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Samaritani, Emanuela
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Samaritani, Emanuela
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- PublicationAccès librePatterns of earthworm communities and species traits in relation to the perturbation gradient of a restored floodplain(2012-3-29)
; ; ; Little is known about the diversity and ecology of earthworms in floodplains, as well as their response to natural and anthropic perturbations (e.g. floods, river channelisation, floodplain restoration). We characterised the patterns of earthworm communities and species traits in the different habitats of a lowland restored floodplain in Switzerland. In addition to classical species-based metrics, such as species richness and Shannon diversity, species traits were used to calculate the community weighted means (CWMs) of traits and functional dispersion (FDis). We hypothesised that trait-based metrics would reveal clearer patterns than classical approaches. The distribution of earthworm traits varied among habitats in relation to changes in flooding frequency: poorly developed gravel bar soils most exposed to flooding were characterised by high abundance of small epigeic species and low abundance of large anecic species. Differences in anecic and endogeic earthworm community structure matched flood frequency. In agreement with our hypothesis, CWMs were more strongly correlated to environmental variables than species composition, diversity, or functional diversity. Based on these results, the ratio of the relative abundances of epigeic and anecic species, and the differences in species composition within anecic and endogeic ecological types of earthworms were identified as indicators of soil development in floodplains. - PublicationAccès libreHeterogeneity of soil carbon pools and fluxes in a channelized and a restored floodplain section (Thur River, Switzerland)(2011)
; ; ; ; Luster, J.Due to their spatial complexity and dynamic nature, floodplains provide a wide range of ecosystem functions. However, because of flow regulation, many riverine floodplains have lost their characteristic heterogeneity. Restoration of floodplain habitats and the rehabilitation of key ecosystem functions, many of them linked to organic carbon (C) dynamics in riparian soils, has therefore become a major goal of environmental policy. The fundamental understanding of the factors that drive the processes involved in C cycling in heterogeneous and dynamic systems such as floodplains is however only fragmentary.
We quantified soil organic C pools (microbial C and water extractable organic C) and fluxes (soil respiration and net methane production) in functional process zones of adjacent channelized and widened sections of the Thur River, NE Switzerland, on a seasonal basis. The objective was to assess how spatial heterogeneity and temporal variability of these pools and fluxes relate to physicochemical soil properties on one hand, and to soil environmental conditions and flood disturbance on the other hand.
Overall, factors related to seasonality and flooding (temperature, water content, organic matter input) affected soil C dynamics more than soil properties did. Coarse-textured soils on gravel bars in the restored section were characterized by low base-levels of organic C pools due to low TOC contents. However, frequent disturbance by flood pulses led to high heterogeneity with temporarily and locally increased C pools and soil respiration. By contrast, in stable riparian forests, the finer texture of the soils and corresponding higher TOC contents and water retention capacity led to high base-levels of C pools. Spatial heterogeneity was low, but major floods and seasonal differences in temperature had additional impacts on both pools and fluxes. Soil properties and base levels of C pools in the dam foreland of the channelized section were similar to the gravel bars of the restored section. By contrast, spatial heterogeneity, seasonal effects and flood disturbance were similar to the forests, except for indications of high CH4 production that are explained by long travel times of infiltrating water favoring reducing conditions. Overall, the restored section exhibited both a larger range and a higher heterogeneity of organic C pools and fluxes as well as a higher plant biodiversity than the channelized section. This suggests that restoration has indeed led to an increase in functional diversity. - PublicationAccès librePatterns of earthworm communities and species traits in relation to the perturbation gradient of a restored floodplain
; ; ; Le Bayon Renée-ClaireLittle is known about the diversity and ecology of earthworms in floodplains, as well as their response to natural and anthropic perturbations (e.g. floods, river channelisation, floodplain restoration). We characterised the patterns of earthworm communities and species traits in the different habitats of a lowland restored floodplain in Switzerland. In addition to classical species-based metrics, such as species richness and Shannon diversity, species traits were used to calculate the community weighted means (CWMs) of traits and functional dispersion (FDis). We hypothesised that trait-based metrics would reveal clearer patterns than classical approaches. The distribution of earthworm traits varied among habitats in relation to changes in flooding frequency: poorly developed gravel bar soils most exposed to flooding were characterised by high abundance of small epigeic species and low abundance of large anecic species. Differences in anecic and endogeic earthworm community structure matched flood frequency. In agreement with our hypothesis, CWMs were more strongly correlated to environmental variables than species composition, diversity, or functional diversity. Based on these results, the ratio of the relative abundances of epigeic and anecic species, and the differences in species composition within anecic and endogeic ecological types of earthworms were identified as indicators of soil development in floodplains.