Collaborative Research: Developing Methods to Study Age-Related Changes in the Physiology of Forest Trees
September 2001-August 2004
Level of Access
Trees continue to increase in size and complexity over life spans that may last many centuries, and each year the growing regions of their shoots produce new foliage and reproductive structures. As they grow older and larger, forest trees appear to grow more slowly, produce thicker foliage and more reproductive structures. These changes are likely to be associated with age-related declines in the growth rates of forest stands, which occur before the mid-point of the lifespan of important timber species. Although similar patterns of age- and size-related change in the morphology and physiology of foliage have been described for numerous species, the mechanisms governing these changes are virtually unknown. Possible explanations for these phenomena range from decreased photosynthesis due to increased resistance of water flow to a genetically controlled ageing process that slows growth and photosynthesis. Processes regulating maturation, ageing and senescence are fundamental to biology, and some of these processes are probably unique to large, long-lived trees. A more complete understanding of the basis for this decline is necessary to model and accurately predict the growth of forests over time.
Reciprocal grafting of shoots between trees of different ages offers great potential as a tool to distinguish among explanations for changes in growth behavior. In this approach, shoots from old growth trees are grafted onto juvenile and young-mature trees, and shoots from juvenile and young-mature trees are grafted into the crowns of old-growth trees. The extent, direction and time-course of changes in the growth, morphology, and physiology of foliage produced by the grafted shoots will provide insight into the mechanisms governing age-related change. This study will attempt reciprocal grafting on two species of long-lived trees, red spruce and Douglas fir. These species are adapted to substantially different climatic regimes, so a comparative study will provide insights into the universality or variability of processes associated with age-related changes in tree growth.
Rights and Access Note
This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. In addition, no permission is required from the rights-holder(s) for educational uses. For other uses, you need to obtain permission from the rights-holder(s).
Greenwood, Michael S., "Collaborative Research: Developing Methods to Study Age-Related Changes in the Physiology of Forest Trees" (2004). University of Maine Office of Research Administration: Grant Reports. 180.
Oregon State University