Skip to main content Accessibility help
×
Home
  • Get access
    Check if you have access via personal or institutional login
  • Cited by 4
  • Print publication year: 2010
  • Online publication date: May 2010

4 - Determination of soil carbon stocks and changes

Summary

INTRODUCTION

Soil carbon pools and the global carbon cycle

In terrestrial ecosystems soils represent the major reservoir of organic carbon (Table 4.1), but with large and yet unquantified uncertainties in their estimates (mainly due to low soil sample numbers used for global up-scaling and assumptions on mean soil depths). At the global level, the soil organic matter (SOM) pool (estimated to 1 m depth) contains about 1580 Pg of carbon (Pg = 1015 g), about 610 Pg are stored in the vegetation and about 750 Pg are present in the atmosphere (Schimel, 1995). Carbon is found in soils both in organic and inorganic forms (Table 4.2). Organic carbon is commonly classified into three ‘arbitrary’ pools, mostly for modelling purposes (such as in CENTURY), i.e. fast, slow and passive reflecting the rate of turnover. However, it is difficult to relate these pools to soil carbon fractions (see Section 4.1.5). The total amount of carbonate carbon to 1 m depth is estimated at 695–748 Pg carbon (Batjes, 1996). About one third of organic soil carbon occurs in forests and another third in grasslands and savannas, the rest in wetlands, croplands and other biomes (Janzen, 2004). The global soil organic carbon map (Fig. 4.1, ISLSCP II; ORNL DAAC, http://daac.ornl.gov/) shows the areas of high soil organic carbon predominantly in cold boreal (e.g. Northern Canada) and warm and humid tropical regions (e.g. South-East Asia), reflecting areas of deep organic soils (i.e. peatlands).

Related content

Powered by UNSILO
REFERENCES
Amundson, R. (2001) The carbon budget in soils. Annual Review of Earth Planetary Science, 29, 535–62.
Batjes, N. H. (1996) Total carbon and nitrogen in the soils of the world. European Journal of Soil Science, 47, 151–63.
Batjes, N. H. (2002) Carbon and nitrogen stocks in the soils of Central and Eastern Europe. Soil Use and Management, 18, 324–9.
Bellamy, P. H., Loveland, P. J., Bradley, R. I., Lark, R. M. and Kirk, G. J. D. (2005) Carbon losses from all soils across England and Wales 1978–2003. Nature, 437, 245–8.
Berg, B. (2000) Litter decomposition and organic matter turnover in northern forest soils. Forest Ecology and Management, 133, 13–22.
Berg, B. and Meentemeyer, V. (2002) Litter quality in a north European transect versus carbon storage potential. Plant and Soil, 242, 83–92.
Bertrand, I., Chabbert, B., Kurek, B. and Recous, S. (2006) Can the biochemical features and histology of wheat residues explain their decomposition in soil?Plant and Soil, 281, 291–307.
Bisutti, I., Hilke, I. and Raessler, M. (2004) Determination of total organic carbon: an overview of current methods. Trends in Analytical Chemistry, 23, 716–26.
Bolin, B., Sukumar, R., Ciais, P.et al. (2001) The global perspective. In IPCC Special Report on Land Use, Land-use Change and Forestry, ed. Watson, R. T., Noble, I. R., Bolin, B.et al. Cambridge: Cambridge University Press, pp. 23–51.
Briones, M. J. I. and Ineson, P. (1996) Decomposition of eucalyptus leaves in litter mixtures. Soil Biology and Biochemistry, 28, 1381–8.
Burtnor, J. R., Doolittle, J. A., Johnsen, K. H.et al. (2003) Utility of ground penetrating radar as a root biomass survey tool in forest systems. Soil Science Society of America Journal, 67, 1607–15.
