Evidence for sensitivity of dune wetlands to groundwater nutrients

Rhymes, Jennifer; Wallace, Hilary; Fenner, Nathalie; Jones, Laurence. 2014 Evidence for sensitivity of dune wetlands to groundwater nutrients. Science of the Total Environment, 490. 106-113.

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Dune slacks are seasonal wetlands, high in biodiversity, which experience considerable within-year and between-year variations in water-table. They are subject to many pressures including climate change, land use change and eutrophication. Despite their biological importance and the threats facing them, the hydrological and nutrient parameters that influence their soil properties and biodiversity are poorly understood and there have been no empirical studies to date testing for biological effects in dune systems resulting from groundwater nutrients at low concentrations. In this study we examined the impact of groundwater nutrients on water chemistry, soil chemistry and vegetation composition of dune slacks at three distance classes (0-150 m, 150–300 m, 300–450 m) away from known (off-site) nutrient sources at Aberffraw dunes in North Wales, whilst controlling for differences in water-table regime. Groundwater nitrate and dissolved inorganic nitrogen (DIN) and soil nitrate and nitrite all had significantly higher concentrations closest to the nutrient source. Multivariate analysis showed that although plant species composition within this site was primarily controlled by water table depth and water table fluctuation, nitrogen from groundwater also influenced species composition, independently of water table and soil development. A model containing all hydrological parameters explained 17% of the total species variance; an additional 7% was explained following the addition of NO3 to this model. Areas exposed to elevated, but still relatively low, groundwater nutrient concentrations (mean 0.204 mg/L +/- 0.091 of DIN) had greater abundance of nitrophilous species and fewer basipholous species. This shows clear biological impact below previously suggested DIN thresholds of 0.20 – 0.40 (mg/L).

Item Type: Publication - Article
Digital Object Identifier (DOI):
UKCEH and CEH Sections/Science Areas: Emmett
ISSN: 0048-9697
Additional Keywords: dune slacks, nitrogen, groundwater, contamination, sand dunes, ecohydrology
NORA Subject Terms: Ecology and Environment
Date made live: 27 Jan 2015 12:47 +0 (UTC)

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