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1.
Critique of present wetlands mitigation policies in the united states based on an analysis of past restoration projects in San Francisco Bay 总被引:1,自引:1,他引:1
Margaret Seluk Race 《Environmental management》1985,9(1):71-81
A detailed evaluation of past wetland restoration projects in San Francisco Bay was undertaken to determine their present status and degree of success. Many of the projects never reached the level of success purported and others have been plagued by serious problems. On the basis of these findings, it is debatable whether any sites in San Francisco Bay can be described as completed, active, or successful restoration projects at present. In spite of these limited accomplishments, wetland creation and restoration have been adopted in the coastal permit process as mitigation to offset environmental damage or loss of habitat. However, because the technology is still largely experimental, there is no guarantee that man-made wetlands will persist as permanent substitutes for sacrificed natural habitats. Existing permit policies should be reanalyzed to insure that they actually succeed in safeguarding diminishing wetlands resources rather than bartering them away for questionable habitat substitutes. Coastal managers must be more specific about project requirements and goals before approval is granted. Continued research on a regional basis is needed to advance marsh establishment techniques into a proven technology. In the meantime, policies encouraging or allowing quid pro quo exchanges of natural wetlands with man-made replacements should proceed with caution. The technology and management policies used at present are many steps ahead of the needed supporting documentation. 相似文献
2.
Ten intertidal salt marshes along the Rhode Island coast were sampled and compared in terms of the relative standing crop and height of tallSpartina alterniflora, density of shoots, seed production and size, fish populations, and the abundance of grass shrimp, fiddler crabs, insects, and birds. The marshes ranged from 0.49 to 52.61 hectares (1.2 to 130 acres) and included fringe marsh in dense urban developments as well as unspoiled waterfowl preserves in rural isolation. Large variation in most parameters made it impossible to separate the sites with statistical significance using either univariate or multivariate techniques. Moreover, there was little meaningful intercorrelation among the parameters. Although more intensive sampling might make it possible to separate individual marshes with statistical rigor, these results suggest that the necessary effort may be too great to allow comparative field sampling to play a practical part in wetlands evaluation programs. The results also indicate that there is little, if any, correlation between visual esthetic perceptions of a marsh and its ecological characteristics. This work suggests that the development of ecological rating systems will not provide a reliable tool for the management of coastal wetlands. 相似文献
3.
Trends and patterns in section 404 permitting requiring compensatory mitigation in Oregon and Washington,USA 总被引:1,自引:4,他引:1
Mary E. Kentula Jean C. Sifneos James W. Good Michael Rylko Kathy Kunz 《Environmental management》1992,16(1):109-119
The effects of permitting decisions made under Section 404 of the Clean Water Act for which compensatory mitigation was required
were examined. Information was compiled on permits issued in Oregon (January 1977–January 1987) and Washington (1980–1986).
Data on the type of project permitted, wetland impacted, and mitigation project were collected and analyzed. The records of
the Portland and Seattle District Offices of the US Army Corps of Engineers and of Environmental Protection Agency Region
X were the primary sources of information.
The 58 permits issued during the years of concern in Oregon document impacts to 82 wetlands and the creation of 80. The total
area of wetland impacted was 74 ha while 42 ha were created, resulting in a net loss of 32 ha or 43%. The 35 permits issued
in Washington document impacts to 72 wetlands and the creation of 52. The total area of wetland impacted was 61 ha while 45
ha were created, resulting in a net loss of 16 ha or 26%. In both states, the number of permits requiring compensation increased
with time. The area of the impacted and created wetlands tended to be ≤0.40 ha. Permitted activity occurred primarily west
of the Cascade Mountains and in the vicinity of urban centers. Estuarine and palustrine wetlands were impacted and created
most frequently. The wetland types created most often were not always the same as those impacted; therefore, local gains and
losses of certain types occurred. In both states the greatest net loss in area was in freshwater marshes.
This study illustrates how Section 404 permit data might be used in managing a regional wetland resource. However, because
the data readily available were either incomplete or of poor quality, the process of gathering information was very labor
intensive. Since similar analyses would be useful to resource managers and scientists from other areas, development of an
up-to-date standardized data base is recommended. 相似文献
4.
