• Title/Summary/Keyword: anamorphic and polymorphic function

Search Result 2, Processing Time 0.018 seconds

Developing and Comparing Site Index Curves Using Polymorphic and Anamorphic Equations for Douglas-fir (다변태(多變態)와 변태(變態) 방정식(方程式)을 이용(利用)한 미송(美松)의 지위지수(地位指數) 곡선(曲線) 추정(推定)과 비교(比較))

  • Lee, Sang Hyun
    • Journal of Korean Society of Forest Science
    • /
    • v.88 no.2
    • /
    • pp.142-148
    • /
    • 1999
  • This research describes the construction of a site index equation and curves for Douglas-fir plantation (Pseudotsuga menziesii Mirb. Franco) in Nelson, New Zealand. The data sets of 146 Permanent Sample Plots (PSP) were used to build the model, and it was developed using the difference equation method. Parameter estimates were obtained using the non-linear routine of the SAS, PROC NLIN procedure. Of the models tested, a variant of the Schumacher polymorphic yield function showed the higher precision of fitting. About 95% of the observations used to fit the model could be predicted within ${\pm}1.2m$ of the actual values. Therefore, polymorphic family of site index curves, which reflect different shapes for the different site index classes, were derived from the Schumacher equation. It was found that the polymorphic site index equation was more accurate than the anamorphic equation in this study.

  • PDF

Estimating Diameter and Height Growth for Pinus densiflora S. et Z. Using Non-linear Algebraic Difference Equations (비선형(非線型) 대수차분(代數差分) 방정식(方程式)을 이용(利用)한 소나무 직경(直徑) 및 수고(樹高) 생장(生長) 추정(推定))

  • Lee, Sang-Hyun
    • Journal of Korean Society of Forest Science
    • /
    • v.90 no.2
    • /
    • pp.210-216
    • /
    • 2001
  • Pinus densiflora S. et Z. has widely been distributed, and is one of the important main foret resources in Korea. Diameter and height growth patterns were estimated using non-linear algebraic difference equation, which requires two-measurement times $T_1$ and $T_2$. To maximize data use, all possible measurement interval data were derived using Lag and Put statements in the SAS. In results, of the algebraic difference equations applied, the Schumacher and the Gompertz polymorphic equations for diameter and height, respectively showed the higher precision of the fitting. In order to allow more precise estimation of growth than those of the basic Schumacher and the Gompertz, further refinement that combine biological realism as input into the equation would be necessary.

  • PDF