Hierarchical factor classification of variables in ecology

A dendrochronological analysis of Pinus pinea L. on the Italian mid-Tyrrhenian coast

“…Relations between the tree-ring chronologies were explored with both ordination and classification multidimensional analyses (Whittaker, 1973;Tukey, 1977, Camiz et al, 2006. For the ordination, the classical Principal Component Analysis was run (PCA; Orlóci, 1978;Jolliffe, 1986;Legendre and Legendre, 1998).…”

“…At each step, a node is composed by merging two already existing groups and to it HFC associates a factor plane where to represent both aggregated variables and units. Thus, HFC acts simultaneously as both classification and factor analysis tools (Camiz et al, 2006;Camiz and Pillar, 2007). Indeed, at each step, given a node, the associated first principal component represents what the variables of the merging groups have in common, whereas the second one represents the main differences between the groups (Camiz et al, 2006).…”

“…Thus, HFC acts simultaneously as both classification and factor analysis tools (Camiz et al, 2006;Camiz and Pillar, 2007). Indeed, at each step, given a node, the associated first principal component represents what the variables of the merging groups have in common, whereas the second one represents the main differences between the groups (Camiz et al, 2006). As the latter is adopted as hierarchy index, its value suggests the cut-point to identify the partitions.…”

Growth-Climate Response of Young Turkey Oak (Quercus cerris L.) Coppice Forest Stands along Longitudinal Gradient in Albania

“…Thus, one cluster or node is established by merging two or more oak chronologies. The HFC can simultaneously be both a classification and a factor analysis tool and therefore different clusters of grouped chronologies can be distinguished [27,28]. At each cluster node, the first component represents what the merging groups of chronologies have in common, whereas the second one represents the main differences between the clusters [27].…”

“…The HFC can simultaneously be both a classification and a factor analysis tool and therefore different clusters of grouped chronologies can be distinguished [27,28]. At each cluster node, the first component represents what the merging groups of chronologies have in common, whereas the second one represents the main differences between the clusters [27]. In the HFC analysis, the fusion level is a measure of the diversity of the groups obtained by cutting the dendrogram at each level.The PCA and HFC analyses were performed using SPSS 17 software (SPSS inc).…”