The Environmental Impact of Shrimp Aquaculture: Causes, Effects, and Mitigating Alternatives 总被引:3,自引:0,他引:3
FEDERICO PÁEZ-OSUNA 《Environmental management》2001,28(1):131-140
Attracted by the demand for shrimp in the developed countries, shrimp aquaculture has expanded rapidly, mainly in the subtropical
and tropical lowlands of America and Asia. This work provides a global review and viewpoint on the environmental impacts of
shrimp aquaculture, considering the causes and effects of the siting and operation of shrimp ponds and abandonment of farm
facilities. Additionally, mitigating alternatives are discussed. To date, approximately 1–1.5 million ha of coastal lowlands
have been converted into shrimp ponds, comprising mainly salt flats, mangrove areas, marshes, and agricultural lands. The
impact of shrimp farming of most concern is the destruction of mangroves and salt marshes for pond construction. Compatibility
with other users, the presence of buffer zones, maintaining an acceptable balance between mangroves and shrimp pond area,
improved pond design, reduction of water exchange, and an improved residence time of water, size and capacity to assimilate
effluents of the water body, are examples of ways to mitigate the adverse effects. The use of mangroves and halophytes as
biofilters of shrimp pond effluents offers an attractive tool for reducing the impact in those regions where mangrove wetlands
and appropriate conditions for halophyte plantations exist. Healthy seed supply, good feed with the use of prophylactic agents
(including probiotics), good water quality, and lower stocking densities are examples of actions suggested to control disease
in shrimp farming. Finally, in the context of integrated management, research priorities are suggested. 相似文献
5.
Coastal wetlands are a valuable resource to North Carolina, USA, representing important habitat for marine organisms and providing flood control areas and buffer zones from marine storms. An analysis of wetland development trends in coastal North Carolina from 1970 to 1984 was conducted using over 3000 files containing 15 years of permitting records. The total amount of coastal wetland area altered due to authorized development under the Coastal Area Management Act (CAMA), the Dredge and Fill Law, and Section 404 of the Federal Water Pollution Control Act is 1740 ha. This represents nearly 2% of the salt marsh wetlands along the coast of North Carolina. The number of permits issued steadily increased during the 1980s; however, the total amount of wetland loss decreased each year. A few large projects in the early 1970s accounted for nearly 70% of all wetland area developed during the 15-year period. Nearly two-thirds of all projects involving wetland destruction involved impacts on high marsh ecosystems. Bulkheads, canals, and filling activities made up 80% of the projects requiring permits; 62% of the permits were issued to private landowners, but this group accounted for only 16% of the losses of wetland area. Utility companies, which accounted for less than 1% of the permits issued, were responsible for 46% of the permitted wetland loss during the 15-year study period. Future studies should address agriculture and forestry practices which are exempt under CAMA laws and therefore their effects on wetland alteration have not been quantified. 相似文献
6.
Berberoglu S 《Environmental management》2003,31(3):0442-0451
The objective of this article is to propose a program for the integrated coastal zone management that is required to stimulate
and guide sustainable development of the Mediterranean coastal zone of Turkey.
Improved data collection, quality control, analysis, and data management will provide a firm basis for future scientific understanding
of the East Mediterranean coast of Turkey and will support long-term management. Various innovative procedures were proposed
for a promising ecosystem-based approach to manage coastal wetlands in the Mediterranean: remote data acquisition with new
technologies; environmental quality monitoring program that will provide a baseline for monitoring; linking a Geographic Information
System (GIS) with natural resource management decision routines in the context of operational wetlands, fisheries, tourism
management system; environmental sensitivity analysis to ensure that permitted developments are environmentally sustainable;
and use of natural species to restore the wetlands and coastal dunes and sustain the system processes. The proposed management
scheme will benefit the scientific community in the Mediterranean and the management/planning community in Eastern Turkey. 相似文献
7.
