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Keywords:

  • dendrochemistry;
  • isotope dendroclimatology;
  • autocorrelation;
  • Larix cajanderi;
  • carbon allocation;
  • tree rings;
  • starch;
  • Siberia

Summary

  • • 
    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.