BG Biogeosciences BG Biogeosciences 1726-4189 Copernicus Publications Göttingen, Germany 10.5194/bg-10-3455-2013 Low vertical transfer rates of carbon inferred from radiocarbon analysis in an Amazon Podzol Sierra C. A. https://orcid.org/0000-0003-0009-4169 1 Jiménez E. M. 1 2 Reu B. 3 Peñuela M. C. 2 Thuille A. 1 Quesada C. A. 4 Max Planck Institute for Biogeochemistry, Hans-Knöll-Str. 10, 07745 Jena, Germany Research Group on Ecology of Tropical Terrestrial Ecosystems, National University of Colombia Sede Amazonia, Leticia, Colombia Institute of Biology, University of Leipzig, 04103 Leipzig, Germany Instituto Nacional de Pesquisas da Amazônia, Manaus, Brazil 01 06 2013 10 6 3455 3464 Copyright: © 2013 C. A. Sierra et al. 2013 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://bg.copernicus.org/articles/10/3455/2013/bg-10-3455-2013.html The full text article is available as a PDF file from https://bg.copernicus.org/articles/10/3455/2013/bg-10-3455-2013.pdf

Hydromorphic Podzol soils in the Amazon Basin generally support low-stature forests with some of the lowest amounts of aboveground net primary production (NPP) in the region. However, they can also exhibit large values of belowground NPP that can contribute significantly to the total annual inputs of organic matter into the soil. These hydromorphic Podzol soils also exhibit a horizon rich in organic matter at around 1–2 m depth, presumably as a result of eluviation of dissolved organic matter and sesquioxides of Fe and Al. Therefore, it is likely that these ecosystems store large quantities of carbon by (1) large amounts of C inputs to soils dominated by their high levels of fine-root production, (2) stabilization of organic matter in an illuviation horizon due to significant vertical transfers of C. To assess these ideas we studied soil carbon dynamics using radiocarbon in two adjacent Amazon forests growing on contrasting soils: a hydromorphic Podzol and a well-drained Alisol supporting a high-stature <i>terra firme</i> forest. Our measurements showed similar concentrations of C and radiocarbon in the litter layer and the first 5 cm of the mineral soil for both sites. This result is consistent with the idea that the hydromorphic Podzol soil has similar soil C storage and cycling rates compared to the well-drained Alisol that supports a more opulent vegetation. However, we found important differences in carbon dynamics and transfers along the vertical profile. At both soils, we found similar radiocarbon concentrations in the subsoil, but the carbon released after incubating soil samples presented radiocarbon concentrations of recent origin in the Alisol, but not in the Podzol. There were no indications of incorporation of C fixed after 1950 in the illuvial horizon of the Podzol. With the aid of a simulation model, we predicted that only a minor fraction (1.7%) of the labile carbon decomposed in the topsoil is transferred to the subsoil of the Podzol, while this proportional transfer is about 30% in the Alisol. Furthermore, our estimates were 8 times lower than previous estimations of vertical C transfers in Amazon Podzols, and question the validity of these previous estimations for all Podzols within the Amazon Basin. Our results also challenge our previous ideas about the genesis of these particular soils and suggest that either they are not true Podzols or the podzolization processes had already stopped.

