Showing papers on "Wetland published in 1988"
TL;DR: In this article, the authors used multivariate vegetation data to describe vegetation-environment relationships in a set of riverine wetlands and then explored general relationships between pattern and process in shoreline vegetation.
Abstract: Although freshwater shorelines occupy extensive areas of the temperate zone, we still have few conceptual models for pattern and process in shoreline vegetation. This study uses multivariate vegetation data to describe vegetation-environment relationships in a set of riverine wetlands and then explores general relationships between pattern and process. Samples were collected from five marshes along the Ottawa River (eastern Canada) (n = 94 sample units). Detrended correspondence analysis was used to describe major gradients, and TWINSPAN was used to classify vegetation types. TWINSPAN produced four major classes dominated by Sparganium eurycarpum, Eleocharis smalkii, Scirpus americanus, and Typha latifolia. Within each class, two associations could be recognized, differing in the degree to which one species managed to dominate the vegetation. Ordination showed that these vegetation types were arranged along two major axes: a standing crop and litter gradient, and a water depth gradient. Species richness was greatest just above the late August waterline in Eleocharis smallii vegetation that had low fertility, intermediate total biomass (250g/m2) and low littermass (30 g/m2). Very high biomass (>400g/m2) was observed where indices of high fertility and low disturbance coincided. Low species richness in this Typha-dominated vegetation is thought to be a result of competitive exclusion. Exposure to waves, ice, and flowing water produced a fertility gradient. The least fertile sites had small evergreen species such as Eriocaulon septangulare and Ranunculus flam- mula. These species possessed traits associated with Grime's "stress tolerator" strategy. The three main factors controlling vegetation composition were water depth, the effects of spring flooding in removing litter, and the fertility gradient produced by waves and flowing water. These were incorporated into a conceptual model including both patterns and pro- cesses observed along the Ottawa River.
275 citations
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30 Dec 1988
TL;DR: A regional symposium was held at the Northern Prairie Wildlife Research Center, Jamestown, N.D., and sponsored by the National Wetlands Technical Council (NWTC).
Abstract: Papers presented at a regional symposium held Novermber 1985 at the Northern Prairie Wildlife Research Center, Jamestown, N.D., and sponsored by the National Wetlands Technical Council. Topics include: politico-economics of prairie potholes, nitrogen and phosphorus dynamics, algae, food chains. Anno
227 citations
01 Jun 1988
TL;DR: There has been an overall decrease in excess of 70 percent in the suspended load transported by the Lower Mississippi River since 1850 as mentioned in this paper, which may be due to a decline in discharge and a change in land use practices.
Abstract: Since 1850, there has been an overall decrease in excess of 70 percent in the suspended load transported by the Lower Mississippi River. A decrease of 25 percent between the earliest measurements and 1950 may be partly the result of a decline in discharge and partly the result of a change in land use practices. The largest decrease occurred in 1952–53 following construction of major main-stem reservoirs on the Missouri River. Similar construction on the Arkansas River has resulted in a further decrease in 1962–63. The decrease in suspended load, combined with the artificial levee construction program and the overall enhancement of the river channel for navigation has been accompanied by an accelerating decline in land area of the Louisiana coastal zone from 17 km2/yr in 1913 to 102 km2/yr in 1980.
207 citations
TL;DR: In this article, the authors examined the cycle of atmospheric CO2 over the Amazon Basin using measured vertical profiles of CO2 concentrations in the canopy and aloft, and direct measurements of emissions from soils.
Abstract: As a part of the NASA's Amazon Boundary Layer Experiment 2A mission, the cycle of atmospheric CO2 over the Amazon Basin was examined using measured vertical profiles of CO2 concentrations in the canopy and aloft, and direct measurements of CO2 emissions from soils. The results provide a detailed picture of daily exchanges of air between the tropical forest (0-30) and the atmospheric boundary layer (30-2000 m). A comparison of atmospheric CO2 distributions over forests, wetlands, and rivers shows that the lower atmosphere over forests functions separately from that over rivers or wetlands during the night and to some extent during the day; the basic diurnal cycle of CO2 over wetlands is much weaker than over forests, and the cycle is almost absent over rivers. This result is consistent with expectations based on the biogeochemistry of organic carbon in these systems.
