scholarly journals A Merchantable and Total Height Model for Tree Species in Maine

2006 ◽  
Vol 23 (4) ◽  
pp. 241-249 ◽  
Author(s):  
James A. Westfall ◽  
Kenneth M. Laustsen
Keyword(s):  
Tree Height ◽  
Mixed Effects ◽  
Site Quality ◽  
Tree Level ◽  
Mixed Effects Modeling ◽  
Height Prediction ◽  
Species Groups ◽  
Total Tree ◽  
Height Model ◽  
Tree Characteristics

Abstract A model for predicting merchantable and total tree height for 18 species groups in Maine is presented. Only tree-level predictor variables are used, so stand-level attributes, such as age and site quality, are not required. A mixed-effects modeling approach accounts for the correlated within-tree measurements. Data-collection protocols encompass situations in which merchantability to a specified top diameter is not attained due to tree characteristics. The advantage of using the height prediction model over taper-derived estimates of merchantable height is demonstrated.

Mixed-effects modeling for tree height prediction models of Oriental beech in the Hyrcanian forests

2017 ◽  
Vol 29 (5) ◽  
pp. 1195-1204 ◽  
Author(s):  
Siavash Kalbi ◽  
Asghar Fallah ◽  
Pete Bettinger ◽  
Shaban Shataee ◽  
Rassoul Yousefpour
Keyword(s):  
Prediction Models ◽  
Tree Height ◽  
Mixed Effects ◽  
Oriental Beech ◽  
Hyrcanian Forests ◽  
Mixed Effects Modeling ◽  
Height Prediction

scholarly journals Modelling the Tree Height, Crown Base Height, and Effective Crown Height of Pinus koraiensis Plantations Based on Knot Analysis

Forests ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1778
Author(s):  
Wancai Zhu ◽  
Zhaogang Liu ◽  
Weiwei Jia ◽  
Dandan Li
Keyword(s):  
Tree Height ◽  
Information Criterion ◽  
Mixed Effects ◽  
Mixed Effects Model ◽  
Pinus Koraiensis ◽  
Tree Level ◽  
Model Parameters ◽  
Crown Height ◽  
Crown Base Height ◽  
Pruning Intensity

Taking 1735 Pinus koraiensis knots in Mengjiagang Forest Farm plantations in Jiamusi City, Heilongjiang Province as the research object, a dynamic tree height, effective crown height, and crown base height growth model was developed using 349 screened knots. The Richards equation was selected as the basic model to develop a crown base height and effective crown height nonlinear mixed-effects model considering random tree-level effects. Model parameters were estimated with the non-liner mixed effect model (NLMIXED) Statistical Analysis System (SAS) module. The akaike information criterion (AIC), bayesian information criterion (BIC), −2 Log likelihood (−2LL), adjusted coefficient (Ra2), root mean square error (RMSE), and residual squared sum (RSS) values were used for the optimal model selection and performance evaluation. When tested with independent sample data, the mixed-effects model tree effects-considering outperformed the traditional model regarding their goodness of fit and validation; the two-parameter mixed-effects model outperformed the one-parameter model. Pinus koraiensis pruning times and intensities were calculated using the developed model. The difference between the effective crown and crown base heights was 1.01 m at the 15th year; thus, artificial pruning could occur. Initial pruning was performed with a 1.01 m intensity in the 15th year. Five pruning were required throughout the young forest period; the average pruning intensity was 1.46 m. The pruning interval did not differ extensively in the half-mature forest period, while the intensity decreased significantly. The final pruning intensity was only 0.34 m.

scholarly journals Evaluation of Different Calibration Approaches for Merchantable Volume Predictions of Norway Spruce Using Nonlinear Mixed Effects Model

Forests ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 1104
Author(s):  
Zdeněk Adamec ◽  
Radim Adolt ◽  
Karel Drápela ◽  
Jiří Závodský
Keyword(s):  
Norway Spruce ◽  
Tree Height ◽  
Mixed Effects ◽  
Mixed Effects Model ◽  
Wood Volume ◽  
Nonlinear Mixed Effects Model ◽  
Breast Height ◽  
Stem Taper ◽  
Total Tree

