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Short‐term dynamics of abiotic and biotic soil 13 CO 2 effluxes after in situ 13 CO 2 pulse labelling of a boreal pine forest
Author(s) -
Subke JensArne,
Vallack Harry W.,
Magnusson Tord,
Keel Sonja G.,
Metcalfe Daniel B.,
Högberg Peter,
Ineson Phil
Publication year - 2009
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.2009.02883.x
Subject(s) - abiotic component , tracer , autotroph , flux (metallurgy) , environmental science , environmental chemistry , soil water , biotic component , atmospheric sciences , chemistry , soil science , ecology , biology , physics , nuclear physics , genetics , organic chemistry , bacteria
Summary• Physical diffusion of isotopic tracers into and out of soil pores causes considerable uncertainty for the timing and magnitude of plant belowground allocation in pulse‐labelling experiments. • Here, we partitioned soil CO 2 isotopic fluxes into abiotic tracer flux (physical return), heterotrophic flux, and autotrophic flux contributions following 13 CO 2 labelling of a Swedish Pinus sylvestris forest. Soil CO 2 efflux and its isotopic composition from a combination of deep and surface soil collars was monitored using a field‐deployed mass spectrometer. Additionally, 13 CO 2 within the soil profile was monitored. • Physical (abiotic) efflux of 13 CO 2 from soil pore spaces was found to be significant for up to 48 h after pulse labelling, and equalled the amount of biotic label flux over 6 d. Measured and modelled changes in 13 CO 2 concentration throughout the soil profile corroborated these results. Tracer return via soil CO 2 efflux correlated significantly with the proximity of collars to trees, while daily amplitudes of total flux (including heterotrophic and autotrophic sources) showed surprising time shifts compared with heterotrophic fluxes. • The results show for the first time the significance of the confounding influence of physical isotopic CO 2 ‐tracer return from the soil matrix, calling for the inclusion of meaningful control treatments in future pulse‐chase experiments.