161 citations
TL;DR: In this article, the basic techniques and procedures have been worked out for propagation of several marsh angiosperms, and a variety of locations to vegetate intertidal dredged material disposal sites, stabilize shorelines, mitigate damage to natural marshes and to revegetate one marsh destroyed by an oil spill.
157 citations
TL;DR: In this paper, a sediment budget for Chesapeake Bay was constructed and a variety of wetland types was used to assess the trapping ability of marshes in large estuaries, which indicated that estuarine marshes trap 5-11% of the annual Chesapeake bay sediment input.
153 citations
TL;DR: In this paper, the cumulative effects of one or more of these disturbances on the hydrologic system as related to wetlands must take into account uncertainty in the measurements and in the assumptions that are made in hydrology studies.
Abstract: Wetlands occur in geologic and hydrologic settings that enhance the accumulation or retention of water. Regional slope, local relief, and permeability of the land surface are major controls on the formation of wetlands by surface-water sources. However, these landscape features also have significant control over groundwater flow systems, which commonly play a role in the formation of wetlands. Because the hydrologic system is a continuum, any modification of one component will have an effect on contiguous components. Disturbances commonly affecting the hydrologic system as it relates to wetlands include weather modification, alteration of plant communities, storage of surface water, road construction, drainage of surface water and soil water, alteration of groundwater recharge and discharge areas, and pumping of groundwater. Assessments of the cumulative effects of one or more of these disturbances on the hydrologic system as related to wetlands must take into account uncertainty in the measurements and in the assumptions that are made in hydrologic studies. For example, it may be appropriate to assume that regional groundwater flow systems are recharged in uplands and discharged in lowlands. However, a similar assumption commonly does not apply on a local scale, because of the spatial and temporal dynamics of groundwater recharge. Lack of appreciation of such hydrologic factors can lead to misunderstanding of the hydrologic function of wetlands within various parts of the landscape and mismanagement of wetland ecosystems.
146 citations
TL;DR: The Pantanal region is a threatened region in Brazil as discussed by the authors, due to deforestation, expanding agriculture, illegal hunting and fishing, and pollution of the water with herbicides, pesticides, and by-products of fuel alcohol production.
Abstract: ment was part of the opening ceremonies of a worldwide campaign directed at the conservation of wetlands. The campaign was promoted by UNESCO, with the cooperation of the International Union for the Conservation of Nature and Natural Resources (IUCN) and the World Wildlife Fund (WWF). The Pantanal, with its extraordinary diversity and abundance of wildlife, is a threatened region. Deforestation; expanding agriculture; illegal hunting and fishing; and pollution of the water with herbicides, pesticides, and by-products of fuel alcohol production have caused a progressive deterioration of the natural environment, placing at risk one of Brazil's most important ecosystems.
145 citations
TL;DR: In this article, the authors suggest that a landscape approach might be useful in evaluating the effects of cumulative impacts on freshwater wetlands and suggest that most watersheds contain more than one wetland, and effects on water quality depend on the types of wetlands and their position in the landscape.
Abstract: In this article, we suggest that a landscape approach might be useful in evaluating the effects of cumulative impacts on freshwater wetlands. The reason for using this approach is that most watersheds contain more than one wetland, and effects on water quality depend on the types of wetlands and their position in the landscape. Riparian areas that border uplands appear to be important sites for nitrogen processing and retention of large sediment particles. Fine particles associated with high concentrations of phosphorus are retained in downstream wetlands, where flow rates are slowed and where the surface water passes through plant litter. Riverine systems also may play an important role in processing nutrients, primarily during flooding events. Lacustrine wetlands appear to have the least impact on water quality, due to the small ratio of vegetated surface to open water. Examples are given of changes that occurred when the hydrology of a Maryland floodplain was altered.