Coleman, K. and Jenkinson, D. S. (1996) RothC 26.3: a model for the turnover of carbon in soil. In Evaluation of Soil Organic Matter Models Using Existing Long-term Datasets, ed. Powlson, D. S., Smith, P. and Smith, J. U., Vol. 38, NATO ASI Series I. Heidelberg: Springer-Verlag, pp. 237–46.
Conen, F., Zerva, A., Arrouays, D.et al. (2005) The carbon balance of forest soils: detectability of changes in soil carbon stocks in temperate and boreal forests. In The Carbon Balance of Forest Biomes, ed. Griffiths, H. and Jarvis, P. G.. Oxford: Bios Scientific Press, pp. 233–47.
Cox, P. M., Betts, R. A., Jones, C. D.et al. (2000) Acceleration of global warming due to carbon-cycle feedbacks in a coupled climate model. Nature, 408, 184–7.
Davidson, E. A., Janssens, I. A. and Luo, Y. (2006) On the variability of respiration in terrestrial ecosystems: moving beyond Q10. Global Change Biology, 12, 154–64.
Debano, L. F. and Conrad, C. E. (1978) The effect of fire on nutrients in a chaparral ecosystem. Ecology, 59, 489–97.
Gruijter, J., Brus, D., Bierkens, M. and Knotters, M. (2006) Sampling for Natural Resource Monitoring. Berlin: Springer.
Derenne, S. and Largeau, C. (2001) A review of some important families of refractory macromolecules: composition origin, and fate in soils and sediments. Soil Science, 166, 833–47.
Vos, B., Meirvenne, M., Quataert, P., Deckers, J. and Muys, B. (2005) Predictive quality of pedotransfer functions for estimating bulk density of forest soils. Soil Science Society of America Journal, 69, 500–10.
Duguy, B., Rovira, P. and Vallejo, R. (2006) Land-use history and fire effects on soil fertility in eastern Spain. European Journal of Soil Science, 58, 83–91.
Ellert, B. H., Jazen, H. H. and McConkey, B. G. (2001) Measuring and comparing soil carbon storage. In Chapter 10: Assessment Methods for Soil Carbon, ed. Lal, R., Kimble, J. M., Follet, R. F. and Stewart, B. A.. Boca Raton, FL: CRC Press, pp. 131–46.
Ellert, B. H., Jazen, H. H. and Entz, T. (2002) Assessment of a method to measure temporal change in soil carbon storage. Soil Science Society of America Journal, 66, 1687–95.
Eriksson, P. C. and Holmgren, P. (1996) Estimating stone and boulder content in forest soils: evaluating the potential of surface penetration method. Catena, 28, 121–34.
Fahey, T. J., Siccama, T. G., Driscoll, C. T.et al. (2005) The biogeochemistry of carbon at Hubbard Brook. Biogeochemistry, 75, 109–76.
Ferran, A., Delitti, W. and Vallejo, V. R. (2005) Effects of fire recurrence in Quercus coccifera L. shrublands of the Valencia Region (Spain): II. Plant and soil nutrients. Plant Ecology, 177, 71–83.
Freeman, C., Evans, C. D. and Monteith, D. T. (2001) Export of organic carbon from peat soils. Nature, 412, 785.
Galloway, J. N. and Cowling, E. B. (2002) Reactive nitrogen and the world: 200 years of change. Ambio, 31, 64–71.
Garnett, M. H., Ineson, P., Stevenson, A. C. and Howard, D. C. (2001) Terrestrial organic carbon storage in a British moorland. Global Change Biology, 7, 375–88.
Garten Jr., C. T. (2004) Soil Carbon Dynamics Along an Elevation Gradient in the Southern Appalachian Mountains. US Department of Energy, Environmental Science Division, Oak Ridge National Laboratory, ORNL/TM-2004/50, pp. 1–26.
Garten, C. T. and Wullschleger, S. D. (1999) Soil carbon inventories under a bioenergy crop (Panicum virgatum): measurements limitations. Journal of Environmental Quality, 28, 1359–65.
