Correlations Among Wood Properties and with Growth Rate

Abstract

If any breeding program for wood properties is to be successful, it is essential to understand how the different characteristics relate to one another. The relationships are usually reported as correlations. There are both phenotypic and genetic correlations reported in the literature. One would think that the two should be similar and they sometimes are. Frequently, however, they are different and, can be very different, as shown for white spruce (Picea glauca) by Yanchuk and Kiss (1992), who found a phenotypic correlation of r = −0.40 between wood density and height growth but observed essentially no genetic correlation. It would be ideal to report only genetic correlations but nearly all values available in the literature are phenotypic correlations. Even more confusing, many references do not state the type of correlation being reported. Thus, in this chapter we are forced to report correlations as found in the literature, assuming that when unstated most are phenotypic. However, when specifically indicated, genetic correlations will be mentioned.