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Stable Carbon Isotope Ratio and Composition of Microbial Fatty Acids in Tropical Soils
Author(s) -
Burke Roger A.,
Molina Marirosa,
Cox Julia E.,
Osher Laurie J.,
Piccolo Marisa C.
Publication year - 2003
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2003.1980
Subject(s) - chronosequence , oxisol , soil water , environmental science , microbial population biology , ecosystem , soil organic matter , agronomy , soil carbon , microorganism , vegetation (pathology) , ecology , environmental chemistry , biology , chemistry , soil science , bacteria , genetics , medicine , pathology
The soil microbial community plays a critical part in tropical ecosystem functioning through its role in the soil organic matter (SOM) cycle. This study evaluates the relative effects of soil type and land use on (i) soil microbial community structure and (ii) the contribution of SOM derived from the original forest vegetation to the functioning of pasture and sugarcane ( Saccharum spp.) ecosystems. We used principal components analysis (PCA) of soil phospholipid fatty acid (PLFA) profiles to evaluate microbial community structure and PLFA stable carbon isotope ratios (δ 13 C) as indicators of the δ 13 C of microbial substrates. Soil type mainly determined the relative proportions of Gram positive versus Gram negative bacteria whereas land use primarily determined the relative proportion of fungi, protozoa, and actinomycetes versus other types of microorganisms. Comparison of a simple model to our PLFA δ 13 C data from land use chronosequences indicates that forest‐derived SOM is actively cycled for appreciably longer times in sugarcane ecosystems developed on Andisols (mean turnover time = 50 yr) than in sugarcane ecosystems developed on an Oxisol (mean turnonver time = 13 yr). Our analyses indicate that soil chronosequence PLFA δ 13 C measurements can be useful indicators of the contribution that SOM derived from the original vegetation makes to continued ecosystem function under the new land use.