Wigand C McKinney RA Chintala MM Charpentier MA Groffman PM 《Journal of environmental quality》2004,33(3):1144-1151
Coastal salt marshes are a buffer between the uplands and adjacent coastal waters in New England (USA). With increasing N loads from developed watersheds, salt marshes could play an important role in the water quality maintenance of coastal waters. In this study we examined seasonal relationships between denitrification enzyme activity (DEA) in salt marshes of Narragansett Bay, Rhode Island, and watershed N loadings, land use, and terrestrial hydric soils. In a manipulative experiment, the effect of nutrient enrichment on DEA was examined in a saltmeadow cordgrass [Spartina patens (Aiton) Muhl.] marsh. In the high marsh, DEA significantly (p < 0.05) increased with watershed N loadings and decreased with the percent of hydric soils in a 200-m terrestrial buffer. In the low marsh, we found no significant relationships between DEA and watershed N loadings, residential land development, or terrestrial hydric soils. In the manipulation experiment, we measured increased DEA in N-amended treatments, but no effect in the P-amended treatments. The positive relationships between N loading and high marsh DEA support the hypothesis that salt marshes may be important buffers between the terrestrial landscape and estuaries, preventing the movement of land-derived N into coastal waters. The negative relationships between marsh DEA and the percent of hydric soils in the adjacent watershed illustrate the importance of natural buffers within the terrestrial landscape. Denitrification enzyme activity appears to be a useful index for comparing relative N exposure and the potential denitrification activity of coastal salt marshes. 相似文献
8.
The coastal landscapes in southwestern Korea include a diverse array of tidal wetlands and salt marshes. These coastal zones
link the ecological functions of marine tidal wetlands and freshwater ecosystems with terrestrial ecosystems. They are rich
in biological diversity and play important roles in sustaining ecological health and processing environmental pollutants.
Korean tidal wetlands are particularly important as nurseries for economically important fishes and habitats for migratory
birds. Diking, draining, tourism, and conversion to agricultural and urban uses have adversely affected Korean tidal wetlands.
Recent large development projects have contributed to further losses. Environmental impact assessments conducted for projects
affecting tidal wetlands and their surrounding landscapes should be customized for application to these special settings.
Adequate environmental impact assessments will include classification of hydrogeomorphic units and consideration of their
responses to biological and environmental stressors. As is true worldwide, Korean laws and regulations are changing to be
more favorable to the conservation and protection of tidal wetlands. More public education needs to be done at the local level
to build support for tidal wetland conservation. Some key public education points include the role of tidal wetlands in maintaining
healthy fish populations and reducing impacts of nonpoint source pollution. There is also a need to develop procedures for
integrating economic and environmental objectives within the overall context of sustainable management and land uses. 相似文献
9.
Denise J. Reed 《Environmental management》1992,16(1):55-65
Sediment deposition both inside and outside of fixed-crest weirs was measured for fresh/intermediate, brackish, and saline
marsh areas in coastal Louisiana, USA. Sediment traps, collected on a weekly basis, were used to monitor short-term changes
in sediment deposition. Feldspar marker horizons were used to measure cumulative marsh accretion during the 16-week monitoring
period. Results show that for most sites less sediment is deposited in marsh behind weirs than at the control sites outside
the weirs. Patterns at each site are consistent throughout the 16 monitoring periods. At only one site was no significant
difference found. Streamside areas both inside and outside the weirs were found to have higher rates of sediment deposition
than backmarsh areas. At both marsh locations, sediment deposition rates were higher outside the weirs than inside. More sediment
was deposited in saline marshes than in brackish or fresh/intermediate areas. The vertical accretion data shows that marshes
in most areas are accreting sufficiently rapidly to keep pace with local rates of sea-level rise, except for two areas, both
of which are inside weirs. 相似文献
10.
Many marshes in the Gulf Coast Chenier Plain, USA, are managed through a combination of fall or winter burning and structural
marsh management (i.e., levees and water control structures; hereafter SMM). The goals of winter burning and SMM include improvement
of waterfowl and furbearer habitat, maintenance of historic isohaline lines, and creation and maintenance of emergent wetlands.
Although management practices are intended to influence the plant community, effects of these practices on primary productivity
have not been investigated. Marsh processes, such as vertical accretion and nutrient cycles, which depend on primary productivity
may be affected directly or indirectly by winter burning or SMM. We compared Chenier Plain plant community characteristics
(species composition and above- and belowground biomass) in experimentally burned and unburned control plots within impounded
and unimpounded marshes at 7 months (1996), 19 months (1997), and 31 months (1998) after burning. Burning and SMM did not
affect number of plant species or species composition in our experiment. For all three years combined, burned plots had higher
live above-ground biomass than did unburned plots. Total above-ground and dead above-ground biomasses were reduced in burned
plots for two and three years, respectively, compared to those in unburned control plots. During all three years, belowground
biomass was lower in impounded than in unimpounded marshes but did not differ between burn treatments. Our results clearly
indicate that current marsh management practices influence marsh primary productivity and may impact other marsh processes,
such as vertical accretion, that are dependent on organic matter accumulation and decay. 相似文献
11.
