scholarly journals A New Diameter Distribution Model for Unmanaged Loblolly Pine Plantations in East Texas

2006 ◽  
Vol 30 (1) ◽  
pp. 13-20 ◽  
Author(s):  
Young-Jin Lee ◽  
Dean W. Coble
Keyword(s):  
Loblolly Pine ◽  
Pine Plantations ◽  
Growth And Yield ◽  
Distribution Model ◽  
Diameter Distribution ◽  
Yield Prediction ◽  
East Texas ◽  
Distribution Models ◽  
Parameter Recovery ◽  
Diameter Classes

Abstract A parameter recovery procedure for the Weibull distribution function based on four percentile equations was used to develop a diameter distribution yield prediction model for unmanaged loblolly pine (Pinus taeda L.) plantations in East Texas. This model was compared with the diameter distribution models of Lenhart and Knowe, which have been used in East Texas. All three models were evaluated with independent observed data. The model developed in this study performed better than the other two models in prediction of trees per acre and cubic-foot volume per acre (wood and bark, excluding stump) across diameter classes. Lenhart’s model consistently underestimated the larger-diameter classes because it was developed originally with data mostly collected in young plantations. Knowe’s model overestimated volume in sawtimber-sized trees, which could lead to overestimations of volume in older loblolly pine plantations found in East Texas. An example also is provided to show users how to use this new yield prediction system. These results support the recommendation that forest managers should use growth and yield models designed and/or calibrated for the region in which they are implemented.South. J. Appl.For. 30(1):13–20.

scholarly journals A New Diameter Distribution Model for Unmanaged Slash Pine Plantations in East Texas

2008 ◽  
Vol 32 (2) ◽  
pp. 89-94 ◽  
Author(s):  
Dean W. Coble ◽  
Young-Jin Lee
Keyword(s):  
Loblolly Pine ◽  
Pinus Elliottii ◽  
Slash Pine ◽  
Pine Plantations ◽  
Distribution Model ◽  
Diameter Distribution ◽  
Yield Prediction ◽  
Prediction System ◽  
East Texas ◽  
New Model

Abstract A parameter recovery procedure for the Weibull distribution function based on four percentile equations was used to develop a new diameter distribution yield prediction model for unmanaged slash pine (Pinus elliottii Engelm.) plantations in East Texas. This new model was similar in structure to the model of Lee and Coble (Lee, Y.J., and D.W. Coble. 2006. A new diameter distribution model for unmanaged loblolly pine plantations in east Texas. South. J. Appl. For. 30(1):13–20) in their work with East Texas loblolly pine plantations. The new model was compared with the diameter distribution model of Lenhart (Lenhart, J.D. 1988. Diameter distribution yield prediction system for unthinned loblolly and slash pine plantations on non-old-fields in east Texas. South. J. Appl. For. 12(4):239–242. 1988), which was developed for slash pine plantations in East Texas, as well as to two other models developed using iterative techniques suggested and inspired by Cao (Cao, Q. 2004. Predicting parameters of a Weibull function for modeling diameter distribution. For. Sci. 50(5):682–685). The model developed in this study was preferred over Lenhart (Lenhart 1988) and the other two models in prediction of total trees per acre, basal area per acre, quadratic mean diameter, and cubic-foot volume per acre (wood and bark, excluding stump). An example also is provided to show users how to use this new yield prediction system. We recommend that the model developed in this study be used to estimate growth and yield of East Texas slash pine plantations.

scholarly journals A Comparison of Loblolly Pine Plantation Growth and Yield Models for Inventory Updating

1996 ◽  
Vol 20 (1) ◽  
pp. 15-22 ◽  
Author(s):  
James S. Shortt ◽  
Harold E. Burkhart
Keyword(s):  
Loblolly Pine ◽  
Growth And Yield ◽  
Diameter Distribution ◽  
Distribution Models ◽  
Tree Model ◽  
Individual Tree ◽  
Parameter Recovery ◽  
Individual Tree Model ◽  
The Individual ◽  
Growth And Yield Models

