Heartwood Durability: The Quest for Natural Decay Resistance in a Changing Resource

Purpose of Review: Fast-growing plantation resources will increasingly be relied upon to meet global demand for renewable timber products. Concerns exist regarding the quality of wood from plantations and second-growth forests; however, the heartwood quality of timber sourced from plantations and grown for its distinctive color and durability has received little attention. We examine the current status of selected species (in terms of research and development related to heartwood quality) known for their valuable heartwood and explore options that might maintain or improve heartwood quality of plantation grown trees. Findings: Plantation grown trees of all species examined had heartwood inferior to that sourced from natural forests. Management of plantation forests to maximize growth can unintentionally promote one process (growth) over other processes (heartwood formation) that may be detrimental to the management objectives related to heartwood durability and color. Heartwood characteristics can be targeted for improvement via breeding or by clonal forestry. Silvicultural interventions to induce a stress response may also improve heartwood quality. Summary: Failure to produce quality heartwood has manifold implications, both for plantation growers who may be unable to sell their products for the highest price, and retailers whose reputations depend on meeting customer performance expectations. Management decisions that deliberately cause a stress response (as opposed to maximizing growth) should be considered if plantations are being established using species valued for their heartwood properties. Advanced genetics and silvicultural strategies to promote heartwood formation on suitable sites are necessary to ensure that high value heartwood can be obtained from plantation forests.