125 citations
TL;DR: In this article, the authors proposed a new policy structure for the river-sediment distribution, recognizing the new role for river sediment distribution, and showed that 9.2% of the river's annual suspended sediment load would be required to sustain the deltaic plain wetlands.
Abstract: Loss of Louisiana's coastal wetlands has reached catastrophic proportions. The loss rate is approximately 150 km2/yr (100 acres/day) and is increasing exponentially. Total wetland loss since the turn of the century has been almost 0.5 million ha (1.1 million acres) and represents an area larger than Rhode Island. The physical cause of the problem lies in man's attempts to control the Mississippi River's flooding, while enhancing navigation and extracting minerals. Levee systems and control structures confine sediments that once nourished the wetlands to the river channel. As a consequence, the ultimate sediment deposition is in deep Gulf waters off the Louisiana coast. The lack of sediment input to the interdistributary wetlands results in an accretion deficit. Natural and human-induced subsidence exceeds accretion so that the wetlands sink below sea level and convert to water. The solution is to provide a thin veneer of sediment (approximately 0.6 cm/yr; an average of 1450 g m−2 yr−1) over the coastal marshes and swamps and thus prevent the submergence of vegetation. The sediment source is the Mississippi River system. Calculations show that 9.2% of the river's annual suspended sediment load would be required to sustain the deltaic plain wetlands. It should be distributed during the six high-water months (December–June) through as disaggregated a network as possible. The problem is one of distribution: how can the maximum acres of marsh be nourished with the least cost? At present, the river is managed through federal policy for the benefit of navigation and flood control. A new policy structure, recognizing the new role for the river-sediment distribution, is recommended.
TL;DR: In this paper, a review of data from over 50 freshwater and about 50 saltwater sites revealed that freshwater and saltwater forested wetlands exhibit parallel responses to hydrologic factors.
Abstract: A review of data from over 50 freshwater and about 50 salt-water sites revealed that freshwater and salt-water forested wetlands exhibit parallel responses to hydrologic factors. Greater ecosystem complexity and productivity are associated with higher hydrologic energy and more fertile conditions (riverine > fringe 1 basin > dwarf = scrub). However, structural complexity is greater in freshwater forested wetlands than in salt-water forested wetlands. Net primary productivity, litter fall, and export of organic matter are higher in salt-water forested wetlands. These differences raise questions about the efficiency with which nutrients are used in forested wetlands. Available data suggest that nutrient-use efficiency by litter fall and litter turnover are higher in tidal salt-water wetlands than in freshwater wetlands,
TL;DR: In this article, the authors consider the effect of cumulative impacts on the water quality functions of wetlands and make guided judgements about the probable effects of a given suite of impacts, and suggest that many common wetland alterations probably do entail cumulative impact.
Abstract: The total effect of cumulative impacts on the water quality functions of wetlands cannot be predicted from the sum of the effects each individual impact would have by itself. The wetland is not a simple filter; it embodies chemical, physical, and biotic processes that can detain, transform, release, or produce a wide variety of substances. Because wetland water quality functions result from the operation of many individual, distinct, and quite dissimilar mechanisms, it is necessary to consider the nature of each individual process. Sound knowledge of the various wetland processes is needed to make guided judgements about the probable effects of a given suite of impacts. Consideration of these processes suggests that many common wetland alterations probably do entail cumulative impact. In addition to traditional assessment methods, the wetland manager may need to obtain appropriate field measurements of water quality-related parameters at specific sites; such data can aid in predicting the effects of cumulative impact or assessing the results of past wetland management.
TL;DR: Weighted averages of vegetation data proved to be a useful tool for assessing wetland status of the vegetation types included in the study as discussed by the authors, and the results of weighted average scores close to the break-point should be considered provisional and must be verified with supplementary data on soils and hydrology.
