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Silva Fennica 1926-1997
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Acta Forestalia Fennica
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Articles by Harry T. Valentine

Category: Article

article id 5623, category Article
Harry T. Valentine. (1997). Height growth, site index, and carbon metabolism. Silva Fennica vol. 31 no. 3 article id 5623. https://doi.org/10.14214/sf.a8524

A metabolic model of height growth and site index is derived from a parametrization of the annual carbon balance of a tree. The parametrization is based on pipe-model theory. Four principal variants of the height-growth model correspond to four combinations of assumptions regarding carbon allocation: (a) the apical shoot is autonomous or (b) it is not; and (A) the specific rate of elongation of a shoot equals that of a woody root or (B) it does not. The bB model is the most general as it includes the aA, bA, and aB models as special cases. If the physiological parameters are constant, then the aA model reduces to the form of the Mitscherlich model and the bA model to the form of a Bertalanffy model. Responses of height growth to year-to-year variation in atmospheric conditions are rendered through adjustments of a subset of the model's parameters, namely, the specific rate of production of carbon substrate and three specific rates of maintenance respiration. As an example, the effect of the increasing atmospheric concentration of CO2 on the time-course of tree height of loblolly pine (Pinus taeda) is projected over 50-year span from 1986. Site index is predicted to increase and, more importantly, the shape of the site-index curve is predicted to change.

  • Valentine, ORCID ID:E-mail:
article id 5615, category Article
Andrew P. Robinson, Timothy G. Gregoire, Harry T. Valentine. (1997). Cut-off importance sampling of bole volume. Silva Fennica vol. 31 no. 2 article id 5615. https://doi.org/10.14214/sf.a8516

Cut-off importance sampling (CIS) is introduced as a means of sampling individual trees for the purpose of estimating bole volume. The novel feature of this variant of importance sampling is the establishment on the bole of a cut-off height, HC, above which sampling is precluded. An estimator of bole volume between predetermined heights HL and HU > HC is proposed, and its design-based bias and mean square error are derived. In an application of CIS as the second stage of a two-stage sample to estimate aggregate bole volume, the gain in precision realized from CIS more than offset its bias when compared to the precision of importance sampling when HC = HU.

  • Robinson, ORCID ID:E-mail:
  • Gregoire, ORCID ID:E-mail:
  • Valentine, ORCID ID:E-mail:

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