武汉市湿地破碎化对生态系统服务价值的影响研究

以湖泊资源丰富的武汉市为例,通过景观格局指数测定该市湿地破碎化程度,借助GIS技术评估该市湿地生态系统服务价值,并探讨了城市湿地破碎化对生态系统服务价值的影响。结果表明:①2000—2015年武汉市湿地总体破碎化趋势有所缓和,但人工湿地相较于自然湿地破碎化程度要高,特别是2010—2015年湿地总面积下降了2.80%,而斑块密度上升了4.12%,湖泊破碎化程度较高。②2000—2015年,武汉市湿地ESV增长了323.27亿元,各类型湿地的生态系统服务价值表现为湖泊>水库坑塘>河流>沼泽。③湿地景观破碎化与部分调节性、支持性和文化性服务功能存在着显著相关关系。     

御临河流域河流湿地生态系统服务价值评价

御临河流域河流湿地具有非常重要的生态服务功能,包括直接使用价值和间接使用价值。直接使用价值有物质生产功能、水资源服务、旅游休闲功能、科研文化功能等,间接使用价值包括气体调节功能、水分调蓄功能及河岸带湿地污染净化功能的价值等。本研究采用市场价值法、碳税法、影子工程法、类比法及旅行费用法对御临河流域河流湿地生态系统服务价值进行了初步估算,其生态系统服务总价值为4.39亿元人民币,是2000年该流域GDP的28.52%。研究结果表明,御临河流域河流湿地生态系统的服务价值是不容忽视的。在进行流域规划管理时必须重视自然生态系统的潜在价值,才能保证流域生态系统的健康及可持续发展。     

湿润区与干旱区典型湖泊湿地对比案例研究

选取东部湿润区与西北干早区典型湖泊湿地--洞庭湖湿地与艾比湖湿地,对其湿地资源特征、湿地生态服务功能及价值、湿地退化的表征和退化湿地生态恢复对策等方面进行了比较研究.通过研究发现,湿润区湖泊湿地资源禀赋优于干早区湖泊湿地,湿润区湖泊湿地与干旱区湖泊湿地均具有较强的生态服务功能和较高的价值,在湿地退化表征方面有共性也有差异,针对不同气候区域的退化湖泊湿地应采取不同的恢复对策.     

Effects of Land Use Changes on the Ecosystem Service Values of Coastal Wetlands

Changes in the coastal landscape of Southern Sinaloa (Mexico), between 2000 and 2010, were analyzed to relate spatial variations in wetlands extent with the provision and economic value of the ecosystem services (ES). Remote sensing techniques applied to Landsat TM imagery were used to evaluate land use/land cover changes while the value transfer method was used to assess the value of ES by land cover category. Five wetland types and other four land covers were found as representative of the coastal landscape. Findings reveal a 14 % decrease in the saltmarsh/forested mangrove area and a 12 % increase in the area of shrimp pond aquaculture (artificial wetland) during the study period. ES valuation shows that the total value flow increased by 9 % from $215 to $233 million (2007 USD) during the 10-year period. This increase is explained as result of the high value worldwide assigned to saltmarsh. We recognize limitations in the transfer-based approach in quantifying and mapping ES values in the region, but this method provides with value estimates spatially defined, and also provides some guidance in the preliminary screening of policies and projected development in the context of data-scarce regions.     

Changes in wetlands on nonfederal rural land of the conterminous United States from 1982 to 1987

Recent wetland area trends were estimated from the National Resources Inventory (NRI) for nonfederal rural lands for the period 1982–1987. NRI-based estimates of wetland area for states comprising the conterminous United States were highly correlated with estimates made by the US Fish and Wildlife Service and with estimates of coastal salt marsh wetlands made by the National Oceanic and Atmospheric Administration. Net wetland area declined by 1.1% (≈363,200 ha) during the five-year study period. Conversion to open water, primarily caused by natural flooding in western inland basins, was responsible for altering extensive wetland areas (≈171,400 ha). Of the human-induced wetland conversions, urban and built-up land was responsible for 48% of the wetland loss, while agricultural development was indicated in 37% of the converted wetland area. A decrease in rural land, and increases in both population, and urban and built-up land were associated with wetland loss among states. Potential reasons for wetland loss were different in 20 coastal states than in 28 inland states. Proportionately, wetland loss due to development was three times greater in coastal states than inland states, while agriculturally induced wetland losses were similar in both groups. The proportionate declines of forested vs nonforested wetlands were not significantly different among states.     

