Article abstract
Nature Geoscience 1, 543 - 548 (2008)
Published online: 11 July 2008 | doi:10.1038/ngeo252
Subject Categories: Biogeochemistry | Ecology
Mechanisms for retention of bioavailable nitrogen in volcanic rainforest soils
Dries Huygens1,2, Pascal Boeckx2, Pamela Templer3, Leandro Paulino4, Oswald Van Cleemput2, Carlos Oyarzún5, Christoph Müller6 & Roberto Godoy7
Abstract
Nitrogen cycling is an important aspect of forest ecosystem functioning. Pristine temperate rainforests have been shown to produce large amounts of bioavailable nitrogen, but despite high nitrogen turnover rates, loss of bioavailable nitrogen is minimal in these ecosystems. This tight nitrogen coupling is achieved through fierce competition for bioavailable nitrogen by abiotic processes, soil microbes and plant roots, all of which transfer bioavailable nitrogen to stable nitrogen sinks, such as soil organic matter and above-ground forest vegetation. Here, we use a combination of in situ15N isotope dilution and 15N tracer techniques in volcanic soils of a temperate evergreen rainforest in southern Chile to further unravel retention mechanisms for bioavailable nitrogen. We find three processes that contribute significantly to nitrogen bioavailability in rainforest soils: heterotrophic nitrate production, nitrate turnover into ammonium and into a pool of dissolved organic nitrogen that is not prone to leaching loss, and finally, the decoupling of dissolved inorganic nitrogen turnover and leaching losses of dissolved organic nitrogen. Identification of these biogeochemical processes helps explain the retention of bioavailable nitrogen in pristine temperate rainforests.
- Instituto de Ingeniería Agraria y Suelos, Universidad Austral de Chile, Casilla 567, Valdivia, Chile
- Laboratory of Applied Physical Chemistry (ISOFYS), Ghent University, Coupure 653, B-9000 Gent, Belgium
- Department of Biology, Boston University, 5 Cummington Street, Boston, Massachusetts 02215, USA
- Departamento de Suelos y Recursos Naturales, Universidad de Concepción, Casilla 537, Chillán, Chile
- Instituto de Geociencias, Universidad Austral de Chile, Casilla 567, Valdivia, Chile
- School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland
- Instituto de Botánica, Universidad Austral de Chile, Casilla 567, Valdivia, Chile
Correspondence to: Dries Huygens1,2 e-mail: Dries.Huygens@Ugent.be
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