Showing papers by "Volkmar Wolters published in 1997"

Spiders, Carabids, and Staphylinids: The Ecological Potential of Predatory Macroarthropods

Abstract: MICHAEL W EBER Institute of Zoology, Johannes Gutenberg University, Mainz, GermanyMany carabids and staphylinids as well as a great part of the known species of spiders live on the soil surface or in soil crevices, invade the natural pore system of soils, or are in some way closely associated with the soil system. Many carabid and staphylinid larvae actively burrow through the soil. These groups thus form an integral part of the soil macrofauna. Carabids, staphylinids, and spiders are treated here together in a separate chapter because they have in common that they are mostly polyphagous predators, and that they can significantly affect the population dynamics of many phytophagous and saprophagous invertebrates. In natural ecosystems spiders constitute the main invertebrate predatory group together with the carabids and staphylinids by the number of individuals and in some habitats also by the number of species. An economically important eco­ logical function is their contribution to pest control.

Mycorrhizal colonization and lead distribution in root tissues of Norway spruce seedlings

Abstract: Non-inoculated spruce seedlings (Picea abies Karst.) and spruce seedlings colonized with Lactarius rufus Fr., Pisolithus tinctorius Coker & Couch or Paxillus involutus Fr. were grown for 35 or 37 weeks in a microcosm system on two types of natural forest humus differing in Pb content. Using X-ray microanalysis, the distribution and content of Pb in the tissues of mycorrhizal and non-mycorrhizal root tips were compared. No significant difference in the Pb contents of root cortex cell walls of non-mycorrhizal and seedlings colonized by Lactarius rufus, Pisolithus tinctorius, or indigenous mycorrhizal fungi (mainly Tylospora sp.) was found. However, in root tips of seedlings colonized by Paxillus involutus, due to a higher binding capacity for cations, the Pb content in cell walls of the root cortex were higher than in non-mycorrhizal roots. Pb contents in cell walls of the cortex of mycorrhizal and non-mycorrhizal roots were 3 times higher in plants growing in humus with a high Pb content than in plants growing in humus with a low Pb content. It is concluded that increasing contents of Pb in the organic matter may lead to an increased loading of the apoplast with Pb. The mycobionts tested in this investigation did not exclude Pb from root tissues. Mykorrhiza und die Verteilung von Blei im Wurzelgewebe von Fichtenkeimlingen Nichtmykorrhizierte und mit Lactarius rufus Fr., Pisolithus tinctorius Coker & Couch oder Paxillus involutus Fr. beimpfte Fichtenkeimlinge (Picea abies Karst.) wurden in Kulturgefase gepflanzt, die mit Humusmaterial aus zwei unterschiedlich mit Blei belasteten Waldokosystemen gefullt waren. Nach 35 bzw. 37 Wochen wurde mittels Rontgenmikroanalyse der Bleigehalt in den Geweben mykorrhizierter und nichtmykorrhizierter Wurzelspitzen gemessen. Die Bleigehalte in den Cortexzellwanden der Mykorrhizen von L. rufus, P. tinctorius oder Tylospora sp. (gebildet durch spontane Infektion) unterschieden sich nicht signifikant von denen nichtmykorrhizierter Wurzelspitzen. Aufgrund einer hoheren Bindungskapazitat fur Kationen war der Bleigehalt der Cortexzellwande in Paxillus-involutus-Mykorrhizen hoher als in nicht-mykorrhizierten Wurzeln. Wurzeln, die in Humus mit hohem Pb-Gehalt wuchsen, hatten einen dreimal hoheren Pb-Gehalt der Cortexzellwande als vergleichbare Wurzeln aus Humus mit geringem Bleigehalt. Die Daten dieser Arbeit zeigen, das mit ansteigenden Pb-Gehalten im Humus die Beladung des Cortex-Apoplasten mit Pb zunimmt. Die untersuchten Mykobionten waren nicht in der Lage, die Bleiaufnahme in das Wurzelgewebe zu reduzieren.