Butterbach-Bahl, K.

Dannenmann, M.

Gundersen, P.

Kiese, R.

KITopen

K. Butterbach-Bahl | IMK-IFU | May 2008KIT – die Kooperation vonForschungszentrum Karlsruhe GmbHund Universität Karlsruhe (TH)Nitrogen turnover processes and effects in terrestrial ecosystems Klaus Butterbach-Bahla, Per Gundersenb,Michael Dannenmanna, Ralf KieseaaInstitute of Meteorology and Climate Research, Karlsruhe Institute of Technology, Garmisch-Partenkirchen, GermanybDanish Centre for Forest, Landscape and Planning, University ofCopenhagen, Hoersholm, DenmarkK. Butterbach-Bahl | IMK-IFU | May 2008KIT – die Kooperation vonForschungszentrum Karlsruhe GmbHund Universität Karlsruhe (TH)Atmosphere3.0-4.9 109 Tg(107 yr)Terrestrial biomas3.5 104 Tg(50 yr)Soil9.5 104 Tg(~2000 yr)Sediments4.0 108 Tg(107 yr)Marine biomass4.7 102 TgOcean2.2 107 TgSchlesinger & Hartley, 1992Galloway et al., 1995Gruber & Galloway, 2008~570 TG~570 TG???K. Butterbach-Bahl | IMK-IFU | May 2008KIT – die Kooperation vonForschungszentrum Karlsruhe GmbHund Universität Karlsruhe (TH)Biological N2-fixation (BNF)• Major natural process to create Nr, highly energy demanding • Different ecophysiological groups involved• Symbiotic association between microbes and plant roots (e.g. legumes; 10-100 kg N ha-1 yr-1)• Cyanobacteria (e.g. crusts in semiarid regions; 1-40 kg N ha-1 yr-1)• Heterotrophic N2-fixation (upland: 1-5 kg N ha-1 yr-1 or wetland: 50-100 kg N ha-1 yr-1)• Understanding of ecological controls of BNF is limited (except agricultural crops)• Cyano-bacteria: light (e.g. steppe)• Heterotrophic N2 fixation: substrate (carbon) quality > substrate quantity• General: pH, drought, temperature, salinity • Uncertainties:• Knowledge about the biology of N fixers is limited• Biological N2 fixation only assessed for a few systems• Contribution of BNF to ecosystem N cycling highly uncertainK. Butterbach-Bahl | IMK-IFU | May 2008KIT – die Kooperation vonForschungszentrum Karlsruhe GmbHund Universität Karlsruhe (TH)Processes involved in N-cyclingSchimel & Bennett, 2004• Only since approx. 10 – 15 yrs we are talking about gross rates• Competition between microbes and plants• Role of organic N for N cycling, mediated by mycorrhiza?K. Butterbach-Bahl | IMK-IFU | May 2008KIT – die Kooperation vonForschungszentrum Karlsruhe GmbHund Universität Karlsruhe (TH)-25-20-15-10-505101520010203040baabaacbabaacbacbabaacbaaabbababa   Gross ammonification(mg N kg-1 SDW d-1)010203040aaabaabaabbaaaaaaabaaabacbaaaaabaaan.d.  Gross nitrification(mg N kg-1 SDW d-1) Feb 03May 03Aug 03Nov 03Feb 04May 04Aug 04Nov 04Feb 05May 05Aug 05Nov 050100200300400babaaaaaaaabaabbacbaaaaabbababaaaabbaaaa  Heterotrophic soil respiration(mg C kg-1 SDW d-1)0150300450600750 Gravimetric water content(% SDW) USC STB CCBTinc (°C)abbabaabaabaaaaaaaaabbaababaabbacbaaaaGross-Ammonification:800 – 1000 kg N ha-1 yr-1Gross-nitrification:480 – 590 kg-1 N ha-1 yr-1Heterotrophic respiration:8000 – 9000 kg C ha-1 yr-1Rosenkranz et al., 2008, Biogeochem. Subm.N-cycling at the Höglwald Forest, GermanyK. Butterbach-Bahl | IMK-IFU | May 2008KIT – die Kooperation vonForschungszentrum Karlsruhe GmbHund Universität Karlsruhe (TH)NitroEurope – Towards full N balance studiesHöglwald, spruce forest  (Germany), N Brüggemann, H Papen, K Butterbach-Bahl (FZK9000150050010090Plant N turnoverMicrobial N turnover20Volatilisation10LeachingN-DepositionNH3/NO2NH3/NH4NO2/NO3DON40N2O ~ 1NO ~ 3-4K. Butterbach-Bahl | IMK-IFU | May 2008KIT – die Kooperation vonForschungszentrum Karlsruhe GmbHund Universität Karlsruhe (TH)Wrage et al., 2001, Soil Biol. Biochem.Ecological niche of nitrifier-denitrificationTools for process identification:Stable isoptope techniques(15N/ 18O) ± C2H2Bio-Molecular techniquesRNA/DNA extractionsPLFA analysisDEA, etc.K. Butterbach-Bahl | IMK-IFU | May 2008KIT – die Kooperation vonForschungszentrum Karlsruhe GmbHund Universität Karlsruhe (TH)Wrage et al., 2005, RCMSImportance of nitrifier denitrification for soil N2O emissionsK. Butterbach-Bahl | IMK-IFU | May 2008KIT – die Kooperation vonForschungszentrum Karlsruhe GmbHund Universität Karlsruhe (TH)Potential positive feedbacks between plant invasion and carbon and nitrogen cycles in invaded ecosystems. Liao et al., 2008Vegetation changes and ecosystem N cyclingK. Butterbach-Bahl | IMK-IFU | May 2008KIT – die Kooperation vonForschungszentrum Karlsruhe GmbHund Universität Karlsruhe (TH)Only 25% of the N inputs are exported via the streamflow.Is 75% denitrified in soils and groundwater? Van Breemen et al., 2002: Where did all the nitrogen go?K. Butterbach-Bahl | IMK-IFU | May 2008KIT – die Kooperation vonForschungszentrum Karlsruhe GmbHund Universität Karlsruhe (TH)9%6%5%9%20%11%3%37% Denitrificationin landscapeNH3-VolatilisationDenitrificationin riversRiverineexport BiomassincreaseWoodexportFoodexportSoil storageincrease23%24%15%33%5% Net importfood & feedAgriculturalfixationForestfixationAtmosphericdepositionFertilizeruseVan Breemen et al., 2002: Where did all the nitrogen go?Van Breemen et al., 2002, BiogeochemistryK. Butterbach-Bahl | IMK-IFU | May 2008KIT – die Kooperation vonForschungszentrum Karlsruhe GmbHund Universität Karlsruhe (TH)Approx. 270 TgNr additionsto terrestrialsystemsSeitzinger et al., 2006, Ecol. Applic., 16Seitzinger et al., 2006: 40% of N input is denitrified in soilsK. Butterbach-Bahl | IMK-IFU | May 2008KIT – die Kooperation vonForschungszentrum Karlsruhe GmbHund Universität Karlsruhe (TH)It seems that we do know the “big” numbers quite well, but how good is our knowledge on site and landscape scales?K. Butterbach-Bahl | IMK-IFU | May 2008KIT – die Kooperation vonForschungszentrum Karlsruhe GmbHund Universität Karlsruhe (TH)1990 1995 2000 20050100200300400Number of ISI listed publicationsPublication year "Soil and Denitrification" "Soil and N2O"Publications on denitrification and soils increased by a factor of four within the last 20 yrsK. Butterbach-Bahl | IMK-IFU | May 2008KIT – die Kooperation vonForschungszentrum Karlsruhe GmbHund Universität Karlsruhe (TH)Variability of denitrification estimatesDenitrification & texture(grasslands)Barton et al.,1999, Aust J Soil ResWhen and where does denitrification occur?K. Butterbach-Bahl | IMK-IFU | May 2008KIT – die Kooperation vonForschungszentrum Karlsruhe GmbHund Universität Karlsruhe (TH)Annual mean N2+N2O losses Estimating landscape scale denitrification lossesOehler et al., 2007, Agr. Ecosys. Envrionm.Main findings:• 50% of denitrification occurs at hillslopes• 20-40 cm layer contributed 50% to N losses• N2O:N2 ratio approx. 1, i.e. main losses via N2OK. Butterbach-Bahl | IMK-IFU | May 2008KIT – die Kooperation vonForschungszentrum Karlsruhe GmbHund Universität Karlsruhe (TH)Uncertainties of denitrification estimatesHofstra & Bouwman, 2005, Nutr Cycl Agroecosys0255075100125Grassland: well drained soilsUpland crops: well drained soilsGrassland: poorly drained soilsUpland crops: poorly drained soils  Denitrification losses [kg N ha-1 yr-1] mass balance approach soil core approach0 1-75 75-150 150-225 225-300 >3000 1-75 75-150 150-225 225-300 >3000 1-75 75-150 150-225 225-300 >3000255075100125N fertilization rate [kg N ha-1 yr-1]  0 1-75 75-150 150-225 225-300 >300 0 1-75 75-150 150-225 225-300 >300N fertilization rate [kg N ha-1 yr-1]0255075100125  Denitrification losses [kg N ha-1 yr-1]0255075100125  K. Butterbach-Bahl | IMK-IFU | May 2008KIT – die Kooperation vonForschungszentrum Karlsruhe GmbHund Universität Karlsruhe (TH)N2 fixationDenitrificationBiologicallyAvailable NN-CycleClimate warmingLand use change Fossil fuelburningAtmosphericreactive NAtmosphericCO2gypdriversdrivers+ ++ ?Industrial N2fixation++−+ ?+−?? ??+PrimaryproductionCarbon CycleC/Nratio ++?+ −?−+Gruber & Galloway, Nature 2008K. Butterbach-Bahl | IMK-IFU | May 2008KIT – die Kooperation vonForschungszentrum Karlsruhe GmbHund Universität Karlsruhe (TH)• Uncertainties with regard to Nr input• BNF not well understood• Dry deposition not well constrained• Uncertainty with regard to Nr cycling• Microbial processes and microbial diversity• Plant-microbe competition and species composition• Organic N cycling• Uncertainty with regard to Nr output• Denitrification (when and where?)• Changes in stocks versus external losses• Uncertainties with regard to feedbacks to global changesSummary and conclusions

Nitrogen turnover processes and effects in terrestrial ecosystems

https://publikationen.bibliothek.kit.edu/230072662/3815300

Nitrogen turnover processes and effects in terrestrial ecosystems

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