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Microhabitat effects on N2O emissions from semiterrestrial soils

Applicant Luster Jörg
Number 147002
Funding scheme Project funding (Div. I-III)
Research institution Swiss Federal Research Inst. WSL Direktion
Institution of higher education Swiss Federal Institute for Forest, Snow and Landscape Research - WSL
Main discipline Pedology
Start/End 01.02.2014 - 31.01.2018
Approved amount 282'695.00
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Keywords (10)

nitrogen transformations; floodplains; stable isotopes; semiterrestrial soils; nitrous oxide; greenhouse gases; forests; rhizosphere; soil aggregation; buried organic matter

Lay Summary (German)

Lead
Auenböden und Gleye, welche unter dem Einfluss wechselnder Grundwasser-Spiegel stehen, sind potentielle „Hot Spots“ der Emission von Lachgas, welches ein ca. 300 mal stärkeres „Global Warming“-Potential hat als Kohlendioxid. Generell sind Lachgas-Emissionen aus Böden zeitlich und räumlich stark variabel und deshalb schwierig vorherzusagen. Wir benötigen deshalb ein besseres Verständnis der Variabilität und der Interaktionen der wichtigsten Einflussfaktoren.
Lay summary

Inhalt und Ziel des Forschungsprojektes

In früheren Untersuchungen wurde gezeigt, dass sogenannte „Mikrohabitate“ in Böden wie Aggregate, die Rhizosphäre oder Anreicherungen von leicht abbaubarem organischem Material Orte sind, an denen die Produktion bzw. die Konsumation von Lachgas besonders hoch sein können. Im weiteren wurde gezeigt, dass innerhalb von Nass-Trocken-Zyklen besonders starke Lachgas-Emissionen auftreten. In Labor-Versuchen wollen wir deshalb den relativen Einfluss der Faktoren „Aggregatbildung“, „Wurzel-Boden-Interaktionen“ und „Streu-Anreicherung“ auf die Netto-Lachgas-Produktion in Auenböden und Gleyen während gut definierten Nass-Trocken-Zyklen untersuchen. Für spezifische Phasen innerhalb der Zyklen wollen wir zudem die Brutto-Produktion, die Brutto-Konsumation und die zugrunde liegenden Prozesse des Stickstoff-Kreislaufes bestimmen. Dafür kommen innovative methodische Ansätze zum Zug, die entweder auf der Anwendung isotopischer Tracer oder auf der Analyse der natürlichen Isotopen-Verhältnisse im produzierten Lachgas beruhen.

 

Wissenschaftlicher und gesellschaftlicher Kontext des Forschungsprojektes

 Wir erwarten, dass die Resultate unserer Arbeit dazu beitragen werden, biogeochemische Modelle zur Vorhersage von Lachgas-Emissionen aus Böden natürlicher und naturnaher Ökosysteme zu verbessern. Im weiteren helfen sie bei der Entwicklung von Indikatoren für das Lachgas-Emissions-Potential von Böden. Letzteres ist ein wichtiger Faktor, der bei der Beurteilung der Klimaregulations-Funktion von Ökosystemen zu berücksichtigen ist.

Direct link to Lay Summary Last update: 08.01.2014

Responsible applicant and co-applicants

Employees

Name Institute

Publications

Publication
Alteration of nitrous oxide emissions from floodplain soils by aggregate size, litter accumulation and plant–soil interactions
Ley Martin, Lehmann Moritz F., Niklaus Pascal A., Luster Jörg (2018), Alteration of nitrous oxide emissions from floodplain soils by aggregate size, litter accumulation and plant–soil interactions, in Biogeosciences, 15(22), 7043-7057.

