Environmental manipulation experiments showed that species respond individualistically to each environmental-change variable. The greatest responses of plants were generally to nutrient, particularly nitrogen, addition. Summer warming experiments showed that woody plant responses were dominant and that mosses and lichens became less abundant. Responses to warming were controlled by moisture availability and snow cover. Many invertebrates increased population growth in response to summer warming, as long as desiccation was not induced. CO2 and UV-B enrichment experiments showed that plant and animal responses were small. However, some microorganisms and species of fungi were sensitive to increased UV-B and some intensive mutagenic actions could, perhaps, lead to unexpected epidemic outbreaks. Tundra soil heating, CO2 enrichment and amendment with mineral nutrients generally accelerated microbial activity. Algae are likely to dominate cyanobacteria in milder climates. Expected increases in winter freeze-thaw cycles leading to ice-crust formation are likely to severely reduce winter survival rate and disrupt the population dynamics of many terrestrial animals. A deeper snow cover is likely to restrict access to winter pastures by reindeer/caribou and their ability to flee from predators while any earlier onset of the snow-free period is likely to stimulate increased plant growth. Initial species responses to climate change might occur at the sub-species level: an Arctic plant or animal species with high genetic/racial diversity has proved an ability to adapt to different environmental conditions in the past and is likely to do so also in the future. Indigenous knowledge, air photographs, satellite images and monitoring show that changes in the distributions of some species are already occurring: Arctic vegetation is becoming more shrubby and more productive, there have been recent changes in the ranges of caribou, and "new" species of insects and birds previously associated with areas south of the treeline have been recorded. In contrast, almost all Arctic breeding bird species are declining and models predict further quite dramatic reductions of the populations of tundra birds due to warming. Species-climate response surface models predict potential future ranges of current Arctic species that are often markedly reduced and displaced northwards in response to warming. In contrast, invertebrates and microorganisms are very likely to quickly expand their ranges northwards into the Arctic. 相似文献
Recent experimental studies indicate that microorganisms play a passive role in silicification. The organic functional groups that comprise the outer cell surfaces simply serve as heterogeneous nucleation sites for the adsorption of polymeric and/or colloidal silica, and because different microorganisms have different cell ultrastructural chemistry, species-specific patterns of silicification arise. Despite their templating role, they do not appear to increase the kinetics of silicification, and at the very most, they contribute only marginally to the magnitude of silicification. Instead, silicification is due to the polymerization of silica-supersaturated hydrothermal fluids upon discharge at the surface of the hot spring. Microorganisms do, however, impart an influence on the fabric of the siliceous sinters that form around hot spring vents. Different microorganisms have different growth patterns, that in turn, affect the style of laminations, the primary porosity of the sinter and the distribution of later-stage diagenetic cementation. 相似文献
We synthesized nine studies that examined the influence of land use at different spatial scales in structuring biotic assemblages
and stream channel characteristics in southeastern Minnesota streams. Recent studies have disagreed about the relative importance
of catchment versus local characteristics in explaining variation in fish assemblages. Our synthesis indicates that both riparian-
and catchment-scale land use explained significant variation in water quality, channel morphology, and fish distribution and
density. Fish and macroinvertebrate assemblages can be positively affected by increasing the extent of perennial riparian
and upland vegetation. Our synthesis is robust; more than 425 stream reaches were examined in an area that includes a portion
of three ecoregions. Fishes ranged from coldwater to warmwater adapted. We suggest that efforts to rehabilitate stream system
form and function over the long term should focus on increasing perennial vegetation in both riparian areas and uplands and
on managing vegetation in large, contiguous blocks.
Minnesota Cooperative Fish and Wildlife Research Unit is jointly sponsered by U.S. Geological Survey Biological Resources
Division, the University of Minnesota, The Minnesota Department of Natural Resources, and the Wildlife Management Institute. 相似文献
Shadrach Woods, The Man in the Street, Harmondsworth, Penguin, 1975
W. Houghton Evans, Planning Cities, London, Lawrence & Wishart, 1975, £7
R. Taylor, M. Cox & I. Dickens eds., Britain's Planning Heritage, London, Croom Helm for The Royal Town Planning Institute, 1975. £5.75 (hardcover) £3.50 (paperback)
Development Plan Evaluation and Robustness: Application of an Analytical Programme and a Review of Measures of Performance, Department of the Environment Research Report 5 Local Government Operations Research Unit Report C217, 1976. Gratis.
J. Appleton, The Experience of Landscape, London, John Wiley, 1975
J. D. Hunt & P. Willis eds., The Genius of the Place: The English Landscape Garden 1620–1820, London, Paul Elek, 1976. £12.50
N. Pevsner, Staffordshire, Harmondsworth, Middx., Penguin Buildings of England Series, 1974, £3.50 (hardcover)
R. Bailey & M. Brake eds., Radical Social Work, London: Edward Arnold, 1975. £4.25 (hardcover) £1.95 (paperback)
and
The Use of Action Research in Developing Urban Planning Policy: Report of Colloquium, Bristol, June 1975 London, Department of the Environment, 1975.
