共查询到20条相似文献,搜索用时 26 毫秒
1.
During the last 200 years, many rivers in industrialized countries have been modified by canalization. In the last two decades, the philosophy of river management has changed considerably, and restoration of ecological integrity has become an important management goal. One appealing restoration approach is to create “river widenings” that permit braiding within a limited area. This study presents a new and efficient framework for rapidly assessing such widening projects and offers a novel method to comparing restored sites with near-natural stretches (stencil technique). The proposed framework evaluates spatial patterns of riparian habitat types using landscape metrics as indicators. Three case studies from river restoration (river widening) in Switzerland are presented for demonstration purposes.The method compares restored sites with prerestoration conditions and near-natural conditions, which are assumed to represent the worst and best case states of a river system. To take into account the limited spatial extent of the restored sites, the so-called “stencil technique” was developed, where the landscape metrics of the near-natural reference sites are calculated for both the entire study area and smaller sections (clips). The clips are created by using a stencil that has the exact shape and size of the restored area (random window-sampling technique). Subsequently, the calculated metrics for the restored sites are compared to the range of values calculated for the near-natural data subset. Our studies show that the proposed method is easy to apply andprovides a valid way to assess the restoration success of river widenings. We found that river widenings offer real opportunities for establishing riparian habitats. However, they promote mainly pioneer successional stages and the habitat mosaic of the restored section is more complex than at the near-natural reference sites. 相似文献
2.
Landscape Planning for Agricultural Nonpoint Source Pollution Reduction III: Assessing Phosphorus and Sediment Reduction Potential 总被引:2,自引:0,他引:2
Riparian buffers have the potential to improve stream water quality in agricultural landscapes. This potential may vary in
response to landscape characteristics such as soils, topography, land use, and human activities, including legacies of historical
land management. We built a predictive model to estimate the sediment and phosphorus load reduction that should be achievable
following the implementation of riparian buffers; then we estimated load reduction potential for a set of 1598 watersheds
(average 54 km2) in Wisconsin. Our results indicate that land cover is generally the most important driver of constituent loads in Wisconsin
streams, but its influence varies among pollutants and according to the scale at which it is measured. Physiographic (drainage
density) variation also influenced sediment and phosphorus loads. The effect of historical land use on present-day channel
erosion and variation in soil texture are the most important sources of phosphorus and sediment that riparian buffers cannot
attenuate. However, in most watersheds, a large proportion (approximately 70%) of these pollutants can be eliminated from
streams with buffers. Cumulative frequency distributions of load reduction potential indicate that targeting pollution reduction
in the highest 10% of Wisconsin watersheds would reduce total phosphorus and sediment loads in the entire state by approximately
20%. These results support our approach of geographically targeting nonpoint source pollution reduction at multiple scales,
including the watershed scale. 相似文献
3.
Bellmore JR Baxter CV Ray AM Denny L Tardy K Galloway E 《Environmental management》2012,49(3):734-750
Pre-restoration studies typically focus on physical habitat, rather than the food-base that supports aquatic species. However,
both food and habitat are necessary to support the species that habitat restoration is frequently aimed at recovering. Here
we evaluate if and how the productivity of the food-base that supports fish production is impaired in a dredge-mined floodplain
within the Yankee Fork Salmon River (YFSR), Idaho (USA); a site where past restoration has occurred and where more has been
proposed to help recover anadromous salmonids. Utilizing an ecosystem approach, we found that the dredged segment had comparable
terrestrial leaf and invertebrate inputs, aquatic primary producer biomass, and production of aquatic invertebrates relative
to five reference floodplains. Thus, the food-base in the dredged segment did not necessarily appear impaired. On the other
hand, we observed that off-channel aquatic habitats were frequently important to productivity in reference floodplains, and
the connection of these habitats in the dredged segment via previous restoration increased invertebrate productivity by 58%.
However, using a simple bioenergetic model, we estimated that the invertebrate food-base was at least 4× larger than present
demand for food by fish in dredged and reference segments. In the context of salmon recovery efforts, this observation questions
whether additional food-base productivity provided by further habitat restoration would be warranted in the YFSR. Together,
our findings highlight the importance of studies that assess the aquatic food-base, and emphasize the need for more robust
ecosystem models that evaluate factors potentially limiting fish populations that are the target of restoration. 相似文献
4.