ECONOMIC ANALYSIS OF WETLAND RESTORATION ALONG THE ILLINOIS RIVER1

Creating and restoring wetland and riparian ecosystems between farms and adjacent streams and rivers in the Upper Mississippi River Basin would reduce nitrogen loads and hypoxia in the Gulf of Mexico and increase local environmental benefits. Economic efficiency and economic impacts of the Hennepin and Hopper Lakes Restoration Project in Illinois were evaluated. The project converted 999 ha of cropland to bottomland forest, backwater lakes, and flood‐plain wetland habitat. Project benefits were estimated by summing the economic values of wetlands estimated in other studies. Project costs were estimated by the loss in the gross value of agricultural production from the conversion of corn and soybean acreage to wetlands. Estimated annual net benefit of wetland restoration in the project area amounted to US$1,827 per ha of restored wetland or US$1.83 million for the project area, indicating that the project is economically efficient. Impacts of the project on the regional economy were estimated (using IMPLAN) in terms of changes in total output, household income, and employment. The project is estimated to increase total output by US$2,028,576, household income by US$1,379,676, and employment by 56 persons, indicating that it has positive net economic impacts on the regional economy.     

Land loss in coastal Louisiana (U.S.A.)

This paper examines causes and consequences of wetland losses in coastal Louisiana. Land loss is a cumulative impact, the result of many impacts both natural and artificial. Natural losses are caused by subsidence, decay of abandoned river deltas, waves, and storms. Artificial losses result from flood-control practices, impoundments, and dredging and subsequent erosion of artificial channels. Wetland loss also results from spoil disposal upon wetlands and land reclamation projects.Total land loss in Louisiana's coastal zone is at least 4,300 ha/year. Some wetlands are converted to spoil banks and other eco-systems so that wetland losses are probably two to three times higher. Annual wetland losses in the Barataria Bay basin are 2.6% of the wetland area. Human activities are the principal determinants of land loss. The present total wetland area directly lost because of canals may be close to 10% if spoil area is included. The interrelationship between hydrology, land, vegetation, substrate, subsidence, and sediment supply are complicated; however, hydrologic units with high canal density are generally associated with higher rates of land loss and the rate may be accelerating.Some cumulative impacts of land loss are increased saltwater intrusion, loss of capacity to buffer the impact of storms, and large additions of nutrients. One measure of the impact is that roughly $8–17 × 10⁶ (U.S.A.) of fisheries products and services are lost annually in Louisiana.Viewed at the level of the hydrologic unit, land loss transcends differences in local vegetation, substrate, geology, and hydrology. Land management should therefore focus at that level of organization. Proper guideline recommendations require an appreciation of the long-term interrelations of the wetland estuarine system.     

Drainage Investment and Wetlands Loss: an Analysis of the National Resources Inventory Data

The United States Soil Conservation Service (SCS) conducts a survey for the purpose of establishing an agricultural land use database. This survey is called the National Resources Inventory (NRI) database. The complex NRI land classification system, in conjunction with the quantitative information gathered by the survey, has numerous applications. The current paper uses the wetland area data gathered by the NRI in 1982 and 1987 to examine empirically the factors that generate wetland loss in the United States. The cross-section regression models listed here use the quantity of wetlands, the stock of drainage capital, the realty value of farmland and drainage costs to explain most of the cross-state variation in wetland loss rates. Wetlands preservation efforts by federal agencies assume that pecuniary economic factors play a decisive role in wetland drainage. The empirical models tested in the present paper validate this assumption.     

乌苏-奎屯-独山子地区生态系统服务功能变化研究

在3S技术的支持下,以1990年和2005年的TM图像解译数据为基础,采用谢高地的评价方法分析了乌苏-奎屯-独山子地区景观类型与生态系统服务功能的变化特征,为研究该地区水土开发与生态环境演变提供了依据。结果表明,1990-2005年,乌苏-奎屯-独山子地区农田、灌木林地、城镇及工业用地、盐碱地、水域和未利用地面积增加,其他乔木林地、草地、冰川和沼泽面积均减少;区域生态系统服务功能从1990年的9 182.84×106元减少到2005年的8 627.96×106元,减少量为554.87×106元,减少率为6.04%。保护区域生态环境,恢复和提高区域生态系统服务功能是该区域生态环境建设的重要任务。     

Land-cover change in upper Barataria Basin estuary,Louisiana, 1972-1992: increases in Wetland area

