51 research outputs found
Diversity and Distribution of Braconidae, a Family of Parasitoid Wasps in the Central European Peatbogs of South Bohemia, Czech Republic
An ecological overview of seven years investigation of Braconidae, a family of parasitoid wasps (Hymenoptera: Ichneumonoidea) and a tyrpho-classification of parasitoids in peatbog areas of South Bohemia, Czech Republic are given. A total of 350 species were recorded in investigated sites, but only five tyrphobionts (1.4%) are proposed: Microchelonus basalis, Microchelonus koponeni, Coloneura ate, Coloneura danica and Myiocephalus niger. All of these species have a boreal-alpine distribution that, in Central Europe, is associated only with peatbogs. Tyrphophilous behaviour is seen in at least four (1.1%) species: Microchelonus pedator, Microchelonus subpedator, Microchelonus karadagi and Microchelonus gravenhorstii; however, a number of other braconids prefer peatbogs because they were more frequently encountered within, rather than outside, the bog habitat. The rest of the braconids (342 species, 97.5%) are tyrphoneutrals, many of them being eurytopic components of various habitats throughout their current ranges. Lists of tyrphobiontic braconids and a brief commentary on species composition, distributional picture of actual ranges, and parasitoid association to bog landscape are provided. Being true refugial habitats for populations in an ever-changing world, peatbogs play a significant role in harboring insect communities
Human transformations of the Wadden Sea ecosystem through time: a synthesis
Todayrsquos Wadden Sea is a heavily human-altered ecosystem. Shaped by natural forces since its origin 7,500 years ago, humans gradually gained dominance in influencing ecosystem structure and functioning. Here, we reconstruct the timeline of human impacts and the history of ecological changes in the Wadden Sea. We then discuss the ecosystem and societal consequences of observed changes, and conclude with management implications. Human influences have intensified and multiplied over time. Large-scale habitat transformation over the last 1,000 years has eliminated diverse terrestrial, freshwater, brackish and marine habitats. Intensive exploitation of everything from oysters to whales has depleted most large predators and habitat-building species since medieval times. In the twentieth century, pollution, eutrophication, species invasions and, presumably, climate change have had marked impacts on the Wadden Sea flora and fauna. Yet habitat loss and overexploitation were the two main causes for the extinction or severe depletion of 144 species (~20% of total macrobiota). The loss of biodiversity, large predators, special habitats, filter and storage capacity, and degradation in water quality have led to a simplification and homogenisation of the food web structure and ecosystem functioning that has affected the Wadden Sea ecosystem and coastal societies alike. Recent conservation efforts have reversed some negative trends by enabling some birds and mammals to recover and by creating new economic options for society. The Wadden Sea history provides a unique long-term perspective on ecological change, new objectives for conservation, restoration and management, and an ecological baseline that allows us to envision a rich, productive and diverse Wadden Sea ecosystem and coastal society
Bedeutung des Eises als Archiv fuÌr Klima- und UmweltveraÌnderungen der Vergangenheit
FuÌr die Rekonstruktion der Klimageschichte spielen Eisbohrkerne aus den Polarregionen und den Hochgebirgsgletschern eine herausragende Rolle unter den Klimaarchiven auf unserer Erde. Nur im Eis ist alte atmosphaÌrische Luft, mit EinschluÌssen von z.B. Kohlendioxid und Methan, in bestimmbarer zeitlicher Abfolge gespeichert. Tiefe Eiskerne aus der Ostantarktis dokumentieren bislang etwa die letzten 800.000 Jahre. Die letzte Kaltzeit und die vorletzte Zwischeneiszeit, also etwa die letzten 100.000-130.000 Jahre, werden mit Eisbohrkernen aus der Westantarktis und von GroÌnland erfasst, die letzten 100-2.000 Jahre sind auch in Eisbohrkernen aus Hochgebirgsgletschern und den arktischen Eiskappen enthalten. Die Entwicklung der Messtechnik zur Bestimmung von Gehalten an stabilen Wasserisotopen und chemischen Substanzen im Eis in den letzen zwei Jahrzehnten hat die zeitliche AufloÌsung der gewonnenen Information deutlich erhoÌht.
Ice cores from the polar regions and high alpine glaciers play an important role for the reconstruction of the climate history on earth. Old atmospheric gases like carbon dioxide or methane have been stored only in the climate archive ice where their concentrations and ages can be determined. Until now deep ice cores from East Antarctica provide information about the past 800,000 years. The last ice age and the previous interglacial, approximately the past 100,000 to 130,000 years, are included in ice cores from West Antarctica and Greenland. In addition, ice cores from high alpine areas and arctic ice caps provide information about the past 100 to 2,000 years. During the past two decades technical improvements to measure the content of stable isotopes in the water molecule and trace elements included in ice enabled us to get a much higher time resolution than it was possible in earlier investigations
- âŠ