Spatial hydrological flow processes, water quality and vegetation community distributions in a natural floodplain fen

Abstract

We studied spatial patterns in inundation water quality in a floodplain fen in Poland, resulting from interacting hydrological flow processes. Using PCA and K-means cluster analysis, we identified four clearly distinguishable water types, related to river water inundation, discharge of clean and polluted groundwater, and precipitation and snowmelt dilution. Spatially, these hydrochemically separable types are related to known water sources in the floodplain and occupy distinctive zones. River water is found along the river, clean and polluted groundwater at the valley margins and groundwater diluted with precipitation and snowmelt water in the central part of the floodplain. This means that despite the floodplain being completely inundated, nutrients from river water are only brought in to a relatively narrow zone of the floodplain. Our findings question the relevance of the edge of inundation, presented in the Flood Pulse Concept, for spatial patterns in input and turnover of nutrients. Secondly, we studied rich-fen and freshwater vegetation community distributions in relation to the presented inundation water quality types. We successfully determined inundation water quality preference of 14/17 studied rich-fen and freshwater communities. Spatial patterns in preference show vegetation with attributed river water preference to occur close to the river channel, with increasing distance to the river followed by communities with no preference, diluted groundwater preference in the central part, and clean and polluted groundwater preference at the valley margins. We compared our findings to similar wetlands across Canada and Eurasia, and found relations could not be extrapolated, possibly due to geographical variation between wetlands.