TY - JOUR A1 - Lambeets, Kevin A1 - Vandegehuchte, Martijn L. A1 - Maelfait, Jean-Pierre A1 - Bonte, Dries T1 - Understanding the impact of flooding on trait-displacements and shifts in assemblage structure of predatory arthropods on river banks N2 - 1. Species assemblages of naturally disturbed habitats are governed by the prevailing disturbance regime. Consequently, stochastic flood events affect river banks and the inhabiting biota. Predatory arthropods occupy predominantly river banks in relation to specific habitat conditions. Therefore, species sorting and stochastic processes as induced by flooding are supposed to play important roles in structuring riparian arthropod assemblages in relation to their habitat preference and dispersal ability. 2. To ascertain whether assemblages of spiders and carabid beetles from disturbed river banks are structured by stochastic or sorting mechanisms, diversity patterns and assemblage-wide trait-displacements were assessed based on pitfall sampling data. We tested if flooding disturbance within a lowland river reach affects diversity patterns and trait distribution in both groups. 3. Whereas the number of riparian spider species decreased considerably with increased flooding, carabid beetle diversity benefited from intermediate degrees of flooding. Moreover, regression analyses revealed trait-displacements, reflecting sorting mechanisms particularly for spiders. Increased flooding disturbance was associated with assemblage-wide increases of niche breadth, shading and hygrophilic preference and ballooning propensity for spider (sub)families. Trait patterns were comparable for Bembidiini carabids, but were less univocal for Pterostichini species. Body size decreased for lycosid spiders and Bembidiini carabids with increased flooding, but increased in linyphiid spiders and Pterostichini carabids. 4. Our results indicate that mainly riparian species are disfavoured by either too high or too low degrees of disturbance, whereas eurytopic species benefit from increased flooding. Anthropogenic alterations of flooding disturbance constrain the distribution of common hygrophilous species and/or species with high dispersal ability, inducing shifts towards less specialized arthropod assemblages. River banks with divergent degrees of flooding impact should be maintained throughout dynamic lowland river reaches in order to preserve typical riparian arthropod assemblages. KW - Flussufer KW - body size KW - dispersal ability KW - niche breadth KW - riparian ecology KW - trait-displacement Y1 - 2008 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-49580 ER - TY - JOUR A1 - Lambeets, Kevin A1 - Vandegehuchte, Martijn L. A1 - Maelfait, Jean-Pierre A1 - Bonte, Dries T1 - Integrating environmental conditions and functional life-history traits for riparian arthropod conservation planning N2 - River banks are naturally disturbed habitats, in which local flood events and the landscape structure are expected to govern riparian species assemblages. Not solely effects of flooding per se, but also related changes in vegetation structure will affect species’ distribution. By elucidating the relationships between species’ occurrence and multivariate habitat conditions on a restricted spatial scale, insight into conservation strategies to preserve riparian species is gained. Ordination and grouping methods revealed important environmental and functional trait constraints on species composition of predatory riparian arthropod assemblages. Mainly flooding disturbance appeared to affect spider and carabid beetle species composition. Habitat affinity and dispersal ability were retained as important traits explaining similarity between arthropod assemblages. River banks similar in species composition differed in absolute and functional group species richness. Furthermore, Poisson regressions demonstrated the importance of variation in discharge regime, sediment composition and vegetation structure for the preservation of rare riparian arthropods. Whereas hygrophilic species benefited from increased vegetation cover, xerothermophilic specialists were favoured by increased flooding disturbance. In contrast to flight-active riparian carabids occurring throughout the river system, especially cursorial spiders are expected to go extinct under increased anthropogenic alterations of discharge regimes. We show the importance of a dynamic and evidence-based approach of river management on a local scale to preserve vulnerable riparian arthropods. In general, river restoration should generate the required heterogeneity in environmental conditions (e.g. dynamic processes) at the river bank level, thereby increasing the sustainability of riverine landscapes. More-over, we argue that the understanding of functional responses towards environmental factors results in general and widely applicable guiding concepts for species conservation. KW - Laufkäfer KW - Flussufer KW - carabid beetles KW - flooding disturbance KW - multi-species approach KW - lowland river banks KW - river restoration KW - spiders Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-50148 ER -