Garten Jr., C. T., Post III, W. M., Hanson, P. J. and Cooper, L. W. (1999) Forest soil carbon inventories and dynamics along an elevation gradient in the southern Appalachian Mountains. Biogeochemistry, 45, 115–45.
Giardina, C. P., Coleman, M. D., Hancock, J. E.et al. (2005) The response of belowground carbon allocation in forests to global change. In Tree Species Effects on Soils: Implications for Global Change, ed. Binkley, D. and Menyailo, O., NATO Science Series. Dordrecht: Kluwer Academic Publishers, pp. 120–54.
Gill, R. A., Polley, H. W., Johnson, H. B.et al. (2002) Nonlinear grassland responses to past and future atmospheric CO2. Nature, 417, 279–82.
,GLC (2003) Global Land Cover 2000 database. European Commission, Joint Research Centre. Available at: www.gvm.jrc.it/glc2000.
Grace, P. R. and Ladd, J. N. (1995) SOCRATES v2.00 User Manual. Cooperative research centre for soil and land management, PMB 2 Glen Osmond 5064, South Australia.
Guo, Y., Amundson, R., Gong, P. and Yu, Q. (2006) Quantity and spatial variability of soil carbon in the conterminous United States. Soil Science Society of America Journal, 70, 590–600.
Gupta, R. K. and Rao, D. L. N. (1994) Potential of wastelands for sequestering carbon by reforestation. Current Science, 66, 378–80.
Hanson, P. J., Edwards, N. T., Garten, C. T. and Andrews, J. A. (2000) Separating root and soil microbial contributions to soil respiration: a review of methods and observations. Biogeochemistry, 48, 115–46.
Harrison, R. B., Adams, A. B., Licata, C.et al. (2003) Quantifying deep-soil and coarse-soil fractions: avoiding sampling bias. Soil Science Society of America Journal, 67, 1602–6.
Harmon, M. E. and Sexton, J. (1996) Guidelines for Measurements of Woody Detritus in Forest Ecosystems. US LTER Publication No. 20. Seattle: LTER Network Office, University of Washington.
Heath, J., Ayres, E., Possell, M.et al. (2005) Rising atmospheric CO2 reduces sequestration of root-derived soil carbon. Science, 309, 1711–13.
Hirano, Y., Dannoura, M., Aono, K.et al. (2009) Limiting factors in the detection of tree roots using ground-penetrating radar. Plant and Soil, 319, 15–24.
Hopmans, P., Bauhus, J., Khanna, P. and Weston, C. (2005) Carbon and nitrogen in forest soils: potential indicators for sustainable management of eucalypt forests in south-eastern Australia. Forest Ecology and Management, 220, 75–87.
Irvine, J., Law, B. E. and Hibbard, K. A. (2007) Postfire carbon pools and fluxes in semiarid ponderosa pine in Central Oregon. Global Change Biology, 13, 1–13.
,IPCC (1990) Climate Change: The IPCC Scientific Assessment, ed. Houghton, J. T., Jenkins, G. J. and Ephraums, J. J.. Cambridge: Cambridge University Press.
,IPCC (2003) Good Practice Guidance for Land Use, Land Use Change and Forestry, ed. Penman, J., Gytarsky, M., Hiraishi, T.et al. Japan: IPCC/OECD/IEA/IGES.
,IPCC (2006) Guidelines for National Greenhouse Gas Inventories, Prepared by the National Greenhouse Inventories Programme, ed. Eggleston, H. S., Buendia, L., Miwa, K., Ngara, T. and Tanabe, K., Vol. 4, Agriculture, forestry and other land use. Hayama, Japan: IGES.
,IPCC (2007) Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, ed. Solomon, S., Qin, D., Manning, M.et al. Cambridge: Cambridge University Press.