 References Aragão,&nbsp;L.&nbsp;E.&nbsp;O.&nbsp;C., Malhi,&nbsp;Y., Metcalfe,&nbsp;D.&nbsp;B., Silva-Espejo,&nbsp;J.&nbsp;E., Jiménez,&nbsp;E., Navarrete,&nbsp;D., Almeida,&nbsp;S., Costa,&nbsp;A.&nbsp;C.&nbsp;L., Salinas,&nbsp;N., Phillips,&nbsp;O.&nbsp;L., Anderson,&nbsp;L.&nbsp;O., Alvarez,&nbsp;E., Baker,&nbsp;T.&nbsp;R., Goncalvez,&nbsp;P.&nbsp;H., Huamán-Ovalle,&nbsp;J., Mamani-Solórzano,&nbsp;M., Meir,&nbsp;P., Monteagudo,&nbsp;A., Patiño,&nbsp;S., Peñuela,&nbsp;M.&nbsp;C., Prieto,&nbsp;A., Quesada,&nbsp;C.&nbsp;A., Rozas-Dávila,&nbsp;A., Rudas,&nbsp;A., Silva Jr.,&nbsp;J.&nbsp;A., and Vásquez,&nbsp;R.: Above- and below-ground net primary productivity across ten Amazonian forests on contrasting soils, Biogeosciences, 6, 2759–2778, https://doi.org/<a href="http://dx.doi.org/10.5194/bg-6-2759-2009">10.5194/bg-6-2759-2009</a>, 2009. Baisden,&nbsp;W. and Parfitt,&nbsp;R.: Bomb <sup>14</sup>C enrichment indicates decadal C pool in deep soil?, Biogeochemistry, 85, 59–68, 2007. Bravard,&nbsp;S. and Righi,&nbsp;D.: Geochemical differences in an oxisol-spodosol toposequence of Amazonia, Brazil, Geoderma, 44, 29–42, https://doi.org/<a href="http://dx.doi.org/10.1016/0016-7061(89)90004-9">10.1016/0016-7061(89)90004-9</a>, 1989. Buurman, P. and Jongmans, A.: Podzolisation and soil organic matter dynamics, Geoderma, 125, 71–83, 2005. Chapin,&nbsp;F.&nbsp;S., Woodwell,&nbsp;G.&nbsp;M., Randerson,&nbsp;J.&nbsp;T., Rastetter,&nbsp;E.&nbsp;B., Lovett,&nbsp;G.&nbsp;M., Baldocchi,&nbsp;D.&nbsp;D., Clark,&nbsp;D.&nbsp;A., Harmon,&nbsp;M.&nbsp;E., Schimel,&nbsp;D.&nbsp;S., Valentini,&nbsp;R., Wirth,&nbsp;C., Aber,&nbsp;J.&nbsp;D., Cole,&nbsp;J.&nbsp;J., Goulden,&nbsp;M.&nbsp;L., Harden,&nbsp;J.&nbsp;W., Heimann,&nbsp;M., Howarth,&nbsp;R.&nbsp;W., Matson,&nbsp;P.&nbsp;A., McGuire,&nbsp;A.&nbsp;D., Melillo,&nbsp;J.&nbsp;M., Mooney,&nbsp;H.&nbsp;A., Neff,&nbsp;J.&nbsp;C., Houghton,&nbsp;R.&nbsp;A., Pace,&nbsp;M.&nbsp;L., Ryan,&nbsp;M.&nbsp;G., Running,&nbsp;S.&nbsp;W., Sala,&nbsp;O.&nbsp;E., Schlesinger,&nbsp;W.&nbsp;H., and Schulze,&nbsp;E.&nbsp;D.: Reconciling carbon-cycle concepts, terminology, and methods, Ecosystems, 9, 1041–1050, https://doi.org/<a href="http://dx.doi.org/10.1007/s10021-005-0105-7">10.1007/s10021-005-0105-7</a>, 2006. Chauvel, A., Lucas, Y., and Boulet, R.: On the genesis of the soil mantle of the region of manaus, central Amazonia, Brazil, Experientia 43, 234–241, 1987. Cleveland,&nbsp;C.&nbsp;C., Townsend,&nbsp;A.&nbsp;R., Taylor,&nbsp;P., Alvarez-Clare,&nbsp;S., Bustamante,&nbsp;M.&nbsp;M.&nbsp;C., Chuyong,&nbsp;G., Dobrowski,&nbsp;S.&nbsp;Z., Grierson,&nbsp;P., Harms,&nbsp;K.&nbsp;E., Houlton,&nbsp;B.&nbsp;Z., Marklein,&nbsp;A., Parton,&nbsp;W., Porder,&nbsp;S., Reed,&nbsp;S.&nbsp;C., Sierra,&nbsp;C.&nbsp;A., Silver,&nbsp;W.&nbsp;L., Tanner,&nbsp;E.&nbsp;V.&nbsp;J., and Wieder,&nbsp;W.