Protozoan Pulses Unveil Their Pivotal Position Within the Soil Food Web
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Protozoa are one of the most abundant groups of bacterivores within the soil and are responsible for mineralisation of bacterial biomass, having a large impact on C and N cycling. Little is known of their contribution to soil nutrient transfers or the identity of their consumers. Here, for the first time indigenous flagellates and ciliates, enriched to 83 atom% for 13C and 10 atom% for 15N, were introduced to soil cores from two different land managements, grassland and woodland with the same soil type, to trace the flow of protozoan C and N through the soil food web. Nematodes, Collembola, earthworms and insect larvae obtained the greatest amounts of C and N of protozoan origin, either through direct consumption or uptake of biomass post-cell death. Our results show that changes in management, affect the functioning of the soil food web and the utilisation of protozoa as a food source.
KeywordsStable Isotope Soil Respiration Soil Core Natural Abundance Gini Coefficient
The authors would like to thank Dan Dhanoa for statistical advice, Dr. Barry Thornton at the Macaulay Institute (UKAS accredited laboratory) for operation of the elemental analyser linked to an isotope ratio mass spectrometer and Liz Dixon at Rothamsted Research, North Wyke, for operation of the trace gas analyser linked to a mass spectrometer. Rothamsted Research is sponsored by the UK Biotechnology and Biological Sciences Research Council. This work was carried out as part of a BBSRC DTG studentship.
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