Variance propagation in growth and yield projections

1986 ◽  
Vol 16 (6) ◽  
pp. 1196-1200 ◽  
Author(s):  
H. T. Mowrer ◽  
W. E. Frayer
Keyword(s):  
Forest Growth ◽  
Growth And Yield ◽  
Yield Model ◽  
Estimation Errors ◽  
Bias Assessment ◽  
Substantial Error ◽  
Growth And Yield Model ◽  
Growth Projection ◽  
Variance Estimates ◽  
Assessment Procedures

This paper reports the results of a study on the propagated variance associated with stand estimates in a forest growth and yield model. A cumulative variance as a result of input measurement and regression estimation errors is propagated in a growth and yield model using the method of statistical differentials. To provide an assessment of relative performance, these variance estimates are compared with a Monte Carlo simulation estimate of propagated error for increasing levels of sampling intensity. The method of statistical differentials is used to estimate the propagated variance through five 10-year growth projections. The results indicate growth projection estimates may have substantial error components that are not readily apparent from model calibration statistics or bias assessment procedures.

A Growth and Yield Model for Improved Eastern Cottonwood Plantations in the Lower Mississippi Delta

1991 ◽  
Vol 15 (4) ◽  
pp. 213-216 ◽  
Author(s):  
Quang V. Cao ◽  
Kenneth M. Durand
Keyword(s):  
Populus Deltoides ◽  
Mississippi Delta ◽  
Basal Area ◽  
Site Index ◽  
Growth And Yield ◽  
Annual Increment ◽  
Yield Model ◽  
Eastern Cottonwood ◽  
Volume Yield ◽  
Growth And Yield Model

Abstract A compatible growth and yield model was developed based on remeasurement data collected from 183 plots on unthinned improved eastern cottonwood (Populus deltoides Bartr.) plantations in the lower Mississippi Delta. The Sullivan and Clutter (1972) equation form was selected for predicting cubic-foot volume yield and projecting volume from site index and initial age and basal area. Yield equations explained 97% and 94%, respectively, of the variations in total outside bark and merchantable inside bark volumes. Mean annual increment of merchantable volume culminated between 8 and 15 years, depending on site index and initial basal area. South. J. Appl. For. 15(4):213-216.

scholarly journals Stand-Level Components of a Growth and Yield Model for Nothofagus Mixed Forests from Southern Chile

Forests ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 810
Author(s):  
Sebastian Palmas ◽  
Paulo C. Moreno ◽  
Wendel P. Cropper ◽  
Alicia Ortega ◽  
Salvador A. Gezan
Keyword(s):  
Forest Type ◽  
Geographical Area ◽  
Basal Area ◽  
Forest Growth ◽  
Model Systems ◽  
Growth And Yield ◽  
Permanent Plots ◽  
Stand Age ◽  
Yield Model ◽  
Mixed Forests

Reliable information on stand dynamics and development is needed to improve management decisions on mixed forests, and essential tools for this purpose are forest growth and yield (G&Y) models. In this study, stand-level G&Y models were built for cohorts within the natural mixed second-growth Nothofagus-dominated forests in Chile. All currently available (but limited) data, consisting of a series of stratified temporary and permanent plots established in the complete range of this forest type, were used to fit and validate these models. Linear and nonlinear models were considered, where dominant stand age, number of trees, and the proportion of basal area of Nothofagus species resulted in significant predictors to project future values of stand basal area for the different cohorts (with R2 > 0.51 for the validation datasets). Mortality was successfully modeled (R2 = 0.79), based on a small set of permanent plots, using the concept of self-thinning with a proposed model defined by the idea that, as stands get closer to a maximum density, they experience higher levels of mortality. The evaluation of these models indicated that they adequately represent the current understanding of dynamics of basal area and mortality of Nothofagus and companion species in these forests. These are the first models fitted over a large geographical area that consider the dynamics of these mixed forests. It is suggested that the proposed models should constitute the main components of future implementations of G&Y model systems.

scholarly journals Assessing the Applicability of Growth Models to New Species and Regions: An Example Comparing Mediterranean Maritime Pine in Central Spain to Ponderosa Pine in Southwestern Oregon, USA

2007 ◽  
Vol 22 (4) ◽  
pp. 269-277
Author(s):  
D. Pascual ◽  
D.A. Maguire ◽  
F. Bravo
Keyword(s):  
Growth Model ◽  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Maritime Pine ◽  
Growth And Yield ◽  
Diameter Growth ◽  
Growth Equation ◽  
Similar Species ◽  
Yield Model ◽  
Growth And Yield Model

Abstract Evaluations of response to variable silvicultural treatments play a key role in developing sustainable forest management. To evaluate silvicultural response, a growth and yield model is needed. A comparison between similar species could act as a logical first step toward building a growth and yield model and to test the efficiency of the calibration of an existing ponderosa pine (Pinus ponderosa Dougl. ex Laws.) growth model to a Mediterranean maritime pine (Pinus pinaster Ait. ssp. mesogeensis) growth model. This study aimed at (1) comparing the diameter growth pattern between ponderosa and Mediterranean maritime pine, and (2) assessing the potential of ORGANON for simulating Mediterranean maritime pine growth and yield. The first objective was addressed by fitting a diameter growth equation for Mediterranean maritime pine and comparing it with patterns in ponderosa pine growth represented by the corresponding equation in ORGANON. The second objective was addressed by growing Mediterranean maritime pine as ponderosa pine in ORGANON, conditional on observed diameter growth rates of Mediterranean maritime pine in Spain. The results emphasized the unsuitability of ORGANON for predicting diameter growth of Mediterranean maritime pine in Spain. Mediterranean maritime pine diameter growth depended on basal area in trees with a diameter larger than the subject tree, (BAL) which, in our context is a subrogate of competition from above.

