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Interpretation of soil δ 13 C as an indicator of vegetation change in African savannas
Author(s) -
Gillson L.,
Waldron S.,
Willis K.J.
Publication year - 2004
Publication title -
journal of vegetation science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 115
eISSN - 1654-1103
pISSN - 1100-9233
DOI - 10.1111/j.1654-1103.2004.tb02270.x
Subject(s) - vegetation (pathology) , soil carbon , organic matter , abundance (ecology) , soil organic matter , soil science , environmental science , total organic carbon , productivity , litter , soil water , ecology , carbon fibers , environmental chemistry , chemistry , mathematics , biology , economics , medicine , macroeconomics , pathology , algorithm , composite number
Question: The relationship between carbon‐13 in soil organic matter and C 3 and C 4 plant abundance is complicated because of differential productivity, litter fall and decomposition. As a result, applying a mass balance equation to δ 13 C data from soils cannot be used to infer past C 3 and C 4 plant abundance; only the proportion of carbon derived from C 3 and C 4 plants can be estimated. In this paper, we compare δ 13 C of surface soil samples with vegetation data, in order to establish whether the ratio of C 3 :C 4 plants (rather than the proportion of carbon from C 3 and C 4 plants) can be inferred from soil δ 13 C. Location: The Tsavo National Park, in southeastern Kenya. Methods: We compare vegetation data with δ 13 C of organic matter in surface soil samples and derive regression equations relating the δ 13 C of soil organic matter to C 3 :C 4 plant abundance. We use these equations to interpret δ 13 C data from soil profiles in terms of changes in inferred C 3 :C 4 plant ratio. We compare our method of interpretation with that derived from a mass balance approach. Results: There was a statistically significant, linear relationship between the δ 13 C of organic matter in surface soil samples and the natural logarithm of the ratio of C 3 :C 4 plants in the 100m 2 surrounding the soil sample. Conclusions: We suggest that interpretation of δ 13 C data from organic matter in soil profiles can be improved by comparing vegetation surveys with δ 13 C of organic matter in surface soil samples. Our results suggest that past C 3 plant abundance might be under‐estimated if a mass balance approach is used.