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Estimation of stem volume is needed to determine timber yield and forest carbon, but equations to estimate volume from easily assessed inventory measures are lacking for hardwood plantation species...

Tree-stem volumes constitute critical measurements for forest management. We propose a general two-criterion procedure for choosing the most reliable and robust volume equation(s), among a set of t...

The parametrization of wood volume equations has traditionally been carried out with destructive samplings, which are highly resource-intensive. These equations must be specifically set up for each...

Stem volume models using diameter at breast height (DBH) and height were developed for Pinus densiflora, Pinus koraiensis, and Larix kaempferi. The data were obtained from Gangwon, Gyeonggi, and North Gyeongsang provinces in South Korea, and the sample trees felled were used to provide the parameter estimates of volume equations. The combined-variable function, , was shown to be the best model through the validation of the equation. Also, the model using only DBH, was also evaluated to be applicable in the field. These models revealed higher accuracy when compared with previous studies. Both equations are considered to be easily used in the field.

Development of stem volume for umbrella-shaped crown trees remains a big challenge for efficient use of forest resources in Mozambique. In this study, species-specific stem volume equations were developed for the first time for three of the most important timber species in Mozambique: Afzelia quanzensis Welw. (Chanfuta), Millettia stuhlmannii Taub. (Jambire), and Pterocarpus angolensis D.C. (Umbila). The study was carried out at three locations in Mozambique: Inhaminga, Mavume, and Tome covering 58 trees from which, 24 of Chanfuta, 15 of Jambire, and 19 of Umbila. The volume of the sampled stem sections (logs) was calculated using Smalian’s formula, where stem volume total was obtained through the sum of the respective defined sections. Using a nonlinear procedure, different volume models were tested for each tree species independently. The coefficient of the determination of the tested equations in the tree species ranged from .90 to .95, making the equations potential candidate models for the stem volum...

Although the small-leaved lime (Tilia cordata Mill.) is a native tree in the Czech Republic, there are no volume tables, and its volume has so far been estimated according to beech (Fagus sylvatica L.) tables. In order to increase accuracy of timber volume calculations, the most appropriate volume equations should be selected to develop volume tables specifically for lime. Based on literature sources eight volume equations were selected, and their accuracy was tested by statistical evaluation of assessed parameters and differences between calculated and sampled lime tree volume. Eighty-one sample trees were randomly selected for this study. The most suitable equation was Borset's equation according to the evaluation of equation parameters and comparison of the results obtained from the volume formula and from sample trees (difference of mean value 0.000009 m3). Finally, the calculated lime volumes were compared with the beech tables. The lime volumes are higher than beech volumes according to beech tables...

Tectona grandis (teak) is one of the most important timber species worldwide and India is one of the major teak growing countries. Though some volume equations were developed in the past in India, merchantable volume equations (any top diameter or bole length) are not available. Moreover, the models developed were neither quantitatively and qualitatively evaluated nor validated with independent data sets. Hence, the objective of this study was to develop appropriate volume equations to predict total tree volume and merchantable volume for teak in Karnataka. Linear and non-linear equations were used to model the relationship of the volume with respect to diameter at breast height (dbh) and total height. Merchantable volume equations for estimating merchantable volume to any minimum top diameter or bole length have also been constructed. The equations tested mostly fitted well to the data. Other models developed elsewhere tended to underestimate the volume, especially at dbh ≥ 23 cm. The geometric cylinder ...

Volume equations for poplars growing on farmland in Sweden. The aim of the study was to construct a simple volume equation for poplar and to evaluate the equation together with seven published equations. Data from 72 poplars were collected from 37 stands in central and southern Sweden (lat. 55–60°N). The stands’ mean age and density was 21 years and 940 stems ha−1, respectively and the trees’ mean diameter at breast height (DBH) was 25 cm. One simple volume equation with three parameters to be estimated for poplar was constructed with DBH and total height (H) as independent variables. This equation was analyzed and compared to seven published simple equations. The best performance, in terms of low values of Root Mean Square Error (RMSE) and Absolute Bias, was achieved by the equations developed by Eriksson and by Scott. However, due to these equations high level of multicollinearity an alternative recommendation was made where the constructed equation is recommended.

