Over the past years, a great deal has been learned about variation in
wood prop- erties. Genetic control is a major source of variation in
most wood properties. Wood is controlled genetically both directly in
the developmental or internal pro- cesses of wood formation and
indirectly by the control of tree form and growth patterns. Emphasis in
this book will be on the internal control of wood production by genetics
although there will be two chapters dealing with the indirect genetic
control of wood, which was covered in detail in the previous book by
Zobel and van Buijtenen (1989). The literature on the genetics of wood
is very variable, SO'lle quite superficial, on which little reliance can
be placed, and some from well-designed and correctly executed research.
When suitable, near the end of each chapter, there will be a summary
with the authors' interpretation of the most important information in
the chapter. The literature on the genetics of wood can be quite
controversial. This is to be expected, since both the environment and
its interaction with the genotype of the tree can have a major effect on
wood properties, especially when trees of similar genotypes are grown
under widely divergent conditions. Adding to the confusion, studies
frequently have been designed and analyzed quite differently, resulting
in conflicting assessments of results.