We inventoried wetland impoundments in the Louisiana, USA, coastal zone from the late 1900s to 1985. Historically, impoundment
of wetlands for reclamation resulted in direct wetland loss after levees (dikes) failed and the impounded area was permanently
flooded, reverting not to wetland, but to open-water habitat. A current management approach is to surround wetlands by levees
and water control structures, a practice termed semi-impoundment marsh management. The purpose of this semi-impoundment is
to retard saltwater intrusion and reduce water level fluctuations in an attempt to reduce wetland loss, which is a serious
problem in coastal Louisiana. In order to quantify the total impounded area, we used historic data and high-altitude infrared
photography to map coastal impoundments. Our goal was to produce a documented inventory of wetlands intentionally impounded
by levees in the coastal zone of Louisiana in order to provide a benchmark for further research.
We inventoried 370,658 ha within the coastal zone that had been intentionally impounded before 1985. This area is equal to
about 30% of the total wetland area in the coastal zone. Of that total area, approximately 12% (43,000 ha) is no longer impounded
(i.e., failed impoundments; levees no longer exist or only remnants remain). Of the 328,000 ha still impounded, about 65%
(214,000 ha) is developed (agriculture, aquaculture, urban and industrial development, and contained spoil). The remaining
35% (114,000 ha) of impoundments are in an undeveloped state (wetland or openwater habitat). In December 1985, approximately
50% (78,000 ha) of the undeveloped and failed impoundments were open-water habitat. This inventory will allow researchers
to monitor future change in land-water ratios that occur within impounded wetlands and thus to assess the utility of coastal
wetland management using impoundments. 相似文献
12.
In order to balance pressures for land-use development with protection of wetland resources, artificial wetlands have been
constructed in an effort to replace lost ecosystems. Despite its regulatory appeal and prominent role in current mitigation
strategies, it is unclear whether or not created systems actually compensate for lost wetland resources. Mitigation predictions
that rely on artificial wetlands must be analyzed critically in terms of their efficacy. Destruction of wetlands due to burial
by coal fly ash at a municipal landfill in Danvers, Massachusetts, USA, provided an opportunity to compare resulting growth
of created cattail (Typha) marshes with natural wetland areas. Once the appropriate cattail species was identified for growth under disturbed landfill
conditions, two types of artificial wetlands were constructed. The two systems differed in their hydrologic attributes: while
one had a surface water flow characteristic of most cattail wetlands, the second system mimicked soil and water conditions
found in naturally occurring floating cattail marshes. Comparison of plant growth measurements for two years from the artificial
systems with published values for natural cattail marshes revealed similar structure and growth patterns. Experiments are
now in progress to investigate the ability of created cattail marshes to remove and accumulate heavy metals from polluted
landfill leachate. Research of the type reported here must be pursued aggressively in order to document the performance of
artificial wetlands in terms of plant structure and wetland functions. Such research should allow us to start to evaluate
whether artificial systems actually compensate for lost wetlands by performing similar functions and providing the concomitant
public benefits. 相似文献
13.
Construction of 653 ha of salt marsh habitat from dredged material near the Aransas National Wildlife Refuge, Texas, has been
proposed, with the goal of increasing the area of habitat available to endangered whooping cranes (Grus americana). We assessed prototype created wetlands, and their similarity to natural reference sites, in terms of topography, vegetation,
and hydrology. The created sites were steeply sloped relative to natural sites and were dominated by monotypic stands of Spartina alterniflora. Natural sites were dominated by vegetation more tolerant of desiccation and hypersalinity and by unvegetated salt pans.
Differences in vegetation communities and distributions of habitat types resulted from efforts to enhance habitat diversity
in created marsh cells through manipulation of marsh topography. However, the scale at which this diversity occurred in natural
marsh of the study area was not considered. When constructing wetlands in cellular configurations, we recommend creation of
large complexes of adjoining, hydrologically linked, cells wherein the desired habitat diversity is created at the scale of
the entire complex, rather than within a single cell. Suggested design modifications would increase the similarity of created
marshes to natural reference sites, potentially improving habitat function. 相似文献
14.
