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31.
Validity of Performance Criteria and a Tentative Model for Regulatory Use in Compensatory Wetland Mitigation Permitting 总被引:1,自引:1,他引:0
The purpose of this paper is to develop the principles for a manageable and practical set of performance criteria that will
reasonably assure no net loss in a situation in which it cannot be absolutely assured. To this end, the performance criteria
proposed for 116 compensatory wetland projects on file with the Army Corps of Engineers in San Francisco, between 1988 and
1995, were examined. The trends discerned in the project proposals were analyzed and evaluated in light of the current state
of wetland science. Specific suggestions for the development of uniform criteria in each of four major wetland types—riparian,
perennial tidal, perennial nontidal, and seasonal—are discussed, and a system of regulation tying qualitative assessment with
quantitative requirements is outlined as a reasonable solution to the enforcement of the no-net-loss policy. 相似文献
32.
Thomas Hruby 《Environmental management》1999,23(1):75-85
/ Many methods have been developed over the last two decades to provide information about wetland functions, but there has been little discussion of the models and algorithms used. Methods for generating information about wetlands were analyzed to understand their similarities, differences, and the type of information provided. Methods can first be grouped by the type of information they provide-classifications, characterizations, ratings, assessments, and evaluations. Methods that characterize, rate, or assess wetlands may generate information using one of two conceptual approaches-logic and mechanistic. Most methods that generate a numeric assessment of performance or value of wetland functions rely on the mechanistic approach to constructing models. Rapid assessment methods based on mechanistic models, however, do not assess the rates or dynamics of ecological processes occurring in wetlands. Rather, they provide a clear and concise way of organizing our current, and often subjective, knowledge about wetland functions. This is one limitation of current methods that is often misunderstood both by wetland managers and the scientific community. The advantages and limitations of the assumptions and the computational elements inherent in these approaches are discussed to provide wetland managers and regulators a better understanding of the information they are using. KEY WORDS: Wetlands; Functions; Assessment; Models; Methods 相似文献
33.
This article focuses on modelling above and below-ground mass loss and nitrogen (N) dynamics based on the wooden dowels (Gonystylus bancanus [Miq.] Kurz) of the decadal Long-term Intersite Decomposition Experiment (LIDET) data. These dowels were placed at 27 locations across North and Central America, involving tropical, temperate and boreal forests, grasslands, wetlands and the tundra. The dowel, inserted vertically into the soil with one half remaining exposed to the air, revealed fast mass and N losses under warm to humid conditions, and slow losses under wet as well as cold to dry conditions. The model formulation, referred to as the Wood Decomposition Model, or WDM, related these losses to (i) mean annual precipitation, mean monthly January and July air temperatures, and (ii) mean annual actual evapotranspiration (AET) at each location. The resulting calibrations conformed well to the time-in-field averages for mass remaining by location: R2 = 0.83 and 0.90 for the lower and upper parts, respectively. These values dropped, respectively, to 0.41 and 0.55 for the N concentrations, and to 0.28 and 0.43 for N remaining. These reductions likely refer to error propagation and to as yet unresolved variations in N transference into and out of the wood specific to each individual dowel location. Recalibrating the model parameters by ecosystem type reduced the R2 values for actual versus best-fitted mass loss by about 0.15. Doing the same without location- or ecosystem-specific adjustments reduced the R2 values further, by about 0.3. 相似文献
34.
三江平原典型湿地植物枯落物中汞的变异特征 总被引:3,自引:1,他引:2
在野外进行现场实验 ,研究了 2种典型湿地植物枯落物经一个生长季的分解后汞的变化 ,并探讨了其影响因素 .在实验的 3 0d后 ,2种湿地大部分层次植物枯落物汞的浓度表现为先升高 ,随后降低 ,最后又明显升高 .枯落物分解程度影响着汞浓度的变化 .前 90d枯落物质量减少快 ,且汞的浓度降低 ,枯落物中的汞以损失为主 ,后期因植物残体吸附汞的能力增强 ,汞损失减少 .汞的损失率和水中溶解性汞的浓度呈显著负相关关系 .在 2 0cm和 3 0cm深度上 ,枯落物汞的损失率与积水深度和地温都具有显著相关关系 (P <0 0 5 ) .微环境的差异尤其是积水的变化对小叶章各层汞的损失的影响大于毛果苔草 相似文献
35.
盐城海岸湿地资源环境压力与生态调控响应 总被引:21,自引:0,他引:21
江苏盐城海岸湿地拥有以保护丹顶鹤和麋鹿为特色的两个国家级自然保护区。然而强烈的人类活动贯穿于海岸湿地发育的每一个阶段,包括湿地围垦、资源酷取滥采以及环境污染等,使得该区资源环境面临的压力不断增大。通过对其资源环境特征、人口经济发展压力、湿地不合理开发利用压力以及水资源污染压力的分析,进而利用生态调控设计相应的政策措施响应方案,包括生态规划与设计---科学的生态功能区划,调整若干原缓冲区中生物多样性热点区为核心区;生态工程---生境更新与调整,建立人工湿地生态工程、芦苇生态工程、生态旅游等生态示范区;生态系统管理与能力建设---社区共管,与周围社区居民建立有效的伙伴关系。 相似文献
36.
