPS threshold of 25%. The areas characterized by mineral soils, such as hydromorphic Vertisols and various marl redoximorphic soils, have a high probability (>60%) of exceeding the threshold value. The ability to predict the concentrations of dissolved P in ground water based on DPS values was somewhat impaired because of the preferential flow characteristics in this altered wetland.

Application of the EPA Wetland Research Program approach to a floodplain wetland restoration assessment

Kolka, R.K., C.C. Trettin, E.A. Nelson, C.D. Barton, and D.E. Fletcher. 2002. Application of the EPA Wetland Research Program Approach to a floodplain wetland restoration assessment. J. Env. Monitoring & Restoration 1(1):37-51. Forested wetland restoration assessment is difficult because of the timeframe necessary for the development of a forest ecosystem. The development of a forested wetland ecosystem includes the recovery of hydrology, soils, vegetation, and faunal communities. To assess forested wetland restoration projects, measures need to be developed that are sensitive to early changes in community development and are predictive of future conditions. In this study we apply the EPS's Wetland Research Program's (WRP) approach to assess the recovery of two thermally altered riparian wetland systems in South Carolina. In one of the altered wetland systems, approximately 75% of the wetland was planted with bottomland tree seedlings in an effort to hasten recovery. Individual studies addressing hydrology, soils, vegetation, and faunal communities indicate variable recovery responses.