&nbsp;R.: Relationships among net primary productivity, nutrients and climate in tropical rain forest: a pan-tropical analysis, Ecol. Lett., 14, 939–947, 2011. do Nascimento,&nbsp;N., Bueno,&nbsp;G., Fritsch,&nbsp;E., Herbillon,&nbsp;A., Allard,&nbsp;T., Melfi,&nbsp;A., Astolfo,&nbsp;R., Boucher,&nbsp;H., and Li,&nbsp;Y.: Podzolization as a deferralitization process: a study of an Acrisol–Podzol sequence derived from Palaeozoic sandstones in the northern upper Amazon Basin, Eur.&nbsp;J. Soil Sci., 55, 523–538, https://doi.org/<a href="http://dx.doi.org/10.1111/j.1365-2389.2004.00616.x">10.1111/j.1365-2389.2004.00616.x</a>, 2004. Duivenvoorden,&nbsp;J. and Lips,&nbsp;J.: A land-ecological study of soils, vegetation, and plant diversity in Colombian Amazonia, Trobenbos Series 12, Tropenbos Foundation, 1995. Gaudinski,&nbsp;J., Trumbore,&nbsp;S., Davidson,&nbsp;E., and Zheng,&nbsp;S.: Soil carbon cycling in a temperate forest: radiocarbon-based estimates of residence times, sequestration rates and partitioning fluxes, Biogeochemistry, 51, 33–69, 2000. Horbe,&nbsp;A.&nbsp;M.&nbsp;C., Horbe,&nbsp;M.&nbsp;A., and Suguio,&nbsp;K.: Tropical Spodosols in northeastern Amazonas state, Brazil, Geoderma, 119, 55–68, https://doi.org/<a href="http://dx.doi.org/10.1016/S0016-7061(03)00233-7">10.1016/S0016-7061(03)00233-7</a>, 2004. Jackson, R., Canadell, J., Ehleringer, J., Mooney, H., Sala, O., and Schulze, E.: A global analysis of root distributions for terrestrial biomes, Oecologia, 108, 389–411, 1996. Janzen, D.&nbsp;H.: Tropical blackwater rivers, animals, and mast fruiting by the dipterocarpaceae, Biotropica, 6, 69–103, 1974. Jiménez,&nbsp;E.&nbsp;M., Moreno,&nbsp;F.&nbsp;H., Peñuela,&nbsp;M.&nbsp;C., Patiño,&nbsp;S., and Lloyd,&nbsp;J.: Fine root dynamics for forests on contrasting soils in the Colombian Amazon, Biogeosciences, 6, 2809–2827, https://doi.org/<a href="http://dx.doi.org/10.5194/bg-6-2809-2009">10.5194/bg-6-2809-2009</a>, 2009. Jiménez, E. M., Peñuela, M. C., Sierra, C. A., Patiño, S., Lloyd, J., Phillips, O., Navarrete, D., Prieto, A., Rudas, A., Álvarez, E., Quesada, C. A., and Grande, M. A.: Carbon allocation depends on soils and varies over time in two tropical forests, in preparation, 2013. Jobb{á}gy,&nbsp;E. and Jackson,&nbsp;R.: The vertical distribution of soil organic carbon and its relation to climate and vegetation, Ecol. Appl., 10, 423–436, 2000. Jungkunst,&nbsp;H.&nbsp;F. and Fiedler,&nbsp;S.: Latitudinal differentiated water table control of carbon dioxide, methane and nitrous oxide fluxes from hydromorphic soils: feedbacks to climate change, Glob. Change Biol., 13, 2668–2683, https://doi.org/<a href="http://dx.doi.org/10.1111/j.1365-2486.2007.01459.x">10.1111/j.1365-2486.2007.01459.x</a>, 2007. Klinge,&nbsp;H.: Podzol soils in the Amazon basin,&nbsp;J. Soil Sci., 16, 95–103, https://doi.org/<a href="http://dx.doi.org/10.1111/j.1365-2389.1965.tb01423.x">10.1111/j.1365-2389.1965.tb01423.x</a>, 1965. Leenheer, J. A.: Origin and nature of humic substance in the waters of the amazon river basin. Acta Amazonica, 10, 513–526, 1980. Levin,&nbsp;I. and Kromer,&nbsp;B.: The tropospheric \chem{^{14}CO_2} level in mid-latitudes of the Northern Hemisphere (1959–2003), Radiocarbon, 46, 1261–1272, 2004. Lucas,&nbsp;Y., Montes,&nbsp;C.