Publication Date:
2015-11-21
Description:
Significant gaps still exist in our knowledge about post-photosynthetic leaf level and downstream metabolic processes and isotopic fractionations. This includes their impact on the isotopic climate signal stored in the carbon isotope composition ( 13 C) of leaf assimilates and tree rings. For the first time, we compared the seasonal 13 C variability of leaf sucrose with intra-annual, high-resolution 13 C signature of tree rings from larch ( Larix gmelinii Rupr.). The trees were growing at two sites in the continuous permafrost zone of Siberia with different growth conditions. Our results indicate very similar low-frequency intra-seasonal trends of the sucrose and tree ring 13 C records with little or no indication for the use of ‘old’ photosynthates formed during the previous year(s). The comparison of leaf sucrose 13 C values with that in other leaf sugars and in tree rings elucidates the cause for the reported 13 C-enrichment of sink organs compared with leaves. We observed that while the average 13 C of all needle sugars was 1.2 more negative than 13 C value of wood, the 13 C value of the transport sugar sucrose was on an average 1.0 more positive than that of wood. Our study shows a high potential of the combined use of compound-specific isotope analysis of sugars (leaf and phloem) with intra-annual tree ring 13 C measurements for deepening our understanding about the mechanisms controlling the isotope variability in tree rings under different environmental conditions.
Print ISSN:
0829-318X
Electronic ISSN:
1758-4469
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
