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Analysis of Yield-Density Relationships in Experimental Stands of Douglas-Fir and Red Alder Seedlings

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Seedlings of red alder (Alnus rubra Bong.) and Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) were planted into a two-species density matrix composed of five monoculture densities and mixed stands with all possible pairwise combinations of the monoculture densities. Regression equations were fit to the response of mean tree stem volume to the two species' densities generated in this matrix. Regression coefficients quantifying the intensity of competition indicated that alder density had approximately twice the effect of Douglas-fir density on individual tree stem volume of both species. The densities of the two species had a multiplicative effect on mean tree stem volume. In addition, the effects of alder and Douglas-fir densities on tree size were interdependent. The effects of alder density on stem volume varied with Douglas-fir density and declined as Douglas-fir density increased. Similarly, the effects of Douglas-fir density on stem volume varied with alder density. The interdependency between the two species' densities resulted in an unusual pattern in which Douglas-fir individual stem volume increased as Douglas-fir density increased at high densities of alder. For. Sci. 37(2):574-592.

Keywords: Competition coefficients; density interactions; interspecific competition; intraspecific competition

Document Type: Journal Article

Affiliations: Professor, College of Forestry, Oregon State University, Corvallis OR 97331

Publication date: 1991-06-01

More about this publication?
  • Forest Science is a peer-reviewed journal publishing fundamental and applied research that explores all aspects of natural and social sciences as they apply to the function and management of the forested ecosystems of the world. Topics include silviculture, forest management, biometrics, economics, entomology & pathology, fire & fuels management, forest ecology, genetics & tree improvement, geospatial technologies, harvesting & utilization, landscape ecology, operations research, forest policy, physiology, recreation, social sciences, soils & hydrology, and wildlife management.
    Forest Science is published bimonthly in February, April, June, August, October, and December.

    2015 Impact Factor: 1.702
    Ranking: 16 of 66 in forestry

    Average time from submission to first decision: 62.5 days*
    June 1, 2016 to Feb. 28, 2017

    Also published by SAF:
    Journal of Forestry
    Other SAF Publications
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