scholarly journals Effect of Rotation Age and Thinning Regime on Visual and Structural Lumber Grades of Douglas-Fir Logs

Forests ◽  
2018 ◽  
Vol 9 (9) ◽  
pp. 576
Author(s):  
Eini Lowell ◽  
Eric Turnblom ◽  
Jeff Comnick ◽  
CL Huang
Keyword(s):  
Stand Density ◽  
Tree Height ◽  
Douglas Fir ◽  
Timber Species ◽  
Market Demand ◽  
Rotation Age ◽  
The Impact ◽  
Grade Yield ◽  
Structural Lumber ◽  
Lumber Grade

Douglas-fir, the most important timber species in the Pacific Northwest, US (PNW), has high stiffness and strength. Growing it in plantations on short rotations since the 1980s has led to concerns about the impact of juvenile/mature wood proportion on wood properties. Lumber recovered from four sites in a thinning trial in the PNW was analyzed for relationships between thinning regime and lumber grade yield. Linear mixed-effects models were developed for understanding how rotation age and thinning affect the lumber grade yield. Log small-end diameter was overall the most important for describing the presence of an appearance grade, generally exhibiting an indirect relationship with the lower quality grades. Stand Quadratic Mean Diameter (QMD) was found to be the next most uniformly important predictor, its influence (positive or negative) depending on the lumber grade. For quantity within a grade, as log small-end diameter increased, the quantity of the highest grade increased, while decreasing the quantity of the lower grades differentially. Other tree and stand attributes were of varying importance among grades, including stand density, tree height, and stand slope, but logically depicted the tradeoffs or rebalancing among the grades as the tree and stand characteristics change. Structural lumber grade presence was described best by acoustic wave flight time, log position (decreasing presence in upper logs), and an increasing presence with rotation age. A smaller set of variables proved useful for describing quantity within a structural grade. Forest managers can use these results in planning to best capture value in harvesting, allowing them to direct raw materials (logs) to appropriate manufacturing facilities given market demand.

HEIGHT GROWTH LOSSES DUE TO ANIMAL FEEDING IN DOUGLAS FIR PLANTATIONS, VANCOUVER ISLAND, B.C.

1964 ◽  
Vol 40 (3) ◽  
pp. 298-307 ◽  
Author(s):  
K. J. Mitchell
Keyword(s):  
Pseudotsuga Menziesii ◽  
East Coast ◽  
Growth Curves ◽  
Tree Height ◽  
Vancouver Island ◽  
Height Growth ◽  
Douglas Fir ◽  
Average Height ◽  
Animal Feeding ◽  
Rotation Age

Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) plantations on the east coast of Vancouver Island, British Columbia, were examined to determine the effect of animal feeding upon height growth.Length of internodes and evidence of past leader damage were recorded and cumulative average height-age growth curves compared for undamaged trees and for trees suffering various intensities of damage.The average reduction in tree height attributable to animal feeding in heavily browsed plantations varied from one-half to two feet over a period of 8 to 10 years. It is unlikely that either tree volume or quality at rotation age would be seriously affected.Exposed trees were browsed more heavily than those protected by vegetation or logging slash.

Analysis and comparison of nonlinear tree height prediction strategies for Douglas-fir forests

2008 ◽  
Vol 38 (3) ◽  
pp. 553-565 ◽  
Author(s):  
H. Temesgen ◽  
V. J. Monleon ◽  
D. W. Hann
Keyword(s):  
Relative Position ◽  
Fixed Effects ◽  
Stand Density ◽  
Tree Height ◽  
Predictive Performance ◽  
Douglas Fir ◽  
Fixed Effects Model ◽  
Nonlinear Mixed Effects Models ◽  
Data Set ◽  
Height Prediction

Using an extensive Douglas-fir data set from southwest Oregon, we examined the (1) performance and suitability of selected prediction strategies, (2) contribution of relative position and stand-density measures in improving tree height (h) prediction values, and (3) effect of different subsampling designs to fill in missing h values in a new stand using a regional nonlinear model. Nonlinear mixed-effects models (NMEM) substantially improved the accuracy and precision of height prediction over the conventional nonlinear fixed-effects model (NFEM) that assumes the observations are independent, particularly when a few trees are subsampled for height. The predictive performance of a correction factor on a NFEM with relative position and stand-density measures was comparable to that of a NMEM when four or more trees were subsampled for height. When two or more heights were randomly subsampled, the NMEM efficiently explained the differences in the height–diameter relationship because of the variations in relative position of trees and stand density without having to incorporate them into the model. When only one height was subsampled, selecting the largest diameter tree in the stand would result in a lower predicted root mean square error (RMSE) than randomly selecting the height, regardless of the model form or fitting strategy used.

scholarly journals Spring Freeze Damage of Pecan Bloom: A Review

Horticulturae ◽  
2020 ◽  
Vol 6 (4) ◽  
pp. 82
Author(s):  
Amandeep Kaur ◽  
Louise Ferguson ◽  
Niels Maness ◽  
Becky Carroll ◽  
William Reid ◽  
...  
Keyword(s):  
Tree Height ◽  
The United States ◽  
Reproductive Organs ◽  
Tree Age ◽  
The Us ◽  
Nut Production ◽  
Freeze Damage ◽  
Terminal Buds ◽  
And Function ◽  
The Impact

