Iron-rich dune grasslands: Relations between soil organic matter and sorption of Fe and P |
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Authors: | A.M. Kooijman I. Lubbers M. van Til |
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Affiliation: | aInstitute of Biodiversity and Ecosystem Dynamics, Paleoecology & Landscape Ecology, University of Amsterdam, Nieuwe Achtergracht 166, 1018 WV Amsterdam, The Netherlands;bWaternet Research & Development, P.O. Box 94370, 1090 GJ Amsterdam, The Netherlands |
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Abstract: | Effects of high atmospheric nitrogen-deposition partly depend on availability of phosphate. Lime-poor, but iron-rich dune grasslands are supposedly protected from grass-encroachment, due to P-fixation in iron phosphate. However, in iron-rich Dutch hinterdunes, dunes have low, but dry former beach plains high grass-encroachment. To test whether these zones differ in nutrient availability, and whether this changed with duration of grass-encroachment, we measured net N-mineralization, microbial characteristics and different fractions of P and Fe from pioneer and shortgrass to tallgrass stages approximately 10, 20 and >25 years old. N-mineralization did not differ between zones, but increased in older tallgrass stages in the organic layer. P-availability was significantly lower in the low grass-encroachment zone, with SOM values below 3% and mineral Fe above 40% allowing for P-fixation in iron phosphates. In the high grass-encroachment zone, however, P-availability increased, because SOM increased and Fe became incorporated in organic matter complexes, with more reversible P-sorption. |
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Keywords: | Carex arenaria Calamagrostis epigejos Coastal dunes Grass-encroachment Microorganism N-mineralization Netherlands Nutrient availability Succession |
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