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231.
A teacher of ours used to say, “Like ice in a fire, something for nothing you will never acquire”, which is a poetic equivalent of “there is no such a thing as a free lunch”. Human economies are dependent on high quality fossil fuels and will likely continue depending on them for some time to come. Value of a resource is not only what one pays for it, or what can be extracted from it, but also value can be attributed to the “effort” required in its production. In this analysis we apply the emergy synthesis method to evaluate the work invested by the geobiosphere to generate the global storages of fossil energy resources. The upgrading of raw resources to secondary fuels is also evaluated. The analysis relies on published estimates of historic, global net primary production (NPP) on land and oceans, published preservation and conversion factors of organic matter, and assessments of the present total global storages of coal, petroleum, and natural gas. Results show that the production of coal resources over geologic time required between 6.63E4 (±0.51E4) seJ/J and 9.71E4 (±0.79E4) seJ/J, while, oil and natural gas resources required about 1.48E5 (±0.07 E5) seJ/J and 1.70E5 (±0.06E5) seJ/J, respectively. These values are between 1.5 and 2.5 times larger than previous estimates and acknowledge a far greater power of fossil fuels in driving and shaping modern society. 相似文献
232.
Gavin Bridge 《Local Environment》2013,18(1):61-83
A central problematic for researchers working at the interface of economic and environmental change is the development of research designs and methodologies that can satisfactorily link economic processes of global reach (such as direct investment) to environmental change at local and regional scales. This article reviews recent efforts to couple economic and environmental change and finds that relatively little effort has been made to use the direct investment process as a means of linking industrial restructuring to land use change. The article argues that direct investment, when conceptualised as a political-economic process involving the assemblage of a package of rights (to land, water, pollution permits etc), can be an effective vehicle for tracing through the impacts of industrial restructuring on local environments. To develop this analytical approach, an empirical case of mineral investment in the Gila Valley of eastern Arizona is presented. The case study identifies the acquisition of land and water rights as central strategic issues for mineral firms seeking to make investment, and traces through the impact of these acquisition strategies on existing patterns of land ownership and land use. 相似文献
233.
Marcelo H. Cassini Laura Fasola Claudio Chehébar David W. Macdonald 《Die Naturwissenschaften》2009,96(5):593-599
The Southern river otter or ‘huillin’, Lontra provocax, is an endangered species endemic of the Andean Patagonian region of Argentina and Chile. It feeds almost exclusively on
the genera of macro-crustacea: Aegla and Sammastacus. The aim of this study was to analyse the role of food availability on the huillin’s distribution using a scale-dependent
analysis of crustacean and otter distributions. We compared the distributions of otters and macro-crustaceans along a north–south
regional gradient, between river basins of northern Patagonia, in an altitudinal gradient within a river basin, and between
habitat types within a lake. We investigated the distribution of otters by sign surveys along lake shores, river banks and
marine coasts, and of crustaceans using surveys in the water, undigested remains in mink (Mustela vison) scats, presence of external skeletons at the waterside and through interviews with local people. Our results show that there
were heterogeneities in the distributions of macro-crustaceans at four scales and these were generally reflected in the distributions
of freshwater otters. We conclude that the main factor limiting the distributions of L. provocax in freshwater environments is the availability of macro-crustaceans. This paper shows how scale-dependent type analyses of
population distribution serves as a method for identifying key environmental factors for species for which the use of long-term
demographies is unfeasible. 相似文献
234.
235.
Set-aside management: How do succession, sowing patterns and landscape context affect biodiversity? 总被引:1,自引:0,他引:1
Teja Tscharntke Péter BatáryCarsten F. Dormann 《Agriculture, ecosystems & environment》2011,143(1):37-44
European Union (EU) member states set aside between 5 and 15% of arable land during the last two decades, but abolition of the set-aside scheme in 2008 caused a sudden loss in habitat availability and biodiversity in agricultural landscapes. Management of set-aside has many facets and in this perspective paper we focus on the biodiversity effects of successional age, sowing strategies and landscape context. Young, 1-2-year-old set-asides have been initially considered to be too ephemeral to have any conservation value. However, when a rich seed and bud bank is available, a species-rich natural (secondary) succession can be observed. Arable (annual) weed communities in the first two years of succession can even include endangered plant species with associated rare insect consumers. Furthermore, many bird species benefit from early-successional habitats, whereas small mammal communities are richer in older habitats. If the local plant species pool is poor, sowings of diverse mixtures from regional seed collections can be recommended. Set-aside managers using species-rich sowings often experience that dominant weeds suppress the less competitive annual species. This trend to species-poor communities can be avoided by intraspecific aggregation of competitively weak species. Broadening the spatial scale from the plot to the landscape, efficiency of set-aside is highest in simple landscapes, where set-aside exhibits greatest effect in enhancement of biodiversity and associated services such as pollination and biological control. In complex landscapes, however, additional set-aside does not add much to the high level of biodiversity and ecological processes already present. Twenty percent of semi-natural, non-crop habitat appears to be a rough threshold for enhancing biodiversity and sustaining services such as pollination and biological control, but improved set-aside management should have the potential to reduce the percentage of semi-natural non-crop habitat needed. EU policy should tailor set-aside schemes for the maintenance of biodiversity and also consider that management efficiency is higher in simple than complex landscapes. 相似文献
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239.
Abstract The current pressure on production resources of North China Plain, such as land and water to feed the growing population, necessitates the assessment of the sustainability of farming practices. This study focuses on the sustainability of farming practices related to groundwater and soil fertility management. The assessment is based on selected site-specific key indicators and their established threshold limits. The current farming practices in the study area are clearly unsustainable. Only about 6% of the surveyed farm households practice sustainable farming. The study stresses that farming practice, which is economically sustainable, should not be promoted at the cost of environment. Holistic strategies need to be developed and implemented that aim at balanced use of inputs, which satisfy both productivity and environmental concerns. 相似文献
240.
《Environmental Communication: A Journal of Nature and Culture》2013,7(4):373-392
This essay attempts to address the lack of critical analyses of images of toxins by examining the photography of landscape artists whose goal is to create a presence for contaminated sites. Imaging toxicity is no simple task as many pollutants are invisible and sites of contamination are concealed, especially for those of privilege. Contemporary artists who attempt this challenge are often criticized that the beauty of their images obfuscates the health and environmental risk of the polluted sites they photograph. In response, this essay introduces the concept of the toxic sublime as a means of analyzing the tensions arising from visual representations of environmental contamination: beauty and ugliness, magnitude and insignificance, the known and the unknown, inhabitation and desolation, security and risk. The essay charts the evolution of the sublime in the US, describing how it has evolved from sites of nature to sites of technology to human damaged landscapes, some of which produce a toxic sublime. Through a close examination of Manufactured Landscapes, a twenty-five year retrospective of the images of noted environmental photographer Edward Burtynsky, this essay extends our understanding of the invention of the sublime in images, reconceptualizes the sublime response to contaminated places, as well as adding to our knowledge of how visual texts function to encourage contemplation of the viewers’ position within a polluted world. 相似文献