,ISLSCP II (2005) Global Gridded Surfaces of Selected Soil Characteristics for the International Satellite Land Surface Climatology Project (ISLSCP) Initiative. II. Data Collection, ed. Hall, F. G., Collatz, G., Los, S., Colstoun, E. Brown and Landis, D., ISLSCP Initiative II. NASA. DVD/CD-ROM. NASA, 2005. Available at: http://islscp2.sesda.com/ISLSCP2_1/html_pages/groups/hyd/islscp2_soils_1deg.html.
,ISO (2002) Soil Quality – Sampling – Part 1: Guidance on the design of sampling programmes, ISO/FDIS 10381–1:2002.
,ISO (2003) Soil Quality – Sampling – Part 4: Guidance on the procedure for investigation of natural, near natural and cultivated sites, ISO/FDIS 10381–4:2003.
Jankauskas, B., Slepetiene, A., Jankauskiene, G., Fullen, M. A. and Booth, C. A. (2006) A comparative study of analytical methodologies to determine the soil organic matter content of Lithuanian Eutric Albeluvisols. Geoderma, 136, 763–73.
Jandl, R., Linder, M., Vesterdal, L.et al. (2007) How strongly can forest management influence soil carbon sequestration?Geoderma, 137, 253–68.
Janssens, I. A., Freibauer, A., Schlamadinger, B.et al. (2005) The carbon budget of terrestrial ecosystems at country-scale: a European case study. Biogeosciences, 2, 15–26.
Jazen, H. H., Campbell, C. A., Brandt, S. A., Lafond, G. P. and Townley-Smith, L. (1992) Light-fraction organic matter in soil from long-term rotations. Soil Science Society of America Journal, 56, 1799–806.
Janzen, H. H. (2004) Carbon cycling in earth systems: a soil science perspective. Agriculture, Ecosystems and Environment, 104, 399–417.
Janzen, H. H. (2006) The soil carbon dilemma: shall we hoard it or use it?Soil Biology and Biochemistry, 38, 419–24.
Jones, R. J. A., Hiederer, R., Rusco, E. and Montanarella, L. (2005) Estimating organic carbon in the soils of Europe for policy support. European Journal of Soil Science, 56, 655–71.
Kirschbaum, M. U. F. (1995) The temperature dependence of soil organic matter decomposition and the effect of global warming on soil organic carbon storage. Soil Biology and Biochemistry, 27, 753–60.
Kirschbaum, M. U. F. (2000) Will changes in soil organic carbon act as a positive or negative feedback on global warming?Biogeochemistry, 48, 21–51.
Kleber, M., Mikutta, R., Torn, M. S. and Jahn, R. (2005) Poorly crystalline mineral phases protect organic matter in acid subsoil horizons. European Journal of Soil Science, 56, 717–25.
Konen, M. E., Jacobs, P. M., Burras, C. L., Talaga, B. J. and Mason, J. A. (2002) Equations for predicting soil organic carbon using loss-on-ignition for North Central U.S. Soils. Soil Science Society of America Journal, 66, 1878–81.
Kool, D. M., Chung, H., Tate, K. R.et al. (2007) Hierarchical saturation of soil carbon pools near a natural CO2 spring. Global Change Biology, 13, 1282–93.
Laiho, R., Penttilä, T. and Laine, J. (2004) Variation in soil nutrient concentrations and bulk density within peatland forest sites. Silva Fennica, 38, 29–41.
Lal, R. (2001) Fate of the eroded soil carbon: emission or sequestration. In Soil Carbon Sequestration and the Greenhouse Effect, ed. Lal, R., Vol. 57. Madison, WI: Soil Science Society of America special publication, pp. 173–81.
Lal, R. (2004). Soil carbon sequestration to mitigate climate change. Geoderma, 123, 1–22.
Leemans, R. (1992) Global Holdridge life zone classifications. Digital raster data on a 0.5-degree Cartesian orthonormal geodetic (lat/long) 360 × 720 grid. In Global ecosystems database Version 2.0. Boulder, CO: NOAA National Geophysical Data Center. Two independent single-attribute spatial layers. 537 430 bytes in 8 files. (First published in 1989).
