Converting Volume Equations to Compatible Taper Equations

Demaerschalk, J. P.

doi:10.1093/forestscience/18.3.241

Cited by 118 publications

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“…There are very few references to taper functions for P. pinaster in the available literature; one example is the study by Prieto and Tolosana (1991) and another that of Palma (1998), who used the taper equations developed by Kozak et al (1969) and Demaerschalk (1972) to establish the influence of age on the stem form of the species sampled in the Portuguese coast. A taper function has not yet been developed for P. pinaster in Galicia.…”

Section: Introductionmentioning

confidence: 99%

Stem taper functions for maritime pine (Pinus pinaster Ait.) in Galicia (Northwestern Spain)

et al. 2005

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A total of 31 taper functions from 3 different groups of models (single, segmented and variable-form taper functions) were fitted to diameter-height data from 203 Pinus pinaster trees sampled across even-aged stands in Galicia (northwestern Spain). Most of the taper functions analyzed showed problems of multicollinearity as indicated by the condition number. A second-order autoregressive CAR(2) error process was incorporated into the models to minimize the effect of autocorrelation inherent in the longitudinal data used, and to provide valid tests of significance for model parameter estimates. In general, variable-form taper functions provided the most accurate predictions. The flexibility and predictive performance of the variable-form model developed by Kozak (For Chron 80(4):507-515, 2004) indicated its usefulness for estimating diameter at a specific height, merchantable volume, and total volume of Maritime pine in the study area.

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Section: Introductionmentioning

confidence: 99%

Stem taper functions for maritime pine (Pinus pinaster Ait.) in Galicia (Northwestern Spain)

et al. 2005

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“…In this study, volume equation (1) and stem taper equation (2) were derived with the procedure given by Demaerschalk (1972) and they were as follows,…”

Section: Methodsmentioning

confidence: 99%

“…Parameters of the taper equation were known from the volume equation as given below, except for the parameter p, when the total volume estimates based on integration of the taper equation were assumed identical to those given by the volume equation (Demaerschalk 1972).…”

Section: Methodsmentioning

confidence: 99%

“…To assess practical applicability, the bole length (l) and the volume (v l ) up to the top diameter 20 cm, the diameter size regarded as merchantable for sawn timber in Indonesia, were predicted for the trees with a dbh above 20 cm using the following equations (Demaerschalk 1972), …”

Section: Methodsmentioning

confidence: 99%

“…The compatible stem taper equation was firstly proposed by Demaerschalk (1972), and then it was further extended as a polynomial taper equation (Goulding and Murray 1975). Although the equation was not the best choice to describe tree taper of loblolly pine (Cao et al 1980), it has in practical terms the desirable property that the equation can be integrated to calculate sectional volumes, and the total volume calculated is compatible with an existing total-volume equation (Goulding and Murray 1975).…”

Section: Introductionmentioning

confidence: 99%

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A stem taper equation compatible to volume equation forParaserianthes falcatariain Pare, East Java, Indonesia: its implications for the plantation management

Kurinobu

Prehatin

Mohanmad

et al. 2007

Journal of Forest Research

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A stem taper equation compatible to the volume equation was derived from the data of 172 trees sampled in the three plantations of Paraserianthes falcataria in Pare, East Java. The stem taper equation in this study was based on a conventional logarithmic volume equation, with the addition of one free parameter that minimized the standard errors of estimate to the observed diameter of stems at 1.0-m intervals. The derived equation was able to predict the stem taper of P. falcataria reasonably well, while it was not flexible enough to describe delicate changes of the taper in the upper portion of stem. The equation was able to predict bole length and the volume up to the top diameter 20 cm, the diameter size merchantable for sawn timber in Indonesia, with reasonable accuracy. An appropriate rotation age for sawn-timber production was found to be 8-9 years old, at which the mean annual increment of sawn timber would be maximized.

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Modeling Forest Trees and Stands

Burkhart

Tomé²

2012

565

376

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Growth functions describe the change in size of an individual or population with time. The selection of appropriate growth functions for tree and stand modeling is an important aspect in the development of growth and yield models. Here we present information on the forms and characteristics of the more commonly-used growth functions for modeling forest development. When fitted to data, a number of these functions will give essentially equivalent results within the range of the observations used for estimating the equation's coefficients. However, their behavior when extrapolated may be quite different depending on the underlying mathematical properties involved. Hence, understanding these properties is helpful to modelers to determine which candidate functions to consider for specific applications.Unless the data available for modeling cover a very small range of time, there are certain properties that a growth function should exhibit to be consistent with the principles of biological growth (Fig. 6.1): (i) The curve is often limited by the value zero at a specific beginning (t D 0 or t D t 0 ), depending if the variable that is being modeled starts at t D 0, as is the case for the great majority of the tree and stand variables, or later on, as happens with tree diameter at breast height or stand basal area; (ii) The curve generally should exhibit a maximum value usually achieved at an older age (existence of an asymptote); (iii) The slope of the curve should increase with increasing growth rate in the initial phase and decrease in the final stages (show an inflection point).At this point it is important to understand the concepts of growth and yield. Growth is the increase in size of an individual or population per unit of time (for instance volume growth in m 3 ha 1 year 1 ) while yield is the size of the tree or population at a certain point in time (for instance total volume at age 50

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Converting Volume Equations to Compatible Taper Equations

Cited by 118 publications

References 0 publications

Stem taper functions for maritime pine (Pinus pinaster Ait.) in Galicia (Northwestern Spain)

Stem taper functions for maritime pine (Pinus pinaster Ait.) in Galicia (Northwestern Spain)

A stem taper equation compatible to volume equation forParaserianthes falcatariain Pare, East Java, Indonesia: its implications for the plantation management

Modeling Forest Trees and Stands

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