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Gertjan Dijkink 《GeoJournal》2000,51(1-2):65-71
The capital is the centre of the established order but it always had to accept a relatively uncontrollable world of individuals redefining urban space in their own way or pioneering new means of support. As their existence is both a political nuisance and a foreshadowing of institutional changes (sometimes revolutionary) of nation-wide importance, I call such ways of life political frontiers. One may wonder what will become of political frontiers in the information society (or postmodern society) that, apart from borderless, has been described as society without a centre as well. Actually information society is the prototype of a frontier society with self-responsible groups and individuals. However, capitals – even stripped of their governmental functions – may offer a symbolical environment (a condensation of space and time) that precisely satisfies the wants of those who wish to politicise a way of life. Niches for pioneering behaviour may get dispersed over a wider territory but new types of political activity will gravitate to the capital even if the capital's official political status has dwindled. 相似文献
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Jochem Verrelst Gertjan W. Geerling Karle V. Sykora Jan G.P.W. Clevers 《International Journal of Applied Earth Observation and Geoinformation》2009
Combined optical and laser altimeter data offer the potential to map and monitor plant communities based on their spectral and structural characteristics. A problem unresolved is, however, that narrowly defined plant communities, i.e. plant communities at a low hierarchical level of classification in the Braun-Blanquet system, often cannot be linked directly to remote sensing data for vegetation mapping. We studied whether and how a floristic dataset can be aggregated into a few major discrete, mappable classes without substantial loss of ecological meaning. Multi-source airborne data (CASI and LiDAR) and floristic field data were collected for a floodplain along the river Waal in the Netherlands. Mapping results based on floristic similarity alone did not achieve highest levels of accuracy. Ordination of floristic data showed that terrain elevation and soil moisture were the main underlying environmental drivers shaping the floodplain vegetation, but grouping of plant communities based on their position in the ordination space is not always obvious. Combined ordination-based grouping with floristic similarity clustering led to syntaxonomically relevant aggregated plant assemblages and yielded highest mapping accuracies. 相似文献
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Mijke van Oorschot Maarten Kleinhans Gertjan Geerling Hans Middelkoop 《地球表面变化过程与地形》2016,41(6):791-808
Dynamic interaction between river morphodynamics and vegetation affects river channel patterns and populations of riparian species. A range of numerical models exists to investigate the interaction between vegetation and morphodynamics. However, many of these models oversimplify either the morphodynamics or the vegetation dynamics, which hampers the development of predictive models for river management. We have developed a model coupling advanced morphodynamics and dynamic vegetation, which is innovative because it includes dynamic ecological processes and progressing vegetation characteristics as opposed to commonly used static vegetation without growth and mortality. Our objective is to understand and quantify the effects of vegetation‐type dependent settling, growth and mortality on the river pattern and morphodynamics of a meandering river. We compared several dynamic vegetation scenarios with different functional trait sets to reference scenarios without vegetation and with static vegetation without growth and mortality. We find distinct differences in morphodynamics and river morphology. The default dynamic vegetation scenario, based on two Salicaceae species, shows an active meandering behaviour, while the static vegetation scenario develops into a static, vegetation‐dominated state. The diverse vegetation patterns in the dynamic scenario reduce lateral migration, increase meander migration rate and create a smoother floodplain compared to the static scenario. Dynamic vegetation results in typical vegetation patterns, vegetation age distribution and river patterns as observed in the field. We show a quantitative interaction between vegetation and morphodynamics, where increasing vegetation cover decreases sediment transport rates. Furthermore, differences in vegetation colonization, density and survival create distinct patterns in river morphology, showing that vegetation properties and dynamics drive the formation of different river morphologies. Our model demonstrates the high sensitivity of channel morphodynamics to various species traits, an understanding which is required for floodplain and stream restoration and more realistic modelling of long‐term river development. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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Gertjan Dijkink 《GeoJournal》1998,46(4):293-299
Geopolitical codes – intellectual tools for practising statecraft – share a certain basic understanding of the world with less articulate, popular representations. Both are influenced by national geographies and histories. The international power game may (particularly in large countries) temporarily alienate codes from popular representations but the ensuing conflicts also prove the solidity of popular visions about the world order. Change is nevertheless possible and should be one of the central themes of research in geopolitical representations. This article concludes with specifying five perspectives that can be adopted in cross-national research: time/space models of the world, national myths, territorial narratives, active/passive approach of international relations and reactions to international crises. 相似文献
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European regions increasingly develop inter-regional and transnational visions. They not only compete with each other on the basis of traditional location factors (transport, taxes, and labour market) but also by calling up the image of an entirely alternative society which is portrayed as both flexible and capable of self-reproduction. In this article the presence of this (postfordist) discourse is investigated in Web sites of four European regions: Baden-Württemberg, Cataluña, Leningrad and Friesland. Baden-Württemberg confirms its reputation as one of the most outspoken representatives of the new regional assertiveness. Its rhetoric relies on a mixture of cultural, individual and technological arguments largely neglecting internal geographical variation. Although this type discourse can be easily emulated – irrespective of real world differences in the regimes of accumulation – not all regions seem to have (yet) succumbed to its formula. 相似文献
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