Dendrochronology

Tree ring research on conifers in the Alps
Dendroecology, dendroclimatology and climatic studies

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Desplanque C., Rolland C., Schweingruber F.H. (1999). Influence of species and abiotic factors on extreme tree ring modulation: Picea abies and Abies alba in Tarentaise and Maurienne (French Alps). Trees, Structure and Function 13: 218-227.
  • TITLE Influence of species and abiotic factors on extreme tree ring modulation: Picea abies and Abies alba in Tarentaise and Maurienne (French Alps)
  • LANGUAGE English , with English abstract.
  • SPECIES Abies alba Mill., Picea abies (L.) Karst.
  • KEY WORDS Silver fir, Norway spruce, Dendroecology, Pointer years.
  • MOTS CLES Sapin, Epicéa, Dendroécologie, Années caractéristiques.
  • SITES Tarentaise, Maurienne (France).
  • ABSTRACT (English)

    • The influence of biotic (tree species) and abiotic factors (regional climate, altitude and stand aspect) on extreme tree-ring widths was dendroecologically investigated. Negative pointer years are observed when abrupt radial growth reductions (exceeding 40%r) occurred synchronously in a given tree population. Pointer year intensity is expected to follow several theoretical models when tree are sampled along ecological gradients in various site conditions. Hypotheses are made about expected patterns of pointer year spatial distribution. They are compared with observed results obtained with Norway spruce [Picea abies (L.) Karst.] and silver fir (Abies alba Mill.) sampled in two French Alpine valleys (Tarentaise and Maurienne) with different regiona1 climates, on two aspects and three altitude levels. Results reveal that extreme years follow expected patterns well. Thus, clear site modulations are observed in 1956 and 1986 (only trees located in Maurienne reacted). Moreover, species differences are observed, with typical cases of single species sensitivity (for spruce, occurring in 1962 and 1992). Abiotic factors such as altitude and aspect also involve clear pointer year patterns, such as narrow rings in 1976 due to summer drought that occurred especially at lower altitudes. However, some observed extreme years sometimes appear to be a combination of two (or three) of these one-factor theoretical models (e.g. 1921 with both lower altitude level and only observed in Tarentaise; l948 involving both higher altitude and northern slopes). These results demonstrate the consistency of various tree-ring and climate relationships along ecological gradients.
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