scholarly journals Site Specific Stem Volume Models for Pinus patula and Pinus oocarpa

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Herbert Malata ◽  
Elisha S. Ngulube ◽  
Edward Missanjo
Keyword(s):  
Stem Volume ◽  
Accurate Estimation ◽  
Pinus Patula ◽  
Volume Data ◽  
Site Specific ◽  
Pinus Oocarpa ◽  
Relative Errors ◽  
Total Tree ◽  
Volume Models ◽  
Modelling Approach

Sustainable management of timber forests requires availability and adequacy of models for accurate estimation of tree volumes. This study was conducted to develop site specific models for estimating individual total tree stem volume of Pinus patula and Pinus oocarpa at Chongoni Timber Plantation in Central Malawi. A total of 32 trees from Pinus patula compartment and 48 trees from Pinus oocarpa compartment were destructively sampled. Various predictors including diameter at breast height (dbh) and height (ht) were run against total stem volume using a nonlinear mixed-effects modelling approach. The results indicate that the developed site specific models showed a significant association between total stem volume and the predictors (dbh and ht). The developed volume models accounted for at least 99% of the total variation in the total stem volume data. This suggests that application of the developed site specific models is highly recommended when accurate results are required. The appropriateness of the developed models was also supported by the fact that the total relative errors (TRE) of these models were lower (range: −0.04% to 0.06%) than the TRE of some previously developed models (range: −12.40% to 41.70%) tested on the present data.

scholarly journals Allometric Models for Estimating Tree Volume and Aboveground Biomass in Lowland Forests of Tanzania

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Wilson Ancelm Mugasha ◽  
Ezekiel Edward Mwakalukwa ◽  
Emannuel Luoga ◽  
Rogers Ernest Malimbwi ◽  
Eliakimu Zahabu ◽  
...  
Keyword(s):  
Aboveground Biomass ◽  
Site Specific ◽  
Tree Allometry ◽  
Allometric Models ◽  
Specific Biomass ◽  
Lowland Forests ◽  
Study Sites ◽  
Biased Estimates ◽  
Total Tree ◽  
Volume Models

Models to assist management of lowland forests in Tanzania are in most cases lacking. Using a sample of 60 trees which were destructively harvested from both dry and wet lowland forests of Dindili in Morogoro Region (30 trees) and Rondo in Lindi Region (30 trees), respectively, this study developed site specific and general models for estimating total tree volume and aboveground biomass. Specifically the study developed (i) height-diameter (ht-dbh) models for trees found in the two sites, (ii) total, merchantable, and branches volume models, and (iii) total and sectional aboveground biomass models of trees found in the two study sites. The findings show that site specific ht-dbh model appears to be suitable in estimating treeheightsince the tree allometry was found to differ significantly between studied forests. The developed general volume models yielded unbiased mean prediction error and hence can adequately be applied to estimate tree volume in dry and wet lowland forests in Tanzania. General aboveground biomass model appears to yield biased estimates; hence, it is not suitable when accurate results are required. In this case, site specific biomass allometric models are recommended. Biomass allometric models which include basic wood density are highly recommended for improved estimates accuracy when such information is available.

scholarly journals Evaluation of Compatible Taper and Volume Models for Combretum hartmannianum and Lonchocarpus laxiflorus Tree Species.

2021 ◽  
pp. 50-70
Keyword(s):  
Tree Species ◽  
Tree Height ◽  
Coefficient Of Determination ◽  
Accurate Estimation ◽  
Diameter At Breast Height ◽  
Breast Height ◽  
Regression Parameters ◽  
Absolute Residual ◽  
Total Tree ◽  
Volume Models