&nbsp;R., Mounier,&nbsp;S., Loustau Cazalet,&nbsp;M., Ishida,&nbsp;D., Achard,&nbsp;R., Garnier,&nbsp;C., Coulomb,&nbsp;B., and Melfi,&nbsp;A.&nbsp;J.: Biogeochemistry of an Amazonian podzol-ferralsol soil system with white kaolin, Biogeosciences, 9, 3705–3720, https://doi.org/<a href="http://dx.doi.org/10.5194/bg-9-3705-2012">10.5194/bg-9-3705-2012</a>, 2012. Malhi,&nbsp;Y., Doughty,&nbsp;C., and Galbraith,&nbsp;D.: The allocation of ecosystem net primary productivity in tropical forests, Philos.&nbsp;T. Roy. Soc. B, 366, 3225–3245, 2011. Montes,&nbsp;C.&nbsp;R., Lucas,&nbsp;Y., Pereira,&nbsp;O.&nbsp;J.&nbsp;R., Achard,&nbsp;R., Grimaldi,&nbsp;M., and Melfi,&nbsp;A.&nbsp;J.: Deep plant-derived carbon storage in Amazonian podzols, Biogeosciences, 8, 113–120, https://doi.org/<a href="http://dx.doi.org/10.5194/bg-8-113-2011">10.5194/bg-8-113-2011</a>, 2011. Quesada,&nbsp;C.&nbsp;A., Lloyd,&nbsp;J., Schwarz,&nbsp;M., Patiño,&nbsp;S., Baker,&nbsp;T.&nbsp;R., Czimczik,&nbsp;C., Fyllas,&nbsp;N.&nbsp;M., Martinelli,&nbsp;L., Nardoto,&nbsp;G.&nbsp;B., Schmerler,&nbsp;J., Santos,&nbsp;A.&nbsp;J.&nbsp;B., Hodnett,&nbsp;M.&nbsp;G., Herrera,&nbsp;R., Luizão,&nbsp;F.&nbsp;J., Arneth,&nbsp;A., Lloyd,&nbsp;G., Dezzeo,&nbsp;N., Hilke,&nbsp;I., Kuhlmann,&nbsp;I., Raessler,&nbsp;M., Brand,&nbsp;W.&nbsp;A., Geilmann,&nbsp;H., Moraes Filho,&nbsp;J.&nbsp;O., Carvalho,&nbsp;F.&nbsp;P., Araujo Filho,&nbsp;R.&nbsp;N., Chaves,&nbsp;J.&nbsp;E., Cruz Junior,&nbsp;O.&nbsp;F., Pimentel,&nbsp;T.&nbsp;P., and Paiva,&nbsp;R.: Variations in chemical and physical properties of Amazon forest soils in relation to their genesis, Biogeosciences, 7, 1515–1541, https://doi.org/<a href="http://dx.doi.org/10.5194/bg-7-1515-2010">10.5194/bg-7-1515-2010</a>, 2010. Quesada,&nbsp;C.&nbsp;A., Lloyd,&nbsp;J., Anderson,&nbsp;L.&nbsp;O., Fyllas,&nbsp;N.&nbsp;M., Schwarz,&nbsp;M., and Czimczik,&nbsp;C.&nbsp;I.: Soils of Amazonia with particular reference to the RAINFOR sites, Biogeosciences, 8, 1415–1440, https://doi.org/<a href="http://dx.doi.org/10.5194/bg-8-1415-2011">10.5194/bg-8-1415-2011</a>, 2011. Quesada,&nbsp;C.&nbsp;A., Phillips,&nbsp;O.&nbsp;L., Schwarz,&nbsp;M., Czimczik,&nbsp;C.&nbsp;I., Baker,&nbsp;T.&nbsp;R., Patiño,&nbsp;S., Fyllas,&nbsp;N.&nbsp;M., Hodnett,&nbsp;M.&nbsp;G., Herrera,&nbsp;R., Almeida,&nbsp;S., Alvarez Dávila,&nbsp;E., Arneth,&nbsp;A., Arroyo,&nbsp;L., Chao,&nbsp;K.&nbsp;J., Dezzeo,&nbsp;N., Erwin,&nbsp;T., di Fiore,&nbsp;A., Higuchi,&nbsp;N., Honorio Coronado,&nbsp;E., Jimenez,&nbsp;E.&nbsp;M., Killeen,&nbsp;T., Lezama,&nbsp;A.&nbsp;T., Lloyd,&nbsp;G., López-González,&nbsp;G., Luizão,&nbsp;F.&nbsp;J., Malhi,&nbsp;Y., Monteagudo,&nbsp;A., Neill,&nbsp;D.&nbsp;A., Núñez Vargas,&nbsp;P., Paiva,&nbsp;R., Peacock,&nbsp;J., Peñuela,&nbsp;M.&nbsp;C., Peña Cruz,&nbsp;A., Pitman,&nbsp;N., Priante Filho,&nbsp;N., Prieto,&nbsp;A., Ram\'{i}rez,&nbsp;H., Rudas,&nbsp;A., Salomão,&nbsp;R., Santos,&nbsp;A.&nbsp;J.