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The effect of time and environmental factors on lignin turnover in soils

Description: Das Projekt "The effect of time and environmental factors on lignin turnover in soils" wird vom Umweltbundesamt gefördert und von Universität Zürich, Geographisches Institut durchgeführt. Soils store about twice as much carbon (C) than exists in the atmosphere as carbon dioxide (CO2). Terrestrial ecosystems are driving forces in the global carbon cycle and, if acting as carbon sinks, can become key to mitigate increasing CO2 concentrations in the atmosphere. Global warming probably will affect soil organic carbon (SOC) decomposition and will determine how much carbon will be transferred to the atmosphere or sequestered in soils. The project takes up urgent tasks, also pointed out during the IPCC meeting on terrestrial carbon stocks (IPCC, 2003), including a) factoring out effects causing carbon stock changes, b) employing high-technology measurements, e.g. isotope tracers, molecular markers, and c) elucidating soil mechanisms in addition to measuring fluxes. The aspects b) and c) are especially considered for the project. Lignin is one of the main constituents of the cell walls of woody plants and a large contributor to soil organic matter (SOM). The lignin macromolecule is generally believed to be relatively resistant against microbial degradation. Consequently, lignin residues are considered to form a large proportion of the stock of old, slowly degradable organic matter in the soil. However, analytical information of lignin biodegradation has mostly been addressed in short-term (days to weeks) in-vitro experiments. In-vivo experiments mimic natural processes in soils over many years much better but are sparse. Direct molecular-level information on long-term lignin turnover could come from field studies using the natural stable isotopic difference between C4 plant and C3 plant isotopes. When C4 vegetation replaces C3 vegetation, the new isotopically heavier C4-derived carbon subsequently replaces the old decaying C3 carbon. Thus, increasing ?13C values are directly related to the proportion of the new C4-derived biomass, and can be used to estimate the residence time and pool size of individual soil organic matter components. Stable carbon isotope analysis has been successfully applied to bulk soil organic matter and solvent-extractable compounds such as soil n-alkanes, but only very recently to individual lignin monomers, although analytical limitations still exist. In the project we will expand the number (arable soil, grassland) and types (forest) of studied ecosystems combined with different treatments (time, soil pH, nitrogen (N) availability, tillage). This project may provide a novel, improved analytical tool to gain isotopic information of lignin in plants and soil organic matter. It may also help to clarify our fundamental understanding of the global carbon cycle and thus carbon sequestration in soils, and will improve urgently needed plot based and global turnover models.

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SupportProgram

Origin: /Bund/UBA/UFORDAT

Tags: Spülsaum ? Atmosphärische CO2-Konzentration ? Lignin ? Tierhaltungsanlage ? Kohlenstoffverbindung ? Vegetation ? Saumgesellschaft ? Organischer Kohlenstoff ? Zürich ? Bodenkohlenstoff ? Stickstoff ? THM-Prozess ? Fischer-Tropsch-Verfahren ? Humus ? Kohlenstoff ? Skigebiet ? Tracer ? Verrottung ? Wiese ? Zellwand ? Main ? Bodenverbesserung ? Gesamtkohlenstoff ? Kohlendioxid ? Kohlenstoffsenke ? Verdunstung ? Naturstein ? Staude ? Technosol ? Globale Erwärmung ? Persistenter Stoff ? Grünlandökosystem ? Ackerboden ? Gelöster organischer Kohlenstoff ? Gehölzpflanze ? Boden ? In-vivo-Test ? Bodenluft ? Ackerland ? Technik ? Feldstudie ? Rechtsverfahren ? Verwitterung ? Globalmodell ? Naturfaser ? Isotop ? Bodenbewirtschaftung ? Stoff ? Wertermittlung ? Bodenbelastung ? Kohlenstoffkreislauf ? Globale Veränderung ? Messung ? Terrestrisches Ökosystem ? Biologischer Abbau ? Abbaubarkeit ? Rückstand ? Versuchsanlage ? Globale Aspekte ? Bedarf ? Wald ? Analyse ? Lagerung ? Atmosphäre ? Ökologischer Faktor ? CCS-Technologie ? Naturpotential ? Ökosystem ? Abbau ? Vegetationsgrenze ? Biomasse ? Saarberg-Hölter-Verfahren ? Stall ? Makromolekül ? Bram-Verfahren ? Bricollare-Verfahren ? Kohlenstoffisotop ? In-Vivo ? Vermehrung ? Adsox-Verfahren ? Zeitverlauf ?

License: cc-by-nc-nd/4.0

Language: Deutsch

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Time ranges: 2005-08-01 - 2007-07-31

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