Refine
Has Fulltext
- yes (3)
Is part of the Bibliography
- yes (3)
Document Type
- Doctoral Thesis (2)
- Journal article (1)
Keywords
- Landschaft (3) (remove)
Nowadays, agriculturally used areas form a major part of the German landscape. The conversion from natural habitats to agriculturally used grasslands fundamentally influences the diversity of plants and animals. Intensive use of these areas increases indeed the productivity of crop or biomass on meadows as food source for cattle. How these influences affect biodiversity, ecosystems and trophic interactions over years is still not understood completely. To understand biodiversity functions in an agriculturally used area my study focused on the influence of land use (fertilization, grazing and mowing) on a herbivore-parasitoid system of Plantago lanceolata. The ribwort plantain is a generalist herb of cosmopolitan distribution. It can grow in a very broad range of ground conditions (both in wet and dry habitats), which makes P. lanceolata an ideal model system for investigating tritrophic interactions in a gradient of land use intensity. The weevils Mecinus labilis and M. pascuorum feed and oviposit on P. lanceolata. Mesopolobus incultus is a generalist parasitoid that parasitizes different insect orders. However its only hosts on P. lanceolata are the two weevil species mentioned before. The intention of my study was to investigate the influence of land use on a tritrophic system and its surrounding vegetation (structure, density and species richness) at different spatial scales like subplot, plot and landscape level in three different regions (north, middle and south of Germany). I studied the influence of land use intensity not only correlative but also experimentally. Additionally I aimed to reveal how vegetation composition changes host plant metabolites and whether these changes impact higher trophic levels in the field.
Background: Patterns that arise from an ecological process can be driven as much from the landscape over which the process is run as it is by some intrinsic properties of the process itself. The disentanglement of these effects is aided if it possible to run models of the process over artificial landscapes with controllable spatial properties. A number of different methods for the generation of so-called ‘neutral landscapes’ have been developed to provide just such a tool. Of these methods, a particular class that simulate fractional Brownian motion have shown particular promise. The existing methods of simulating fractional Brownian motion suffer from a number of problems however: they are often not easily generalisable to an arbitrary number of dimensions and produce outputs that can exhibit some undesirable artefacts. Methodology: We describe here an updated algorithm for the generation of neutral landscapes by fractional Brownian motion that do not display such undesirable properties. Using Monte Carlo simulation we assess the anisotropic properties of landscapes generated using the new algorithm described in this paper and compare it against a popular benchmark algorithm. Conclusion/Significance: The results show that the existing algorithm creates landscapes with values strongly correlated in the diagonal direction and that the new algorithm presented here corrects this artefact. A number of extensions of the algorithm described here are also highlighted: we describe how the algorithm can be employed to generate landscapes that display different properties in different dimensions and how they can be combined with an environmental gradient to produce landscapes that combine environmental variation at the local and macro scales.
Beschäftigt man sich mit der griechischen Religion, beschäftigt man sich zwangsläufig auch mit der griechischen Polis. Denn sie war Trägerin der griechischen Religion. So sind die sich daraus ergebenden „sakralen Landschaften“ im Sinne der Humangeographie bzw. Raumsoziologie eine Konstruktion von Raum und damit ein relationales System, das vielfachen Formen der Umgestaltung unterliegt. Denn Religion ist genauso wie der Raum nicht statisch konstruiert. Vielmehr beschreibt sie ein Spannungsfeld von Kontinuitäten, Umdeutungen und Brüchen. wie sie sich besonders in Zeiten des Wandels offenbaren. Eine solche Phase bedeutete auch die Integration Griechenlands in das Römische Reich. So galt das Hauptinteresse der Arbeit der Periode nach Oktavians Sieg bei Actium und der darauffolgenden Etablierung der Provinz Achaia 27 v. Chr. bis hin zu Caracallas constitutio Antoniniana. Der geographische Rahmen orientierte sich an den peloponnesischen Regionen Achaia, Argolis und Arkadien. Sie ermöglichten es, das römische Griechenland jenseits der immer wieder erwähnten Orte Athen, Sparta und Korinth zu erfassen. Die Ergebnisse werden zusammen mit historischen Fakten, Siedlungsstrukturen und wirtschaftlichen Bedingungen in einem ersten, topographisch orientierten Abschnitt formuliert. Im zweiten Teil der Abhandlung steht dagegen eine gesonderte Untersuchung übergreifender Phänomene und ihre Einbindung in einen weitergefaßten geographischen Kontext im Vordergrund.