Dredged material levees in coastal Louisiana are normally associated with pipeline canals or, more frequently, canals dredged
through the wetlands to allow access to drilling locations for mineral extraction. The hydrologic impact on marshes behind
the levee is of concern to coastal resource managers because of the potential impact on sediment transport and deposition,
and the effect on estuarine organism access to valuable nursery habitat. This study examined the effects of gaps in dredged
material levees, compared to continuous levees and natural channel banks, on these two aspects of marsh function. Field studies
for sediment deposition were conducted biweekly for a year, and nekton samples were collected in spring and fall. Variation
in nekton density among study arears and landscape types was great in part because of the inherent sampling gear issues and
in part because of differences in characteristics among areas. Nekton densities were generally greater in natural compared
to leveed and gapped landscapes. Differences in landscape type did not explain patterns in sediment deposition. The gaps examined
appear to be too restrictive of marsh flooding to provide efficient movements of floodwaters onto the marsh during moderate
flooding events. The “trapping” effect of the levees increases sediment deposition during extreme events. Gapping material
levees may be an effective method of partially restoring upper marsh connection to nekton, but this method may work best in
lower elevation marshes where nekton use is greater. 相似文献
15.
Construction of 653 ha of salt marsh habitat from dredged material near the Aransas National Wildlife Refuge, Texas, has been proposed, with the goal of increasing the area of habitat available to endangered whooping cranes (Grus americana). We assessed prototype created wetlands, and their similarity to natural reference sites, in terms of topography, vegetation, and hydrology. The created sites were steeply sloped relative to natural sites and were dominated by monotypic stands of Spartina alterniflora. Natural sites were dominated by vegetation more tolerant of desiccation and hypersalinity and by unvegetated salt pans. Differences in vegetation communities and distributions of habitat types resulted from efforts to enhance habitat diversity in created marsh cells through manipulation of marsh topography. However, the scale at which this diversity occurred in natural marsh of the study area was not considered. When constructing wetlands in cellular configurations, we recommend creation of large complexes of adjoining, hydrologically linked, cells wherein the desired habitat diversity is created at the scale of the entire complex, rather than within a single cell. Suggested design modifications would increase the similarity of created marshes to natural reference sites, potentially improving habitat function. 相似文献
16.
Since tidal marshes and estuaries cover large areas of the world's coasts and exhibit a very high net primary productivity, they offer a most important food source for an ever increasing world population. The food web of numerous estuaries and coastal waters is based on the primary productivity of coastal marshes that constitute centers of solar energy fixation and an important link in the mineral cycles. The fixed carbon and minerals enterthe water primarily as detritus where a complex food web makes them accessible to commercially important fish and benthic communities. With the launch of LANDSAT, NOAA-2, and Skylab, relatively high resolution spacecraft data became available for mapping and inventorying tidal marshes and their productivity on a global scale. Upwelling regions that attract large fish populations as well as other coastal water properties relating to the presence of finfish, Crustacea, and shellfish could be identified and observed. Using multispectral analysis techniques, classification accuracies greater than 80 percent have been obtained for most marsh plant species, and greater than 90 percent for key types such asSpartina alterniflora, which is the primary producer in large tide marshes of the coastal eastern USA. The capacity of remote sensors on spacecraft such as NOAA-2, LANDSAT, and Skylab to assess coastal food resources on a global scale is discussed from the point of view of resolution, classification accuracy, and cost effectiveness. 相似文献
17.
Waterbird Population Changes in the Wetlands at Chongming Dongtan in the Yangtze River Estuary,China 总被引:1,自引:0,他引:1
Zhijun Ma Yong Wang Xiaojing Gan Bo Li Yinting Cai Jiakuan Chen 《Environmental management》2009,43(6):1187-1200
We studied the changes in wetland habitats and waterbird communities between the 1980s and the 2000s at Chongming Dongtan,
a Ramsar site in the Yangtze River estuary, an ecologically important region. This region is an important stopover site for
shorebirds along the East Asian–Australasian flyway and is extensively used by waterfowl. A net loss of 11% of the wetland
area was estimated during study periods at Chongming Dongtan. The change was dependent on wetland types: while the area of
artificial habitats such as paddy fields and aquacultural ponds more than doubled, more than 65% of natural habitats including
sea bulrush (Scirpus mariqueter) and common reed (Phragmites australis) marshes were lost over the two decades. An exotic plant species introduced from North America, smooth cordgrass (Spartina alterniflora), occupied 30% of the vegetated intertidal zone by the 2000s. Although waterbird species richness did not change between
the 1980s (110) and the 2000s (111), 13 species found in 1980s were replaced by 14 newly recorded species. Moreover, there
were more species with declining trends (58) than with increasing trends (19). The population trends of species were affected
by residential status and habitat types. Transients, wintering migrants, and habitat specialists were more likely to show
declining trends compared to those breeding at Dongtan (including year-round and summer residents) and habitat generalists.