37.
An ecological economics approach to the management of a multi-purpose coastal wetland 总被引:1,自引:1,他引:0
R. K. Turner I. J. Bateman S. Georgiou A. Jones I. H. Langford N. G. N. Matias L. Subramanian 《Regional Environmental Change》2004,4(2-3):86-99
Three interrelated management problems—eutrophication of multiple use shallow lakes, sea level rise and flood risk mitigation and tourism pressures—are analysed in the context of an internationally important wetland area, the Norfolk and Suffolk Broads in the UK. The ecological-economic research findings presented should provide essential information to underpin the regulatory and management process in this internationally important conservation area. The relevant authority somehow has to integrate the maintenance of public navigation rights, nature conservation, and tourism promotion in a highly dynamic ecosystems setting. Because of the stakeholder conflicts, potential and actual, a more inclusionary decision-making procedure is required, and is currently being implemented. 相似文献
38.
Leon Liegel David Cassell Donald Stevens Paul Shaffer Robbins Church 《Environmental management》1991,15(2):269-279
The Direct/Delayed Response Project (DDRP) is one of several studies being conducted by the United States Environmental Protection
Agency to assess risk to surface waters from acidic deposition in the eastern United States. In one phase of DDRP, land use,
wetland, and forest cover data were collected for statistical samples of 145 Northeast lake and 35 Southern Blue Ridge Province
stream watersheds in the United States. Land-use and other data then were extrapolated from individual to target watershed
populations. Project statistical design allows summarization of results for various subsets of the target population. This
article discusses results and implications of the land-use and land-cover characterization for both regions.
Forest cover was the primary land use in both regions. In the Northeast, developed (agriculture and urban) land was positively
associated with surface-water chemistry values for acid neutralizing capacity, Ca plus Mg, pH, and sulfate in the Pocono/Catskill
subregion. Extensive wetlands and beaver activity occur in parts of the Northeast region, whereas topography limits wetland
and riparian development in the Southern Blue Ridge Province. Northeast soils have low sulfate adsorption capacity, most watersheds
are near sulfur steady state, and lake sulfate concentrations are controlled principally by levels of sulfur deposition. Net
annual sulfur retention in Northeast watersheds is positively correlated with occurrence of wetlands and beaver impoundments.
In contrast, most Southern Blue Ridge Province soils have high sulfate adsorption capacities, resulting in high net watershed
sulfur retention. At the present time, stream sulfate concentrations and percent sulfur retention are controlled principally
by soil chemical properties related to adsorption rather than atmospheric deposition and land use.
The information in this document has been funded wholly by the United States Environmental Protection Agency. It has been
subjected to the agency's peer and administrative review, and it has been approved for publication as an EPA document. Mention
of trade names or commercial products does not constitute endorsement or recommendation for use. 相似文献
39.
Coal companies are reluctant to include wetland development in reclamation plans partly due to a lack of information on the
resulting characteristics of such sites. It is easier for coal companies to recreate terrestrial habitats than to attempt
experimental methods and possibly face significant regulatory disapproval. Therefore, we studied a young (10 years) wetland
on a reclaimed surface coal mine in southern Illinois so as to ascertain soil and water characteristics such that the site
might serve as a model for wetland development on surface mines. Water pH was not measured because of equipment problems,
but evidence (plant life, fish, herpetofauna) suggests suitable pH levels. Other water parameters (conductivity, salinity,
alkalinity, chloride, copper, total hardness, iron, manganese, nitrate, nitrite, phosphate, and sulfate) were measured, and
only copper was seen in potentially high concentrations (but with no obvious toxic effects). Soil variables measured included
pH, nitrate, nitrite, ammonia, potassium, calcium, magnesium, manganese, aluminum, iron, sulfate, chloride, and percent organic
matter. Soils were slightly alkaline and most parameters fell within levels reported for other studies on both natural and
manmade wetlands. Aluminum was high, but this might be indicative more of large amounts complexed with soils and therefore
unavailable, than amounts actually accessible to plants. Organic matter was moderate, somewhat surprising given the age of
the system. 相似文献
40.
Kevin K. Moorhead 《Environmental management》1990,14(2):241-247
Hydric soils are used as supportive evidence for wetland delineations by federal and state agencies and by the private sector
in North Carolina, USA. An analysis of hydric soil distribution and hydric soil characteristics was conducted with county
soil surveys and soil taxonomy of the USA. Approximately 100 hydric soils have been used for soil mapping in North Carolina,
and they represent seven of the ten soil orders in soil taxonomy. An estimated 23% (2.9 million ha) of the land surface area
in North Carolina supports hydric soils.
Approximately 96% of the known hydric soil acreage was found in the coastal plain of North Carolina. Over one-third of the
soils were hydric Ultisols, which represented close to 10% of the land surface area. The other soil orders with extensive
hydric soil acreage included Histosols, Inceptisols, and Entisols. The soil orders were separated into great groups of soil
taxonomy to discuss soil profile characteristics. Landscape positions and associated wetland communities were also presented.
In North Carolina, a statewide inventory of wetlands does not exist and soil surveys offer a resource for a first approximation
of wetland boundaries. 相似文献