Compartmentalization, Resource Allocation, and Wood Quality

The concept of a trade-off of tree resources between growth and defense is readily grasped. The most detailed development of the concept is for the growth-differentiation balance hypothesis that predicts that resources for normal growth and primary metabolism are diverted to support plant defense and secondary or stress metabolism. This hypothesis has been applied to the biosynthetic cost of stress metabolites that protect wood and foliage from herbivory. This review suggests that the trade-offs of primary to stress metabolism is an ongoing theme throughout the evolution of land plants. This review extends the concept of the growth/defense trade-off to processes of apoptosis in the constitutive development of tracheary elements and heartwood as well as to the induced boundary-setting processes of compartmentalization of decay in living trees. For wood utilization, the confusion of heartwood with wound-initiated discoloration continues to obscure the sources of value loss, particularly for high-value hardwood lumber. Examples are drawn from the anatomical effects of tree injury from fire, storms, and vascular wilt disease.