scholarly journals Precommercial Thinning Increases Spruce Yields in Boreal Mixedwoods in Alberta, Canada

Forests ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 412
Author(s):  
Ivan Bjelanovic ◽  
Phil Comeau ◽  
Sharon Meredith ◽  
Brian Roth
Keyword(s):  
Growth Models ◽  
Growth And Yield ◽  
Diameter Growth ◽  
Growth Responses ◽  
Projection System ◽  
Precommercial Thinning ◽  
Thinning Intensity ◽  
Boreal Mixedwoods ◽  
Using Data ◽  
Mixedwood Stands

A few studies in young mixedwood stands demonstrate that precommercial thinning of aspen at early ages can improve the growth of spruce and increase stand resilience to drought. However, information on tree and stand responses to thinning in older mixedwood stands is lacking. To address this need, a study was initiated in 2008 in Alberta, Canada in 14 boreal mixedwood stands (seven each at ages 17 and 22). This study investigated growth responses following thinning of aspen to five densities (0, 1000, 2500, 5000 stems ha−1 and unthinned (control)). Measurements were collected in the year of establishment, and three and eight years later. Mortality of aspen in the unthinned plots was greater than in the thinned plots which were not significantly different amongst each other. Eight years following treatment, aspen diameter was positively influenced by thinning, while there was no effect on aspen height. The density of aspen had no significant effect on the survival of planted spruce. Spruce height and diameter growth increased with both aspen thinning intensity and time since treatment. Differentiation among treatments in spruce diameter growth was evident three years from treatment, while differentiation in height was not significant until eight years following treatment. Yield projections using two growth models (Mixedwood Growth Model (MGM) and Growth and Yield Projection System (GYPSY)) were initialized using data from the year eight re-measurements. Results indicate that heavy precommercial aspen thinning (to ~1000 aspen crop trees ha−1) can result in an increase in conifer merchantable volume without reducing aspen volume at the time of harvest. However, light to moderate thinning (to ~2500 aspen stems ha−1 or higher), is unlikely to result in gains in either deciduous or conifer merchantable harvest volume over those of unthinned stands.

scholarly journals Evaluation of Individual Distance-Independent Diameter Growth Models for Japanese Cedar (Cryptomeria japonica) Trees under Multiple Thinning Treatments

Forests ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 344 ◽  
Author(s):  
Keiko Fukumoto ◽  
Tomohiro Nishizono ◽  
Fumiaki Kitahara ◽  
Kazuo Hosoda
Keyword(s):  
Forest Management ◽  
Tree Growth ◽  
Cryptomeria Japonica ◽  
Growth Models ◽  
Japanese Cedar ◽  
Diameter Growth ◽  
Model Accuracy ◽  
Thinning Intensity ◽  
Diameter Growth Models

Understanding the tree growth process is essential for sustainable forest management. Future yields are affected by various forest management regimes such as thinning; therefore, accurate predictions of tree growth are needed under various thinning intensities. This study compared the accuracy of individual-level distance-independent diameter growth models constructed for different thinning intensities (thinning intensity-dependent multiple models: TDM model) against the model designed to include all thinning intensities (thinning intensity-independent single model: TIS model) to understand how model accuracy is affected by thinning intensity. We used long-term permanent plot data of Japanese cedar (Cryptomeria japonica) stands in Japan, which was gathered from four plots where thinning was conducted at different thinning intensities: (1) intensive (41% and 38% of trees removed at 25 and 37 years old, respectively), (2) moderate (38% and 34%), (3) light (32% and 34%), and (4) no thinning. First, we specified high interpretability distance-independent competition indices, and we compared the model accuracy both in TDM and TIS models. The results show that the relative spacing index was the best competition index both in TDM and TIS models across all thinning intensities, and the differences in the RMSE (Root mean square error) and rRMSE (relative RMSE) in both TDM and TIS models were 0.001–0.01 cm and 0.2–2%, respectively. In the TIS model, rRMSE varied with thinning intensity; the rRMSE was the lowest for moderate thinning intensity (45.8%) and the highest for no thinning (59.4%). In addition, bias values were negative for the TIS model for all thinning intensities. These results suggest that the TIS model could express diameter growth regardless of thinning intensities. However, the rRMSE had varied with thinning intensity and bias had negative values in the TIS model. Therefore, more model improvements are required for accurate predictions of long-term growth of actual Japanese cedar stands.