This paper developed and evaluated the performance of the current functional tree taper and volume models. The models were applied to some selected economically important natural tree species common to central Sudan, namely, Combretum hartmannianum and, Lonchocarpus Laxiflorus. The tree variables measured were the diameter at breast height (DBH, cm), diameter at the base of the tree (d0, cm), upper stem diameters (di), total tree height (H), and height to the base of the crown (Hb). In total, 19 taper and 32 volume models were tested and evaluated (22 models were two-variable models (Diameter at breast height and total tree height or bole height) and 10 were three-variable models (Diameter at ground level, Diameter at breast height and total tree height or bole height). The model goodness of fit was evaluated in terms of adjusted coefficient of determination (Ra2), standard error (SE), mean absolute residual (MAR), bias (BI) Akaike’s information criterion (AIC), homogeneity of the residuals and significance of the regression parameters. As far as taper models is concerned, Models, some of the models were found to yield satisfactory results for the tow selected species with R2 range of 0.94 – 0.96. For the within species variation of models on the basis of the AIC values, the ranking of the models (smaller AIC first) were in consistant with the rankings due to SE and Ra2 values although AIC penalizes models in proportion to the number regression parameters. In general the results of the study indicated that higher residuals valuse are in most of the cases associated with the lower parts of the bole, the butress portion of the stem. This suggests that care should be taken during the application of such models for hardwood species, especially in open woodlands where butress is a common characteristic.The results for volume models revealed differences in the behaviour of different models for each species as the degree of significance of the regression parameters varies between tree species. However, the replacement of the total tree height by the bole height (merchantable height) improves both the level of parameter significance and the coefficient of determination. The results also reveal that inclusion of diameter at grown level to the original two variables (DBH, Ht) and the replacement of the original model total height with the bale height results in quite significant improvement of the Ra2 values. In general, the study concluded that taper and volume models can provide precise and accurate estimation of tree growth variables for the studied species with reasonable cost and time, but care should be taken when dealing with same model for the same species across varying growth and management condition, or when dealing with different species. country.

scholarly journals Assessment of Stem Volume on Plots Using Terrestrial Laser Scanner: A Precision Forestry Application

Sensors ◽  
2021 ◽  
Vol 21 (1) ◽  
pp. 301
Author(s):  
Dimitrios Panagiotidis ◽  
Azadeh Abdollahnejad ◽  
Martin Slavík
Keyword(s):  
Norway Spruce ◽  
Laser Scanner ◽  
Estimation Methods ◽  
Coefficient Of Determination ◽  
Stem Volume ◽  
Small Scale ◽  
Terrestrial Laser Scanner ◽  
Precision Forestry ◽  
Total Tree ◽  
European Oak

Timber volume is an important asset, not only as an ecological component, but also as a key source of present and future revenues, which requires precise estimates. We used the Trimble TX8 survey-grade terrestrial laser scanner (TLS) to create a detailed 3D point cloud for extracting total tree height and diameter at breast height (1.3 m; DBH). We compared two different methods to accurately estimate total tree heights: the first method was based on a modified version of the local maxima algorithm for treetop detection, “HTTD”, and for the second method we used the centers of stem cross-sections at stump height (30 cm), “HTSP”. DBH was estimated by a computationally robust algebraic circle-fitting algorithm through hierarchical cluster analysis (HCA). This study aimed to assess the accuracy of these descriptors for evaluating total stem volume by comparing the results with the reference tree measurements. The difference between the estimated total stem volume from HTTD and measured stems was 2.732 m3 for European oak and 2.971 m3 for Norway spruce; differences between the estimated volume from HTSP and measured stems was 1.228 m3 and 2.006 m3 for European oak and Norway spruce, respectively. The coefficient of determination indicated a strong relationship between the measured and estimated total stem volumes from both height estimation methods with an R2 = 0.89 for HTTD and R2 = 0.87 for HTSP for European oak, and R2 = 0.98 for both HTTD and HTSP for Norway spruce. Our study has demonstrated the feasibility of finer-resolution remote sensing data for semi-automatic stem volumetric modeling of small-scale studies with high accuracy as a potential advancement in precision forestry.

scholarly journals Comprehensive yield model for plantation teak in Panama

Silva Fennica ◽  
2020 ◽  
Vol 54 (5) ◽  
Author(s):  
Petteri Seppänen ◽  
Antti Mäkinen
Keyword(s):  
Input Parameter ◽  
Large Diameter ◽  
Measurement Data ◽  
Growth And Yield ◽  
Tree Level ◽  
Stem Volume ◽  
Yield Model ◽  
Individual Tree ◽  
Support Tool ◽  
Volume Models