Lettens, S., Orshoven, J. V., Wesemael, B., Muys, B. and Perrin, D. (2005) Soil organic carbon changes in landscape units of Belgium between 1960 and 2000 with reference to 1990. Global Change Biology, 11, 2128–40.
Lettens, S., Vos, B., Quataert, P.et al. (2007) Variable carbon recovery of Walkley–Black analysis and implications for national soil organic carbon accounting. European Journal of Soil Science, 58, 1244–53.
Li, C., Frolking, S. and Harriss, R. (1994) Modeling carbon biogeochemistry in agricultural soils. Global Biogeochemical Cycles, 8, 237–54.
MacDicken, K. G. (1997) A Guide to Monitoring Carbon Storage in Forestry and Agroforestry Projects. Winrock: International Institute for Agricultural Development.
Majdi, H. (2001) Changes in fine root production and longevity in relation to water and nutrient availability in a Norway spruce stand in northern Sweden. Tree Physiology, 21, 1057–61.
Miltner, A., Kopinke, F. D., Kindler, R.et al. (2005) Non-phototrophic CO2 fixation by soil microorganisms. Plant and Soil, 269, 193–203.
Mikutta, R., Kleber, M., Torn, M. S. and Jahn, R. (2006) Stabilization of soil organic matter: association with minerals or chemical recalcitrance?Biogeochemistry, 77, 25–56.
Moore, T. R. and Turunen, J. (2004) Carbon accumulation and storage in mineral subsoil beneath peat. Soil Science Society of America Journal, 68, 690–6.
Nadelhoffer, K. J. and Raich, J. W. (1992) Fine root production estimates and belowground carbon allocation in forest ecosystems. Ecology, 73 (4), 1139–47.
Neary, D. G., Klopatek, C. C., DeBano, L. F. and Folliot, P. F. (1999) Fire effects on belowground sustainability: a review and synthesis. Forest Ecology and Management, 122, 51–71.
Neff, J. C., Townsend, A. R., Gleixner, G.et al. (2002) Variable effects of nitrogen addictions on the stability and turnover of soil carbon. Nature, 419, 915–17.
Nelson, D. W. and Sommers, L. E. (1996) Total carbon, organic carbon, and organic matter. In Methods of Soil Analysis, ed. Sparks, D. L.. SSSA Book Series no. 5, Part 3. Chemical methods. Madison, WI: SSSA/ASA, pp. 961–1010.
Page, S. E., Siegert, F., Rieley, J. O.et al. (2002) The amount of carbon released from peat and forest fires in Indonesia during 1997. Nature, 420, 61–5.
Page-Dumroese, D. S., Jurgensen, M. F., Brown, R. E. and Mroz, G. D. (1999) Comparison of methods for determining bulk densities of rocky forest soils. Soil Science Society of America Journal, 63, 379–83.
Palmer, C. J. (2002) Techniques to measure and strategies to monitor forest soil carbon. In The Potential of U.S. Forest Land to Sequester Carbon and Mitigate the Greenhouse Effect, ed. Kimble, J. R., Lal, R., Heath, L. and Birdsey, R.. Boca Raton, FL: CRC Press, pp. 73–90.
Palmer, C. J., Smith, W. D. and Conkling, B. L. (2002) Development of a protocol for monitoring status and trends in forest soil carbon at a national level. Environmental Pollution, 116, 209–19.
Parton, W. J., Stewart, J. W. B. and Cole, C. V. (1988) Dynamics of C, N, P and S in grasslands soils: a model. Biogeochemistry, 5, 109–31.
Paul, K. I., Polglase, P. J., Nyakuengama, J. G. and Khanna, P. K. (2002) Change in soil carbon following afforestation. Forest Ecology and Management, 168, 241–57.
Post, W. M. and Kwon, K. C. (2000) Soil carbon sequestration and land use change: processes and potential. Global Change Biology, 6, 317–27.