Stand growth projection: simultaneous estimation of growth and mortality using a single probabilistic function

1987 ◽  
Vol 17 (11) ◽  
pp. 1466-1470 ◽  
Author(s):  
K. E. Lowell ◽  
R. J. Mitchell
Keyword(s):  
Logistic Model ◽  
Forest Growth ◽  
Growth And Yield ◽  
Diameter Distribution ◽  
Simultaneous Estimation ◽  
Binary Event ◽  
Probabilistic Function ◽  
Growth Projection ◽  
Individual Trees ◽  
Stand Characteristics

Logistic regression analysis can be used to estimate the probability of a binary event. In forestry, its use largely has been limited to predicting the probability of mortality of individual trees. However, the potential for broader application in forest growth and yield modelling has largely been overlooked. A logistic model to predict the probability that a tree will attain a specified future diameter can be produced by establishing a series of growth "success" criteria. Given the initial diameter distribution of a forest stand, a future diameter distribution and stand characteristics can be estimated probabilistically by estimating the proportion of stems in each diameter class of the distribution which attains a specified future diameter (the "success" criterion) and the proportion which fails to achieve at least zero growth (i.e., mortality). Using permanent plot data, such a logistic model was calibrated and validated for an oak–hickory forest in southeastern Missouri. Validation indicated that the model performs satisfactorily (estimates are unbiased) for individual trees over a 5-year prediction period, and for stand characteristics over 5-, 10-, 15-, and 20-year prediction periods though precision suffers as prediction period lengthens.

A simple growth and yield model for assessing changes in standing volume across Canada’s forests

2009 ◽  
Vol 85 (1) ◽  
pp. 57-64 ◽  
Author(s):  
C -H. Ung ◽  
P Y Bernier ◽  
X J Guo ◽  
M -C. Lambert
Keyword(s):  
Predictive Power ◽  
Robust Regression ◽  
Forest Growth ◽  
Growth Potential ◽  
Growth And Yield ◽  
Stand Age ◽  
Yield Model ◽  
Wood Volume ◽  
National Model ◽  
Growth And Yield Models

We have adjusted two growth and yield models to temporary sample plots from across Canada, and used climate variables in lieu of phytometric indices such as site index to represent, in part, the site-level variability in growth potential. Comparison of predicted increments in plot-level height, basal area and merchantable wood volume to increments of these variables measured in permanent sample plots shows a moderate to poor predictive ability. Comparison with the performance of four operational growth and yield models from different provinces across Canada shows comparable predictive power of this new model versus that of the provincial models. Based on these results, we suggest that the simplification of regional growth and yield models may be achieved without further loss of predictive power, and that the large error in the prediction of growth increment is mostly associated with the use of temporary sample plots which, by definition, contain little information on stand dynamics. We also suggest that, because of the empirical nature of these growth and yield models, the scale of application should determine the appropriate scale of the model. National estimates of forest growth are therefore less likely to be biased if obtained from a national model only than if obtained from a combination of regional models, where those exist, gap-filled with estimates from a national model. Key words: yield model, merchantable wood volume, stand age, climatic variables, simultaneous regression, robust regression

Predicted Genetic Gains from one Generation of Slash Pine Tree Improvement

1989 ◽  
Vol 13 (1) ◽  
pp. 51-56 ◽  
Author(s):  
G. R. Hodge ◽  
T. L. White ◽  
G. L. Powell ◽  
S. M. De Souza
Keyword(s):  
First Generation ◽  
Pinus Elliottii ◽  
Tree Improvement ◽  
Slash Pine ◽  
Growth And Yield ◽  
Yield Model ◽  
Individual Tree ◽  
Fusiform Rust ◽  
Pine Tree ◽  
Growth And Yield Model

Abstract Gains over unimproved seed for progeny from first generation--un-rogued, first generation--rogued, and one and one-half generation orchards of slash pine (Pinus elliottii var. elliottii) for individual tree volume at 15 years are predicted to be 10%, 15%, and 19%, respectively. Rustinfection of orchard progeny on sites where unimproved material incurs 50% infection are predicted to be 49%, 41%, and 35% for the three orchard types. Using a growth and yield model that incorporates fusiform rust, gains in individual tree volume and increased rust resistance were combinedto estimate effects on per acre yields. Percent volume per acre gains are predicted to be 7.0%, 13.2%, and 18.0% for the three orchard types. Collection and deployment of the most rust resistant seed to high rust hazard sites raises the gain on these sites and becomes increasingly beneficialas the rust hazard increases. South. J. Appl. For. 13(1): 51-56.

Compatible basal-area growth and yield model for thinned and unthinned stands

1984 ◽  
Vol 14 (2) ◽  
pp. 295-295
Author(s):  
Robert L. Bailey ◽  
Kenneth D. Ware
Keyword(s):  
Basal Area ◽  
Growth And Yield ◽  
Yield Model ◽  
Basal Area Growth ◽  
Area Growth ◽  
Growth And Yield Model

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