Temporal dynamics of the carbon isotope composition in a Pinus sylvestris stand: from newly assimilated organic carbon to respired carbon dioxide.

@article{citeulike:2793819, abstract = {The (13)C isotopic signature (C stable isotope ratio; delta(13)C) of CO(2) respired from forest ecosystems and their particular compartments are known to be influenced by temporal changes in environmental conditions affecting C isotope fractionation during photosynthesis. Whereas most studies have assessed temporal variation in delta(13)C of ecosystem-respired CO(2) on a day-to-day scale, not much information is available on its diel dynamics. We investigated environmental and physiological controls over potential temporal changes in delta(13)C of respired CO(2) by following the short-term dynamics of the (13)C signature from newly assimilated organic matter pools in the needles, via phloem-transported organic matter in twigs and trunks, to trunk-, soil- and ecosystem-respired CO(2). We found a strong 24-h periodicity in delta(13)C of organic matter in leaf and twig phloem sap, which was strongly dampened as carbohydrates were transported down the trunk. Periodicity reappeared in the delta(13)C of trunk-respired CO(2), which seemed to originate from apparent respiratory fractionation rather than from changes in delta(13)C of the organic substrate. The diel patterns of delta(13)C in soil-respired CO(2) are partly explained by soil temperature and moisture and are probably due to changes in the relative contribution of heterotrophic and autotrophic CO(2) fluxes to total soil efflux in response to environmental conditions. Our study shows that direct relations between delta(13)C of recent assimilates and respired CO(2) may not be present on a diel time scale, and other factors lead to short-term variations in delta(13)C of ecosystem-emitted CO(2). On the one hand, these variations complicate ecosystem CO(2) flux partitioning, but on the other hand they provide new insights into metabolic processes underlying respiratory CO(2) emission.}, address = {Institute of Forest Botany and Tree Physiology, University of Freiburg, Georges-Koehler Allee 53/54, 79085, Freiburg, Germany.}, author = {Kodama, Naomi and Barnard, Romain L. and Salmon, Yann and Weston, Christopher and Ferrio, Juan P. and Holst, Jutta and Werner, Roland A. and Saurer, Matthias and Rennenberg, Heinz and Buchmann, Nina and Gessler, Arthur }, citeulike-article-id = {2793819}, doi = {http://dx.doi.org/10.1007/s00442-008-1030-1}, issn = {0029-8549}, journal = {Oecologia}, keywords = {isotope, pinus, respiration, translocation}, month = {April}, posted-at = {2008-05-13 08:48:02}, priority = {2}, title = {Temporal dynamics of the carbon isotope composition in a Pinus sylvestris stand: from newly assimilated organic carbon to respired carbon dioxide.}, url = {http://dx.doi.org/10.1007/s00442-008-1030-1}, year = {2008} }

TY - JOUR ID - citeulike:2793819 L3 - citeulike-article-id:2793819 TI - Temporal dynamics of the carbon isotope composition in a Pinus sylvestris stand: from newly assimilated organic carbon to respired carbon dioxide. JF - Oecologia AD - Institute of Forest Botany and Tree Physiology, University of Freiburg, Georges-Koehler Allee 53/54, 79085, Freiburg, Germany. SN - 0029-8549 N2 - The (13)C isotopic signature (C stable isotope ratio; delta(13)C) of CO(2) respired from forest ecosystems and their particular compartments are known to be influenced by temporal changes in environmental conditions affecting C isotope fractionation during photosynthesis. Whereas most studies have assessed temporal variation in delta(13)C of ecosystem-respired CO(2) on a day-to-day scale, not much information is available on its diel dynamics. We investigated environmental and physiological controls over potential temporal changes in delta(13)C of respired CO(2) by following the short-term dynamics of the (13)C signature from newly assimilated organic matter pools in the needles, via phloem-transported organic matter in twigs and trunks, to trunk-, soil- and ecosystem-respired CO(2). We found a strong 24-h periodicity in delta(13)C of organic matter in leaf and twig phloem sap, which was strongly dampened as carbohydrates were transported down the trunk. Periodicity reappeared in the delta(13)C of trunk-respired CO(2), which seemed to originate from apparent respiratory fractionation rather than from changes in delta(13)C of the organic substrate. The diel patterns of delta(13)C in soil-respired CO(2) are partly explained by soil temperature and moisture and are probably due to changes in the relative contribution of heterotrophic and autotrophic CO(2) fluxes to total soil efflux in response to environmental conditions. Our study shows that direct relations between delta(13)C of recent assimilates and respired CO(2) may not be present on a diel time scale, and other factors lead to short-term variations in delta(13)C of ecosystem-emitted CO(2). On the one hand, these variations complicate ecosystem CO(2) flux partitioning, but on the other hand they provide new insights into metabolic processes underlying respiratory CO(2) emission. KW - isotope KW - pinus KW - respiration KW - translocation AU - Kodama, Naomi AU - Barnard, Romain AU - Salmon, Yann AU - Weston, Christopher AU - Ferrio, Juan AU - Holst, Jutta AU - Werner, Roland AU - Saurer, Matthias AU - Rennenberg, Heinz AU - Buchmann, Nina AU - Gessler, Arthur PY - 2008/04/05/ UR - http://dx.doi.org/10.1007/s00442-008-1030-1 ER -