Detection of Atypical Years in the Tree-Ring Series by Construction of a Temporal Walk in the Principal Components Planes

摘要

The purpose of this paper is to introduce a method for identifying years of anomalous radial growth, which are called atypical years and are characterized by particularly narrow rings for certain trees or sites, and wide for the others. With this aim, we use principal components analysis (PCA) of tree -ring series, where years are the variables and trees or sites are the individuals, even though in classical dendrochronological applications of PCA, the trees or sites are considered as variables and the years as cases. The relevant method is explained and results are given for five cedar forests (Cedrus atlantica (Endl.) Carrière) in Morocco.