Do seed and germination traits determine plant distribution patterns in riparian landscapes?

This study tested several seed, germination and seedling traits in 20 floodplain pioneer species for their ability to discriminate two groups of species differentiated by their distribution patterns in floodplain landscapes. The tell species of the first group are restricted to semi-terrestrial habitats with high river-floodplain connectivity, such as river margins and permanently connected side arms. The second group is characterised by having no connectivity preferences or by occurring mainly in isolated habitats in front of and behind the dykes. The traits under consideration were seed properties Such as size, weight and seed buoyancy and germination properties including germination ability under water in light and darkness, in and oil sediments with respect to different moisture conditions as well as under different pH conditions. Furthermore, the ability of seedlings germinated under water to take root oil the soil surface was tested for all species. The results of generalised linear modelling (GLM) identified several traits as significantly different among the groups. The pattern of a principal components analysis (PCA) of all species traits revealed that both groups are distinctively separated from each other, implying that the considered traits call explain the distribution pattern or the groups. Responsible for group differentiation are the seed traits as well as the germination ability tinder water and on soil surface. The Study revealed that species restricted to highly connected habitats have distinctive seed and germination properties, which enable them to cope with severe disturbances and Unpredictable conditions. (C) 2008 Gesellschart fur Okologic. Published by Elsevier GmbH. All rights reserved.