• Dendrochronological Investigations in Iran

      Liphschitz, Nili; Waisel, Y.; Lev-yadun, S.; Department of Botany, Tel-Aviv University, Israel (Tree-Ring Society, 1979)
      Dendrochronological research on Juniperus polycarpos growing in west and central Iran reveals that the radial growth in this species depends mainly on the amount of precipitation in the more arid regions. When the amount of rain is sufficient, i.e. above 450 mm, the prevailing summer temperature seems to become the limiting factor. Favorable conditions which prevailed during the periods 1685-1695 and 1790-1800 resulted in better width growth, while less favorable conditions which prevailed during the years 1725-1735 and 1855-1865 resulted in narrow rings.
    • Tree-Rings and Climate in Morocco

      Berger, A. L.; Guiot, J.; Mathieu, L.; Munaut, A. V.; Institut d'Astronomie et de Géophysique, Université Catholique de Louvain-la-Neuve; Laboratoire de Science du Sol, Faculté des Sciences Agronomiques, Gembloux; Laboratoire de Palynologie et Phytosociologie, Université Catholique de Louvain-la-Neuve (Tree-Ring Society, 1979)
      Two sites located near Ketama in the Morocco Rif have been selected, on the basis of limiting climatic factors, in order to study the relationship between tree rings and climate. After the trend associated with biological factors related to increasing age has been removed and all variables have been standardized, some statistical parameters have been computed and a variance analysis has been performed. After the persistence has been eliminated, an original technique of multiple regression on the principal components and of selection of the most significant variables has been built. Twenty -four climatic variables have been used. The principal aim of this paper is to describe this original statistical technique of data analysis and to illustrate its power with dendroclimatological data in Morocco. For the temperate site located in low altitude (1280 m), among the most important variables, we have retained total monthly precipitation for August, mean temperature of January, April, and May of the current year and mean temperature of October of the previous year. For the cold site (2100 m), total monthly precipitation for September and temperatures of January and May of the current year and precipitation for October of the previous year definitely influence the growth rate of cedars.