Remarkably high blue ring occurrence in Estonian Scots pines in 1976 reveals wood anatomical evidence of extreme autumnal cooling

0572173 - ÚVGZ 2024 RIV DE eng J - Journal Article
Greaves, C. - Crivellaro, A. - Piermattei, A. - Krusic, P. J. - Oppenheimer, C. - Potapov, A. - Hordo, M. - Metslaid, S. - Kask, R. - Kangur, A. - Büntgen, Ulf
Remarkably high blue ring occurrence in Estonian Scots pines in 1976 reveals wood anatomical evidence of extreme autumnal cooling.
Trees: structure and function. Roč. 37, č. 2 (2023), s. 511-522. ISSN 0931-1890. E-ISSN 1432-2285
R&D Projects: GA MŠMT(CZ) EF16_019/0000797
Research Infrastructure: CzeCOS IV - 90248
Institutional support: RVO:86652079
Keywords : Climate change * Dendrochronology * Europe * Lignification * Pinus sylvestris * Temperature reconstruction * Wood anatomy
OECD category: Forestry
Impact factor: 2.3, year: 2022
Method of publishing: Open access
https://link.springer.com/article/10.1007/s00468-022-02366-1

Key message An exceptionally high number of blue rings were formed within and between Scots pine trees from Estonia in 1976: a year that is well known for its outstanding summer heatwave over Western Europe, but its extreme autumnal cooling over Eastern Europe has so far been neglected in scientific literature. 'Blue rings' (BRs) are visual indicators of less lignified cell walls typically formed towards the end of a tree's growing season. Though BRs have been associated with ephemeral surface cooling, often following large volcanic eruptions, the intensity of cold spells necessary to produce BRs, as well as the consistency of their formation within and between trees still remains uncertain. Here, we report an exceptionally high BR occurrence within and between Scots pine (Pinus sylvestris L.) trees at two sites in Estonia, including the first published whole-stem analysis for BRs. Daily meteorological measurements from a nearby station allowed us to investigate the role temperature has played in BR formation since the beginning of the twentieth century. The single year in which BRs were consistently formed within and amongst most trees was 1976. While the summer of 1976 is well known for an exceptional heatwave in Northwest Europe, mean September and October temperatures were remarkably low over Eastern Europe, and 3.8 degrees C below the 1961-1990 mean at our sites. Our findings contribute to a better eco-physiological interpretation of BRs, and further demonstrate their ability to reveal ephemeral cooling not captured by dendrochronological ring width and latewood density measurements.
Permanent Link: https://hdl.handle.net/11104/0342968