Decades-long effects of high CO2 concentration on soil nitrogen dynamics at a natural CO2 spring
The effects of high atmospheric CO2 concentration ([CO2]) on ecosystem processes have been explored using temporal facilities such as open-top-chambers and free-air CO2 enrichment. However, the effects of high [CO2] on soil properties takes decades and may not be captured by short-term experiments. Natural CO2 springs provide a unique opportunity to study the long-term effects of high [CO2]. In this study, we investigated soil properties at a natural CO2 spring. We found that the amounts of total carbon (C) and nitrogen (N) stored in the soil at the high [CO2] site exceeded those in the reference site by 60 and 30%, respectively. The effects of high [CO2] were large in the upper slope position where the canopy openness was high and plants grew faster, but no effects were detected in the lowest position where the canopy openness was lower (half of that at the upper slope position). In contrast, effects of high [CO2] on soil N dynamics, such as N mineralization and nitrification rates, did not exhibit a slope gradient. This suggests that effects of high [CO2] differed among soil stoichiometric characteristics and N dynamics. These complicated effects of high [CO2] imply that the future effects of high [CO2] on ecosystems could vary widely in conjunction with environmental conditions such as light availability and/or topographic conditions.
KeywordsGross mineralization Gross nitrification Net NH4-N production C:N ratio Elevated CO2
We thank Aomori Prefecture for permission to conduct this research. The study was supported by KAKENHI (No. 14J04339) to M.U.U. and (Nos. 20677001, 21114009, 19370008, and 16687001) and CREST, JST, Japan to K.H. We also thank Mr. Tomomi Kojima, Dr. Tomoyuki Itagaki and Mr. Shota Hoshino for their help during our field work.
- Barnard R, Leadley PW, Hungate BA (2005) Global change, nitrification, and denitrification: A review. Glob Biogeogr Cycles 19:1–13Google Scholar
- Dieleman WIJ, Luyssaert S, Rey A, De Angelis P, Barton CVM, Broadmeadow MSJ, Broadmeadow SB, Chigwerewe KS, Crookshanks M, Dufrene E, Jarvis PG, Kasurinen A, Kellomaki S, Le Dantec V, Liberloo M, Marek M, Medlyn B, Pokorny R, Scarascia-Mugnozza G, Temperton VM, Tingey D, Urban O, Ceulemans R, Janssens IA (2010) Soil N modulates soil C cycling in CO2-fumigated tree stands: a meta-analysis. Plant Cell Environ 33:2001–2011CrossRefPubMedGoogle Scholar
- Dieleman WIJ, Vicca S, Dijkstra FA, Hagedorn F, Hovenden MJ, Larsen KS, Morgan JA, Volder A, Beier C, Dukes JS, King J, Leuzinger S, Linder S, Luo YQ, Oren R, de Angelis P, Tingey D, Hoosbeek MR, Janssens IA (2012) Simple additive effects are rare: a quantitative review of plant biomass and soil process responses to combined manipulations of CO2 and temperature. Glob Change Biol 18:2681–2693CrossRefGoogle Scholar
- Drake JE, Gallet-Budynek A, Hofmockel KS, Bernhardt ES, Billings SA, Jackson RB, Johnsen KS, Lichter J, McCarthy HR, McCormack ML, Moore DJP, Oren R, Palmroth S, Phillips RP, Pippen JS, Pritchard SG, Treseder KK, Schlesinger WH, DeLucia EH, Finzi AC (2011) Increases in the flux of carbon belowground stimulate nitrogen uptake and sustain the long-term enhancement of forest productivity under elevated CO2. Ecol Lett 14:349–357CrossRefPubMedGoogle Scholar
- Gahrooee FR (1998) Effects of elevated atmospheric CO2 on soil organic carbon dynamics in a Mediterranean forest ecosystem. PhD Thesis, WageningenGoogle Scholar
- IPCC (2013) Long-term climate change: projections, commitments and irreversability. In: StockerTF Qin D, Plattner GK, Tignor M, Allen SK, Boschung J, Nauels A, Xia Y, Bex V, Midgley PM (eds) Climate change 2013: The Physical Science Basis Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, New YorkGoogle Scholar
- Kuroiwa M, Koba K, Isobe K, Tateno R, Nakanishi A, Inagaki Y, Toda H, Otsuka S, Senoo K, Suwa Y, Yoh M, Urakawa R, Shibata H (2011) Gross nitrification rates in four Japanese forest soils: heterotrophic versus autotrophic and the regulation factors for the nitrification. J For Res 16:363–373CrossRefGoogle Scholar
- Onoda Y, Hikosaka K, Hirose T (2005) Natural CO2 springs in Japan: a case study of vegetation dynamics. Phyton 45:389–394Google Scholar
- Zak DR, Pregitzer KS, Curtis PS, Holmes WE (2000) Atmospheric CO2 and the composition and function of soil microbial communities. Ecol Appl 10:47–59Google Scholar