Elisabetta Peccol Chris A. Bird Tim R. Brewer 《Journal of environmental management》1996,47(4):355-367
The county of Bedfordshire is typical of landscape in lowland England with land cover dominant over land form and agriculture forming the major land use. Landscape change can be influenced by planning policies through their control of land use. A number of designated areas such as Areas of Great Landscape Value, Areas of Outstanding Natural Beauty and Green Belt have been defined where particular planning priorities for the conservation of the countryside apply. This paper reports work where an attempt has been made to measure the influence of these designations on landscape change using the tools of aerial photograph interpretation and Geographic Information Systems (GIS). Aerial photographs were available for the study area for 1968, 1981 and 1991. These were interpreted to a landscape classification scheme in terms of point, linear and area features such as trees, hedgerows and cultivated land, respectively. Field work was carried out to assess the accuracy of the interpretation. The resulting data were input to a GIS for each date of photography. Digital maps were created for the land cover features and tables were generated of lengths of linear features or counts of point features for each kilometre square in the study area. Spatial analysis tools provided by the GIS were used to describe the landscape character of each of the designated areas and then to measure the change that had taken place within them over the time period defined by the photography. Areas which were not designated for conservation of scenic beauty were shown to be poorer in traditional landscape features. 相似文献
5.
Riggs Rebecca Anne Langston James Douglas Beauchamp Emilie Travers Henry Ken Sereyrotha Margules Chris 《Environmental management》2020,66(1):72-90
Environmental Management - Tropical forest landscapes are undergoing rapid transition. Rural development aspirations are rising, and land use change is contributing to deforestation, degradation,... 相似文献
6.
7.
8.
以1987年和2000年TM影像为数据源,在ENVI 4.4平台下提取淮北市(相山建成区)1987-2000年土地利用/覆盖动态变化信息,利用FRAGSTATS 3.3软件提取研究区的斑块指数、多样性指数、优势度、破碎度、分维度及形状指数等景观格局指标,并进行分析. 相似文献
9.
Given that they represent the most economical option for disposing of refuse, waste landfills are widespread in urban areas. However, landfills generate air and water pollution and require restoration for landscape development. A number of unsanitary waste landfills have caused severe environmental problems in developing countries. This study aimed to investigate the colonization status of different tree species on waste landfills to assess their potential for restoring unsanitary landfills in South Korea. Plot surveys were conducted using 10 × 10-m quadrats at seven waste landfill sites: Bunsuri, Dugiri, Hasanundong, Gomaeri, Kyongseodong, Mojeonri, and Shindaedong. We determined the height, diameter at breast height (DBH), and number of tree species in the plots, and enumerated all saplings ≤1 m high. Because black locust, Robinia pseudoacacia, was the dominant tree species in the waste landfills, we measured the distance from the presumed mother plant (i.e., the tallest black locust in a patch), height, and DBH of all individuals in black locust patches to determine patch structure. Robinia pseudoacacia, Salix koreensis, and Populus sieboldii formed canopy layers in the waste landfills. The basal area of black locust was 1.51 m2/ha, and this species had the highest number of saplings among all tree species. The diameter of the black locust patches ranged from 3.71 to 11.29 m. As the patch diameter increased, the number of regenerated saplings also tended to increase, albeit not significantly. Black locust invaded via bud banks and spread clonally in a concentric pattern across the landfills. This species grew well in the dry habitat of the landfills, and its growth rate was very high. Furthermore, black locust has the ability to fix nitrogen symbiotically; it is therefore considered a well-adapted species for waste landfills. Eleven woody species were selected for screening: Acer palmatum, Albizzia julibrissin, Buxus microphylla var. koreana, Ginkgo biloba, Hibiscus syriacus, Koelreuteria paniculata, Ligustrum obtusifolium, Liriodendron tulipifera, Pinus koraiensis, Pinus thunbergii, and Sophora japonica. As a result of a comparison of the total ratio (sum of shoot extension and diameter growth at the landfill relative to a reference site) and mortality, six species (Liriodendron tulipifera, Albizzia julibrissin, Ligustrum obtusifolium, Buxus microphylla var. koreana, Hibiscus syriacus, and Sophora japonica), which had a total ratio >1 and experienced low mortality, are recommended as potentially suitable species for waste landfill remediation. We suggest that mixed plantations of ubiquitous adaptable species and naturally occurring black locust will enhance the landscape through synergistic effects. 相似文献
10.