Abstract: Weighted averages (WA) was investigated as a vegetation-based method for wetland designation, to be used in conjunction with the wetland indicator status of plants from Wetland Plants of the United States of America 1986 (Reed, 1986). Ecological indices were assigned to indicator groups and were used to compute weighted averages for quantitative data obtained from four studies of wetland vegetation conducted in various regions of the United States. Weighted averages of vegetation data proved to be a useful tool for assessing wetland status of the vegetation types included in our study: (1) rankings of vegetation stands or types by WA correlated well with their positions on environmental moisture gradients; and (2) the results of WA could be used, together with a wetland/upland break-point, to designate vegetation types as wetland or upland in a way that agreed well, in three of the four studies, with an alternative classification of wetland habitats. The variation of weighted averages among the sampling units representing a vegetation type was generally small relative to the range of ecological indices assigned. However, designations based on weighted average scores close to the break-point should be considered provisional and must be verified with supplementary data on soils and hydrology.
01 Sep 1988
TL;DR: Tampa Bay is Florida's largest open-water estuary and one of the most highly urbanized. as mentioned in this paper summarizes and synthesizes many years of scientific investigation into Tampa Bay's geology, hydrology and hydrography, water chemistry, and biotic components.
Abstract: Tampa Bay is Florida's largest open-water estuary and one of the most highly urbanized. This report summarizes and synthesizes many years of scientific investigation into Tampa Bay's geology, hydrology and hydrography, water chemistry, and biotic components. The estuary is a phytoplankton-based system, with mangroves being the second most important primary producer. Benthic organisms are abundant and diverse, although in parts of the bay the benthos consists of a relatively few opportunistic and pollution indicator species. The estuary provides habitat for the juveniles and adults of a number of commercial and recreational fishery species. Significant changes occurring as a result of urbanization and industrialization include significant declines in intertidal wetlands and seagrass meadows, changes in circulation and flushing, and degradation of water quality. Important management issues include dredge and fill operations, restoration of fisheries, increasing freshwater flow to the bay, and eutrophication. 257 refs., 85 figs., 27 tabs.
TL;DR: Large-scale spatial and temporal stability of the two mutually exclusive ecosystems, mangrove forest and freshwater wetland, contains considerable small- scale variation and maximum diversity and variability occurred during the time of least environmental stability in the transition phase.
Abstract: The coastal freshwater wetlands of western Arnhem Land in the monsoon tropics of the Northern Territory of Australia are subject to new and increasing pressures from a range of land uses. Wetland history is needed as a basis for management decisions. Radiocarbon dates and pollen analyses of samples from fifty surveyed sites on the Magela floodplain show mangrove vegetation encroaching as sea level rose from about 8000 BP to 6000 BP. The extensive Rhizophora forest established at that time lasted until about 3000 BP, when the sediments built up above the upper tidal limit for these mangroves. Avicennia and other mangrove genera became more abundant in the subsequent transition phase. The floodplain has been a freshwater wetland since about 1300 BP. High resolu- tion pollen analyses of contiguous 1 cm samples through the transition at two sites show parallel sequences of vegetation changes. Large-scale spatial and temporal stability of the two mutually exclusive ecosystems, mangrove forest and freshwater wetland, contains considerable small- scale variation. Maximum diversity and variability occurred during the time of least environmental stability in the transition phase. Vegetation change was discontinuous, with each major shift followed by variation around a new mean. A rise in sea level of 0.5-1.0 m could destroy the present freshwater wetland and allow some mangroves to return to the Magela.
TL;DR: In this article, a direct measurement of CH4 flux from wetland ecosystems of south Florida demonstrates that freshwater wet prairies and inundated sawgrass marsh are the dominant sources of atmospheric CH4 in the region.