Research Highlights: Determination of merchantable wood volume is one of the key preconditions for sustainable forest management. This study explores accuracy of calibrated predictions of merchantable wood volume of Norway spruce (Picea abies (L.) H. Karst.) using stem taper curves (STC) in a form of a mixed model. Background and Objectives: The study is devoted to the determination of merchantable wood volume (over bark) of individual standing stems based on the integration of an STC model calibrated using upper diameter measurements. Various options of upper diameter measurement were tested and their impact on the accuracy of merchantable wood volume prediction was evaluated. Materials and Methods: To model stem taper curves, a Kozak 02 function was applied in a form of a nonlinear, mixed effects model. Accuracies of calibrated merchantable wood volume predictions obtained through remote (optical) upper diameter measurements were compared to accuracies corresponding to contact measurements by a caliper. The performance of two alternative methods used in the Czech National Forest Inventory (NFI) and forestry practice, involving diameter at breast height and total tree height as the only predictors, were also tested. The contact measurements were performed at identical stem positions after felling the respective sample tree. The calibration was done in order to account for factors inherent in particular location, and, optionally, also in a particular sample stem (within the respective location). Input data was sourced as part of a dedicated survey involving the entire territory of the Czech Republic. In total, 716 individual spruce trees were measured, felled and analysed at 169 locations. Results: In general, the best merchantable volume predictions were obtained by integrating the STC fitted (and calibrated) by minimising errors of stem cross-sectional areas instead of diameters. In terms of calibrated predictions, using single-directional, caliper measurement of upper diameter at 7 m (after felling) led to the best accuracy. In this case, the observed mean bias of merchantable volume prediction was only 0.63%, indicating underestimation. The best optical calibration strategy involved upper diameter measurements at two heights (5 and 7 m) simultaneously. Bias of this volume prediction approach was estimated at 2.1%, indicating underestimation. Conclusions: Concerning the prediction of merchantable stem volume of standing Norway spruce trees, STC calibration using two optical upper diameter measurements (at 5 and 7 m) was found to be practically applicable, provided a bias up to 3.7% can be accepted. This method was found to be more accurate than the existing national alternatives using diameter at breast height and the total tree height as the only predictors.

Imputing missing height measures using a mixed-effects modeling strategy

2004 ◽  
Vol 34 (12) ◽  
pp. 2492-2500 ◽  
Author(s):  
Andrew P Robinson ◽  
William R Wykoff
Keyword(s):  
Mean Squared Error ◽  
Mixed Effects ◽  
Mixed Effects Model ◽  
Tree Level ◽  
Root Mean Squared Error ◽  
Mixed Effects Modeling ◽  
Squared Error ◽  
Best Linear Unbiased ◽  
Modeling Strategy ◽  
Point Level

This paper proposes a method whereby height–diameter regression from an inventory can be incorporated into a height imputation algorithm. Point-level subsampling is often employed in forest inventory for efficiency. Some trees will be measured for diameter and species, while others will be measured for height and 10-year increment. Predictions of these missing measures would be useful for estimating volume and growth, respectively, so they are often imputed. We present and compare three imputation strategies: using a published model, using a localized version of a published model, and using best linear unbiased predictions from a mixed-effects model. The bases of our comparison are four-fold: minimum fitted root mean squared error and minimum predicted root mean squared error under a 2000-fold cross-validation for tree-level height and volume imputations. In each case the mixed-effects model proved superior. This result implies that substantial environmental variation existed in the height–diameter relationship for our data and that its representation in the model by means of random effects was profitable.

