Loblolly pine is a commonly planted pine species in the Southern US which is intensively managed as well as a major contributor to the timber industry. Various silvicultural treatments are commonly applied to pine plantations including thinning and sometimes pruning. Tree crowns contain the active photosynthesis region and play a vital role in tree growth. Among various tree crown measurements, live crown ratio (LCR) is derived from height to live crown base (HLCB) and total tree height. Accurate measurement of HLCB is basis for live crown ratio prediction. Due to numerous definitions and practical considerations, HLCB and crown structure are difficult and slow to measure accurately. Despite this, LCR is a useful predictor in various growth and yield models. Due to the challenges in measuring tree crowns, accurate live crown ratio prediction models are useful. The LCR model of (Dyer and Burkhart, 1987) was refit with intensively managed plantation (IMP) data. The parameters were significant, and the residual plots showed no concerning patterns but the prediction of height to live crown base for pruned trees was not logical as it sometimes predicted HLCB lower than pruning height. To address this, the base model was modified to accommodate the pruning effect and provide logical predictions. LCR is in range of 0 - 1 and HLCB is greater or equal to pruning height. If trees are not pruned, it reverts to the original model. The models were validated with a dataset of IMP measurements not used in fitting. Validation statistics suggest the model performs nearly as well as the original, unconstrained base model. It is expected that the new model will be useful for forest managers to predict LCR of both pruned and unpruned trees. The second part of the study is to understand the importance of common tree variables in predicting the lumber recovery in planted loblolly pine. A random forest model was used to determine the variable importance of DBH, total tree height and live crown ratio for total board ft., high-grade, and high-grade lumber proportion compared to total board ft. DBH ranked at the first position followed by total tree height and live crown ratio similarly ranked for volume and high-grade lumber volume. For proportions of high-grade lumber, tree height was at top rank followed by LCR, and DBH. However, the effect of these variables for lumber recovery was not explored. It is suggested that future work can explore parametric model forms for accurately predicting lumber recovery using simple, easy to measure tree variables. / Master of Science / Loblolly pine plantations are found in large areas of southern United States. Significant investments are made for maximizing wood production and economic benefits. The growth of trees is largely governed by its crown which is the green foliage found in upper parts of tree. Planted trees are often thinned to provide crown sufficient light for improved growth. Tree crowns are sometimes pruned to reduce knot size and improve lumber quality. If we can understand how these activities affected the crown length of trees, we can manage our plantation accordingly. With this motivation, the live crown ratio which is the ratio of length of live crown and total tree height was modeled. An existing live crown ratio model for planted loblolly pine trees was modified to provide logical predictions for pruned trees and was updated with newer data. Simple tree measurements like tree diameter, height and age were used in the model. Common tree variables were used because LCR is derived from height to live crown base which is difficult to measure in field. The new model will be useful to forest managers for predicting the growth of loblolly pine plantations subjected to pruning. Similarly, an attempt is made to explore the various standing tree characteristics affecting the amount of lumber that can be obtained. This will assist in understanding the lumber grade by using common tree measurements and value of a stand from lumber production side can be known.

The purpose of this research was to quantify what value could be gained from cutting solid wood products from old-growth western hemlock (Tsuga heterophylla (Raf.) Sarg.) logs that are used to produce pulp in British Columbia. These logs represent a significant portion of the resource and increasing their value recovery would be beneficial to the forest industry. One hundred and sixteen logs were sampled from the coastal and interior regions of British Columbia. Dimension and quality attributes were measured to enable estimates of gross and merchantable volume. Logs deemed likely to yield lumber were sawn with the aim of maximizing value recovery. The nominal dimension and grade of all lumber recovered was recorded. Margins and breakpoints at which sawing became profitable were calculated. Models to predict the volume of lumber and proportion of Clear grade lumber recovered (“C Industrial” grade at the interior mill, “D Select” grade at the coastal mill) were developed. Lumber recovery, especially Clear grade lumber, was significantly higher from logs from the coastal site. At current market prices, cutting lumber from these logs was profitable, with the highest margins achieved when chips were produced from the milling residue. It was not profitable to recover lumber from the interior logs regardless of whether chips were produced. The disparity between locations was attributed to differences between the logs, the sawmilling equipment, the sawyers’ motivations and the lumber grades. Between 60% and 67% of coastal logs and 13% to 21% of interior logs returned a profit, depending on whether chips were produced. Models were developed to better identify these logs using observable attributes. A linear model described the total volume of lumber recovered. Significant predictor variables in the model were the gross log volume, the average width of the sound collar and the stage of butt/heart rot at the large end. A second model predicted the proportion of Clear grade lumber. Regional models were developed to account for different Clear lumber grades between sawmills. Significant predictor variables were knot frequency, diameter at the large end, volume, length, taper and the width of the sound collar at the large end.