Abstract: Direct measurement of methane (CH4) flux from wetland ecosystems of south Florida demonstrates that freshwater wet prairies and inundated sawgrass marsh are the dominant sources of atmospheric CH4 in the region. Fluctuations in soil moisture are an important environmental factor controlling both seasonal and interannual fluctuations in CH4 emissions from undisturbed wetlands. Land use estimates for 1900 and 1973 were used to calculate regional CH4 flux. Human settlement in south Florida has modified wetland sources of CH4, reducing the natural prairies and marsh sources by 37%. During the same period, impoundments and disturbed wetlands were created which produce CH4 at rates approximately 50% higher than the natural wetlands they replaced. Preliminary estimates of urban and ruminant sources of CH4 based on extrapolation from literature data indicate these sources may now contribute approximately 23% of the total regional source. We estimate that the integrated effects of urban and agricultural development in south Florida between 1900 and 1973 resulted in a 26% enhancement in CH4 flux to the troposphere.
01 Jan 1988
TL;DR: In this paper, the management of promising palm populations will contribute to increasing the economic value of such soils by transforming seasonal swamp forests into productive agroforestry fields, which are generally considered as unfit for agriculture.
Abstract: Most palm species are used by Amazonian natives and provide a variety of products, such as edible fruits, oil, palm heart, building materials, and basketry. However, only a few species have significant economic potential. These palms occur essentially in seasonal swamp forests on waterlogged soils covering vast areas in Peruvian Amazonia, or on sandy soils. Three especially promising species- Jessenia bataua, Mauritia flexuosa and Euterpe pre- catoria-constitute dense populations on these soils, which are generally considered as unfit for agriculture. The management of promising palm populations will contribute to increasing the economic value of such soils by transforming seasonal swamp forests into productive agroforestry fields.
TL;DR: In this paper, the authors identify three fundamental wetland categories: basin, riverine, and fringe, and assess the cumulative impacts on wetlands by recognizing the geomorphological settings of these categories.
Abstract: Assessment of cumulative impacts on wetlands can benefit by recognizing three fundamental wetland categories: basin, riverine, and fringe. The geomorphological settings of these categories have relevance for water quality.
TL;DR: In this article, the authors describe temporal patterns in seedling recruitment of seven wetland plant species in a Canadian prairie marsh and compare two-year and one-year drawdown treatments initiated in different years.
Abstract: (1) We describe temporal patterns in seedling recruitment of seven wetland plant species in a Canadian prairie marsh. Recruitment occurred during artificial drawdown or drainage of dyked marshes. Two-year and one-year drawdown treatments initiated in different years are compared. (2) Within a season, most seedlings were recruited during June when soil moisture was high, temperature was moderate, and conductivity was low. (3) Differences between drawdown treatments in first-year recruitment of certain species appear to be due to differences between years in soil moisture and temperature, not differences in densities of seeds in the soil prior to drawdowns. (4) Far fewer emergents but more mud-flat annuals were recruited during the second year of the 2-year drawdown than during the first. Considerable mortality occurred during the second year in seedlings of emergent species established in the first year of the 2-year drawdown. (5) The implications of these results for management of wetlands as waterfowl habitat are discussed.
TL;DR: Water levels in piezometers and hydraulic conductivity of organic and mineral soils were measured during spring and summer 1986 to evaluate the recharge-discharge function of wetlands in the vicinity of the Mendenhall Valley near Juneau, Alaska as discussed by the authors.
Abstract: Water levels in piezometers and the hydraulic conductivity of organic and mineral soils were measured during spring and summer 1986 to evaluate the recharge-discharge function of wetlands in the vicinity of the Mendenhall Valley near Juneau, Alaska. Computer modeling experiments were also done to evaluate the function of a large patterned fen.
The blanket bogs are probably recharge zones, whereas forested wetlands are discharge zones. Approximately the upper third of the patterned fen is a ground-water recharge zone, whereas its northern margin receives ground-water discharge from flow systems recharged on moraines.
The amounts of wetland recharge and discharge are very small. Recharge from wetlands to viable aquifers is probably less than 1% of the total annual recharge to the aquifer system. The amount of ground-water discharge to streams from wetlands is too small to measure.
