An individual tree diameter increment model for white spruce in Alberta

1995 ◽  
Vol 25 (9) ◽  
pp. 1455-1465 ◽  
Author(s):  
Shongming Huang ◽  
Stephen J. Titus
Keyword(s):  
White Spruce ◽  
Model Parameters ◽  
Data Set ◽  
Individual Tree ◽  
Error Structure ◽  
Permanent Sample Plots ◽  
Tree Diameter ◽  
Diameter Increment ◽  
Diameter Increment Model ◽  
Age Independent

Based on a data set from 164 permanent sample plots, an age-independent individual tree diameter increment model is presented for white spruce (Piceaglauca (Moench) Voss) grown in the boreal mixed-species stands in Alberta. The model is age independent in that it does not explicitly require tree or stand age as input variables. Periodic diameter increment is modelled as a function of tree diameter at breast height, total tree height, relative competitiveness of the tree in the stand, species composition, stand density, and site productivity. Because data from permanent sample plots are considered time series and cross sectional, diagnostic techniques were applied to identify the model's error structure. Appropriate fit based on the identified error structure was accomplished using weighted nonlinear least squares with a first-order autoregressive process. Results show that (1) all model parameters are significant at α = 0.05 level, and (2) the plot of studentized residuals against predicted diameter increment shows no consistent underestimate or overestimate for diameter increment. The model was also tested on an independent data set representing the population on which it is to be used. Results show that the average prediction biases are not significant at α = 0.05 level, indicating that the model appropriately describes the data and performs well when predictions are made.

An age-independent individual tree height prediction model for boreal spruce–aspen stands in Alberta

1994 ◽  
Vol 24 (7) ◽  
pp. 1295-1301 ◽  
Author(s):  
Shongming Huang ◽  
Stephen J. Titus
Keyword(s):  
Prediction Model ◽  
Nonlinear Regression ◽  
Prediction Method ◽  
Tree Height ◽  
White Spruce ◽  
Data Set ◽  
Individual Tree ◽  
Permanent Sample Plots ◽  
Height Prediction ◽  
Age Independent

This study presents an individual tree height prediction model for white spruce (Piceaglauca (Moench) Voss) and trembling aspen (Populustremuloides Michx.) grown in boreal mixed-species stands in Alberta. The model is based on a three-parameter Chapman–Richards function fitted to data from 164 permanent sample plots using the parameter prediction method. It is age independent and expresses tree height as a function of tree diameter, tree basal area, stand density, species composition, site productivity, and stand average diameter. This height-prediction model was fitted by weighted nonlinear regression for spruce and unweighted nonlinear regression for aspen. Almost all estimates of parameters were significant at α = 0.05 and model R2-values were high (0.9192 for white spruce and 0.9087 for aspen). No consistent underestimate or overestimate of tree heights was evident in plots of studentized residuals against predicted heights. The model was also tested on an independent data set representing the population on which the model was to be used. Results showed that the average prediction biases were not significant at α = 0.05 for either species, indicating that the model appropriately described the data and performed well when predictions were made.

scholarly journals Distance-independent individual tree diameter-increment model for Thuya [Tetraclinis articulata (VAHL.) MAST.] stands in Tunisia

2013 ◽  
Vol 22 (3) ◽  
pp. 433 ◽  
Author(s):  
T. Sghaier ◽  
M. Tome ◽  
J. Tome ◽  
M. Sanchez-Gonzalez ◽  
I. Cañellas ◽  
...  
Keyword(s):  
Individual Tree ◽  
Tree Diameter ◽  
Diameter Increment ◽  
Tetraclinis Articulata ◽  
Diameter Increment Model ◽  
Independent Individual

Evaluating the influence of stem form and damage on individual-tree diameter increment and survival in the Acadian Region: implications for predicting future value of northern commercial hardwood stands

2018 ◽  
Vol 48 (9) ◽  
pp. 1007-1019 ◽  
Author(s):  
Mark Castle ◽  
Aaron Weiskittel ◽  
Robert Wagner ◽  
Mark Ducey ◽  
Jereme Frank ◽  
...  
Keyword(s):  
Growth And Yield ◽  
Tree Level ◽  
Permanent Plots ◽  
Stem Form ◽  
Individual Tree ◽  
Tree Diameter ◽  
Diameter Increment ◽  
Hardwood Species ◽  
Future Value

Northern hardwood species display a variety of forms and defects that can reduce stem quality and complicate their timber management. However, for the most part, growth and yield models do not account for the influence of stem form and damage. This study determined the influence of stem form and damage on growth, survival, and projected future sawlog value among several northern commercial hardwood species. To accomplish this, hardwood trees on 112 permanent plots across three long-term research sites in Maine were assigned stem form and risk classes using a tree classification system developed in New Brunswick. A highly significant influence of stem form and risk on annualized individual-tree diameter increment and survival was found. Inclusion of these equations into a regional growth and yield model highlighted the importance of stem form and defects on long-term simulations as projected stand-level future value was significantly reduced by over 17%, on average (range of 13% to 28%), when compared with projections that did not include that tree-level information. The results highlight the importance of stem form and defects, as well as the need to account for them, in growth and yield applications that assess the forecasted value of commercially important hardwood stands.