Post, W. M., Izaurralde, R. C., Mann, L. K. and Bliss, N. (2001) Monitoring and verifying changes of organic carbon in soil. Climatic Change, 51, 73–99.
Pregitzer, K. S. and Euskirchen, E. S. (2004) Carbon cycling and storage in world forests: biome patterns related to forest age. Global Change Biology, 10, 2052–77.
Raich, J. W., Potter, C. S. and Bhagawati, D. (2002) Interannual variability in global soil respiration, 1980–94. Global Change Biology, 8, 800–12.
Raison, R. J., Khanna, P. K. and Woods, P. V. (1985) Transfer of elements to the atmosphere during low-intensity prescribed fires in three subalpine eucalypt forests. Canadian Journal of Forest Research, 15, 657–64.
Rasse, D. P., Rumpel, C. and Dignac, M. F. (2005) Is soil carbon mostly root carbon? Mechanisms for a specific stabilisation. Plant and Soil, 269, 341–56.
Rodeghiero, M. (2003) Flussi e depositi di carbonio nei suoli di ecosistemi forestali lungo un gradiente altitudinale: variabilità spazio-temporale e determinanti ecologiche. Ph.D. thesis, Università degli Studi di Padova (in Italian, English abstract).
Rodeghiero, M. and Cescatti, A. (2005) Main determinants of forest soil respiration along an elevation/tempertaure gradient in the Italian Alps. Global Change Biology, 11, 1024–41.
Ruess, R. W., Cleve, K., Yarie, J. and Viereck, L. A. (1996) Contributions of fine root production and turnover to the carbon and nitrogen cycling in taiga forests of the Alaskan interior. Canadian Journal of Forest Research, 26, 1326–36.
Saarnio, S., Morero, M., Shurpali, N. J.et al. (2007) Annual CO2 and CH4 fluxes of pristine boreal mires as a background for the lifecycle analyses of peat energy. Boreal Environment Research, 12, 101–13.
Saby, N. P. A., Bellamy, P. H., Morvan, X.et al. (2008) Will European soil monitoring networks be able to detect changes in topsoil organic carbon context? Global Change Biology, 14, 2432–42.
Scheffer, F. and Schachtschabel, P. (1992) Lehrbuch der Bodenkunde. Stuttgart, Germany: Enke Verlag.
Schimel, D. S. (1995) Terrestrial ecosystems and the carbon cycle. Global Change Biology, 1, 77–91.
Schlesinger, W. H. and Andrews, J. A. (2000) Soil respiration and the global carbon cycle. Biogeochemistry, 48, 7–20.
Scholes, M. and Andreae, M. O. (2000) Biogenic and pyrogenic emissions from Africa and their impact on the global atmosphere. Ambio, 29, 23–9.
Schöning, I. and Kögel-Knabner, I. (2006) Chemical composition of young and old carbon pools throughout Cambisol and Luvisol profiles under forests. Soil Biology and Biochemistry, 38, 2411–24.
Schrumpf, M., Schumacher, J., Schöning, I. and Schulze, E.-D. (2008) Monitoring carbon stock changes in European soils: process understanding and sampling strategies. In The Continental-scale Greenhouse Gas Balance of Europe, ed. Dolman, A. J., Freibauer, A. and Valentini, R.. Ecological Studies 203, Springer.
Schulze, E.-D. and Freibauer, A. (2005) Carbon unlocked from soils. Nature, 437, 205–6.
Siemens, J. (2003) The European carbon budget: a gap. Science, 302, 1681.
Six, J., Elliott, E. T. and Paustian, K. (1999) Aggregate and soil organic matter dynamics under conventional and no-tillage systems. Soil Science Society of America Journal, 63, 1350–8.
Six, J., Callewaert, S., Lenders, S.et al. (2002) Measuring and understanding carbon storage in afforested soils by physical fractionation. Soil Science Society of America Journal, 66, 1981–7.
