Linking plant strategies to environmental processes in floodplains of lowland rivers

Abstract The successful use of relations between environmental processes (filters) and either plant traits or plant strategies has boosted ecological research. Various studies identified environmental filters shaping plant species composition. However, this approach is scarce in research on vegetation succession in floodplains of heavily modified rivers. Especially in these ecosystems, mechanistic knowledge is needed to understand ecological effects of human interventions and to develop strategies for floodplain rehabilitation. The aim of this study is therefore to explore whether the application of the filter-plant strategy concept reveals a better understanding of environmental drivers for vegetation succession than analyses of just species composition. And if so, could this information support floodplain management? Ten plots (1 m2) with herbaceous vegetation were studied in each of three floodplains along two distributaries of the Rhine River in the Netherlands. For each plot, environmental filters for establishment of plant species were measured (e.g. soil moisture, soil nutrient content and grain size). Data on species composition of vegetation and plant strategies, like life and growth form, were collected. The data were analyzed using the combination of fuzzy clustering and multiple regression trees. Both species composition and plant strategy composition reflected a soil moisture and nutrient gradient, but the filter-plant strategy analyses also revealed the importance of disturbances (excavation and summer inundation) for shaping vegetation composition. The plant strategy composition supplemented species surveys and benefitted understanding species assembling by anthropogenic disturbances. Moreover, application of the filter-plant strategy concept can provide insight in functional diversity, biomass and hydraulic roughness of vegetation and may support decision making on the optimization of floodplain functions.