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Nitrogen as a factor of soil organic matter stability in forest soils

Title data

Michel, Kerstin:
Nitrogen as a factor of soil organic matter stability in forest soils.
Bayreuth : Bayreuther Inst. für Terrestrische Ökosystemforschung , 2002 . - IV, 114 S. - (Bayreuther Forum Ökologie ; 98 )
( Doctoral thesis, 2002, Universität Bayreuth, Fakultät für Biologie, Chemie und Geowissenschaften)

Project information

Project financing: Bundesministerium für Bildung und Forschung
Vorhaben-Nr. PT BEO 51 - 0339476 D

Abstract in another language

It is suggested that increasing N inputs to forest ecosystems will result in an accumulation of soil organic matter (SOM). This may be caused by decreased decomposition of SOM in late stages. The objectives of this study were to investigate C dynamics (soil respiration, DOC release), N mineralization and microbial parameters (microbial biomass, extracellular enzyme activities) in dependence on internal N concentration and external N inputs. Furthermore, structure and chemical composition related to SOM with different C-to-N ratios were investigated. Spectroscopic properties of dissolved organic matter (DOM) released from SOM varying in C-to-N ratio and the effect of mineral N on composition of DOM were also determined. Three incubation experiments under standardized laboratory conditions were carried out: (1) the influence of internal N concentrations on C dynamics and N mineralization in late stages of decomposition was investigated using samples from Oa layers of 21 different forest floors under Norway spruce (Picea abies) with varying C-to-N ratios; (2) the influence of periodically added mineral N on the spectroscopic properties of DOM was studied. Oa material percolates of eight selected sites was investigated; (3) was carried out to evaluate the effect of external N inputs on C dynamics, N mineralization and microbial parameters by treating Oa samples of four spruce sites with different concentrations of NH4NO3. Furthermore, the chemical composition of SOM was determined using SOM from Oa and A horizons of 15 Norway spruce sites covering a wide range of C-to-N ratios. Samples were analyzed with solid-state 13C nuclear magnetic resonance (NMR) spectroscopy, along with chemolytic analyses of lignin.There is clear evidence that increasing N inputs to forest ecosystems may result in accumulation of organic matter in forest floors. Decomposition of SOM in late stages is apparently reduced by N as indicated by lower C and N mineralization rates. It appears to be likely that reduced mineralization rates at high concentrations of N were due to changes in the activity and composition of the microbial community and a less efficient use of N.

Further data

Item Type: Doctoral thesis
Additional notes: BAYCEER14435
Institutions of the University: Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences > Chair Soil Ecology
Research Institutions > Research Centres > Bayreuth Center of Ecology and Environmental Research- BayCEER
Faculties
Faculties > Faculty of Biology, Chemistry and Earth Sciences
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences
Research Institutions
Research Institutions > Research Centres
Result of work at the UBT: Yes
DDC Subjects: 500 Science
Date Deposited: 09 Oct 2015 05:56
Last Modified: 15 Feb 2016 09:09
URI: https://eref.uni-bayreuth.de/id/eprint/20255