The purpose of this research was to quantify what value could be gained from cutting solid wood products from old-growth western hemlock (Tsuga heterophylla (Raf.) Sarg.) logs that are used to produce pulp in British Columbia. These logs represent a significant portion of the resource and increasing their value recovery would be beneficial to the forest industry. One hundred and sixteen logs were sampled from the coastal and interior regions of British Columbia. Dimension and quality attributes were measured to enable estimates of gross and merchantable volume. Logs deemed likely to yield lumber were sawn with the aim of maximizing value recovery. The nominal dimension and grade of all lumber recovered was recorded. Margins and breakpoints at which sawing became profitable were calculated. Models to predict the volume of lumber and proportion of Clear grade lumber recovered (“C Industrial” grade at the interior mill, “D Select” grade at the coastal mill) were developed. Lumber recovery, especially Clear grade lumber, was significantly higher from logs from the coastal site. At current market prices, cutting lumber from these logs was profitable, with the highest margins achieved when chips were produced from the milling residue. It was not profitable to recover lumber from the interior logs regardless of whether chips were produced. The disparity between locations was attributed to differences between the logs, the sawmilling equipment, the sawyers’ motivations and the lumber grades. Between 60% and 67% of coastal logs and 13% to 21% of interior logs returned a profit, depending on whether chips were produced. Models were developed to better identify these logs using observable attributes. A linear model described the total volume of lumber recovered. Significant predictor variables in the model were the gross log volume, the average width of the sound collar and the stage of butt/heart rot at the large end. A second model predicted the proportion of Clear grade lumber. Regional models were developed to account for different Clear lumber grades between sawmills. Significant predictor variables were knot frequency, diameter at the large end, volume, length, taper and the width of the sound collar at the large end.

The purpose of this research was to quantify what value could be gained from cutting solid wood products from old-growth western hemlock (Tsuga heterophylla (Raf.) Sarg.) logs that are used to produce pulp in British Columbia. These logs represent a significant portion of the resource and increasing their value recovery would be beneficial to the forest industry. One hundred and sixteen logs were sampled from the coastal and interior regions of British Columbia. Dimension and quality attributes were measured to enable estimates of gross and merchantable volume. Logs deemed likely to yield lumber were sawn with the aim of maximizing value recovery. The nominal dimension and grade of all lumber recovered was recorded. Margins and breakpoints at which sawing became profitable were calculated. Models to predict the volume of lumber and proportion of Clear grade lumber recovered (“C Industrial” grade at the interior mill, “D Select” grade at the coastal mill) were developed. Lumber recovery, especially Clear grade lumber, was significantly higher from logs from the coastal site. At current market prices, cutting lumber from these logs was profitable, with the highest margins achieved when chips were produced from the milling residue. It was not profitable to recover lumber from the interior logs regardless of whether chips were produced. The disparity between locations was attributed to differences between the logs, the sawmilling equipment, the sawyers’ motivations and the lumber grades. Between 60% and 67% of coastal logs and 13% to 21% of interior logs returned a profit, depending on whether chips were produced. Models were developed to better identify these logs using observable attributes. A linear model described the total volume of lumber recovered. Significant predictor variables in the model were the gross log volume, the average width of the sound collar and the stage of butt/heart rot at the large end. A second model predicted the proportion of Clear grade lumber. Regional models were developed to account for different Clear lumber grades between sawmills. Significant predictor variables were knot frequency, diameter at the large end, volume, length, taper and the width of the sound collar at the large end. / Forestry, Faculty of / Graduate