TL;DR: In this paper, a simple mathematical model is developed which permites dynamic simulation of wetland hydrology and of nutrient-driven interactions between wastewater and the wetland ecosystem, and the model is compared with operating data from the Porter Ranch wastewater treatment facility at Houghton Lake, Michigan.
TL;DR: In this article, several approaches for estimating bird habitat losses are derived from population curves based on natural and experimentally induced population fluctuations, and additional research needs and experimental approaches are identified for addressing cumulative impacts on wildlife habitat values.
Abstract: Wetlands are attractive to vertebrates because of their abundant nutrient resources and habitat diversity. Because they are conspicuous, vertebrates commonly are used as indicators of changes in wetlands produced by environmental impacts. Such impacts take place at the landscape level where extensive areas are lost; at the wetland complex level where some (usually small) units of a closely spaced group of wetlands are drained or modified; or at the level of the individual wetland through modification or fragmentation that impacts its habitat value. Vertebrates utilize habitats differently according to age, sex, geographic location, and season, and habitat evaluations based on isolated observations can be biased. Current wetland evaluation systems incorporate wildlife habitat as a major feature, and the habitat evaluation procedure focuses only on habitat. Several approaches for estimating bird habitat losses are derived from population curves based on natural and experimentally induced population fluctuations. Additional research needs and experimental approaches are identified for addressing cumulative impacts on wildlife habitat values.
TL;DR: Although the least disturbed habitat (swamps) supported the least number of exotic species, there was no further evidence of a positive relationship between degree of disturbance and degree of invasion and the results provided some support for the hypothesis that maximum species-richness occurs under conditions of moderate disturbance.
Abstract: A combination of field surveys and seed-bank measurements were used to describe the macrophytic vegetation of intermittent wetlands on the Riverine Plain, in New South Wales. Three habitat types were sampled, representing wetland vegetation subjected to varying intensities of exogenous (human-induced) disturbance: swamps (least disturbed), roadside table drains (moderately disturbed), and rice crops (highly disturbed). Forty-two plant species were common to all three habitats and 36 species occurred in two of the three habitats. Of the 82 species that were restricted to a single habitat type, 33 were recorded for swamps, 19 for roadsides and 30 for rice fields.
Species-richness (number of species per 50 m2) was found to be significantly lower in rice fields compared with either roadsides or swamps, which were not significantly different. Richness of native vascular species differed significantly among all habitat types, with swamps > roadsides > rice fields. Richness of exotic species also differed: roadsides > rice fields > swamps. Although the least disturbed habitat (swamps) supported the least number of exotic species, there was no further evidence of a positive relationship between degree of disturbance and degree of invasion. The results provided some support for the hypothesis that maximum species-richness occurs under conditions of moderate disturbance.
A small negative correlation (r=−0.178, P < 0.01) was found between the number of exotic species and the number of native species occurring at a site. This suggests that, in this case, species-richness is not an important factor in the resistance of vegetation to invasion by exotic species. The vegetation of intermittent wetlands appears to have a relatively high degree of resistance to invasion. This is attributed to the high level of endogenous disturbance to which the native vegetation is adapted.
TL;DR: In this article, the authors studied the production of runoff from a small drainage basin in the continuous permafrost area of continental Canada for two years, which comprises two main land types (dry tundra slopes and valley bottom wetlands) and several lakes.
TL;DR: Aquatic pollen, charcoal, sediment, and accumulation-rate changes from radiocarbon-dated cores from two sites in south-central Wisconsin were studied to explore the evolution of local wetlands since deglaciation as mentioned in this paper.
