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301.
Jane Southworth R. A. Pfeifer M. Habeck J. C. Randolph O. C. Doering J. J. Johnston D. G. Rao 《Climatic change》2002,53(4):447-475
This modeling study addresses the potential impacts of climate change and changing climate variability due to increased atmospheric CO2 concentration on soybean (Glycine max (L.) Merrill) yields in theMidwestern Great Lakes Region. Nine representative farm locations and six future climate scenarios were analyzed using the crop growth model SOYGRO. Under the future climate scenarios earlierplanting dates produced soybean yield increases of up to 120% above current levels in the central and northern areas of the study region. In the southern areas, comparatively small increases (0.1 to 20%) and small decreases (–0.1 to–25%) in yield are found. The decreases in yield occurred under the Hadley Center greenhouse gas run (HadCM2-GHG), representing a greater warming, and the doubled climate variability scenario – a more extreme and variableclimate. Optimum planting dates become later in the southern regions. CO2fertilization effects (555 ppmv) are found to be significant for soybean, increasing yields around 20% under future climate scenarios.For the study region as a whole the climate changes modeled in this research would have an overall beneficial effect, with mean soybean yield increases of 40% over current levels. 相似文献
302.
A computerised algorithm is used to arrange fluid-absent reactions about invariant points in P—T space for an end-member model of blueschist facies metamorphism at Port Macquarie, N.S.W., consisting of the nine phases quartz, albite, jadeite, lawsonite, zoisite, paragonite, glaucophane, pyrope and chlorite. Inspection of the print-out (a table of reaction take-off angles for each invariant point) indicates that this multisystem consists of two mutually exclusive sets of invariant points; lawsonite-absent, paragonite-absent and glaucophane-absent versus the other six. The algorithm is completely general for any two intensive variables and can treat solid solution minerals or degeneracy in reactions/invariant points.Terms ABS(X)
Absolute value of X
- A(J)
Slope of reaction J in degrees
-
V(J)
Denominator variable in the slope fraction for reaction J
- R(K, J)
Reaction coefficient of phase K in reaction J
- S(K, J)
Stability pointer for phase K in reaction J, in degrees
- SGN (X)
Library function: =–1 when X<0; =+1 when X0
- B(Q)
Correct take-off angle for the Q-absent reaction in degrees 相似文献
303.
Melanie J. Leng Neil Roberts Jane M. Reed Hilary J. Sloane 《Journal of Paleolimnology》1999,22(2):187-204
The Konya plain in south central Anatolia, Turkey, which is now largely dry, was occupied around the time of the Last Glacial Maximum by a fresh-oligosaline lake covering more than 4000 km2. Sediment cores from three residual water bodies (Pinarbai, Akgöl and Süleymanhaci) within the larger Pleistocene lake basin, have been analysed using a multidisciplinary approach. The sediment sequences are dated as spanning the last 50 Ka years, although breaks in sedimentation mean that there is only partial chronological overlap between them. Carbon and oxygen isotope analyses on lacustrine carbonate from the three cores give contrasting isotope profiles which reflect the different ages and independent hydrological behaviour of different sub-basins through the late Quaternary. Distinguishing changes that are regional from local effects is aided by modern isotope hydrology studies and by comparing the carbonate 13C and 18O values to diatom and other analyses undertaken on the same cores. 相似文献
304.
A substantial proportion of the glacial sediments of East Anglia, England, are chaotic and highly deformed. This has been attributed to (a) direct glaciotectonic deformation or (b) slumping of glaciomarine sediments. We show that interpretation (a) leads to a classification of subglacial glaciotectonic deposits into sites of ‘constructional deformation’, where little or no erosion of the preglacial deposits has occurred and styles of deformation are preserved moving up in the sequence, and ‘excavational deformation’, where substantial erosion of preglacial sediments has occurred and deformational styles are superimposed on each other. By using glaciological and geotechnical theory, we show that the expression of these deformational styles in East Anglia is a natural response to the stress fields imposed by the ice-sheet, and that in consequence their spatial relationships are explicable. The depth of deformation is related to the geotechnical properties of till and substrate, the stress and effective stress fields, and found to be consistent with observations. 相似文献
305.
