Age-effect on intra-annual δ13C-variability within scots pine tree-rings from central Siberia

Abstract

Intra-annual tree-ring parameters are increasingly used in dendroecology thanks to their high temporal resolution. To better understand the nature of intra-ring proxy signals, we compared old and young trees according to the different ways in which they respond to climate. The study was carried out in central Siberia (Russia, 60°75' N, 89°38' E) in two even-aged Pinus sylvestris L. stands of different ages (20 and 220 years). Ring width, cell size, and intra-annual δ13C were measured for 4 to 27 tree rings, depending on age group (young vs. old) and tree-ring parameter. Wood formation was monitored to link tree-ring position to its time of formation. Results indicated more distinct intra-annual δ13C patterns at both the beginning and end of the ring of young trees compared to old ones. Older trees showed a stronger significant correlation between δ13C across the ring border, indicating a stronger carry-over effect of the previous year's growing conditions on current year wood production. This suggests that tree age/size influences the magnitude of the transfer of mobile carbon reserves across the years.