Abstract Four different loblolly pine growth and yield models were evaluated for the purpose of updating forest inventory data. The types of growth and yield models examined were: a whole stand, a diameter distribution-parameter prediction, a diameter distribution-parameter recovery, and an individual tree model. Three different approaches were used to create fitting and validation data sets from permanent plot remeasurement data; each of the four growth and yield models was evaluated at varying projection periods. The periods used were 0, 3, 6, and 9 yr. Evaluations were based solely on the capability of each model to predict merchantable volume. In terms of root mean square error of prediction, the individual tree and whole stand models performed better than the diameter distribution models. At shorter projection periods, the individual tree model performed better than the whole stand model, but the whole stand approach was superior at the 9 yr period. Of the diameter distribution models, the parameter recovery model performed better for shorter periods than the parameter prediction model, but this difference diminished with longer periods. South. J. Appl. For. 20(1):15-22.

scholarly journals A New Whole-Stand Model for Unmanaged Loblolly and Slash Pine Plantations in East Texas

2009 ◽  
Vol 33 (2) ◽  
pp. 69-76 ◽  
Author(s):  
Dean W. Coble
Keyword(s):  
Loblolly Pine ◽  
Basal Area ◽  
Pinus Elliottii ◽  
Current Data ◽  
Slash Pine ◽  
Pine Plantations ◽  
Growth And Yield ◽  
East Texas ◽  
Age Classes ◽  
Yield Model

Abstract A new compatible whole-stand growth-and-yield model to predict total tree cubic-foot volume per acre yield (outside and inside bark) was developed for unmanaged loblolly pine (Pinus taeda) and slash pine (Pinus elliottii) plantations in East Texas. This model was compared with the noncompatible whole-stand model of Lenhart (<xref ref-type="bibr" rid="B15-2127">Lenhart, 1996</xref>, Total and partial stand-level yield prediction for loblolly and slash pine plantations in east Texas, South. J. Appl. For. 20(1):36–41) and the <xref ref-type="bibr" rid="B15-2127">Lenhart (1996)</xref> model refit to current data. For the two species, all three models were evaluated with independent observed data. The model developed in this study outperformed both Lenhart models in prediction of future yield and basal area per acre for all age classes combined and by 5-year age classes. The Lenhart models consistently overestimated yield and basal area per acre. All three models predicted surviving trees per acre similarly. An example is also provided to show users how to use the new whole-stand model.

scholarly journals Modeling Diameter Distributions of Loblolly Pine Plantations in Western Gulf Coastal Plain

2021 ◽  
Author(s):  
Xiongwei Lou ◽  
Yuhui Weng ◽  
Luming Fang ◽  
Jason Grogan
Keyword(s):  
Loblolly Pine ◽  
Pine Plantations ◽  
Diameter Distribution ◽  
Gradient Boosting ◽  
Distribution Models ◽  
Management Planning ◽  
Forest Management Planning ◽  
Precise Prediction ◽  
Form Model ◽  
Gb Model

Abstract Diameter distribution models are useful tools for forest management planning, in particular for even-aged plantations of important commercial species such as loblolly pine. Using data collected from loblolly pine plantations across East Texas, two diameter distribution model systems were developed, with the first being a conventional, Weibull-form statistical model system and the second being developed using gradient boosting (GB) technique. Both models were tested using an independent data set and compared with the regional model currently being used, which was developed by Lee and Coble (2006). Compared with Lee and Coble (2006), the Weibull-form model of this study had 66.7% smaller prediction bias, 27.2% lower mean absolute error (MAE), and 18.9% smaller root-mean-square error (RMSE). Compared with the Weibull-form model of this study, the GB model had 33.9% lower MAE, 39.5% smaller RMSE, and greater R2. Thus, the GB model greatly outperformed the Weibull-form model, which, in turn, was greatly improved over the Lee and Coble (2006) in prediction accuracy. By combining a regional volume or weight equation, both proposed diameter distribution models can be used to predict stand wood volume or weight by diameter class. Both models, in particular the GB model, are recommended for use in predicting stand structures and developing stand and stock tables for loblolly pine plantations in the region. Management and Policy Implications: Knowing future stand tree size distributions is important for forest management planning. This study developed two quantitative tools to predict diameter distributions for loblolly pine (Pinus taeda) plantations in the Western Gulf Coastal Plain, with one based on the Weibull function (Weibull-form model) and the other developed using the gradient boosting technique (GB model). For the Weibull-form model, using current stand information, readers can manually calculate future stand trees per acre by diameter class. Importantly, the Weibull-form model provides more accurate (less bias and more precise) prediction than any currently available models for loblolly pine in the region. The GB model, which uses the same predictors as the Weibull-form model, can achieve even better (similar bias but more precise) prediction than the Weibull-form model. However, no equations and model coefficients for the GB model were provided, and use of the GB model relies on computer programming. A computer program was developed to implement the GB model. We recommend use of both models, in particular of the GB model, in managing loblolly pine in the region. The results aid our understanding in loblolly pine stand structure development and management in the region.

