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Paleovegetation reconstruction using δ13C of Soil Organic Matter
1Key Laboratory of Plant -Soil Interactions, Ministry of Education, College of Resources and Environment, China Agricultural University, Beijing 100094, China
2Department of Earth Sciences, Dartmouth College, Hanover, NH, USA
3Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
4College of Environmental Sciences, MOE Laboratory for Earth Surface Processes, Peking University, Beijing 100871, China
Abstract. The relative contributions of C3 and C4 plants to vegetation at a given locality may be estimated by means of δ13C of soil organic matter. This approach holds great potential for paleoecological reconstruction using paleosols. However, two uncertainties exist, which limits the accuracy of this application. One is 13C enrichment as plant carbon becomes incorporated into soil organic matter. The other is due to environmental influences on δ13C of plants. Two types of data were collected and analyzed with an objective of narrowing the error of paleovegetation reconstruction. First, we investigated δ13C variations of 557 C3 and 136 C4 plants along a precipitation gradient in North China. A strong negative relationship is found between the δ13C value of C3 plants averaged for each site and the annual precipitation with a coefficient of −0.40‰/100 mm, while no significant coefficients were found for C4 plants. Second, we measured δ13C of soil organic matters for 14 soil profiles at three sites. The isotopic difference between vegetation and soil organic matter are evaluated to be 1.8‰ for the surface soil and 2.8‰ for the soil at the bottom of soil profiles. Using the new data we conducted a sample reconstruction of paleovegetation at the central Chinese Loess Plateau during the Holocene and the Last Glaciation, and conclude that, without corrections for 13C enrichment by decomposition, the C4 abundance would be overestimated. The importance and uncertainties of other corrections are also discussed.
Discussion Paper (PDF, 807 KB) Interactive Discussion (Final Response, 3 Comments)
Citation: Wang, G., Feng, X., Han, J., Zhou, L., Tan, W., and Su, F.: Paleovegetation reconstruction using δ13C of Soil Organic Matter, Biogeosciences Discuss., 5, 1795-1823, 2008. Bibtex EndNote Reference Manager