Assessing Impacts of Typhoons and the Chi-Chi Earthquake on Chenyulan Watershed Landscape Pattern in Central Taiwan Using Landscape Metrics 总被引:2,自引:1,他引:2
The Chi-Chi earthquake (ML = 7.3) occurred in the central part of Taiwan on September 21, 1999. After the earthquake, typhoons Xangsane and Toraji produced
heavy rainfall that fell across the eastern and central parts of Taiwan on November 2000 and July 2001. This study uses remote
sensing data, landscape metrics, multivariate statistical analysis, and spatial autocorrelation to assess how earthquake and
typhoons affect landscape patterns. It addresses variations of the Chenyulan watershed in Nantou County, near the earthquake’s
epicenter and crossed by Typhoon Toraji. The subsequent disturbances have gradually changed landscape of the Chenyulan watershed.
Disturbances of various types, sizes, and intensities, following various tracks, have various effects on the landscape patterns
and variations of the Chenyulan watershed. The landscape metrics that are obtained by multivariate statistical analyses showed
that the disturbances produced variously fragmented patches, interspersed with other patches and isolated from patches of
the same type across the entire Chenyulan watershed. The disturbances also affected the isolation, size, and shape-complexity
of patches at the landscape and class levels. The disturbances at the class level more strongly affected spatial variations
in the landscape as well as patterns of grasslands and bare land, than variations in the watershed farmland and forest. Moreover,
the earthquake with high magnitude was a starter to create these landscape variations in space in the Chenyulan watershed.
The cumulative impacts of the disturbances on the watershed landscape pattern had existed, especially landslides and grassland
in the study area, but were not always evident in space and time in landscape and other class levels. 相似文献
11.
Mehrey G. Vaghti Marcel Holyoak Amy Williams Theresa S. Talley Alexander K. Fremier Steven E. Greco 《Environmental management》2009,43(1):28-37
Societal constraints often limit full process restoration in large river systems, making local rehabilitation activities valuable
for regeneration of riparian vegetation. A target of much mitigation and restoration is the federally threatened Valley elderberry
longhorn beetle and its sole host plant, blue elderberry, in upper riparian floodplain environments. However, blue elderberry
ecology is not well understood and restoration attempts typically have low success rates. We determined broad-scale habitat
characteristics of elderberry in altered systems and examined associated plant species composition in remnant habitat. We
quantified vegetation community composition in 139 remnant riparian forest patches along the Sacramento River and elderberry
stem diameters along this and four adjacent rivers. The greatest proportion of plots containing elderberry was located on
higher and older floodplain surfaces and in riparian woodlands dominated by black walnut. Blue elderberry saplings and shrubs
with stems <5.0 cm in diameter were rare, suggesting a lack of recruitment. A complex suite of vegetation was associated with
blue elderberry, including several invasive species which are potentially outcompeting seedlings for light, water, or other
resources. Such lack of recruitment places increased importance on horticultural restoration for the survival of an imperiled
species. These findings further indicate a need to ascertain whether intervention is necessary to maintain functional and
diverse riparian woodlands, and a need to monitor vegetative species composition over time, especially in relation to flow
regulation. 相似文献
12.
Douglas J. Norton James D. Wickham Timothy G. Wade Kelly Kunert John V. Thomas Paul Zeph 《Environmental management》2009,44(2):356-368
Common decision support tools and a growing body of knowledge about ecological recovery can help inform and guide large state
and federal restoration programs affecting thousands of impaired waters. Under the federal Clean Water Act (CWA), waters not
meeting state Water Quality Standards due to impairment by pollutants are placed on the CWA Section 303(d) list, scheduled
for Total Maximum Daily Load (TMDL) development, and ultimately restored. Tens of thousands of 303(d)-listed waters, many
with completed TMDLs, represent a restoration workload of many years. State TMDL scheduling and implementation decisions influence
the choice of waters and the sequence of restoration. Strategies that compare these waters’ recovery potential could optimize
the gain of ecological resources by restoring promising sites earlier. We explored ways for states to use recovery potential
in restoration priority setting with landscape analysis methods, geographic data, and impaired waters monitoring data. From
the literature and practice we identified measurable, recovery-relevant ecological, stressor, and social context metrics and
developed a restorability screening approach adaptable to widely different environments and program goals. In this paper we
describe the indicators, the methodology, and three statewide, recovery-based targeting and prioritization projects. We also
call for refining the scientific basis for estimating recovery potential.
