Foliar Morphology and the Acclimation of Shade Tolerant Conifers to Varying Light Levels

Abstract

Shade tolerant conifers are, in general, a neglected resource that is promoted only rarely silviculturally in the Pacific Northwest region. This situation is particularly unfortunate when one considers not only the vast genetic diversity that these species contain, but also the fact that they are among some of the most productive species in the world, as has been demonstrated for both the Pacific Northwest (Fujimori 1971) and Europe (Hamilton and Christie 1971). This thesis examines two aspects of the adaptations and acclimation in foliar morphology to shade by representative Pacific Northwest species. First, it examines the flexibility of plasticity that exists within these species and how this is related to their tolerance to shade. Second, it describes some costs associated with being highly shade tolerant and how a shade tolerant species acclimates to a dramatic and sudden change in light.