scholarly journals An Individual-Tree Mortality Model for Complex Stands of Southeastern British Columbia

2005 ◽  
Vol 20 (2) ◽  
pp. 101-109 ◽  
Author(s):  
Hailemariam Temesgen ◽  
Stephen J. Mitchell
Keyword(s):  
British Columbia ◽  
Tree Species ◽  
Tree Mortality ◽  
Model Development ◽  
Mortality Rates ◽  
Average Deviation ◽  
Individual Tree ◽  
Permanent Sample Plots ◽  
Diameter Increment ◽  
Mortality Model

Abstract An individual-tree mortality model was developed for major tree species in complex stands (multi-cohort, multiaged, and mixed species) of southeastern British Columbia (BC), Canada. Data for 29,773 trees were obtained from permanent sample plots established in BC. Average annual diameter increment and mortality rates ranged from 0.08 to 0.17 cm/year and from 0.3 to 2.6%, respectively. Approximately 70% of the trees were used for model development and 30% for model evaluation. After evaluating the model, all 29,773 trees were used to fit the final model. A generalized logistic model was used to relate mortality to tree size, competition, and relative position of trees in a stand. The evaluation test demonstrated that the model appears to be well behaved and robust for the tree species considered in this study. For the eight tree species, the average deviation between observed and predicted annual mortality rates varied from −0.5 to 0.7% in the test data. West. J. Appl. For. 20(2):101–109.

Effects of precommercial thinning on the forest value chain in northwestern New Brunswick: Part 1 – Roundwood production and stumpage value

2013 ◽  
Vol 89 (04) ◽  
pp. 446-457 ◽  
Author(s):  
Doug G. Pitt ◽  
Len Lanteigne ◽  
Michael K. Hoepting ◽  
Jean Plamondon
Keyword(s):  
Value Chain ◽  
Abies Balsamea ◽  
Stand Age ◽  
Annual Increment ◽  
Data Set ◽  
Individual Tree ◽  
Green River ◽  
Precommercial Thinning ◽  
Permanent Sample Plots ◽  
Sequential Evaluation

The Green River precommercial thinning trials were established between 1959 and 1961 in naturally regenerating balsam fir (Abies balsamea [L.] Mill.)-dominated stands, an average of eight years after overstory removal. Three nominal spacings of 4 ft (1.2 m), 6 ft (1.8 m) and 8 ft (2.4 m) were compared to an unthinned control in six replicate blocks. In the fall of 2008, following completion of the ninth sequential evaluation of the study’s 48 permanent sample plots, three of the six replicates were clearcut harvested and data were collected on roundwood product recovery and value. These data were used to construct treatment-invariant (p ≥ 0.18) functions predicting product volume from tree diameter, allowing the volume of studwood, sawlogs and pulpwood to be predicted for the full Green River data set (all 6 replicates) through time. Mean annual increment of gross merchantable volume culminated in all treatments around stand age 45. Thinning to a nominal spacing of 6 ft, resulting in 1600 merchantable stems per ha by stand age 30, offered the best balance of individual tree and stand growth, producing 20% more gross merchantable volume and 26% more sawlog volume than unthinned stands, potentially increasing landowner stumpage revenues by 22% (p < 0.01). The sawlog volume produced in unthinned stands could be realized up to 15 years sooner in thinned stands, suggesting that PCT may offer substantive flexibility in balancing forest-level wood supply objectives.

scholarly journals Evaluation of Alternative Approaches for Predicting Individual Tree Volume Increment

2010 ◽  
Vol 25 (3) ◽  
pp. 120-126 ◽  
Author(s):  
David W. Hann ◽  
Aaron R. Weiskittel
Keyword(s):  
Direct Method ◽  
Analysis Data ◽  
Stem Volume ◽  
Prediction Errors ◽  
Data Set ◽  
Individual Tree ◽  
Diameter Increment ◽  
Volume Increment ◽  
Alternative Approaches ◽  
Taper Equation

Abstract The volume increment of individual trees is often inferred from a volume or taper equation and predicted or observed diameter and height increments. Prediction errors can be compounded with this type of approach because of the array of equations used and differences in their accuracy. The consequences of several alternative approaches for indirectly or directly estimating individual tree volume increment were examined using an extensive stem analysis data set of Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) in southwest Oregon. The data were used to construct new stem volume, taper, and volume increment equations, which were then used to compare predicted and observed 5-year volume increments. The results of this analysis suggest that the indirect prediction of volume increment is sensitive to both the approach used for estimating stem volume and the use of actual versus predicted diameter and height increment, especially diameter increment. In addition, using the indirect method of volume and taper equations was found to have a slightly lower level of accuracy in predicting stem volume increment than the direct method. It was found that the use of local calibration procedures could help to mitigate possible problems with the bias incurred by using predicted rather than actual diameter increment.

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