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151.
Ecosystem services (ES) is an important approach to biodiversity protection in political rhetoric and policy practice, but it is also highly contested. This paper analyzes the introduction of ES in Swedish environmental policy and how it is contested by key stakeholders and discusses its implications for biodiversity governance. The results show that although ES is widely accepted on an abstract and conceptual level, critical features and functions are highly contested. These primarily concern the valuation of nature, appropriateness of different policy instruments, and institutional structures. The paper concludes that while the controversy surrounding ES fills an important role by reinvigorating debate and stimulating reflections on biodiversity loss, it also illustrates how ES is used to further particular values and beliefs and to challenge traditional biodiversity-protecting strategies. Understanding these policy controversies is central to addressing the challenges of transforming the promises of ES into practical policies. 相似文献
152.
153.
Erik Harms 《Singapore journal of tropical geography》2014,35(3):312-327
Lands cleared for Vietnamese New Urban Zones are commonly described as ‘wastelands’ (??t hoang) in need of development. But clearing these lands in Vietnam's densely populated urban areas requires evicting large numbers of urban residents. How is it possible to render populated spaces as empty wastelands? This paper juxtaposes new ethnographic research in Ho Chi Minh City against historical scholarship on Vietnamese concepts of ‘clearing the wasteland’ and colonial civilizing projects of mise en valeur. In doing so, the article describes these concepts as parallel legitimizing strategies that effectively enable developers and planners to render previously occupied and utilized lands as empty, uninhabited wastelands. The article shows that the same narrative structure used in these earlier contexts is used to justify current urban development projects. 相似文献
154.
We present a complete ray theory for the calculation of surface-wave observables from anisotropic phase-velocity maps. Starting with the surface-wave dispersion relation in an anisotropic earth model, we derive practical dynamical ray-tracing equations. These equations allow calculation of the observables phase, arrival-angle and amplitude in a ray theoretical framework. Using perturbation theory, we also obtain approximate expressions for these observables. We assess the accuracy of the first-order approximations by using both theories to make predictions on a sample anisotropic phase-velocity map. A comparison of the two methods illustrates the size and type of errors which are introduced by perturbation theory. Perturbation theory phase and arrival-angle predictions agree well with the exact calculation, but amplitude predictions are poor. Many previous studies have modelled surface-wave propagation using only isotropic structure, not allowing for anisotropy. We present hypothetical examples to simulate isotropic modelling of surface waves which pass through anisotropic material. Synthetic data sets of phase and arrival angle are produced by ray tracing with exact ray theory on anisotropic phase-velocity maps. The isotropic models obtained by inverting synthetic anisotropic phase data sets produce deceptively high variance reductions because the effects of anisotropy are mapped into short-wavelength isotropic structure. Inversion of synthetic arrival-angle data sets for isotropic models results in poor variance reductions and poor recovery of the isotropic part of the anisotropic input map. Therefore, successful anisotropic phase-velocity inversions of real data require the inclusion of both phase and arrival-angle measurements. 相似文献
155.
The spatial and temporal distributions of marine cold air outbreaks (MCAOs) over the northern North Atlantic have been investigated using re-analysis data for the period from 1958 to 2007. MCAOs are large-scale outbreaks of cold air over a relatively warm ocean surface. Such conditions are known to increase the severity of particular types of hazardous mesoscale weather phenomena. We used a simple index for identifying MCAOs: the vertical potential temperature gradient between the sea surface and 700 hPa. It was found that atmospheric temperature variability is considerably more important than the sea surface temperature variability in governing both the seasonal and the inter-annual variability of MCAOs. Furthermore, a composite analysis revealed that a few well-defined and robust synoptic patterns are evident during MCAOs in winter. Over the Labrador and Irminger Seas the MCAO index was found to have a correlation of 0.70 with the North Atlantic Oscillation index, while over the Barents Sea a negative correlation of 0.42 was found. 相似文献
156.
For the first time, new material of one of the world's oldest known tetrapods, Acanthostega, has been studied in its sedimentological context. The reported evidence suggests that Acanthostega was primarily aquatic and inhabited active fluvial channels in fluvial-dominated environments. 相似文献
157.
Manfred Sthli Lars Nyberg Per‐Erik Mellander Per‐Erik Jansson Kevin H. Bishop 《水文研究》2001,15(6):927-941
A physically based SVAT‐model was tested with soil and snow physical measurements, as well as runoff data from an 8600 m2 catchment in northern Sweden in order to quantify the influence of soil frost on spring snowmelt runoff in a moderately sloped, boreal forest. The model was run as an array of connected profiles cascading to the brook. For three winter seasons (1995–98) it was able to predict the onset and total accumulation of the runoff with satisfactory accuracy. Surface runoff was identified as only a minor fraction of the total runoff occurring during short periods in connection with ice blocking of the water‐conducting pores. Little surface runoff, though, does not mean that soil frost is unimportant for spring runoff. Simulations without frost routines systematically underestimated the total accumulated runoff. The possibility of major frost effects appearing in response to specific combinations of weather conditions were also tested. Different scenarios of critical initial conditions for the winter, e.g. high water saturation and delayed snow accumulation leading to an increased frost penetration, were tested. These showed that under special circumstances there is potential for increased spring runoff due to soil frost. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
158.
159.
In this contribution, the regularized Earth’s surface is considered as a graded 2D surface, namely a curved surface, embedded
in a Euclidean space . Thus, the deformation of the surface could be completely specified by the change of the metric and curvature tensors, namely
strain tensor and tensor of change of curvature (TCC). The curvature tensor, however, is responsible for the detection of
vertical displacements on the surface. Dealing with eigenspace components, e.g., principal components and principal directions
of 2D symmetric random tensors of second order is of central importance in this study. Namely, we introduce an eigenspace
analysis or a principal component analysis of strain tensor and TCC. However, due to the intricate relations between elements
of tensors on one side and eigenspace components on other side, we will convert these relations to simple equations, by simultaneous
diagonalization. This will provide simple synthesis equations of eigenspace components (e.g., applicable in stochastic aspects).
The last part of this research is devoted to stochastic aspects of deformation analysis. In the presence of errors in measuring
a random displacement field (under the normal distribution assumption of displacement field), the stochastic behaviors of
eigenspace components of strain tensor and TCC are discussed. It is applied by a numerical example with the crustal deformation
field, through the Pacific Northwest Geodetic Array permanent solutions in period January 1999 to January 2004, in Cascadia
Subduction Zone. Due to the earthquake which occurred on 28 February 2001 in Puget Sound (M
w > 6.8), we performed computations in two steps: the coseismic effect and the postseismic effect of this event. A comparison
of patterns of eigenspace components of deformation tensors (corresponding the seismic events) reflects that: among the estimated
eigenspace components, near the earthquake region, the eigenvalues have significant variations, but eigendirections have insignificant
variations. 相似文献
160.
Shea Christopher J. Steinman Byron A. Brown Erik T. Schreiner Kathryn M. 《Journal of Paleolimnology》2022,67(2):163-182
Journal of Paleolimnology - Analysis of the oxygen isotopic composition (δ18O) of sedimentary carbonates in Turquoise Lake (N50.83°, W121.69°, 807 m), southwestern British... 相似文献