A Blind Spot in the Use of the Weibull Function for Modeling Diameter Distributions

2020 ◽  
Author(s):  
Adrian Norman Goodwin
Keyword(s):  
Lower Bound ◽  
Blind Spot ◽  
Forest Growth ◽  
Growth And Yield ◽  
Diameter Distribution ◽  
Absolute Difference ◽  
Weibull Function ◽  
Distribution Models ◽  
Difference Statistic ◽  
Diameter Distributions

Abstract Diameter distribution models based on probability density functions are integral to many forest growth and yield systems, where they are used to estimate product volumes within diameter classes. The three-parameter Weibull function with a constrained nonnegative lower bound is commonly used because of its flexibility and ease of fitting. This study compared Weibull and reverse Weibull functions with and without a lower bound constraint and left-hand truncation, across three large unthinned plantation cohorts in which 81% of plots had negatively skewed diameter distributions. Near-optimal lower bounds for the unconstrained Weibull function were negative for negatively skewed data, and the left-truncated Weibull using these bounds was 14.2% more accurate than the constrained Weibull, based on the Kolmogorov-Smirnov statistic. The truncated reverse Weibull fit dominant tree distributions 23.7% more accurately than the constrained Weibull, based on a mean absolute difference statistic. This work indicates that a blind spot may have developed in plantation growth modeling systems deploying constrained Weibull functions, and that left-truncation of unconstrained functions could substantially improve model accuracy for negatively skewed distributions.

Comparison of two parameter recovery methods for the transformation of Pinus sylvestris yield tables into a diameter distribution model

2021 ◽  
Vol 78 (1) ◽  
Author(s):  
Francisco Mauro ◽  
Antonio García-Abril ◽  
Esperanza Ayuga-Téllez ◽  
Alberto Rojo-Alboreca ◽  
Ruben Valbuena ◽  
...  
Keyword(s):  
Pinus Sylvestris ◽  
Distribution Model ◽  
Diameter Distribution ◽  
Parameter Recovery ◽  
Two Parameter ◽  
Recovery Methods

scholarly journals Loblolly and Slash Pine Growth and Yield Prediction for Regional Timber Supply Projection Algorithms

1999 ◽  
Vol 23 (4) ◽  
pp. 230-237
Author(s):  
Bruce E. Borders ◽  
Jeffrey B. Jordan
Keyword(s):  
Loblolly Pine ◽  
Analysis Data ◽  
Growth And Yield ◽  
Yield Prediction ◽  
Projection Algorithms ◽  
Timber Supply ◽  
Usda Forest Service ◽  
Forest Inventory And Analysis ◽  
Pine Stands ◽  
Growth And Yield Models

Abstract Regional and national timber supply models require standing inventory update procedures. To date, most inventory update procedures used in regional timber supply algorithms have not made use of growth and yield methodology. We present growth and yield models to update standing inventories for natural and planted slash and loblolly pine stands in Georgia. These models were fitted to USDA Forest Service Forest Inventory and Analysis data obtained from the sixth survey of Georgia and should prove useful in regional timber supply projection algorithms. South. J. Appl. For. 23(4):230-237.

scholarly journals Fusiform Rust Trends in East Texas: 1969-1987

1988 ◽  
Vol 12 (4) ◽  
pp. 259-261 ◽  
Author(s):  
J. David Lenhart ◽  
W. Thomas McGrath ◽  
Terry L. Hackett
Keyword(s):  
Pinus Taeda ◽  
Loblolly Pine ◽  
Pinus Elliottii ◽  
Slash Pine ◽  
Pine Plantations ◽  
East Texas ◽  
Infection Rates ◽  
Fusiform Rust ◽  
Cronartium Quercuum ◽  
Pinus Taeda L

Abstract Five surveys of pine plantations in East Texas over an 18-year period (1969-1987) indicated that fusiform rust (Cronartium quercuum [Berk.] Miyabe ex Shirai f. sp. fusiforme Birdsall and Snow) infection rates have increased to current levels of about 50% on slash pine (Pinus elliottii Engelm.) and are continuing to increase on loblolly pine (Pinus taeda L.) to 10-15% levels. South. J. Appl. For. 12(4):259-261.

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