Profitability of Precommercially Thinning Oak Stump Sprouts

1993 ◽  
Vol 10 (4) ◽  
pp. 179-183 ◽  
Author(s):  
John P. Dwyer ◽  
Daniel C. Dey ◽  
William B. Kurtz
Keyword(s):  
Growth Response ◽  
Management Practice ◽  
Growth And Yield ◽  
Control Treatment ◽  
Diameter Growth ◽  
Early Age ◽  
Precommercial Thinning ◽  
Net Worth ◽  
Substantial Investment ◽  
Stump Sprouts

Abstract Thinning oak stump sprouts to a single stem at an early age will increase diameter growth of the released stem. However, precommercial thinning represents a substantial investment which must be carried for many years before any returns are realized. We estimated the incremental gains in yield and the present net worth for five crop-tree release treatments of 5-yr-old coppice sprouts in the southeastern Missouri Ozarks and compared them to the results from unthinned control plots. The treatments involved thinning 100, 150, 200, 250, and all clumps of sprouts on the plots to a single stem. All thinning treatments increased diameter growth and yield compared to the control, but at a 5% rate of return, the control treatment produced the largest present net worth. We have concluded that based on the growth response and timber price situations within the Ozark Region, precommercial thinning of oak stump sprouts is not an economical management practice. North. J. Appl. For. 10(4):179-183.

A Whole-Stand Growth and Yield Model for Interior Douglas-Fir

1993 ◽  
Vol 8 (4) ◽  
pp. 120-125 ◽  
Author(s):  
Lianjun Zhang ◽  
James A. Moore ◽  
James D. Newberry
Keyword(s):  
Prediction Model ◽  
Model Simulation ◽  
Growth Models ◽  
Basal Area ◽  
Height Growth ◽  
Douglas Fir ◽  
Growth And Yield ◽  
Yield Model ◽  
Projection System ◽  
Tree Survival

Abstract A whole-stand model, Simulation Of Stands (SOS), was developed for even-aged Douglas-fir (Pseudotsuga menziesii var. glauca) stands in the inland Northwest. The model consists of three new components: (1) volume prediction model, (2) basal area prediction model, and (3) survival model. Existing height growth models were used to estimate stand top height growth. The behavior and performance of SOS were evaluated by simulating stand development over time under alternative conditions and comparing the results with growth and yield concepts suggested in the literature. The predicted stand attributes from SOS were also compared with predictions from the Stand Prognosis Model and Stand Projection System (SPS). SOS behavior was similar to Prognosis for lower site indices, but more like SPS for higher site indices. The three models differed mainly with respect to stand top height growth and tree survival. West. J. Appl. For. 8(4):120-125.

scholarly journals Incorporating Thinning Response into a Loblolly Pine Stand Simulator

2001 ◽  
Vol 25 (4) ◽  
pp. 159-164 ◽  
Author(s):  
James A. Westfall ◽  
Harold E. Burkhart
Keyword(s):  
Loblolly Pine ◽  
Growth Models ◽  
Predictive Ability ◽  
Growth And Yield ◽  
Original Form ◽  
Response Variable ◽  
Thinning Intensity ◽  
Diameter Increment ◽  
Growth Simulator ◽  
Pinus Taeda L

Abstract Effects of thinning, such as increased diameter growth and decreased mortality in the residual stand, are largely the result of increased tree vigor induced by a decreased level of competition. These relationships are reflected in the models that are central to PTAEDA2, a growth and yield simulator developed for loblolly pine (Pinus taeda L.) plantations. A long-term thinning study served as a basis for attempting to improve the predictive output of PTAEDA2. The growth models were refit using data from plots that received different thinning intensity treatments. Height increment and mortality models were found to need no additional refinement to account for response changes due to effects of thinning. The refit diameter increment and crown ratio models in PTAEDA2 could not account for thinning effects in their original form, and thinning response functions that exhibit proper behavioral response were added to these models. Models were evaluated individually and in combinations in a reduced growth simulator that contained the growth subroutines from PTAEDA2. Results showed significant improvements in predictive ability when using the diameter increment model with thinning response variable. There were no significant improvements in crown ratio prediction when the crown ratio model with thinning response variable was utilized. The thinning response modifications resulted in unanticipated model behavior when incorporated into the stand simulator, indicating that careful evaluation of the behavior of stand-level prediction is needed. South. J. Appl. For. 25(4):159–164.

scholarly journals Development of Diameter Growth Models by Thinning Intensity of Planted Quercus glauca Thunb. Stands

2021 ◽  
Vol 24 (6) ◽  
pp. 629-638
Author(s):  
Su Young Jung ◽  
Kwang Soo Lee ◽  
Hyun Soo Kim
Keyword(s):  
Mean Squared Error ◽  
Growth Models ◽  
Diameter Growth ◽  
Least Squares Regression ◽  
Permanent Sample Plots ◽  
Thinning Intensity ◽  
Squared Error ◽  
Quercus Glauca ◽  
The Mean ◽  
Diameter Growth Models