The Barataria Basin, Louisiana, USA, is an extensive wetland and coastal estuary system of great economic and intrinsic value. Although high rates of wetland loss along the coastal margin of the Barataria Basin have been well documented, little information exists on whether freshwater wetlands in the upper basin have changed. Our objectives were to quantify land-cover change in the upper basin over 20 years from 1972–1992 and to determine land-cover transition rates among land-cover types. Using 80-m resolution Landsat MSS data from the North American Landscape Characterization (NALC) data archive, we classified images from three time steps (1972, 1985, 1992) into six land-cover types: agriculture, urban, bottomland hardwood forest, swamp forest, freshwater marsh, and open water. Significant changes in land cover occurred within the upper Barataria Basin over the study period. Urban land increased from 8% to 17% of the total upper basin area, primarily due to conversions from agricultural land, and to a lesser degree, bottomland forest. Swamp forest increased from 30% to 41%, associated with conversions from bottomland hardwood forest and freshwater marsh. Overall, bottomland forest decreased 38% and total wetland area increased 21%. Within the upper Barataria, increases in total wetland area may be due to land subsidence. Based on our results, if present trends in the reduction of bottomland forest land cover were to continue, the upper Barataria Basin may have no bottomland hardwood forests left by the year 2025, as it is subjected to multiple stressors both in the higher elevations (from urbanization) and lower elevations (most likely from land subsidence). These results suggest that changes in the upper freshwater portions of coastal estuaries can be large and quite different from patterns observed in the more saline coastal margins.     

A Method for Improving the Management of Controversial Wetland

Valley bottom wetlands in agricultural landscapes often are neglected in national and regional wetland inventories. Although these areas are small, located in the bottomlands of the headwater catchments, and scattered in the rural landscape, they strongly influence hydrology, water quality, and biodiversity over the whole catchment area. Valley bottom wetlands often are considered as controversial wetlands. Awareness of the functional role of wetlands is increasing, in parallel with their progressive disappearance in intensive farming landscapes. The need to improve tools for controlling wetland management is a primary consideration for decision makers and land users. This article proposes a method for the inventory of valley bottom wetlands. The method is based on the functional analysis of potential, existing, and efficient valley bottom wetlands (the PEEW approach). Several indicators are proposed for checking the validity of such an approach. Potential wetlands are delineated by means of a topographic index using topographic and pedoclimatic criteria computed from a Digital Elevation Model and easily accessible databases. Existing wetlands are identified from observed surface moisture, the presence of specific wetland vegetation, or soil feature criteria. Efficient wetlands are defined through a given function, such as flow or pollutant regulation or biodiversity control. An analysis of areas at the limits between potential, existing, and efficient wetlands highlights land cultivated or drained in the past, which currently represents negotiating areas in which rehabilitation and other intended management actions can be implemented.     

The Ecological and Environmental Characteristics and Conservation of the Wetlands in the Changjiang Estuary, China

The natural wetlands in the Changjiang Estuary, China are important ecologically. The total area of the wetlands in the Changjiang Estuary amounts to 215000 ha. The wetlands consist of littoral and sandy estuarine island areas, and are rich in biological resources. There are 136 species of vascular plant, 150 species of bird, and 68 species of benthic macro-invertebrate in the wetlands. However, the wetland in the Changjiang Estuary is a vulnerable ecosystem. Development of the wetland is mainly influenced by intensive human reclamation, pollution, movement of sediments in the Changjiang River, and the effects of tides and waves. Investigations have shown that maintaining biodiversity, providing resources for the living organisms, purifying environments and resisting natural hazards could be regarded as important functions for the protection of the wetlands. It is proposed that sustainable principles should be supported in developing the wetlands in the future.     

Working Wetland Potential: An index to guide the sustainable development of African wetlands

Past experience shows that inappropriate agricultural development in wetlands can undermine sustainability and may have profound social and economic repercussions for people dependent on the range of ecosystem services provided by those wetlands. Nonetheless, there is escalating pressure to expand agriculture within wetlands due to increasing population, in conjunction with efforts to increase food security. This paper describes the development of a semi-analytical framework for identifying, organizing and analyzing the complex factors that link people, agriculture and wetland ecosystems — an index of Working Wetland Potential (WWP). The method is based on a form of multi-criteria analysis that integrates biophysical and socio-economic aspects of wetland utilization. The WWP index emerges from the aggregation of two values: the first arising from an appraisal of both the biophysical and socio-economic suitability of using the wetland for agriculture; and the second resulting from an assessment of the possible hazards, in relation to both social welfare and the ecological character of the wetland. Hence, the approach provides a way to explicitly integrate biophysical and social aspects of wetland utilization in a single index to enable an initial assessment of the suitability of using a wetland for agriculture. Results from three contrasting wetlands in sub-Saharan Africa are presented.     