Modelling the relationship of tree-level product value with tree characteristics in black spruce

2006 ◽  
Vol 82 (5) ◽  
pp. 690-699 ◽  
Author(s):  
S Y Zhang ◽  
Y C Lei ◽  
Z H Jiang
Keyword(s):  
Black Spruce ◽  
Tree Height ◽  
Tree Level ◽  
Elasticity Analysis ◽  
Scale Elasticity ◽  
Stem Taper ◽  
Product Value ◽  
Relationship Of ◽  
The Relationship ◽  
Tree Characteristics

The establishment of the relationship between tree-level product value and tree characteristics will allow for predicting the potential value of individual trees and a stand directly using tree characteristics. Using statistical and elasticity analysis methods this study examined the relationship of tree-level product value with selected tree characteristics in black spruce (Picea mariana). The study was based a sample of 139 trees from 48-year-old black spruce plantations grown in Ontario, Canada. The sample trees showed large variation in tree characteristics and tree-level product value. Models were developed and compared on the basis of statistics of the estimated and predicted criteria. Results show that the model, including only tree DBH, tree height and stem taper, is the best in describing the relationship of the tree-level product value with tree characteristics. Furthermore, relationships including input-output and interaction factors in the model were analyzed by calculating the elasticity of production and scale and the cross partial derivative of output with respect to the inputs. The analyses indicate that tree DBH has the largest and positive influence on tree-level product value, followed by tree height; however, stem taper has a negative effect on tree-level product value. When tree DBH, tree height and stem taper each increase by 1%, the quantities of output elasticity show 2.53%, 0.64% and -0.37% changes in the product value, respectively; while the scale elasticity shows a 2.81% increase in tree-level product value with a simultaneous 1% change in tree DBH, tree height and stem taper. Results indicate that the model is suitable for predicting tree-level product value using those tree characteristics from forest inventory and also reflects biological behaviour.Key words: black spruce, regression models, elasticity analysis, product value, tree characteristics

scholarly journals The Influence of Thinning on Tree Height and Diameter Relationships in Loblolly Pine Plantations

1997 ◽  
Vol 21 (4) ◽  
pp. 199-205 ◽  
Author(s):  
Shaoang Zhang ◽  
Harold E. Burkhart ◽  
Ralph L. Amateis
Keyword(s):  
Loblolly Pine ◽  
Tree Height ◽  
Pine Plantations ◽  
Site Quality ◽  
Diameter Growth ◽  
Total Tree ◽  
Stand Characteristics

Abstract Loblolly pine data from thinned and unthinned plantations were used to evaluate the effects of thinning on tree height-diameter relationships. Results showed that thinning positively influences both tree height and diameter growth in loblolly pine plantations. The intensity of the thinning and the time since thinning, along with the inherent site quality, will determine the magnitude and duration of the thinning response. An equation for predicting total tree height from dbh and certain stand characteristics is developed from the data and can be used for predicting tree height in thinned and unthinned plantations. South. J. Appl. For. 21(4):199-205.

scholarly journals A Mixed-Effects Model for the dbh–Height Relationship of Shortleaf Pine (Pinus echinata Mill.)

2008 ◽  
Vol 32 (1) ◽  
pp. 5-11 ◽  
Author(s):  
Chakra B. Budhathoki ◽  
Thomas B. Lynch ◽  
James M. Guldin
Keyword(s):  
Tree Height ◽  
Ordinary Least Squares ◽  
Mixed Effects ◽  
Mixed Effects Model ◽  
Tree Level ◽  
Permanent Plots ◽  
Pinus Echinata ◽  
Shortleaf Pine ◽  
Individual Tree ◽  
Total Height

Abstract Individual tree measurements were available from over 200 permanent plots established during 1985–1987 and later remeasured in naturally regenerated even-aged stands of shortleaf pine (Pinus echinata Mill.) in western Arkansas and eastern Oklahoma. The objective of this study was to model shortleaf pine growth in natural stands for the region. As a major component of the shortleaf modeling effort, an individual tree-level dbh–total height model was developed in which plot-specific random parameters were fitted using maximum-likelihood methods. The model predicts tree height on the basis of dbh and dominant stand height (which could be obtained from a site-index model). The mixed-effects model approach was found to predict the total height better than the similar models developed previously for this species using ordinary least-squares methods. Moreover, such a model has the appeal of generalization of the results over a region from which the plots were sampled; and also of calibration of parameters for newly sampled stands with minimal measurements.

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