Dendrochronology

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

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Florence J. (1962). Exemple d'étude dendrologique en relation avec la climatologie du Capcir et de la Cerdagne. Thèse de 3ème cycle, Biogéographie. Faculté des Sciences de Toulouse. 149 pp, 5 photos, 2 maps, 72 bibliographical references.
  • TITLE Dendroecological study of Scotch Pine in Capcir and Cerdagne.
  • LANGUAGE French
  • SPECIES Pinus sylvestris (L.).
  • SITES Capcir, Cerdagne, Pyrenees, South West of France
  • ABSTRACT

    • A dendroclimatological study was carried out in the French Pyrenees on two Scotch Pine forests located in « La Matte des Angles » in the Capcir region, and near « Font-Romeu » in the Cerdagne. They are both located on siliceous bedrocks.
    The first one is a pure 300 ha. Pinus sylvestris stand, whereas the second one is a mixed Scotch pine forest with Pinus uncinata.
    Ring-widths were measured from 160 to 200 years and analysed with classical meteorological data. (Precipitation were recorded in Mont-Louis since 1872).
    It appears that minimum and spring temperatures are correlated with small rings. Moreover, the use of rainfall and temperature data at the same time provide better results. The possible influence on sun spot on tree-rings is also discussed.

    The mean sensitivities of the tree-ring widths equal MS = 0.16 in the Matemale forest, and MS = 0.12 in the Font-Romeu stand.
    The severe frost in February 1956 did not affect the scotch Pines there.
    Main results demonstrated that Pinus sylvestris trees require warm conditions in April (and in a less extent in May) during the radial growth begining, a cool September period, and more surprisingly a hot summer (in June and July).
    Rainfall appear to be less important than temperature for tree growth. Summer rainfall are favourable, contrarily to spring precipitations.

    Tree-ring widths and climate relationships were calculated in the 2 stands with the linear correlation method ( + sign means positive linear correlation during that month).
     

    2 forests Climate Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    Font-Romeu Precipitation . . . - . + + . . ++ . .
      Temperature - . . +++ . + + + - . . .
    Matemale Precipitation . ++ . . - . . . . + + ++
      Temperature . . . +++ ++ + + . - . . .
    Therefore, air temperature in April is the most critical factor for ring formation.
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