Dissolved carbon as a component of net biome productivity of major land use systems
Final Report Abstract
Estimates of carbon leaching losses from different land use systems are few and their contribution to the net ecosystem carbon balance is uncertain. The goals of this project were i) to test for the relevance of dissolved carbon leaching to carbon budgets of terrestrial ecosystems, and ii) to quantify effects of land use and agricultural management on carbon leaching. We investigated leaching of dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), and dissolved methane (CH4) at forests, grasslands, and croplands across Europe. Leaching of biogenic DIC was 8.3 ± 4.9 g m–2 a–1 for forests, 24.1 ± 7.2 g m–2 a–1 for grasslands, and 14.6 ± 4.8 g m–2 a–1 for croplands. Dissolved organic carbon leaching was 3.5 ± 1.3 g m–2 a–1 for forests, 5.3 ± 2.0 g m–2 a–1 for grasslands, and 4.1 ± 1.3 g m–2 a–1 for croplands. The average flux of total biogenic carbon across land use systems was 19.4 ± 4.0 g m–2 a–1. Leaching losses of biogenic carbon equalled 1–105% (average 28%, median: 19%) of net ecosystem exchange (NEE) plus carbon inputs with fertilization minus carbon removal with harvest. Leaching losses were most relevant to carbon balances of grasslands and croplands. Leaching of methane was irrelevant to the carbon balance and greenhouse gas balance of the investigated ecosystems. Production of DOC in topsoils was positively related to the soil C/N ratio and DOC retention in subsoils was inversely related to the ratio of organic carbon to iron plus aluminium (hydr)oxides. Reduced tillage plus cover cropping increased leaching of DIC due to a stronger supersaturation of soil water with respect to soil air CO2. Dissolved carbon concentrations under elevated atmospheric CO2 and ambient conditions in the Braunschweig free air carbon dioxide enrichment (FACE) experiment were rather similar and did not differ significantly. A 15% reduction of evapotranspiration under elevated CO2 increased groundwater recharge by 60 mm or 55%, which was the main driver for an observed 81% increase in dissolved carbon leaching. In summary, our studies show that i) carbon leaching is crucial to carbon balances of terrestrial ecosystems, particularly of grasslands and croplands, ii) carbon leaching will likely increase in the future with the implementation of reduced tillage and cover crops and the projected increase of atmospheric CO2 concentrations.
Publications
- 2009. Biosphere–atmosphere exchange of reactive nitrogen and greenhouse gases at the NitroEurope core flux measurement sites: Measurement strategy and first data sets. Agriculture, Ecosystems and Environment 133:139–149
Skiba, U., J. Drewer, Y.S. Tang, N. van Dijk, C. Helfter, E. Nemitz, D. Famulari, J.N. Cape, S.K. Jones, M. Twigg, M. Pihlatie, T. Vesala, K.S. Larsen, M.S. Carter, P. Ambus, A. Ibrom, C. Beier, A. Hensen, A. Frumau, J.W. Erisman, N. Brüggemann, R. Gasche, K. Butterbach-Bahl, A. Neftel, C. Spirig, L. Horvath, A. Freibauer, P. Cellier, P. Laville, B. Loubet, E. Magliulo, T. Bertolini, G. Seufert, M. Andersson, G. Manca, T. Laurila, M. Aurela, A. Lohila, S. Zechmeister-Boltenstern, B. Kitzler, G. Schaufler, J. Siemens, R. Kindler, C. Flechard, M.A. Sutton
- Dissolved carbon leaching from soil is a crucial component of the net ecosystem carbon balance. Global Change Biology
Kindler, R., J. Siemens, K. Kaiser, D.C. Walmsley, C. Bernhofer, N. Buchmann, P. Cellier, W. Eugster, G. Gleixner, T. Grünwald, A. Heim, A. Ibrom, S.K. Jones, M. Jones, K. Klumpp, W. Kutsch, K.S. Larsen, S. Lehuger, B. Loubet, R. McKenzie, E. Moors, B. Osborne, K. Pilegaard, C. Rebmann, M. Saunders, M.W.I. Schmidt, M. Schrumpf, J. Seyfferth, U. Skiba, J.-F. Soussana, M.A. Sutton, C. Tefs, B. Vowinckel, M.J. Zeeman, M. Kaupenjohann
(See online at https://doi.org/10.1111/j.1365-2486.2010.02282.x)
