Seasonal course of translocation, storage and remobilization of 13C pulse-labeled photoassimilate in naturally growing Larix gmelinii saplings


Author for correspondence: A. Kagawa Tel: +81 29 8733211 Fax: +81 29 8743720 Email:


  • • 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.