Springer 2005
Wetlands Ecology and Management (2005) 13: 577–585 DOI 10.1007/s11273-004-6976-0
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Effect of different chloride concentrations on nutrient release in wetland soils: a phytometer assessment in the Botshol wetlands, The Netherlands B. Beltman1,*, W.J. Rip2, A. Bak1,3 and T. Van Den Broek1 1
Department of Geobiology, Section Landscape Ecology, Utrecht University P.O. Box 800.84, NL-3508TB Utrecht, The Netherlands; 2Waterboard Amstel, Gooi & Vecht, P.O. Box 1061, NL-1200BB Hilversum, The Netherlands; 3Bureau Waardenburg, Consultants for Environment & Ecology, PO box 365. NL-41O0AJ Culemborg, The Netherlands; *Author for correspondence (e-mail:
[email protected]; phone: +31302536700; fax: 31-302518366) Received 24 January 2004; accepted in revised form 29 November 2004
Key words: Carex acutiformis, Chloride, Epilobium hirsutum, Internal eutrophication, Peat soil, Phosphate, Phytometer, Restoration
Abstract Turbid water, high phosphorus (P)-loading and disappearing Chara communities forced local water authorities to carry out restoration measures in the lakes and marshes of the Botshol The Netherlands. The reduction of the external-P input could be reached by chemical treatment of the brackish suppletion water and by separating the area from nearby agricultural areas. A side effect of these measures was an increase of chloride from 400 mg l 1 to 1000 mg l 1 in the surface water of Botshol. Internal biogeochemical processes were investigated with phytometers and direct measurements of soil nutrient availability in greenhouse experiments. The increased chloride levels were assumed to increase soil pore water P. The first experiment showed higher P in the peat-soils treated with the highest Cl-concentration and an increased leaching of PO4 from the lake-bottom peat-soils. No reaction of the phytometer Epilobium hirsutum was found. In the second experiment the 800 mg l 1 Cl-treatment resulted in significantly higher biomass of Carex acutiformis grown on treated bank soil. N-uptake by the phytometer Carex acutiformis was significantly higher. The available-P and total-P in the bank soil did not show a treatment effect. The two studies showed under similar ‘standardized’ conditions a treatment effect of chloride on the P-availability, resulting in higher PO4 leaching and increased plant nutrient concentrations and biomass. The field study showed higher availableP concentrations in the shore zone than in remote areas. The high chloride levels after restoration impact internal nutrient availability in the Botshol wetlands, on soil loaded with P in recent and historic times.
Introduction The nature reserve Botshol (5215¢ N 426¢ E, Figure 1) is situated in the Holocene part of The Netherlands. It consists of 200 ha of wetlands (shallow lakes (
