Description: Das Projekt "Physical, molecular and microbial evidence of char degradation" wird/wurde gefördert durch: Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung. Es wird/wurde ausgeführt durch: Universität Zürich, Geographisches Institut.Understanding soil organic matter (SOM) dynamics is critical to meeting many environmental, agricultural, and forestry challenges relating to productivity and sustainability, including the potential of soils to sequester atmospheric CO2. The amount of C as stored as SOM represents twothirds of the terrestrial C pool and is the primary energy source driving several critical biogeochemical processes. The mechanisms of C stabilization in soils remain poorly understood. A critical knowledge gap in soil organic C (SOC) cycling concerns the SOC portion known as pyrogenic C (PyC), which is a chemically heterogeneous class of highly reduced compounds produced by the incomplete combustion. In terrestrial ecosystems, C and N dynamics are closely linked due to the activity of organisms. During the last few decades, atmospheric nitrogen deposition in soils has increased as a result of climate changes and human activities. At present, however, it is not clear whether increased nitrogen deposition will accelerate or decelerate soilorganic-matter turnover. Also, because of these global changes, future summers in temperate regions will be warmer and drier than today, and wildfires will be more frequent, producing more fire-derived (pyrogenic) carbon (PyC), a relatively recalcitrant soil component. . In this proposed long-term experiment, cylindrical mesocosms (10 x 15 cm) will be installed in the soil and filled with (1) 13C/15N labelled pyrolyzed wood, (2) 13C/15N labelled wood and (3) a no litter control, either treated with nitrogen or not, resulting in a two-factor, two-treatment experiment. We propose a post-doc project to identify underlying processes of char and wood degradation under high and low nitrogen -by directly identifying micro-organisms decomposing PyC through the double label (13C, 15N), by describing microorganism community structures, by determining the alteration of the PyC chemical structure of the remaining char (CPMAS 13C and 15N NMR, molecular markers) in the dissolved fraction and in the bulk soil and by using the isotopes to trace the degradation products within the soil fractions and within the intact soil matrix using soil fractionation methods and NanoSIMS technology. This project will be novel and cutting edge for several reasons: For the first time, the proposed project will (1) directly identify PyC decomposers, (2) directly quantify PyC degradation in vivo in a long-term field study, and (3) test the effect of nitrogen on decomposition of PyC and its wood precursor. The project will help to clarify our fundamental understanding of the fate of pyrogenic carbon in forest soil under present and future atmospheric nitrogen deposition, and will improve urgently needed field-based and global turnover models.
SupportProgram
Origins: /Bund/UBA/UFORDAT
Tags: Stickstoffgehalt ? Humus-C ? Bodenstickstoff ? Holzkohle ? Waldbrand ? Bodenkohlenstoff ? Biogeochemie ? Vegetationsbrand ? Humus ? Kohlenstoff ? Stickstoff ? Bodenmikroorganismen ? Bodenstruktur ? Isotopentechnik ? Kohlendioxid ? Primärenergie ? Kohlenstoffsenke ? Struktur-Wirkung-Beziehung ? Waldboden ? Holz ? Unterboden ? Gelöster organischer Kohlenstoff ? Vorläufersubstanz ? Verwitterung ? Biologischer Abbau ? Langzeituntersuchung ? Terrestrisches Ökosystem ? Isotop ? Quantitative Analyse ? Pflanzenorgan ? Bodenprozess ? Wirkung ? Abbauprodukt ? Chemikalien ? Fraktionierung ? Langzeitverhalten ? Nachhaltige Forstwirtschaft ? Vergleichsanalyse ? Physikalischer Vorgang ? Produktivität ? Abbau ? Klimawandel ? Kohlenstoffisotop ? In-Vivo ? pyrogenic carbon ?
License: cc-by-nc-nd/4.0
Language: Englisch/English
Time ranges: 2008-12-01 - 2011-11-30
Accessed 1 times.