Background and objective: This study was conducted to develop diameter growth models for thinned Quercus glauca Thunb. (QGT) stands to inform production goals for treatment and provide the information necessary for the systematic management of this stands.Methods: This study was conducted on QGT stands, of which initial thinning was completed in 2013 to develop a treatment system. To analyze the tree growth and trait response for each thinning treatment, forestry surveys were conducted in 2014 and 2021, and a one-way analysis of variance (ANOVA) was executed. In addition, non-linear least squares regression of the PROC NLIN procedure was used to develop an optimal diameter growth model.Results: Based on growth and trait analyses, the height and height-to-diameter (H/D) ratio were not different according to treatment plot (p > .05). For the diameter of basal height (DBH), the heavy thinning (HT) treatment plot was significantly larger than the control plot (p < .05). As a result of the development of diameter growth models by treatment plot, the mean squared error (MSE) of the Gompertz polymorphic equation (control: 2.2381, light thinning: 0.8478, and heavy thinning: 0.8679) was the lowest in all treatment plots, and the Shapiro-Wilk statistic was found to follow a normal distribution (p > .95), so it was selected as an equation fit for the diameter growth model.Conclusion: The findings of this study provide basic data for the systematic management of Quercus glauca Thunb. stands. It is necessary to construct permanent sample plots (PSP) that consider stand status, location conditions, and climatic environments.

Individual-tree diameter growth models for quantifying within-stand response to nitrogen fertilization

1990 ◽  
Vol 20 (8) ◽  
pp. 1149-1155 ◽  
Author(s):  
Bahman Shafii ◽  
James A. Moore ◽  
James D. Newberry
Keyword(s):  
Growth Models ◽  
Stand Density ◽  
Simulation Models ◽  
Diameter Growth ◽  
Individual Tree ◽  
Diameter Increment ◽  
Prognosis Model ◽  
Using Data ◽  
Individual Trees ◽  
Northern Idaho

Diameter-increment models for nitrogen-fertilized stands were developed using data from permanent research plots in northern Idaho. The equations partially resembled PROGNOSIS model diameter growth formulations. Results indicated that both initial tree size and initial stand density produced significant interactions with treatment to explain an individual tree's response to fertilization. Larger trees in a stand showed more fertilization response than smaller trees. Furthermore, individual trees in low-density stands showed more fertilization response than those growing in high-density stands. These diameter increment predictive equations were formulated to be compatible with individual-tree distance-independent simulation models.

A Comparison of Two Peanut Growth Models for Oklahoma

1988 ◽  
Vol 15 (1) ◽  
pp. 30-35 ◽  
Author(s):  
G. D. Grosz ◽  
R. L. Elliott ◽  
J. H. Young
Keyword(s):  
Growth Models ◽  
Model Performance ◽  
Simulation Models ◽  
Complex Model ◽  
Growth And Yield ◽  
Model Parameters ◽  
Individual Plant ◽  
Climatic Data ◽  
Input Parameters ◽  
Using Data

Abstract Growth simulation models provide potential benefit in the study of peanut (Arachis hypogaea L.) production. Two physiologically-based peanut simulation models of varying complexity were adapted and calibrated to simulate the growth and yield of Spanish peanut under Oklahoma conditions. Field data, including soil moisture measurements and sequential yield samples, were collected at four sites during the 1985 growing season. An automated weather station provided the necessary climatic data for the models. PNUTMOD, the simpler model originally developed for educational purposes, requires seven varietal input parameters in addition to temperature and solar radiation data. The seven model parameters were calibrated using data from two of the four field sites, and model performance was evaluated using the remaining two data sets. The more complex model, PEANUT, simulates individual plant physiological processes and utilizes a considerably larger set of input parameters. Since PEANUT was developed for the Virginia type peanut, several input parameters required adjustment for the Spanish type peanut grown in Oklahoma. PEANUT was calibrated using data from all four study sites. Both models performed well in simulating pod yield. PNUTMOD, which does not allow for leaf senescence, did not perform as well as PEANUT in predicting vegetative growth.

scholarly journals Differential growth and yield responses of local potato cultivars from basic seed tubers

2021 ◽  
Vol 39 (3) ◽  
pp. 272-278
Author(s):  
Mónica Eliana Córdoba-Figueroa ◽  
Hernando Criollo-Escobar ◽  
Sandra Insuasty-Córdoba ◽  
Julián Fernando Mateus-Rodríguez
Keyword(s):  
Leaf Area ◽  
Growth Models ◽  
Block Design ◽  
Potato Cultivars ◽  
Growth And Yield ◽  
Growth Responses ◽  
Differential Growth ◽  
Area Index ◽  
Seed Tubers ◽  
Potato Growth

