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Soil microbial organisms are central to carbon (C) and nitrogen (N) transformations in soils, yet not much is known about the stable isotope composition of these essential regulators of element cycles. We investigated the relationship between C and N availability and stable C and N isotope composition of soil microbial biomass across a three million year old semiarid substrate age gradient in northern Arizona. The δ15N of soil microbial biomass was on average 7.2‰ higher than that of soil total N for all substrate ages and 1.6‰ higher than that of extractable N, but not significantly different for the youngest and oldest sites. Microbial 15N enrichment relative to soil extractable and total N was low at the...
Categories: Publication;
Types: Citation,
Journal Citation;
Tags: Microbial biomass,
Natural isotopic abundance,
Nitrogen and carbon availability,
Nitrogen mineralization,
Piñon–juniper, All tags...
Semiarid,
Soil Biology and Biochemistry,
Stable isotopes,
Substrate age gradient, Fewer tags
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The large land area occupied by arid lands, roughly 36% to 40% globally, underscores the importance for understanding how these ecosystems function in the global carbon cycle. Few studies have directly examined soil organic carbon (SOC) dynamics and the effect of vegetation on SOC and microbial community structure in arid ecosystems. The objective of this study was to determine the effect of vegetation type on SOC dynamics in an arid, hyperthermic Sonoran Desert ecosystem. We specifically examined the influence of Prosopis velutina (mesquite), Larrea tridentata (creosote), and a combination of Bouteloua barbata, Bouteloua aristidoides, Aristida adscensionis, and Cynodon dactylon (mixed grass) vegetation types on...
Categories: Publication;
Types: Citation,
Journal Citation;
Tags: Geoderma,
aggregate stability,
analysis of similarity,
arid ecosystem,
bouteloua aristidoides, All tags...
bouteloua barbata,
carbon mineralization,
hyperthermic,
incubation,
larrea tridentata,
multi-dimensional scaling,
prosopis velutina,
soil organic carbon,
terminal restriction fragment length polymorphism, Fewer tags
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We report the first simultaneous measurements of δ15N and δ13C of DNA extracted from surface soils. The isotopic composition of DNA differed significantly among nine different soils. The δ13C and δ15N of DNA was correlated with δ13C and δ15N of soil, respectively, suggesting that the isotopic composition of DNA is strongly influenced by the isotopic composition of soil organic matter. However, in all samples DNA was enriched in 13C relative to soil, indicating microorganisms fractionated C during assimilation or preferentially used 13C enriched substrates. Enrichment of DNA in 15N relative to soil was not consistently observed, but there were significant differences between δ15N of DNA and δ15N of soil for...
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