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Gross nitrogen dynamics in the mycorrhizosphere of an organic forest soil

Titelangaben

Holz, Maire ; Aurangojeb, Mohammad ; Kasimir, Åsa ; Boeckx, Pascal ; Kuzyakov, Yakov ; Klemedtsson, Leif ; Rütting, Tobias:
Gross nitrogen dynamics in the mycorrhizosphere of an organic forest soil.
In: Ecosystems. Bd. 19 (2015) Heft 2 . - S. 284-295.
ISSN 1435-0629
DOI: https://doi.org/10.1007/s10021-015-9931-4

Abstract

The rhizosphere is a hot-spot for biogeochemical cycles, including production of greenhouse gases, as microbial activity is stimulated by rhizodeposits released by roots and mycorrhizae. The biogeochemical cycle of nitrogen (N) in soil is complex, consisting of many simultaneously occurring processes. In situ studies investigating the effects of roots and mycorrhizae on gross N turnover rates are scarce. We conducted a 15N tracer study under field conditions in a spruce forest on organic soil, which was subjected to exclusion of roots and roots plus ectomycorrhizae (ECM) for 6 years by trenching. The forest soil had, over the 6-year period, an average emission of nitrous oxide (N2O) of 5.9 ± 2.1 kg N2O ha−1 year−1. Exclusion of roots + ECM nearly tripled N2O emissions over all years, whereas root exclusion stimulated N2O emission only in the latest years and to a smaller extent. Gross mineralization–ammonium (NH4 +) immobilization turnover was enhanced by the presence of roots, probably due to high inputs of labile carbon, stimulating microbial activity. We found contrasting effects of roots and ECM on N2O emission and mineralization, as the former was decreased but the latter was stimulated by roots and ECM. The N2O emission was positively related to the ratio of gross NH4 + oxidation (that is, autotrophic nitrification) to NH4 + immobilization. Ammonium oxidation was only stimulated by the presence of ECM, but not by the presence of roots. Overall, we conclude that plants and their mycorrhizal symbionts actively control soil N cycling, thereby also affecting N2O emissions from forest soils. Consequently, adapted forest management with permanent tree cover avoiding clearcutting could be a means to reduce N2O emissions and potential N leaching; despite higher mineralization in the presence of roots and ECM, N2O emissions are decreased as the relative importance of NH4 + oxidation is decreased, mainly due to a stimulated microbial NH4 + immobilization in the mycorrhizosphere.

Weitere Angaben

Publikationsform: Artikel in einer Zeitschrift
Begutachteter Beitrag: Ja
Zusätzliche Informationen: BAYCEER142641
Keywords: Histosol; Mineralization–immobilization turnover; Nitrification; Nitrous oxide; emissions; Norway spruce; 15N tracer
Institutionen der Universität: Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften > Fachgruppe Geowissenschaften > Lehrstuhl Bodenphysik
Forschungseinrichtungen
Forschungseinrichtungen > Forschungszentren
Forschungseinrichtungen > Forschungszentren > Bayreuther Zentrum für Ökologie und Umweltforschung - BayCEER
Fakultäten
Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften
Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften > Fachgruppe Geowissenschaften
Titel an der UBT entstanden: Ja
Themengebiete aus DDC: 500 Naturwissenschaften und Mathematik
Eingestellt am: 22 Jan 2018 14:16
Letzte Änderung: 22 Jan 2018 14:16
URI: https://eref.uni-bayreuth.de/id/eprint/41431