Collaboration

Group / person Country
Types of collaboration
Pascal A. Niklaus, University of Zürich Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Beat Frey, WSL Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Jahrestagung der Deutschen Bodenkundlichen Gesellschaft Talk given at a conference Microhabitat effects on nitrous oxide emissions from floodplain soils 04.09.2017 Göttingen, Germany Ley Martin; Lehmann Moritz; Luster Jörg;
EGU General Assembly 2016 Talk given at a conference Flood effects on efflux and net production of nitrous oxide in river floodplains 18.04.2016 Wien, Austria Luster Jörg;
EGU General Assembly 2016 Poster Microhabitat effects on N2O emissions from floodplain soils under controlled conditions 17.04.2016 Wien, Austria Ley Martin; Lehmann Moritz; Luster Jörg;
13th Swiss Geoscience Meeting Poster Microhabitat effects on N2O emissions from floodplain soils under controlled conditions 20.11.2015 Basel, Switzerland Lehmann Moritz; Luster Jörg; Ley Martin;
Jahrestagung der Deutschen Bodenkundlichen Gesellschaft Talk given at a conference Flood pulse effects on N cycling in floodplain soils and related N2O emissions 08.09.2015 München, Germany Luster Jörg; Ley Martin;
Jahrestagung der Deutschen Bodenkundlichen Gesellschaft Poster Microhabitat effects on N2O emissions from floodplain soils under controlled conditions 08.09.2015 München, Germany Lehmann Moritz; Luster Jörg; Ley Martin;
EGU General Assembly 2015 Poster Microhabitat effects on N2O emissions from floodplain soils under controlled conditions 12.04.2015 Wien, Austria Luster Jörg; Lehmann Moritz; Ley Martin;
RECORD Catchment Meeting Talk given at a conference Interactions between plant roots and soil aggregates in creating hot spots of N cycling in floodplain soils 07.11.2014 Dübendorf, Switzerland Ley Martin; Lehmann Moritz; Luster Jörg;


Associated projects

Number Title Start Funding scheme
170958 Interaction of microhabitats and substrate availability in affecting nitrous oxide emissions from floodplain soils 01.10.2016 International short research visits

Abstract

The potential to emit greenhouse gases such as nitrous oxide (N2O) greatly affects the climate regulation function of ecosystems. However, the generally high spatial and temporal variability of N2O emissions from soils makes their prediction difficult. Semiterrestrial soils such as floodplain soils (fluvisols) and gleysols that have developed and stand under the variable influence of groundwater, are potential hot spots of N2O emissions. Anticipating a higher frequency of drying-re-wetting cycles and flooding events as a consequence of predicted future climate change, the importance of these soil types as terrestrial N2O sources is likely to increase in the upcoming decades. Research so far has shown that N2O production and consumption in soils are strongly linked to micro habitat formation, including microsites in soil aggregates, the rhizosphere or locations where relatively easily degradable soil organic matter has been accumulated. Furthermore, cycles of drying and re-wetting appear to be particularly conducive to the formation of respective hot moments. We therefore argue that in order to develop indicators for the „N2O emission potential“ of soils we need to systematically assess the relative importance of the different microhabitat effects under drying and re-wetting conditions.In this project, we plan to apply such an approach to relatively N-rich soils from near-natural ecosystems, including two fluvisols from a restored river floodplain and a forest gleysol. In controlled laboratory experiments in microcosms, the topsoil layers of the selected soils will be manipulated through various combinations of „microhabitat“ and „soil moisture“ treatments. In the „microhabitat“ treatments the effects of aggregate size and type (coarsly sieved soil, micro aggregates only, earthworm scats), rhizosphere processes (plants growing in coarsly sieved soil or micro aggregates) and organic matter accumulations (leaf litter mixed into coarsly sieved soil or micro aggregates) are tested. The „soil moisture“ treatments include two wetting - drying - re-wetting cycles. In one of the treatments, wetting consists of increasing soil moisture by rainwater to unsaturated conditions that are optimum for denitrification, in the other treatment soil is saturated by groundwater. Data are obtained on three levels. Firstly, by monitoring the N2O efflux from the microcosms during the treatments, the temporal variability of net N2O production, in particular the occurrence of hot moments, is assessed. Secondly, additional data obtained during specific phases within a treatment cycle, in particular during hot moments of N2O emissions, shall provide further insight into production, consumption and source processes of emitted N2O. To this end, we plan to measure gross N2O production, to assess N2O source partitioning, and to quantify soil N transformation rates, substrate and C availability. Thirdly, during the same selected phases, we plan to characterize the nitrifying and denitrifying soil microbial communities. For gross N2O production and source partitioning, innovative isotopic tracer methods - headspace pool dilution and substrate 15N enrichment, respectively - will be adapted. In addition, the feasibility of deducing the main N2O producing N transformation process from the natural abundance isotopic ratio of N in emitted N2O, and/or the site preference of the enriched N will be tested. The results of this experimental project are expected to increase our understanding of how environmental heterogeneity at a small scale affects the occurrence of high N2O emissions. On a qualitative basis, this should help to develop soil and plant/soil indicators for the N2O emission potential of soils. On a quantitative basis, the results from this study may be used to improve biogeochemical models predicting N2O emissions in natural and near-natural ecosystems under current and future climate.
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