Sources of soil CO2 in calcareous grassland with woody plant encroachment
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The objective of this study is to estimate the contribution of various sources that influence soil CO2 concentrations in calcareous grassland.
Materials and methods
The research was performed at the Podgorski Kras plain (45 °33′ N, 13 °55′ E, 400–430 m.a.s.l.) in the sub-Mediterranean region of Slovenia (SW Slovenia), where many meadows and pastures have been abandoned. In parallel to the measurement of soil respiration R s, soil gas was sampled for stable isotope analysis. Samples were taken biweekly at two sites, Grassland and Invaded, from July 2008 until November 2010. In addition, daily variations in concentration and stable isotope composition of soil CO2 were determined in May 2009. The partitioning of soil CO2 concentrations was performed using stable isotope mass balance calculation.
Results and discussion
The concentration and isotope composition of soil CO2 exhibited similar seasonal variations at both sites. Lower δ13CCO2 values, ranging from −28.2 to −15.2 ‰, which occurred during warm periods and higher values, up to −12.1 ‰, were typical of cold winter periods, from December to March. Organic sources were estimated to constitute between 78 and 99 % of total soil CO2 during warmer periods from May until October. This contribution was lower during the winter, ranging from 46 to 77 %. In winter, the atmospheric component to soil CO2 dominated, constituting up to 60 %. On average, the inorganic contribution was estimated to comprise 12 % of the soil CO2 at all sampling locations. The contribution of this source to soil CO2 concentration, at up to 41 %, was highest in Grassland during the growing season. The inorganic source of soil CO2 was also an important component during daily variations. The highest contribution was observed during the day, in parallel to the highest respiration rates.
The inorganic pool is shown to be an important part of soil CO2 in calcareous areas and should be considered as equal to organic CO2 as a source in soil CO2 partitioning.
KeywordsInorganic CO2 Karst grassland Organic CO2 Soil CO2 Stable isotopes
The study was supported by projects J4-1009 and J4-4224 and by the young researcher program (contract no. 1000-09-310206) financed by the Slovenian Research Agency. We thank Marjanca Jamnik, Urška Videmšek, and Anja Marinič for their help during fieldwork, Stojan Žigon for the stable isotope analysis, and Roger Pain for the linguistic corrections.
- Bahn M, Rodeghiero M, Anderson-Dunn M, Dore S, Gimeno C, Drosler M, Williams M, Ammann C, Berninger F, Flechard C, Jones S, Balzarolo M, Kumar S, Newesely C, Priwitzer T, Raschi A, Siegwolf R, Susiluoto S, Tenhunen J, Wohlfahrt G, Cernusca A (2008) Soil respiration in European grasslands in relation to climate and assimilate supply. Ecosystems 11:1352–1367CrossRefGoogle Scholar
- Bahn M, Reichstein M, Davidson EA, Grunzweig J, Jung M, Carbone MS, Epron D, Misson L, Nouvellon Y, Roupsard O, Savage K, Trumbore SE, Gimeno C, Yuste JC, Tang J, Vargas R, Janssens IA (2010) Soil respiration at mean annual temperature predicts annual total across vegetation types and biomes. Biogeosci 7:2147–2157CrossRefGoogle Scholar
- Brüggemann N, Gessler A, Kayler Z, Keel SG, Badeck F, Barthel M, Boeckx P, Buchmann N, Brugnoli E, Esperschutz J, Gavrichkova O, Ghashghaie J, Gomez-Casanovas N, Keitel C, Knohl A, Kuptz D, Palacio S, Salmon Y, Uchida Y, Bahn M (2011) Carbon allocation and carbon isotope fluxes in the plant-soil-atmosphere continuum: a review. Biogeosci 8:3457–3489CrossRefGoogle Scholar
- Cuezva S, Sanchez-Moral S, Saiz-Jimenez C, Canaveras JC (2009) Microbial communities and associated mineral fabrics in Altamira Cave, Spain. Int J Speleol 38:83–92Google Scholar
- R Development Core Team (2009) R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. ISBN 3-900051-07-0, URL http://www.R-project.org
- Huxman TE, Snyder KA, Tissue D, Leffler AJ, Ogle K, Pockman WT, Sandquist DR, Potts DL, Schwinning S (2004) Precipitation pulses and carbon fluxes in semiarid and arid ecosystems. Oecologia 141:254–268Google Scholar
- Inglima I, Alberti G, Bertolini T, Vaccari FP, Gioli B, Miglietta F, Cotrufo MF, Peressotti A (2009) Precipitation pulses enhance respiration of Mediterranean ecosystems: the balance between organic and inorganic components of increased soil CO2 efflux. Glob Chang Biol 15:1289–1301CrossRefGoogle Scholar
- Janssens IA, Lankreijer H, Matteucci G, Kowalski AS, Buchmann N, Epron D, Pilegaard K, Kutsch W, Longdoz B, Grunwald T, Montagnani L, Dore S, Rebmann C, Moors EJ, Grelle A, Rannik U, Morgenstern K, Oltchev S, Clement R, Gudmundsson J, Minerbi S, Berbigier P, Ibrom A, Moncrieff J, Aubinet M, Bernhofer C, Jensen NO, Vesala T, Granier A, Schulze ED, Lindroth A, Dolman AJ, Jarvis PG, Ceulemans R, Valentini R (2001) Productivity overshadows temperature in determining soil and ecosystem respiration across European forests. Glob Chang Biol 7:269–278CrossRefGoogle Scholar
- Kowalski AS, Serrano-Ortiz P, Janssens IA, Sanchez-Moraic S, Cuezva S, Domingo F, Were A, Alados-Arboledas L (2008) Can flux tower research neglect geochemical CO2 exchange? Agricultural and Forest Meteorology 148, 1045–1054Google Scholar
- Liu Z, Zhao J (2000) Contribution of carbonate rock weathering to the atmospheric CO2 sink. Environ Geol 39:1053–1058Google Scholar
- McLean EO (1982) Soil pH and lime requirement. In Page, A. L., R. H. Miller and D. R. Keeney (eds.) Methods of soil analysis. Part 2—chemical and microbiological properties. (2nd Ed.). Agronomy 9:199–223Google Scholar
- Pleničar M, Polšak A, Šikić D (1973) Osnovna geološka karta SFRJ 1:100.000, Tolmač za list Trst (Geological map of Yugoslavia 1:100,000, Commentary to the map section Triest). Savezni geološki zavod, Beograd, p 109Google Scholar
- Plestenjak G, Klemen E, Ferlan M, Čater M, Simončič P, Vodnik D (2012) Soil respiration of karst grassland subjected to woody plants encroachment. Eur J Soil Sci in pressGoogle Scholar
- Plummer LN, Wigley TML, Parkhrust DL (1979) Critical review of the kinetics of calcite dissolution and precipitation. In: Jenne EA (ed) Chemical modeling in aqueous systems, A:C:S: Symp Ser No 9. pp 537–573Google Scholar
- Salomons W, Mook WG (1986) Isotope geochemistry of carbonates in the weathering zone. In: Fritz P, Fontes JC (eds) Handbook of environmental isotope geochemistry: the terrestrial environment, vol 2. Elsevier, Amsterdam, pp 239–270Google Scholar
- Sheldrick BH, Wang C (1993) Particle size distribution. In: Carter MR (ed) Soil sampling and methods of analysis. Canadian Society of Soil Science, Ottawa, pp 499–511Google Scholar
- Williams EL (2005) Carbon cycling and mineral weathering and temperate forested watersheds: an integrated study of solution and soil chemistries. PhD thesis, Ann Harbour, University of MichiganGoogle Scholar