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

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Rolland C., Petitcolas V., Michalet R. (1998). Changes in radial tree growth for Picea abies, Larix decidua, Pinus cembra and Pinus uncinata near the alpine timberline since 1750. Trees, Structure and function 13(1): 40-53.
  • TITLE Changes in radial tree growth for Picea abies, Larix decidua, Pinus cembra and Pinus uncinata near the alpine timberline since 1750.
  • LANGUAGE English , with English abstract.
  • SPECIES Picea abies (L.) Karst., Pinus cembra L., Larix decidua Mill., Pinus uncinata Mill. ex Mirb.
  • KEY WORDS Global change, Timberline, Dendroclimatology, Tree-ring, Conifers.
  • MOTS CLES Changement global, Limite supérieure de la forêt, Dendroclimatologie, Cernes de croissance, Conifères.
  • SITES Achard and Pourettes in Belledonne mountains. Chal, Le Biol, Bellecôte, Tuéda and Saint Jacques in the Moyenne-Tarentaise, Mollard Fleury, Le Jeu, Barbier, Tuéda and Plan d'Amont in the Haute-Maurienne. Les Ayes, Izoard and Granon in the Briançonnais (France).
  • ABSTRACT (English)

  • Changes in radial growth of the four coniferous species growing in the French Alps near the upper treeline were investigated. Thirty-seven populations of Norway spruce [Picea abies (L.) Karst.], European larch (Larix decidua Mill.), Swiss stone pine (Pinus cembra L.) and mountain pine (Pinus uncinata Mill. ex Mirb.) were sampled by taking 1320 cores and analysing tree-ring widths. Sites were chosen in various climatic conditions (macroclimate and aspect) and on two kinds of bedrock in order to take into account the ecological behaviour of these species. Belledonne, Moyenne-Tarentaise, Haute-Maurienne and Briançonnais areas were sampled along increasing gradients of summer aridity and winter continentality. The calculation of time series after removing the age trend brings strong evidence for an increase in radial growth during the two last centuries, but with different stages and fluctuations for each species. This growth trend is signifcantly enhanced since 1860 for the spruce, and since 1920 for the two pine species. Funhermore, it also appears on Larix decidua with the same pattern despite periodical growth reduction due to attacks of the larch bud moth (Zeiraphera diniana Gn.). The analysis of ring-widths at a given cambial age reveals that this enhanced phenomenon is observed especially during the tree's early years (25-75 years). The analysis of four regional climatic series, and three longer series of temperature (in farther single sites) reveals synchronous decadal fluctuations and an evident secular increase in minimum temperatures (especially in January and from July to October), that may be involved in treegrowth enhancement. Thermic amplitudes are significantly reduced during the whole growing period, what is more pronounced in Belledonne, the most oceanic region. Long term growth changes are well described by stepwise regression models, especially for the pine species. These models involved both a linear trend (CO2 concentration or N-deposition) and low frequency of Turin monthly temperatures. However, they show different pattems than those observed from response functions at a yearly scale.
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