Smith, P. (2004) How long before a change in soil organic carbon can be detected?Global Change Biology, 10, 1878–83.
,Soil Science Society of America (1984) Glossary of Soil Science Terms. Madison, WI: Soil Science Society of America.
Subke, J.-A., Inglima, I. and Cotrufo, M. F. (2006) Trends and methodological impacts in soil CO2 efflux partitioning: a metaanalytical review. Global Change Biology, 12, 921–43.
Sulzman, E. W., Brant, J. B., Bowden, R. D. and Lajtha, K. (2005) Contribution of aboveground litter, belowground litter and rhizosphere respiration to total soil CO2 efflux in an old growth coniferous forest. Biogeochemistry, 73, 231–56.
Sun, O. J., Campbell, J., Law, B. E. and Wolf, V. (2004) Dynamics of carbon stocks in soils and detritus across chronosequences of different forest types in the Pacific Northwest, USA. Global Change Biology, 10, 1470–81.
Tilman, D., Reich, P., Phillips, H.et al. (2000) Fire suppression and ecosystem carbon storage. Ecology, 81, 2680–5.
Timoney, K. P. and Wein, R. W. (1991) The areal pattern of burned tree vegetation in the subarctic region of northwestern Canada. Arctic, 44, 223–30.
,UNECE (2003) ICP Forest Manual on Methods and Criteria for Harmonized Sampling, Assessment, Monitoring and Analysis of the Effects of Air Pollution on Forests. Part IIIa, Sampling and Analysis of Soil. United Nations Economic Commission for Europe, Convention on Long-range Transboundary Air Pollution. International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests.
,USDA (2005) United States Department of Agriculture Forest Service, Soil measurements and sampling. In Forest Inventory and Analysis Field Methods for Phase 3 Measurements, 2005. USDA Forest Service and National Association of State Foresters.
Vance, E. D. (2003) Approaches and technologies for detecting changes in forest soil carbon pools. Soil Science Society of America Journal, 67, 1582.
Viro, P. J. (1952) On the determination of stoniness. Summary. Commun. Inst. Forestalia Fennica, 40, 1–19.
Lützow, M., Kögel-Knabner, I., Ekschmitt, K.et al. (2006) Stabilization of organic matter in temperate soils: mechanisms and their relevance under different soil conditions – a review. European Journal of Soil Science, 57, 426–45.
Lützow, M., Kögel-Knabner, I., Ekschmitt, K.et al. (2007) SOM fractionation methods: relevance to functional pools and to stabilization mechanisms. Soil Biology and Biochemistry, 39, 2183–207.
Walter, K. M., Zimov, S. A., Chanton, J. P., Verbyla, D. and Chapin III, F. S. (2006) Methane bubbling from Siberian thaw lakes as a positive feedback to climate warming. Nature, 443, 71–5.
Wang, X. J., Smethurst, P. J. and Herbert, A. M. (1996) Relationships between three measures of organic matter or carbon in soils of eucalypt plantations in Tasmania. Australian Journal of Soil Research, 34, 545–53.
Walkley, A. and Black, I. A. (1934) An examination of the Degtjareff method for determining soil organic matter, and a proposed modification of the chromic acid titration method. Soil Science, 37, 29–38.
Whitney, N. and Zabowski, D. (2004) Total soil nitrogen in the coarse fraction and at depth. Soil Science Society of America Journal, 68, 612–19.
Wiseman, C. L. S. and Püttmann, W. (2005) Soil organic carbon and its sorptive preservation in central Germany. European Journal of Soil Science, 56, 65–76.
Zar, J. H. (1996) Biostatistical Analysis, 3rd edn. London: Prentice-Hall International.
Zianis, D., Muukkonen, P., Mäkipää, R. and Mencuccini, M. (2005) Biomass and stem volume equations for tree species in Europe. Silva Fennica Monographs, 4, 1–63.