Andrea E. Gaughan Michael W. Binford Jane Southworth 《Applied geography (Sevenoaks, England)》2009,29(2):212-223
The Angkor basin of Cambodia, the site of the great Angkor temple complex, has experienced explosive tourism growth since the 1993 onset of national political stability and renewed international investment, which in turn has driven increasing demand for water, wood, and biomass fuel, and rapid and extensive land-use and land-cover change. We use multi-temporal Landsat imagery (1989–2005) to describe the rate and extent of land-cover change throughout the Angkor basin. While 50% of the landscape remained in rice agriculture it is notable that a larger proportion of the area was deforested (23.4%) than experienced forest regrowth (4.9%). Most forest loss occurred between the Angkor temple complex and Phnom Kulen National Park, and was due in part to charcoal production to serve the tourist industry, and also conversion to permanent agriculture. The small area of forest increase was concentrated along the eastern boundary of the main Angkor complex. The interplay among global (tourism, climate), regional (national policies, large-river management), and local (construction and agriculture, energy and water sources to support the tourism industry) factors drives a distinctive but complex pattern of land-use and land-cover change. 相似文献
306.
Involvement in scientifically structured habitat monitoring is a relatively new concept to the peoples of Torres Strait. The approach we used was to focus on awareness, and to build the capacity of groups to participate using Seagrass-Watch as the vehicle to provide education and training in monitoring marine ecosystems. The project successfully delivered quality scientifically rigorous baseline information on the seasonality of seagrasses in the Torres Strait—a first for this region. 相似文献
307.
Modeling biodiversity benefits and external costs from a keystone predator reintroduction policy 总被引:1,自引:1,他引:0
In this paper, an economic model was constructed to determine the optimal wolf population and distribution across the Northern Rocky Mountains. Both ecological and economic concepts were incorporated in an implicitly spatial social welfare maximization problem. This interdisciplinary model relies on multiple data sources, including current wolf population and distribution information, opportunity cost to local landowners, and contingent valuation studies to determine willingness-to-pay for wolves. Economic models tend to externalize ecological concerns and ecological models often omit the complex human dimensions of conservation policy. Accordingly, this model can serve as a guide for integrating best practices from both fields. The model presented here is sufficiently general to apply to wolves in other ecosystems and to other highly interacting species such as beavers and bison. The Northern Rocky Mountain wolf was used as an example of how this economic model works, but this model can be applied far more broadly. 相似文献
308.
During long-lived basaltic eruptions, overflows from lava channels and breaching of channel levées are important processes
in the development of extensive 'a'ā lava flow-fields. Short-lived breaches result in inundation of areas adjacent to the
main channel. However, if a breach remains open, lava supply to the original flow front is significantly reduced, and flow-field
widening is favoured over lengthening. The development of channel breaches and overflows can therefore exert strong control
over the overall flow-field development, but the processes that determine their location and frequency are currently poorly
understood. During the final month of the 2008–2009 eruption of Mt. Etna, Sicily, a remote time-lapse camera was deployed
to monitor events in a proximal region of a small ephemeral lava flow. For over a period of ~10 h, the flow underwent changes
in surface elevation and velocity, repeated overflows of varying vigour and the construction of a channel roof (a required
prelude to lava tube formation). Quantitative interpretation of the image sequence was facilitated by a 3D model of the scene
constructed using structure-from-motion computer vision techniques. As surface activity waned during the roofing process,
overflow sites retreated up the flow towards the vent, and eventually, a new flow was initiated. Our observations and measurements
indicate that flow surface stagnation and flow inflation propagated up-flow at an effective rate of ~6 m h−1, and that these processes, rather than effusion rate variations, were ultimately responsible for the most vigorous overflow
events. We discuss evidence for similar controls during levée breaching and channel switching events on much larger flows
on Etna, such as during the 2001 eruption. 相似文献
309.
Ricketts Hein J Watts D 《Irish geography : bulletin of the Geographical Society of Ireland》2010,43(2):135-147
Recent changes in local food supply systems have attracted substantial research interest, but little consideration has been paid to exactly where they occur. This article combines data from three studies to compare local food system development in England, Wales, Scotland and Ireland using a single index of food relocalisation, thereby exploring the usefulness of the Index across different social and political contexts. Four diagnostic indicators suggest that local food systems in the south west of Ireland and Britain are particularly well developed. The Index itself is a useful tool for making international comparisons, being easy to replicate and allowing the integration of different data sets. Perhaps its greatest utility is that it opens up new avenues for further research. 相似文献
310.