The purpose of this study was to prepare a comprehensive, computerized teak ( L.f) plantation yield model system that can be used to describe the forest dynamics, predict growth and yield and support forest planning and decision-making. Extensive individual tree and permanent sample plot data were used to develop tree-level volume models, taper curve models and stand-level yield models for teak plantations in Panama. Tree volume models were satisfactorily validated against independent measurement data and other published models. Tree height as input parameter improved the stem volume model marginally. Stand level yield models produced comparable harvest volumes with models published in the literature. Stand level volume product outputs were found like actual harvests with an exception that the models marginally underestimate the share of logs in very large diameter classes. The kind of comprehensive model developed in this study and implemented in an easy to use software package provides a very powerful decision support tool. Optimal forest management regimes can be found by simulating different planting densities, thinning regimes and final harvest ages. Forest practitioners can apply growth and yield models in the appropriate stand level inventory data and perform long term harvest scheduling at property level or even at an entire timberland portfolio level. Harvest schedules can be optimized using the applicable financial parameters (silviculture costs, harvesting costs, wood prices and discount rates) and constraints (market size and operational capacity).Tectona grandis

scholarly journals Generic and specific stem volume models for three subtropical forest types in southern Brazil

2015 ◽  
Vol 72 (6) ◽  
pp. 865-874 ◽  
Author(s):  
Alexander C. Vibrans ◽  
Paolo Moser ◽  
Laio Z. Oliveira ◽  
João P. de Maçaneiro
Keyword(s):  
Subtropical Forest ◽  
Stem Volume ◽  
Southern Brazil ◽  
Forest Types ◽  
Volume Models

scholarly journals Biomass and Volume Modeling along with Carbon Concentration Variations of Short-Rotation Poplar Plantations

Forests ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 780 ◽  
Author(s):  
Lihu Dong ◽  
Faris Rafi Almay Widagdo ◽  
Longfei Xie ◽  
Fengri Li
Keyword(s):  
Carbon Sink ◽  
Biomass Conversion ◽  
Model Fitting ◽  
National Forest Inventory ◽  
Model Systems ◽  
Stem Volume ◽  
Crown Length ◽  
Short Rotation ◽  
And Performance ◽  
Volume Models

Short-rotation forestry is of interest to provide biomass for bioenergy and act as a carbon sink to mitigate global warming. The Poplar tree (Populus × xiaohei) is a fast-growing and high-yielding tree species in Northeast China. In this study, a total of 128 Populus × xiaohei trees from the Songnen Plain, Heilongjiang Province, Northeastern China, were harvested. Several available independent variables, such as tree diameter at breast height (D), tree’s total height (H), crown width (CW), and crown length (CL), were differently combined to develop three additive biomass model systems and eight stem volume models for Populus × xiaohei tree. Variance explained within the three additive biomass model systems ranged from 83% to 98%, which was lowest for the foliage models, and highest for the stem biomass models. Similar findings were found in the stem volume models, in which the models explained more than 94% of the variance. The additional predictors, such as H, CL, or CW, evidently enhanced the model fitting and performance for the total and components biomass along with the stem volume models. Furthermore, the biomass conversion and expansion factors (BCEFs) of the root (118.2 kg/m3), stem (380.2 kg/m3), branch (90.7 kg/m3), and foliage (31.2 kg/m3) were also calculated. The carbon concentrations of Populus × xiaohei in root, stem, branch, and foliage components were 45.98%, 47.74%, 48.32%, and 48.46%, respectively. Overall, the newly established models in this study provided complete and comprehensive tools for quantifying the biomass and stem volume of Populus × xiaohei, which might be essential to be specifically utilized in the Chinese National Forest Inventory.

