Equations for Predicting Green Weight of Loblolly Pine Trees in the South

Bullock, Bronson P.; Burkhart, Harold E.

doi:10.1093/sjaf/27.3.153

Cited by 36 publications

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“…KEYWORDS: stem weight estimation, merchantable volume, weight ratio, upper-stem diameter, stem profile, stem form D r a f t Introduction Clutter (1980) derived a taper equation that was mathematically compatible with a volume-to-upper-stem-diameter ratio equation of Burkhart (1977). Jordan et al (2005) used a similar approach to obtain a compatible taper equation from the "exponential ratio" volume-to-upper-stem-diameter equation originally proposed by Van Deusen et al (1981) and later used with slight modifications by several authors including Parresol et al (1987) and Bullock and Burkhart (2003). Several researchers including , , Parresol et al (1987), Bullock and Burkhart (2003) and most recently Zhao and Kane (2017) have used weight and/or volume-to-upper-height ratio functions.…”

Section: R a F Tmentioning

confidence: 99%

“…Jordan et al (2005) used a similar approach to obtain a compatible taper equation from the "exponential ratio" volume-to-upper-stem-diameter equation originally proposed by Van Deusen et al (1981) and later used with slight modifications by several authors including Parresol et al (1987) and Bullock and Burkhart (2003). Several researchers including , , Parresol et al (1987), Bullock and Burkhart (2003) and most recently Zhao and Kane (2017) have used weight and/or volume-to-upper-height ratio functions. Van Deusen et al (1982) and Reed and Green (1984) derived taper functions compatible with merchantable-to-total height volume ratio functions.…”

Section: R a F Tmentioning

confidence: 99%

“…This derivation is essentially similar to derivations found in Van Deusen et al (1982) and Reed and Green (1984). As an example let us derive a taper function compatible to the volume ratio function termed the "modified Burkhart" by , and also used by and for weight ratio estimation by Bullock and Burkhart (2003). found that this equation was superior among several alternatives including taper functions available at that time (e.g.…”

Section: Basic Derivation Of Taper Functionmentioning

confidence: 99%

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Deriving compatible taper functions from volume ratio equations based on upper-stem height

et al. 2017

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A very common model for prediction of tree stem volumes to upper-stem height or diameter limits is the use of a merchantable to total volume ratio function multiplied by a total stem volume function. Many users of these prediction systems also desire taper equations that can predict heights to upper-stem diameters. While taper equations compatible with volume ratio equations have been used for many years, compatible taper equations from volume ratio equations that are functions of upper-stem height have been used infrequently. Yet many studies have indicated that height-based ratio equations perform well and frequently have statistics of fit that are comparable with diameter-based volume ratio equations. Compatible taper equations derived from height-based ratio equations are presented here. The methodology that uses height-based merchantable to total volume ratios does not require the solution of a differential equation after differentiating the height-based volume ratio, as is necessary when using the method of deriving taper equations from diameter-based merchantable to total volume ratios. This could be an advantage depending on the complexity of the ratio function. Example taper equations fitted to loblolly pine (Pinus taeda L.) data from the southeastern USA and the state of Oklahoma, USA, indicate good fit to these data, whether fitted directly to taper data or implicitly by using parameters fitted to volume ratio data.

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Section: R a F Tmentioning

confidence: 99%

Section: R a F Tmentioning

confidence: 99%

Section: Basic Derivation Of Taper Functionmentioning

confidence: 99%

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Deriving compatible taper functions from volume ratio equations based on upper-stem height

et al. 2017

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“…For commercial plantations focused on the production of a single product, there is no need for having highly detailed information. A set of readily available total and merchantable volume tree equations is preferable for parsimony, simplicity and accurate estimation (Bullock and Burkhart 2003). According to Azevedo et al (2011), merchantable and total tree volume equations in Brazil are customarily fitted independently, which increases the possibility of illogical crossing of the estimated values.…”

Section: Introductionmentioning

confidence: 99%

“…Zhao and Kane (2017) proposed a similar formulation for Pinus taeda in the southern USA, while including a constraint that volume should be zero when top diameter is specified at ground height. Bullock and Burkhart (2003) demonstrated that combining the set of equations: 1)…”

Section: Introductionmentioning

confidence: 99%

Generalized stem taper and tree volume equations applied to eucalyptus of varying genetics in Brazil

et al. 2019

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Lack of generalized equations has prevailed in Brazil, because it is assumed that localized or climate-specific equations are needed. This study aimed to develop generalized stem taper and volume equations applicable to 11 eucalyptus clones and evaluate if climate variation impacts the accuracy of the estimates. A total of 693 trees evenly distributed across 11 clones at 21 sites were used for model fittings and predictive validation. The penalized mixed spline (PMS) approach was developed for predicting stem taper and volume along the stem profile. The Schumacher and Hall (1933) equation was used to predict total tree volume, while volume ratio equations were applied to predict merchantable volume. For every fitted equation, an annual climatic variable was included to assess the improvement in model performance. The overall results highlighted that climatic variation does not need to be accounted for in stem taper and volume modeling. All of the equations displayed desirable accuracy, but the generalized PMS equation may be preferred when the forestry enterprise looks to furnish a range of multiple forest products. The generalized total tree volume equation, combined with the ratio equations, is highly recommended when the forestry enterprise produces a single product.

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Modeling Forest Trees and Stands

Burkhart

Tomé²

2012

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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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Equations for Predicting Green Weight of Loblolly Pine Trees in the South

Cited by 36 publications

References 0 publications

Deriving compatible taper functions from volume ratio equations based on upper-stem height

Deriving compatible taper functions from volume ratio equations based on upper-stem height

Generalized stem taper and tree volume equations applied to eucalyptus of varying genetics in Brazil

Modeling Forest Trees and Stands

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