M. Harloe, Swindon: A Town in Transition, London, Heinemann for the centre for Environmental Studies, 1975.
D. W. Pearce ed., The Economics of Natural Resource Depletion, London, Macmillan, 1975.
J. B. Goddard, Office Location in Urban and Regional Development
B. Fullerton, The Development of British Transport Networks
B. T. Robson, Urban Social Areas
P. L. Knox, Social Well‐Being: A Spatial Perspective
Four volumes in the Theory and Practice in Geography series, edited by J. W. House, A. S. Gouldie & J. H. C. Patten and published by Oxford University Press, 1975. All paperback at £0.90.
James A. Swan & William B. Stapp eds., Environmental Education: Strategies Toward a More Liveable Future, Halstead Press — John Wiley, 1974.
A. G. Wilson & M. J. Kirkby, Mathematics for Geographers and Planners, Oxford: Clarendon Press, 1975 相似文献
In this study, synthesis and speciation of polyaluminum chloride (PAC) for application in water treatment was investigated using a colorimetric speciation method. It was possible to produce stable preparations of PAC solutions in which a relatively stable cationic polymer predominated. The mode of preparation has a dramatic effect on the composition of PAC preparation. Some important parameters such as hydroxyl ligand number, mixing intensity, base injection rate and method, and aging were identified in this study. 相似文献
This article covers the strategic, organizational, and operational decisions involved in one automobile manufacturer's efforts to balance its goals of productivity and high quality with the more elusive goal of environmental responsibility. The case material is based on the real-life experiences of Honda of America's two manufacturing plants in East Liberty and Marysville, Ohio. The case unfolds as the environmental manager in charge of the two plants faces the pending visit of her corporate boss from Tokyo, who has made it clear that environmental issues are of growing importance in Honda's overall direction. ISO 14000, the new environmental quality standards being adopted by some other manufacturers, serves as a focusing issue for the environmental manager's thinking, but this issue is really representative of a wider challenge facing the Ohio plants: balancing Honda's core mission of producing the best cars at the lowest cost possible, and being a responsible actor in the environmental arena. Complicating this challenge, the environmental manager has to negotiate another tension common in global manufacturing firms today: balancing the influence of Honda's corporate headquarters in Japan with the local and regional context at its American plant sites. 相似文献
Platanista gangetica ) are threatened in Bangladesh from the effects of dams, large embankment schemes, dredging, fisheries bycatch, directed hunting,
and water pollution. Visual surveys of the section of the Jamuna River located between the divergence of the Old Brahmaputra
River and the confluence of the Padma River and the section of the Kushiyara River located between the Bangladesh–India border
and the confluence of the Korangi River recorded a sighting rate of 0.13 sightings/km (mean group size = 1.8 dolphins) and
0.08 sightings/km (mean group size = 3.8 dolphins), respectively. These sections of river were considered to be priority areas
for investigation because several water development projects have already been constructed and more are planned for the areas.
During the surveys we examined the remains of dolphins caught accidentally in plastic gillnets and observed fishermen catching
the fish species Clupisoma garua using dolphin oil and body parts as a fish attractor. Additional studies are needed to assess the status of dolphins and
effects of water development and fisheries bycatch. Feasibility studies should be conducted on designating dolphin/fish sanctuaries
and creating artificial habitat or enhancing existing habitat in eddy countercurrent scour pools to mitigate deleterious impacts.
The environmental requirements of river dolphins reflect the needs of productive and biotically diverse tropical rivers. 相似文献
This paper reports on two efforts to develop methods for quantifying and analysing greenhouse gas emissions from local places. The International Council for Local Environmental Initiatives-Cities for Climate Protection (ICLEI-CCP) campaign and the Association of American Geographers-Global Change in Local Places (AAG-GCLP) project represent independent efforts with differing origins and objectives. There is a rich and dynamic fine structure to the causal patterns that determine the level of greenhouse gas emissions in the society. This fine structure is essentially opaque to national and state-level inventories and analyses, and yet understanding it is necessary to understanding how human communities can be organised and human enterprise structured in environmentally sustainable ways. Simplified inventory methods that account for most but not all emissions, use readily available local data and, most important, inform efforts at emission reduction are currently available for cities and could be made available for larger or more diverse local regions or areas. 相似文献
Economic incentives for sequestering atmospheric carbon dioxide (CO2) in forests may be an effective way to meet greenhouse gas (GHG) reduction commitments under the Kyoto Protocol (KP). But concerns have been raised that the KP may create unintended incentives to excessively harvest existing forests if regenerated forests qualify for carbon (C) credits under the reforestation provision of Article 3.3. This paper combines an analytical model of the optimal forest rotation with both timber and C as priced outputs with data on timber and C growth and yield to different forest settings in the U.S. C prices of $50 per megagram (Mg) – the highest price evaluated– can considerably lengthen forest rotations (40 years or more), raise forest land values (as much as $1,900 per hectare), and sequester more C in the long run (up to 60 percent per acre), relative to the base case of no C compensation. However, if C payments are made for the regenerated stand only, in some situations, it is optimal to immediately harvest an otherwise premature stand at C prices as low as $20/Mg. The strength of perverse incentives to accelerate harvesting of existing forest varies by forest type, region, C price level, and institutional factors relevant to the compensation system. If C compensation were extended to existing stands, as may be possible under Article 3.4 of the KP, the perverse incentives for prematurely harvesting existing stands would not exist. 相似文献