&nbsp;B., Schmerler,&nbsp;J., Silva,&nbsp;N., Silveira,&nbsp;M., Vásquez,&nbsp;R., Vieira,&nbsp;I., Terborgh,&nbsp;J., and Lloyd,&nbsp;J.: Basin-wide variations in Amazon forest structure and function are mediated by both soils and climate, Biogeosciences, 9, 2203–2246, https://doi.org/<a href="http://dx.doi.org/10.5194/bg-9-2203-2012">10.5194/bg-9-2203-2012</a>, 2012. Reimer, P., Baillie, M., Bard, E., Bayliss, A., Beck, J., Blackwell, P., Ramsey, C., Buck, C., Burr, G., Edwards, R., Friedrich, M., Grootes, P.M., Guilderson, T. P., Hajdas, I., Heaton, T. J., Hogg, A. G., Hughen, K.A., Kaiser, K. F., Kromer, B., McCormac, F. G., Manning, S. W., Reimer, R. W., Richards, D. A., Southon, J. R., Talamo, S., Turney, C. S. M., van der Plicht, J., and Weyhenmeyer, C. E.: IntCal09 and Marine09 radiocarbon age calibration curves, 0–50 000 yr cal BP, Radiocarbon, 51, 1111–1150, 2009. Sierra,&nbsp;C.&nbsp;A., Müller,&nbsp;M., and Trumbore,&nbsp;S.&nbsp;E.: Models of soil organic matter decomposition: the SoilR package, version 1.0, Geosci. Model Dev., 5, 1045–1060, https://doi.org/<a href="http://dx.doi.org/10.5194/gmd-5-1045-2012">10.5194/gmd-5-1045-2012</a>, 2012a. Sierra,&nbsp;C.&nbsp;A., Trumbore,&nbsp;S.&nbsp;E., Davidson,&nbsp;E.&nbsp;A., Frey,&nbsp;S.&nbsp;D., Savage,&nbsp;K.&nbsp;E., and Hopkins,&nbsp;F.&nbsp;M.: Predicting decadal trends and transient responses of radiocarbon storage and fluxes in a temperate forest soil, Biogeosciences, 9, 3013–3028, https://doi.org/<a href="http://dx.doi.org/10.5194/bg-9-3013-2012">10.5194/bg-9-3013-2012</a>, 2012b. Skopp, J. Jawson, M.&nbsp;D., and Doran, J.&nbsp;W.: Steady-state aerobic microbial activity as a function of soil water content, Soil Sci. Soc. Am. J., 54, 1619–1625, 1990. Stuiver,&nbsp;M. and Polach,&nbsp;H.&nbsp;A.: Rerporting of <sup>14</sup>C data, Radiocarbon, 19, 355–363, 1977. Townsend,&nbsp;A.&nbsp;R., Asner,&nbsp;G.&nbsp;P., and Cleveland,&nbsp;C.&nbsp;C.: The biogeochemical heterogeneity of tropical forests, Trends Ecol. Evol., 23, 424–431, 2008. Trumbore,&nbsp;S.: Radiocarbon and soil carbon dynamics, Ann. Rev. Earth Planet. Sci., 37, 47–66, 2009. Trumbore,&nbsp;S.&nbsp;E.: Comparison of carbon dynamics in tropical and temperate soils using radiocarbon measurements, Global Biogeochem. Cy., 7, 275–290, 1993. Trumbore,&nbsp;S.&nbsp;E., Davidson,&nbsp;E.&nbsp;A., Barbosa&nbsp;de Camargo,&nbsp;P., Nepstad,&nbsp;D.&nbsp;C., and Martinelli,&nbsp;L.&nbsp;A.: Belowground cycling of carbon in forests and pastures of eastern Amazonia, Global Biogeochem. Cy., 9, 515–528, 1995. Wieder,&nbsp;W.&nbsp;R., Cleveland,&nbsp;C.&nbsp;C., and Townsend,&nbsp;A.&nbsp;R.: Controls over leaf litter decomposition in wet tropical forests, Ecology, 90, 3333–3341, 2009. Yang,&nbsp;X. and Post,&nbsp;W.&nbsp;M.: Phosphorus transformations as a function of pedogenesis: A synthesis of soil phosphorus data using Hedley fractionation method, Biogeosciences, 8, 2907–2916, https://doi.org/<a href="http://dx.doi.org/10.5194/bg-8-2907-2011">10.5194/bg-8-2907-2011</a>, 2011.