Evidence for sensitivity of dune wetlands to groundwater nutrients

• Published in: The Science of the total environment Vol. 490; pp. 106 - 113
• Main Authors: Rhymes, Jennifer, Wallace, Hilary, Fenner, Nathalie, Jones, Laurence
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 15.08.2014; Elsevier
• Subjects: Animal, plant and microbial ecology; Applied ecology; bioactive properties; Biodiversity; Biological; Biological and medical sciences; botanical composition; Climate Change; Concentration (composition); Conservation, protection and management of environment and wildlife; Contamination; dissolved inorganic nitrogen; Dune slacks; Dunes; Ecohydrology; Environmental degradation: ecosystems survey and restoration; Eutrophication; Fundamental and applied biological sciences. Psychology; Groundwater; Groundwater - chemistry; hydrochemistry; Hydrology; land use change; multivariate analysis; nitrates; nitrites; Nitrogen; Nitrogen - analysis; Nutrients; Phosphorus - analysis; Sand dunes; seasonal wetlands; Soil (material); soil chemistry; soil properties; variance; Wales; Water Pollutants, Chemical - analysis; water table; Wetlands; Wales; British Isles, Wales; Ecohydrology; Dune slacks; Groundwater; Nitrogen; Contamination; Sand dunes; Soil chemistry; Sand; Nitrites; Nitrates; Pollution; Sensitivity; Inorganic anion; Inorganic nitrogen; Nutrient; Agriculture; Water pollution; Wetland; Dunes; Ground water
• ISSN: 0048-9697; 1879-1026; 1879-1026
• DOI: 10.1016/j.scitotenv.2014.04.029

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 (0–150m, 150–300m, 300–450m) away from known (off-site) nutrient sources at Aberffraw dunes in North Wales, whilst accounting 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 0.204mg/L+/−0.091 of DIN) had greater abundance of nitrophilous species and fewer basipholous species than in areas with lower concentrations. This shows that clear biological impact occurs below previously suggested DIN thresholds of 0.20–0.40 (mg/L). •We studied a dune system surrounded by fertilised agricultural land.•Groundwater nutrients affected vegetation and soils in dune slack wetlands.•Change in vegetation and soil were observed at 0.2mg/L of DIN within groundwater.