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Communication Dans Un Congrès Année : 2023

Vegetation community composition and strategies along environmental gradients in an anthropized estuary

Résumé

The tidal marshes in the nature reserve of the Seine Estuary in northern France have been shaped by long-lasting and extensive human activities. In this anthropized setting, we have studied the vegetation communities along gradients of disturbance (inundation and salinity), under different land use types (grazing and mowing) and tidal regimes (tidal restriction and tidal influence) in the – often overlooked – oligohaline marshes of the estuary. Our aim was to identify and hierarchise the instrumental factors behind the characteristic patch dynamics of the vegetation communities along these gradients, and to foresee possible trajectories of the communities in a context of climate change and rising seawater levels. Canonical Correspondence Analysis between vegetation and soil surveys revealed that topography, soil pH, conductivity and organic carbon explained most of the differences between vegetation communities, followed by exchangeable cation availability. Community-weighted means applied to functional trait data from the TRY-database and our vegetation surveys have provided evidence for acquisition- and conservation-based strategies at the community level. This method also revealed the stress- and perturbation gradients of our study sites, through Grime’s CSR strategies. The stress gradient was negatively correlated to topography and acquisition strategy, while disturbance and conservation gradients could mostly be explained by land use. We also found that the local hydrodynamic conditions of each site were responsible for significant shifts in community assemblages. Finally, we measured significantly longer disturbance gradients on the tidally restricted sites, implying larger ecotones. Tidal restriction may therefore be an appealing decision-making tool for ecological conservation and agricultural practices.
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hal-04227537 , version 1 (05-10-2023)

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  • HAL Id : hal-04227537 , version 1

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Markus Neupert, Michaël Aubert, Estelle Langlois. Vegetation community composition and strategies along environmental gradients in an anthropized estuary. 65th Annual IAVS Symposium, IAVS (International Association for Vegetation Science), Sep 2023, Coffs Harbour, Australia. ⟨hal-04227537⟩
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