相似文献
Paul ZephEmail: |
13.
利用两个时期的Landsat TM/ETM遥感影像,结合RS和GIS技术,直接从遥感图像上获得景观格局指数,对安徽省合肥市的景观格局进行了分析。揭示在快速经济发展和不断加快的城市化进程中,合肥市景观形状指数、分形维数和破碎度指数的不同变化趋势。与传统方法相比,该方法具有快速、准确、节省费用、简单易行的特点,有利于对景观格局变化进行动态监测。 相似文献
14.
15.
16.
Bruce K. Ferguson 《Journal of environmental management》1996,48(4):387-395
Land use design that recognizes the landscape attributes that characterize homeostatic health can emphasize them during land use change. The attributes of landscape health are the working mechanisms of all open systems, and can be observed in the homeostatic behavior of forests, deserts and floodplains. These attributes are openness, self-regulation, storage and diversity. The attributes of health comprise criteria for evaluating and guiding land use. To maintain landscape health, land use design can maintain and restore these mechanisms during change of moderate pace and scale. 相似文献
17.
18.
M. J. Riley 《Journal of Environmental Planning and Management》2000,43(5):711-720
The impacts of climate change as described by the United Nations Intergovernmental Panel on Climate Change are accepted as providing the most probable future. A case-study describes the problems that maritime local authorities will need to address in the near future. These are classified as being part of the local authority's responsibilities either as the owner and manager of building assets or as the planning and building control authority. A process called climatic impact assessment is described, which all future built developments should be required to carry out as part of the planning process to approve the development. 相似文献
19.
BOWLER PA 《Environmental management》2000,26(Z1):S85-S96
Extensive acreage loss of coastal sage scrub (CSS), isolation of surviving stands, and the federal listing of several animal species with obligate relationships to this plant community, particularly the threatened California gnatcatcher (Polioptila californica), have led to attempts to create CSS to mitigate habitat lost to urban development and other causes. Many of these creations lie within habitat conservation plan (HCP) sites, and they could play a more prominent role by being repositories for plants taken from a single site having site-specific genetics. Among others, one technique that increases initial resemblance to natural stands uses digitized, to-scale photography, which has been ground-truthed to verify vascular plant associations, which appear as mosaics on a landscape. A combination of placing patches of salvaged, mature canopy plants within larger matrices of imprinted or container plant plots appears to significantly enhance immediate use by CSS obligate bird species, accelerate "spread" or expansion of CSS, and can also introduce many epiphytic taxa that otherwise would be slow or unable to occupy developing CSS creations. Reptile, amphibian, butterfly, and rodent diversity in a salvaged canopy restoration case study at the University of California, Irvine, showed CSS species foraging and inhabiting transplanted canopy patches. Using restoration techniques to expand existing CSS stands has more promise than creating isolated patches, and the creation of canopies resembling CSS mid-fire cycle stands is now common. Gnatcatchers and other birds use restorations for foraging and occasional nesting, and in some cases created stands along "biological corridors" appear to be useful to bird movement. Patches of transplanted sage scrub shrubs along habitat edges appear to break up linear edge effects. There are no data on which long-term survival, succession, or postfire behavior can be predicted for CSS restoration sites, and postfire community changes are not part of either mitigation or restoration planning at present. Long-term planning including burning is needed so that a fire-adapted habitat will develop. Restoration is important in retaining genetic resources, for ameliorating edge effects, as habitat extenders in buffer zones around HCP sites, and by providing areas into which natural stands can expand. 相似文献
20.
为了研究农村景观改变对水环境的影响,选取重庆市河堰村为研究对象,运用SWMM水文模拟软件,分析了研究区域的景观变迁与水量、水质变化的相互关系;通过访谈当地居民,分析了土地利用与景观变化对水环境的影响机制。认为(1)散点状的居民点分布模式与"村村通公路,户户通水泥"的农村道路建设以及庭院硬质化导致农村不透水表面面积迅速增加,缩短了雨水汇流时间并加速了污染物向水体的转移。(2)山体开发和现代农田水利工程的建设,如水库、山坪塘和排灌沟渠等的建设导致水体自净能力降低,加重了水体污染。(3)地表硬质化与河床沟渠化加速了水过程从而加速水环境的破坏。(4)人水关系由"我"、"你"变成"我"、"它",农民在卫生意识上升的同时缺乏相应的环保意识。 相似文献