Rates of change of adaptive variation in Picea mariana visualized by GIS using a differential systematic coefficient

Abstract

Data from a short-term provenancetrial of black spruce (Picea mariana (Mill.)B.S.P.) were used to illustrate a methodology to helplocate breeding zone boundaries using adaptivevariation models. Four height growth and survivalvariables were summarized by principal componentsanalysis (PCA), and the first three axis scores wereregressed against climate data determined from arecently developed Ontario Climate Model. Theregression equations were used to model the PCA axes,and these models were interpreted as the three maincomponents of adaptive variation in the data. Thesemodels were converted to geographic grids using GISsoftware. In a manner similar to that proposed fordifferential systematics applications, theDifferential Systematic Coefficient (DSC) was adaptedto be an indicator of the weighted average rate ofchange of clinally expressed adaptive variation overdistance. An output grid was determined based on theDSC values, such that grid cells with highercoefficient values were made to appear darker on theresultant map; thus, the shaded areas corresponded tosteeper portions of the clines of adaptive variationand serve as desirable indicators of the bestlocations for breeding zone boundaries.