Furthermore, species associated mainly with natural wetlands were more likely to decline than those associated mainly with
artificial wetlands. These patterns suggest that the loss and change of wetland habitats at Chongming Dongtan adversely affected
local population dynamics and might have contributed to the global decline of some waterbird species. Because Chongming Dongtan
provides stopover and wintering habitats for many migratory waterbirds, protection and restoration of natural wetlands at
Chongming Dongtan are urgently needed. 相似文献
18.
辽宁省拥有丰富多样的滨海湿地资源.随着辽宁沿海经济带升级为国家战略,滨海湿地资源将面临不同程度的开发影响.从辽宁滨海湿地资源禀赋与开发现状人手,分析了滨海湿地资源开发与保护中存在的主要问题,探讨了滨海湿地在沿海经济带开发中的重要功能与地位,并提出实现滨海湿地资源可持续开发利用的对策建议. 相似文献
19.
The US Army Corps of Engineers often requires wetland creation or restoration as compensation for wetlands damaged during
development. These wetlands are typically monitored postconstruction to determine the level of compliance with respect to
site-specific performance standards. However, defining appropriate goals and measuring success of restorations has proven
difficult. We reviewed monitoring information for 76 wetlands constructed between 1992 and 2002 to summarize the performance
criteria used to measure progress, assess compliance with those criteria, and, finally, to evaluate the appropriateness of
those criteria. Goals were overwhelmingly focused on plant communities. Attributes used to assess the quality of restored
plant communities, including percent native species and the Floristic Quality Index, increased over time but were apparently
unrelated to the number of species planted. Compliance frequencies varied depending on site goals; sites often failed to comply
with criteria related to survival of planted vegetation or requirements that dominant plant species should not be exotic or
weedy, whereas criteria related to the establishment of cover by vegetation or by wetland-dependent plants were often met.
Judgment of a site’s success or failure was largely a function of the goals set for the site. Some performance criteria were
too lenient to be of value in distinguishing failed from successful sites, whereas other criteria were unachievable without
more intensive site management. More appropriate goals could be devised for restored wetlands by basing performance standards
on past performance of similar restorations, identifying consistent temporal trends in attributes of restored sites, and using
natural wetlands as references. 相似文献
20.
Karageorgis AP Kapsimalis V Kontogianni A Skourtos M Turner KR Salomons W 《Environmental management》2006,38(2):304-315
The Axios River delta and the Inner Thermaikos Gulf coastal zone have experienced a long period of human interventions during
the past 100 years. A post-evaluation of long run coastal zone changes under the Drivers-Pressures-State-Impacts-Response
(DPSIR) conceptual framework is presented. The DPSIR approach is then used to project out into possible futures in order to
connect with policy and management options proposed for the improvement of the current conditions and the achievement of sustainable
development, in the coastal zone. Socio-economic driving forces with their origins in the end of the 19th century have generated numerous pressures in the coastal environment that changed the state of the environment. In the first
part of the last century, there was no coupling between change of state and policy. Due to increasing environmental awareness,
a coupling became more apparent over the last thirty years. Human interventions include river route realignment, extensive
drainage of the plains, irrigation network, roads and dam constructions. The consequences were positive for the economic development
of the area, human health, and navigation for the port of Thessaloniki. In contrast, the manipulation and over-use of natural
resources has led to a reduction of wetlands, biodiversity loss, stress on freshwater supplies, and subsidence of coastal
areas, aquifer salinization, and rapid coastal erosion. Three plausible future scenarios are utilised in order to investigate
the implications of this environmental change process and possible socio-economic consequences. 相似文献