title: Seasonal course of translocation, storage and remobilization of 13C pulse-labeled photoassimilate in naturally growing Larix gmelinii saplings.
abstract: Autocorrelation--correlation of tree-ring parameters such as ring width, density and isotope ratios to the environmental conditions of the previous year(s)--is associated with the use of previous photoassimilate for current year's tree ring formation. To clarify the seasonal course of carbon allocation patterns among needles, branches, stem and roots, we pulse-labeled 10 Larix gmelinii growing in a continuous permafrost zone with 13CO2. Photoassimilate incorporated in June was allocated mainly to above-ground parts, indicating active above-ground growth in spring. Very little was allocated to below-ground parts (2.6-7.9%), probably because root growth is inhibited by low soil temperatures in spring. Conversely, a higher proportion of July and August photoassimilate was allocated to below-ground parts (32-44 and 12-24%, respectively). About half the carbon in new needles was derived from stored material. The starch pool in non-needle parts, which can be used for xylem formation, drew approx. 43% of its carbon from the previous year's photoassimilate, indicating that carbon storage is a key mechanism behind autocorrelation in (isotope) dendroclimatology.
authors.affiliation: Wood Anatomy and Quality Laboratory, Forestry and Forest Products Research Institute, Tsukuba Norin PO Box 16, Ibaraki 305-8687, Japan. akagawa@ffpri.affrc.go.jp
authors.forename: Akira
authors.initials: A
authors.lastname: Kagawa
authors.forename: Atsuko
authors.initials: A
authors.lastname: Sugimoto
authors.forename: Trofim C
authors.initials: TC
authors.lastname: Maximov
mesh_terms: D002244:Carbon / Q000378:metabolism*; D002247:Carbon Isotopes; D028221:Larix / Q000254:growth & development* / Q000378:metabolism*; D035261:Plant Components, Aerial / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism; D012621:Seasons; D013213:Starch / Q000378:metabolism*; D013997:Time Factors
chemical_list: D002247:Carbon Isotopes; D002244:Carbon; D013213:Starch