ABSTRACT Potato quality of seed tubers is a determinant factor that allows obtaining high yields, and its use must be a priority for a country or a producing region. Lack of information about how local cultivars perform differentially according to the environment has been identified in order to support potential seeds production programs. The research was carried out in 2018 at the Obonuco Research Center of Corporación Colombiana de Investigación Agropecuaria (AGROSAVIA), with the aim of analyzing the growth and yield of basic tuber seeds of five potato (Solanum tuberosum spp. andigena) cultivars. 1,080 seed tubers from each cultivar (treatments) were planted in a completely randomized block design and three replications. Mean comparison Tukey-Kramer (p≤0.05) test was performed for the yield analysis. From emergency to final harvest, destructive sampling was carried out every fifteen days in order to calculate dry matter and leaf area and establish growth models based on the accumulated degree-days (DD). The yield and proportion of seed tubers per plant were determined according to local resolution for seed certification in Colombia. Growth variables fitted better with the Hoerl, Gaussian, and third-degree polynomial models. The leaf area index of the potato cultivars reached the maximum value at 876 DD, with values ranging from 2.91 to 6.11 DD. The highest yield per plant was obtained by the Ica Única cultivar (2.73 kg plant-1). However, this cultivar showed the lowest percentage of seed tubers, with 50.59% compared to the others, which ranged between 80.82 and 87.40%. Differential potato growth responses through models based on the DD would explain the differences in final yield and seeds tuber production.

Climate sensitive growth models for predicting diameter growth of western Canadian boreal tree species

2020 ◽  
Author(s):  
Felix O Oboite ◽  
Philip G Comeau
Keyword(s):  
Interspecific Competition ◽  
Tree Species ◽  
Growth Models ◽  
White Spruce ◽  
Tree Size ◽  
Diameter Growth ◽  
Growth Responses ◽  
Individual Tree ◽  
Negative Effect ◽  
Frost Free Period

Abstract In the face of anticipated climate change, growth models require modifications to effectively model likely future growth and survival of trees and stands. To support incorporation of climate effects in the Mixedwood Growth Model (MGM), we developed climate-sensitive mixed effects models for lodgepole pine (Pinus contorta Douglas ex Loudon), jack pine (Pinus banksiana Lamb.), trembling aspen (Populus tremuloides Michx.), balsam poplar (Populus balsamifera L.) and white spruce (Picea glauca (Moench) Voss), and examined how tree size, intra- and interspecific competition and climate will influence individual-tree diameter growth. Remeasurement data from permanent growth and yield sample plots from across the western Canadian boreal forest were used for this study. Based on the model that we developed, tree size, competition and climate had varying effects on growth, among tree species. Although intraspecific competition had a stronger negative effect on growth for deciduous and white spruce trees, interspecific competition had a stronger negative effect on the growth of pine. Deciduous trees growing in stands having longer frost-free period experienced an increase in growth but a negative effect of frost-free period was observed for conifers. In addition, higher moisture was found to increase tree growth, but the influence of available moisture on growth was dependent on competition. Overall, these results suggest that, under climate warming, between-species differences in growth responses will contribute to our understanding of the stand dynamics in the western boreal region of Canada. Climate sensitive growth models developed in this study will be useful in the recalibration of MGM and other individual-tree models, and predictions will contribute to better-informed decisions about silvicultural treatments for these economically important boreal tree species.

Crop Tree Release of a Scarlet-Black Oak Stand

1988 ◽  
Vol 5 (2) ◽  
pp. 96-99 ◽  
Author(s):  
Robert J. Mitchell ◽  
John P. Dwyer ◽  
Ralph A. Musbach ◽  
Harold E. Garrett ◽  
Gene S. Cox ◽  
...  
Keyword(s):  
Stand Age ◽  
Diameter Growth ◽  
Precommercial Thinning ◽  
Tree Thinning ◽  
Black Oak

Abstract In 1953 and 1954 a series of crop tree thinning and pruning studies were initiated in 30- to 35-year-old stands composed predominantly of scarlet oak and black oak. Growth of the crop trees was monitored until the average stand age was 61. Removal of all trees whose crowns were within 8 ft of the 50 crop trees resulted in significantly increased diameter growth and cubic volume of wood produced. The moderate and heavy 50-crop-tree thinning treatments produced the highest net cubic volume per acre. Crop tree thinning also tended to reduce mortality during the study period. Yield increases due to thinning in this study were comparable to those previously determined to economically justify a precommercial thinning of the scarlet and black oak type in Missouri. North. J. Appl. For. 5:96-99, June 1988.

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