Dirnböck, Thomas

Djulic, Ika

Gorfer, Markus

Grandin, Ulf

Hood-Nowotny, Rebecca

Korboulewsky, Nathalie

Schmittner, Kathrin

Stadler, Jutta

Watzinger, Andrea

English

Epsilon Open Archive

Geophysical Research AbstractsVol. 21, EGU2019-16582, 2019EGU General Assembly 2019© Author(s) 2019. CC Attribution 4.0 license.The impact of elevated nitrogen-inputs on organic matter decompositionin European forest soils, determined using a tool-box of stable isotopelabelling techniques.Rebecca Hood-Nowotny (1), Kathrin Schmittner (1), Andrea Watzinger (1), Markus Gorfer (2), Ulf Grandin (3),Nathalie Korboulewsky (3), Jutta Stadler (3), Ika Djulic (4), and Thomas Dirnböck (4)(1) Institute of Soil Research, University of Natural Resources and Life Sciences (BOKU), Peter-Jordan-Straße 82, 1190Vienna, Austria (Rebecca.Hood@boku.ac.at), (2) AIT Austrian Institute of Technology GmbH Konrad-Lorenz-Straße 24,3430, Tulln, Austria., (3) ALTER-net-MSII,Network.4, (4) Ökosystemforschungund Umweltdatenmanagement,Umweltbundesamt GmbH, Spittelauer Lände 5,1090 Wien, Austria.Elevated atmospheric reactive nitrogen (N) deposition is considered one of the key components of global climatechange, threatening biodiversity and possibly altering one of the forest’s key ecosystem services carbon sequestra-tion. Ignoring the impact of N on plant growth, any major physical, biological or anthropogenic process that altersthe rate of conversion of soil organic matter to atmospheric CO2 (decomposition), will have profound implicationsfor the global C budget and consequently climate change. Soil inorganic-N concentrations are predicted to increaseas the result of increased deposition and mineralization due to temperature increases. However, experimentalresults on the effects of increased N input on SOM decomposition in the field are inconsistent, reporting positive,negative and neutral responses of SOM to N input.Recent meta-data analyses and the model based hypotheses state that global soil C storage is controlled bymicrobial scale processes of fungal competition for available nitrogen (N). It has been posited that higher SOMin ectomycorrhizal and ericoid mycorrhiza (EEM) systems is the result of EEM fungi’s ability to uptake andassimilate low molecular weight organic N. It has been hypothesized that EEM’s effectively scavenge all availableorganic and inorganic N leaving little N for the growth of the free-living decomposer microbial communityand preventing further breakdown of SOM. We set out to test this hypothesis empirically in forest soils acrossEurope which had had received a medium term N deposition treatment on soil plots only. We traced carbon andnitrogen transformations of added isotopically labelled litter into inorganic, soil microbial and gaseous pools andmonitored concomitant changes in gross mineralization and nitrification rates and enzymatic activity. We foundno evidence to suggest that substantially increasing available nitrogen increased the decomposition rates of thelabelled litters added. On the contrary in-line with emerging consensus, N deposition significantly reduced grossN mineralization rates and enzyme activity.Having dug deep into the secrets of the soil, using a suite of direct stable isotope labelling methods in the forest,we found no evidence of accelerated organic matter decomposition as a result of experimentally elevated nitrogendeposition in forest soils across Europe.

The impact of elevated nitrogen-inputs on organic matter decomposition in European forest soils, determined using a tool-box of stable isotope labelling techniques

https://pub.epsilon.slu.se/19784/1/hood-nowotny_r_et_al_201229.pdf

The impact of elevated nitrogen-inputs on organic matter decomposition in European forest soils, determined using a tool-box of stable isotope labelling techniques

Abstract

Similar works

Full text

Available Versions

Epsilon Open Archive