Abstract: Aquatic pollen, charcoal, sediment, and accumulation-rate changes from radiocarbon-dated cores from two sites in south-central Wisconsin were studied to explore the evolution of local wetlands since deglaciation. Sphagnum bog evolution in south-central Wisconsin appears to have been directly related to the regional climatic changes during the past 6000 yr (the middle and the late Holocene). Although the two sites had different origins and different early histories, both were deep lakes until 6300 BP when they became shallow ponds dominated by the aquatic macrophyte Brasenia. These wetland changes were concurrent with a regional upland vegetational change from mesophytic forest to Quercus savanna and were caused by a regional decrease in annual precipitation and by an increase in temperature. At 3000 BP, in response to a cooler, wetter climate, both wetlands became Sphagnum-Ericaceae bogs, and the upland vegetation changed to a closed Quercus forest. The paleoecological evidence suggests that bog development is a function of climate and that many bogs have developed in the northern Midwest during the past 3000 yr as effective moisture has increased.
01 Jan 1988
TL;DR: In this paper, the authors do not attempt to define precisely the terms floodplain and swamp, but consider them to reflect opposite ends of a continuum, and they do not use them for classification.
Abstract: Freshwater wetlands exhibit a continuum of variation in space and time, and categorization results in an artificial classification which although useful, often has little real meaning. Wetzel (1978) noted that definitions vary widely and are commonly useful only in detailed analyses of successional changes of wetland conditions and biota. In this discussion we do not attempt to define precisely the terms floodplain and swamp but consider them to reflect opposite ends of a continuum.
TL;DR: In this article, ground-water and surface-water dynamics were continuously measured on four long-term study sites in the Great Dismal Swamp and the relationship between flooding and decay of leaf litter and roots was examined in relation to previously measured processes.
Abstract: Frequency, duration, depth, and timing of flooding are major influences on the structure and functional dynamics of wetland ecosystems. In the present study, ground-water and surface-water dynamics were continuously measured on four long-term study sites in the Great Dismal Swamp. The hydrologic patterns were examined in relation to previously measured processes. Conclusions drawn from these comparisons include (1) increased winter and spring flooding results in greater aboveground production but less belowground production, (2) higher leaf litter decay rates correspond with longer duration of flooding in wet years and with longer duration of saturation of the upper soil layers in dry years, and (3) the relationship between flooding and decay of leaf litter and roots is complicated by the strong influence of the chemical and structural nature of the litter. Erroneous interpretations of hydrologic relationships may result from observations of surface flooding dynamics alone. In the Great Dismal Swamp, a significant reversal occurs in the order of sites ranked on the basis of the amount of flooding aboveground versus the duration of saturation below the soil surface.
TL;DR: The morphology and selected physical, mineralogic, and chemical characteristics of pedons collected in seven North Dakota wetlands were examined to investigate the development of hydric soils associated with wetlands of the Northern Plains as mentioned in this paper.
Abstract: The morphology and selected physical, mineralogic, and chemical characteristics of pedons collected in seven North Dakota wetlands were examined to investigate the development of hydric soils associated with wetlands of the Northern Plains. The wetlands were chosen using established field criteria to be representative of ground-water recharge, flowthrough, and discharge conditions. All profiles collected in recharge wetlands were nonsaline, free of carbonate, and exhibited clay illuviation to some degree, the result of seasonal ponding, fluctuating water tables, and downward, saturated water flow characteristic of recharge conditions. Recharge profiles also exhibited continuous sediment aggradation due to erosion of the surrounding upland and deposition in the wetland. High organic matter production under such conditions resulted in overthickened A-horizons. Soil classes ranged from Typic Argiaquolls if argillic horizons are present, to Cumulic Haplaquolls if illuviation was not as well expressed. Soil development in the wet-meadow and shallow-marsh zones of flowthrough wetlands was influenced by higher, more stable, more brackish water tables. Profile morphology reflected a continuum from dominantly-recharge to dominantly-discharge hydrology. All profiles were calcareous. The more saline profiles also contained gypsum. Soil classes ranged from Cumulic Haplaquolls of calcareous, mixed mineralogy to Typic Calciaquolls. The presence of high, saline water tables and mechanical sorting of soil surfaces by wave action retarded soil development in the discharge wetland periphery. Soils were uniformly saline, calcareous, and gypsiferous. Soil classes ranged from Fluvaquentic Haplaquolls to Typic Fluvaquents.