. The Canadian field-naturalist. 572 The Canadian Field-Naturalist Vol. 113 UPGMA CLUSTERING FOR SPECIES PRESENCE DATA SHOWING RELATIONSHIPS OF 57 ONTARIO ALVARS Napanee Plain 1 Napanee Plain 2 Smiths Falls Plain Garden Plain Bend Bay Trent River Bruce - Escarpment Bruce - Huron Fringe Manitoulin Island Figure 2. UPGMA clustering of 57 alvars from the contact line region of southern Ontario based on Jaccard's coefficients derived from species presence data. The cophenetic correlation was For groupings based on geographic and climatic variables it was necessary
. The Canadian field-naturalist. 572 The Canadian Field-Naturalist Vol. 113 UPGMA CLUSTERING FOR SPECIES PRESENCE DATA SHOWING RELATIONSHIPS OF 57 ONTARIO ALVARS Napanee Plain 1 Napanee Plain 2 Smiths Falls Plain Garden Plain Bend Bay Trent River Bruce - Escarpment Bruce - Huron Fringe Manitoulin Island Figure 2. UPGMA clustering of 57 alvars from the contact line region of southern Ontario based on Jaccard's coefficients derived from species presence data. The cophenetic correlation was For groupings based on geographic and climatic variables it was necessary first to create phenograms, then select groups by splitting the phenogram at the nine branch level. Since coordinate axes values for the different sites were based on presence of vascular flora, the nine floristic groups classification was expected to have the highest F-ratios. In this sense the vascular flora acts as a standard to assess the effectiveness of other grouping variables. Results and Discussion General observations The phenograms leading to grouping variables were reliable representations of the matrices used to produce them based on cophenetic correlations of for flora, for geography, and for climate based on five characteristics (Table 2). The first five PCO axes explain a small amount of the sample variation: , , , and (cumulatively ), which is not unusual for this kind of data. In general major groups were apparent at the nine group level, as seen clearly in the phenogram (Figure 2) based on both floristic data and the PCO with MST (Figure 3) and geo- graphic location (Figure 4). Classification of sites The nine group level on the phenogram which is clearly evident in the PCO with MST, includes the five groups subjectively established and clustered previously (Catling and Brownell 1995, Figure 8), thus providing objective support (Figure 1) for this regional approach. The nine groups included three major groups an
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