EFFECTS OF PRECIPITATION AND LAND USE ON STORM RUNOFF1

ABSTRACT: Storm-runoff quantity and quality were studied in three watersheds located near St. Paul in Ramsey County, Minnesota, from April 15 through September 15 of 1984, 1985, and 1986 to qualitatively determine the effects of precipitation and selected land uses on storm runoff. In respect to precipitation effects, differences in stormrunoff quantity between years in an urban watershed that lacks wetlands appear to be related to the average storm size (amount of precipitation) during the study period of each year. In contrast, the differences in storm-runoff quantity from watersheds that contain wetlands appear to be related to total precipitation during study period of each year. In respect to land use, the differences in storm-runoff quantity appear to be related to the amounts of impervious and wetland area. The watershed that contains the largest amount of impervious area and smallest amount of wetland area has the largest amount of storm runoff. Differences in storm-runoff quality appear to be related to the amounts of wetland and lake area. The watershed that contains the largest amounts of wetland and lake area has the smallest storm-runoff loading of suspended solids, phosphorus, and nitrogen. The wetland and lake areas likely retain the loading and, subsequently, lower the amount of storm-runoff loading exported from a watershed.     

The Effect of Wetland Mitigation Banking on the Achievement of No-Net-Loss

/ This study determines whether the 68 wetland mitigation banks in existence in the United States through 1 January 1996 are achieving no-net-loss of wetland acreage nationally and regionally. Although 74% of the individual banks achieve no-net-loss by acreage, overall, wetland mitigation banks are projected to result in a net loss of 21,328 acres of wetlands nationally, 52% of the acreage in banks, as already credited wetland acreages are converted to otheruses. While most wetland mitigation banks are using appropriate compensation methods and ratios, several of the largest banks use preservation or enhancement, instead of restoration or creation. Most of these preservation/enhancement banks use minimum mitigation ratios of 1:1, which is much lower than ratios given in current guidelines. Assuming that mitigation occurs in these banks as preservation at the minimum allowable ratio, ten of these banks, concentrated in the western Gulf Coast region, will account for over 99% of projected net wetland acreage loss associated with banks. We conclude that wetland mitigation banking is a conceptually sound environmental policy and planning tool, but only if applied according to recently issued guidelines that ensure no-net-loss of wetland functions and values. Wetland mitigation banking inevitably leads to geographic relocation of wetlands, and therefore changes, either positively or negatively, the functions they perform and ecosystem services they provide. KEY WORDS: Mitigation banking; Wetlands; Army Corps of Engineers; No-net-loss     

Social and economic considerations in conserving wetlands of indo-gangetic plains: A case study of Kabartal wetland,India

The Kabartal wetland situated in the upper Indo-Gangetic flood plains in northern India is significant because of its hydrological and ecological services, and the socio-economic and cultural values that it represents. Despite being designated as a wildlife sanctuary, this wetland is under threat from anthropogenic pressures. As in the case of most wetlands, the reason is incomplete information on its ecological services and functions, breakdown of traditional management structures and the lack of appropriate and recognized property rights. Our study assesses the economic linkages between the Kabartal wetland and the local people living around it, through socio-economic surveys and Contingent Valuation Method (CVM). The major objective of the study was to determine the importance of this wetland to the local people and to give an indication of the distribution of the benefits among various stakeholders. The people in the region are poor, have low literacy levels and high dependence on Kabartal and more than 50% want that the wetland should be drained and the land used for agriculture. However, they are willing to participate in collaborative management initiatives with the state. The willingness of people to accept compensation, as an alternative to access to Kabartal wetland, regressed on various socio-economic and attitudinal parameters, gave an estimated mean value of US $27,500 per household over a period of 60 years. This value is a pointer of the total value of access to Kabartal wetland to the surrounding villagers and would be useful when decisions to compensate people for lost access to Kabartal are made.     

ESTABLISHING PRIORITIES FOR WETLAND MANAGEMENT1

Wetlands provide a variety of ecological services, but are attractive sites for many development activities. Between the mid-1950's and mid-1970's about 550,000 acres, or about 0.5 percent, of the vegetated wetlands remaining in the conterminous states were converted to other uses each year. About 80 percent of these losses involved draining and clearing of inland wetlands for agricultural purposes. Recent reductions in national wetland conversion rates are due primarily to declining rates of agricultural drainage and secondarily to government programs that regulate wetlands use. Several governmental policies and programs exist that either encourage or discourage wetland conversions. Section 404 of the Clean Water Act is the major tool for Federal involvement in controlling the conversion of wetlands to other uses. The 404 program, in combination with State regulatory programs, is responsible for reducing annual conversions nationwide by about 50 percent of what is applied for, or 50,000 acres of wetlands per year, primarily through project modifications. Coastal wetlands are reasonably well protected. Inland, freshwater wetlands are generally poorly protected. Efforts to protect wetlands, given a set level of resources, could be improved by categorizing wetlands according to their relative importance and focusing existing wetland programs on high value wetlands.     