Eucalyptus hybrid is one of the most important tree species adopted for large-scale commercial plantations by State Forest Departments, nongovernmental organizations (NGOs), and farmers in India. But accurate volume equations are not available. The aim of this study was to develop equations for predicting individual tree total volume and merchantable volume for E. hybrid. A total of 114 trees with ages between 1 and 19 yr and breast height diameter (dbh) between 4.7 and 33.1 cm were felled for model fitting and analysis. Linear and nonlinear equations were used to model the relationship of total volume with dbh, and with dbh and total height of the trees. Merchantable volume equations for estimating merchantable volume to any minimum bole height are also presented. For this, diameters were measured at different heights along the stem including height to the base of crown. The equations tested fitted the data well. The adjusted R2 and root mean squared error indicated that for estimation of V0 from dbh, an...

Acacia nilotica is one of the most important useful multipurpose tree species for rural population of India but accurate volume equations are not yet available. The aim of this study is to develop ...

The aim of this study was to develop equations which best predict individual-tree total volume and mercahntable volume for T. grandis in Costa Rica. A total of 112 trees with ages between 2 and 47 years and breast height diameter (dbh) between 2.4 and 58.7 cm were felled for stem analysis. Linear and non-linear regression analyses were used to model the relaitonship of total volume with dbh, with dbh and total height, and with age. The study also included merchantable volume equations that estimate merchantable volume to a minimum top diameter or bole length. The equations tested in this study fitted the observed data well. Other models, developed elsewhere, tended to overestimate the stem volume, especially at dbh bigger or the same 30cm. General geometric cylinder volume equations combined with a Stem Form Factor of 0.45 (widely used for T. grandis) were less precise than regression models when applied to this data set. Model validation with an independent data set suggested that the models should be calibrated with local data when grat accuracy is required (error less than 10%).

Three types of taper estimation methods for Eucalyptus cloeziana were applied and compared by using Zambian and Zimbabwean plantation data. The methods are: (1) Schumacher's taper equation, (2) diameter prediction method and (3) polynomial taper curve. The Schumacher's taper equation method uses volume equations to derive taper functions, while the diameter prediction method uses underbark diameters at different relative heights of the stem to describe the tree form. The polynomial taper curve method uses a high degree polynomial equation based on relative diameters and heights along the tree stem to describe the taper. Linear and non-linear regression techniques were used to estimate parameters for these methods. Method 3 was the most reliable, followed by Method 2, while the Schumacher's taper equation method was found to be the least reliable. The polynomial taper curve method also provided the best estimates for a regional model developed from the combined Zambian and Zimbabwean data. It is recommende...

SUMMARY Equations for predicting total stem volume underbark from ground to tip were developed for 25 native forest species in southern New South Wales and Victoria using the best available data from State Forests of New South Wales and the Department of Natural Resources and Environment of Victoria. The equation form for each species was selected from 18 modified versions of the combined variable volume equation (Spurr 1952) which took into account changes in stem form with tree size in order to minimize bias within any specified diameter class in volume prediction. A weight function was used to obtain confidence curves for prediction error over the entire range of diameter in the data for each species. This method overcomes the shortcomings of the commonly used segmented approach of dividing data into diameter classes when evaluating prediction accuracy. In practice, the confidence curves can be used to derive confidence limits for stand volume or any product category when they are estimated from indivi...

Summary Stem volume equations were developed and validated using data from 877 sample trees. Initially, three commonly used models were compared. The least biased and most precise estimates of underbark stem volume was obtained using equations based on the combined variable model. A lower stem form quotient, calculated as the ratio of diameter at 4.5m above ground to diameter at breast height, was subsequently included resulting in a substantial improvement in precision.

Volume equations are presented for eleven plantation species. These are based on currently available equations with provision now made for diameter measurements in millimetres.