Regression-based focal point seed zones for Picea mariana from northwestern Ontario

The results of a recent study of adaptive variation of black spruce in northwestern Ontario, together with additional freezing damage data, were used to produce regression-based focal point seed zones for this species. The procedure required two data bases as follows: (i) the biological data derived from two common garden growth trials, one greenhouse trial, and freezing trials of 75 black spruce seed sources and (ii) climatic data for the period 1951-1980. Principal components analysis (PCA) was used to summarize the main components of growth and freezing variation, and the PCA axis scores for the seed sources were regressed against climatic variables. The regression equations were used to model the patterns of adaptive variation, and these patterns were graphically reproduced as contour maps by a geographic information system (GIS). A series of focal point seed zone maps for black spruce was produced by GIS intersection of the regression-based contour maps. Focal point seed zones were more restricted in the south near Lake Superior, reflecting the more rapidly changing climate in this part of the study area. Since black spruce is closely adapted to local climate, these results will be useful to formulate successful seed transfers in this area. There are additional potential applications for matching seed sources to changing climates and for the identification of genetically unique populations.