Water Quality Trading with Lumpy Investments,Credit Stacking,and Ancillary Benefits

This paper studies the economics of a water quality trading market in a predominantly agricultural watershed, and explores the effects of credit stacking in such a market when buyers and sellers of pollution credits can only reduce pollution with large, discrete investments that yield discontinuous supply and demand. The research simulates hypothetical water quality trading markets in the corn‐belt area of Illinois, where wastewater treatment plants (WWTPs) can pay farmers to reduce nutrients by installing wetlands and farmers may or may not be allowed to earn payments for multiple services from one wetland. We find that wetlands are a more cost‐effective way to mitigate nitrogen pollution than abatement by WWTPs. Stacking credits may improve social welfare while providing more ecosystem services if there is enough demand for the primary credit in the market (nitrogen) to cover most of the cost of installing the wetland but the supply of nitrogen credits is not exhausted. However, in the presence of lumpy pollution reduction activities, the effects of allowing stacked credit sales are idiosyncratic and not necessarily positive; stacked payments may or may not satisfy additionality. The results imply that credit trading for nitrogen is likely to make society better off, but the effects of allowing farmers to receive multiple payments from a single wetland depend on details of the situation.     

Impacts of Adjacent Land Use and Isolation on Marsh Bird Communities

Over the next half century the human population is expected to grow rapidly, resulting in the conversion of rural areas into cities. Wetlands in these regions are therefore under threat, even though they have important ecosystem services and functions. Many obligate marsh-nesting birds in North America have shown declines over the past 40 years, and it is important to evaluate marsh bird community response to increased urbanization. We surveyed 20 coastal marshes in southern Ontario, Canada, and found that obligate marsh-nesting birds preferred rural over urban wetlands, generalist marsh-nesting birds showed no preference, while synanthropic species showed a trend towards increased richness and abundance in urban marshes. The Index of Marsh Bird Community Integrity (IMBCI) was calculated for each wetland and we found significantly higher scores in rural compared to urban wetlands. The presence of a forested buffer surrounding the marsh was not an important factor in predicting the distribution of generalists, obligates, synanthropic species, or the IMBCI. More isolated marshes had a lower species richness of obligate marsh-nesters and a lower IMBCI than less isolated marshes. Based on our results, we recommend that urban land use is not the dominant land use within 1000 m from any wetland, as it negatively affects the abundance and richness of obligate marsh-nesters, and the overall integrity of the avian community. We also recommend that all existing wetlands be conserved to mitigate against isolation effects and to preserve biodiversity.     

Simulated wetland conservation-restoration effects on water quantity and quality at watershed scale

Wetlands are one of the most important watershed microtopographic features that affect hydrologic processes (e.g., routing) and the fate and transport of constituents (e.g., sediment and nutrients). Efforts to conserve existing wetlands and/or to restore lost wetlands require that watershed-level effects of wetlands on water quantity and water quality be quantified. Because monitoring approaches are usually cost or logistics prohibitive at watershed scale, distributed watershed models such as the Soil and Water Assessment Tool (SWAT), enhanced by the hydrologic equivalent wetland (HEW) concept developed by Wang [Wang, X., Yang, W., Melesse, A.M., 2008. Using hydrologic equivalent wetland concept within SWAT to estimate streamflow in watersheds with numerous wetlands. Trans. ASABE 51 (1), 55–72.], can be a best resort. However, there is a serious lack of information about simulated effects using this kind of integrated modeling approach. The objective of this study was to use the HEW concept in SWAT to assess effects of wetland restoration within the Broughton's Creek watershed located in southwestern Manitoba, and of wetland conservation within the upper portion of the Otter Tail River watershed located in northwestern Minnesota. The results indicated that the HEW concept allows the nonlinear functional relations between watershed processes and wetland characteristics (e.g., size and morphology) to be accurately represented in the models. The loss of the first 10–20% of the wetlands in the Minnesota study area would drastically increase the peak discharge and loadings of sediment, total phosphorus (TP), and total nitrogen (TN). On the other hand, the justifiable reductions of the peak discharge and loadings of sediment, TP, and TN in the Manitoba study area may require that 50–80% of the lost wetlands be restored. Further, the comparison between the predicted restoration and conservation effects revealed that wetland conservation seems to deserve a higher priority while both wetland conservation and restoration may be equally important.