Stem volume models with random coefficients for Pinus kesiya in Tanzania, Zambia, and Zimbabwe

2001 ◽  
Vol 31 (5) ◽  
pp. 879-888 ◽  
Author(s):  
Kalle Eerikäinen
Keyword(s):  
Variable Exponent ◽  
Generalized Least Squares ◽  
General Assumption ◽  
Random Coefficients ◽  
Stem Volume ◽  
Random Parameters ◽  
Pinus Kesiya ◽  
Taper Equation ◽  
Volume Models ◽  
Taper Models

The aim of the study was to estimate stem volume and taper models for Pinus kesiya (Royle ex Gordon). The volume function provides a simple prediction model for the stem volume. Taper models were developed for over- and under-bark diameters. The under-bark taper curve was determined with the variable-exponent taper equation, whereas the over-bark taper curve was derived from the predicted under-bark taper model using the variable-exponent form of the bark-thickness model. Because of the spatial correlation structures of the data, the general assumption of uncorrelated residuals did not hold. In addition, the models were assumed to contain random parameters that vary from stand to stand and from tree to tree. Therefore, the fixed and random parameters of the models were estimated with the generalized least squares technique. The results of the study show that the mixed models for stem volume and taper are more reliable volume and diameter predictors for P. kesiya than earlier taper and volume functions.

scholarly journals Effects of Measurement Error in Total Tree Height and Upper-Stem Diameter on Stem Volume Prediction

2017 ◽  
Vol 63 (3) ◽  
pp. 250-260 ◽  
Author(s):  
Manuel Arias-Rodil ◽  
Ulises Diéguez-Aranda ◽  
Harold E. Burkhart
Keyword(s):  
Measurement Error ◽  
Tree Height ◽  
Stem Diameter ◽  
Stem Volume ◽  
Total Tree

scholarly journals Minimum sample size for fitting compatible taper-volume functions for three pine species in Chihuahua

2020 ◽  
Vol 27 (1) ◽  
pp. 143-163
Author(s):  
Juan M. Villela-Suárez ◽  
◽  
Oscar A. Aguirre-Calderón ◽  
Eduardo J. Treviño-Garza ◽  
Marco A. González-Tagle ◽  
...  
Keyword(s):  
Sample Size ◽  
Goodness Of Fit ◽  
Small Samples ◽  
Stem Volume ◽  
Minimum Sample Size ◽  
Forest Regions ◽  
Minimum Number ◽  
Minimum Sample ◽  
Volume Models ◽  
Volume Functions

Introduction: The choice of sample size is an important decision in the development of volume models and taper functions. Objective: To calculate the minimum sample size required for fitting compatible taper-volume functions for Pinus arizonica Engelm., P. durangensis Martínez and P. engelmannii Carr. in Chihuahua. Materials and methods: The methodology was divided into three phases: (i) fitting of a linear regression model to the diameter-height data of 50 trees of each species in the three forest regions; (ii) calculation of the minimum sample size required, and (iii) comparison of the goodness of fit of the taper-volume function using both sample sizes. Results and discussion: The minimum number of trees calculated ranged from 53 (Pinus durangensis) to 88 (P. engelmannii) and it is located in the interval reported in studies carried out to estimate the optimal sample size for the development of taper functions. No significant differences were observed in the goodness of fit (α = 0.05) in terms of the R 2 and the root mean square error, using the full sample size and the calculated minimum sample size; no significant effect was observed in the stem volume estimates. Conclusion: The use of small samples in the fit of taper-volume models generates accurate estimates if adequate representation of the study population is ensured.

scholarly journals Compatible Taper and Stem Volume Equations for Five Pine Species in Mixed-Species Forests in Mexico

2019 ◽  
Vol 65 (5) ◽  
pp. 602-613
Author(s):  
Gerónimo Quiñonez-Barraza ◽  
Dehai Zhao ◽  
Héctor Manuel De los Santos-Posadas
Keyword(s):  
Volume Ratio ◽  
Stem Volume ◽  
Volume Data ◽  
Stem Height ◽  
White Pine ◽  
Mixed Species ◽  
Cumulative Volume ◽  
Volume Equations ◽  
Better Than ◽  
Pine Species

Abstract Ten systems of compatible taper and outside-bark volume equations derived from upper-height-based volume ratio equations were compared with a used segmented-stem system of compatible taper and volume equations. All the systems were simultaneously fitted to cumulative volume data and taper data for Arizona pine, Aztec pine, Durango pine, Mexican white pine, and Smooth-leaved pine species in naturally regenerated mixed-species forests in Mexico. The systems derived from volume ratio equations performed better than the segmented-stem system for most species. The resultant top systems might be easier to implement than the segmented-stem system for predicting upper-stem height, upper-stem diameter, merchantable volume, and total stem volume for considered species.

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