In order to uncover patterns and processes of segregation of co-existing cytotypes, we investigated a zone in the eastern Alps (Austria) where diploid and hexaploid individuals of the alpine herb Senecio carniolicus Willd. (Asteraceae) co-occur. Linking the fine-scale distribution of cytotypes to environmental and spatial factors revealed segregation along an ecological gradient, which was also reflected in the cytotype-associated plant assemblages. Compared to diploids, hexaploids are found in more species-rich and denser communities. This may be due to their better competitive ability and lower tolerance of abiotic stress compared to the diploids. The lack of any intermediate cytotypes suggests the presence of strong reproductive isolation mechanisms, whose nature is, however, elusive.
he breeding bird communities in four networks of line corridors were studied during the period 1993-1996 with the aim to characterise the influence of intersections and dead-ends of corridors on the breeding bird distribution. The results of this study show that species richness and number of territories in line-corridors depend on the vegetation volume, width and distance of the section from the nearest intersection or dead-end. Moreover, the abundance of corridor-dependent species is influenced not only by the distance of the section from the nearest intersection or dead-end, but also by the section type. Sections adjacent to intersections support more territories of corridor-dependent species. In our study we recorded increasing number of territories of nightingale, blackcap, whitethroat, lesser whitethroat along with the decreasing distance of sections from dead-ends or intersections. Territories of great tit and icterine warbler were more common in sections adjacent to intersections. Only one species (tree sparrow) was associated with sections adjacent to dead-ends.