Pecan is native to the United States. The US is the world’s largest pecan producer with an average yearly production of 250 to 300 million pounds; 80 percent of the world’s supply. Georgia, New Mexico, Texas, Arizona, Oklahoma, California, Louisiana, and Florida are the major US pecan producing states. Pecan trees frequently suffer from spring freeze at bud break and bloom as the buds are quite sensitive to freeze damage. This leads to poor flower and nut production. This review focuses on the impact of spring freeze during bud differentiation and flower development. Spring freeze kills the primary terminal buds, the pecan tree has a second chance for growth and flowering through secondary buds. Unfortunately, secondary buds have less bloom potential than primary buds and nut yield is reduced. Spring freeze damage depends on severity of the freeze, bud growth stage, cultivar type and tree age, tree height and tree vigor. This review discusses the impact of temperature on structure and function of male and female reproductive organs. It also summarizes carbohydrate relations as another factor that may play an important role in spring growth and transition of primary and secondary buds to flowers.

scholarly journals Evaluation of P-Band SAR Tomography for Mapping Tropical Forest Vertical Backscatter and Tree Height

2021 ◽  
Vol 13 (8) ◽  
pp. 1485
Author(s):  
Naveen Ramachandran ◽  
Sassan Saatchi ◽  
Stefano Tebaldini ◽  
Mauro Mariotti d’Alessandro ◽  
Onkar Dikshit
Keyword(s):  
Tropical Forest ◽  
Vertical Profile ◽  
Mean Squared Error ◽  
Low Frequency ◽  
Tree Height ◽  
Canopy Layer ◽  
Local Maxima ◽  
Slope Correction ◽  
Compensation Approach ◽  
The Impact

Low-frequency tomographic synthetic aperture radar (TomoSAR) techniques provide an opportunity for quantifying the dynamics of dense tropical forest vertical structures. Here, we compare the performance of different TomoSAR processing, Back-projection (BP), Capon beamforming (CB), and MUltiple SIgnal Classification (MUSIC), and compensation techniques for estimating forest height (FH) and forest vertical profile from the backscattered echoes. The study also examines how polarimetric measurements in linear, compact, hybrid, and dual circular modes influence parameter estimation. The tomographic analysis was carried out using P-band data acquired over the Paracou study site in French Guiana, and the quantitative evaluation was performed using LiDAR-based canopy height measurements taken during the 2009 TropiSAR campaign. Our results show that the relative root mean squared error (RMSE) of height was less than 10%, with negligible systematic errors across the range, with Capon and MUSIC performing better for height estimates. Radiometric compensation, such as slope correction, does not improve tree height estimation. Further, we compare and analyze the impact of the compensation approach on forest vertical profiles and tomographic metrics and the integrated backscattered power. It is observed that radiometric compensation increases the backscatter values of the vertical profile with a slight shift in local maxima of the canopy layer for both the Capon and the MUSIC estimators. Our results suggest that applying the proper processing and compensation techniques on P-band TomoSAR observations from space will allow the monitoring of forest vertical structure and biomass dynamics.

Assessing the impact of N-fertilization on biochemical composition and biomass of a Douglas-fir canopy—A remote sensing approach

2012 ◽  
Vol 153 ◽  
pp. 124-133 ◽  
Author(s):  
Thomas Hilker ◽  
Lucie Lepine ◽  
Nicholas C. Coops ◽  
Rachhpal S. Jassal ◽  
T. Andrew Black ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Biochemical Composition ◽  
N Fertilization ◽  
Douglas Fir ◽  
The Impact

scholarly journals The impact of the Endangered Mauritian flying fox Pteropus niger on commercial fruit farms and the efficacy of mitigation

Oryx ◽  
2018 ◽  
pp. 1-8 ◽  
Author(s):  
Ryszard Z. Oleksy ◽  
Charles L. Ayady ◽  
Vikash Tatayah ◽  
Carl Jones ◽  
Jérémy S.P. Froidevaux ◽  
...  
Keyword(s):  
Tree Height ◽  
Iucn Red List ◽  
Red List ◽  
Litchi Chinensis ◽  
Fold Reduction ◽  
Fungal Damage ◽  
Introduced Birds ◽  
The Government ◽  
The Impact ◽  
Flying Fox

Abstract The endemic Mauritian flying fox Pteropus niger is perceived to be a major fruit pest. Lobbying of the Government of Mauritius by fruit growers to control the flying fox population resulted in national culls in 2015 and 2016, with a further cull scheduled for 2018. A loss of c. 38,318 individuals has been reported and the species is now categorized as Endangered on the IUCN Red List. However, until now there were no robust data available on damage to orchards caused by bats. During October 2015–February 2016 we monitored four major lychee Litchi chinensis and one mango (Mangifera spp.) orchard, and also assessed 10 individual longan Dimocarpus longan trees. Bats and introduced birds caused major damage to fruit, with 7–76% fruit loss (including natural fall and losses from fungal damage) per tree. Bats caused more damage to taller lychee trees (> 6 m high) than to smaller ones, whereas bird damage was independent of tree height. Bats damaged more fruit than birds in tall lychee trees, although this trend was reversed in small trees. Use of nets on fruiting trees can result in as much as a 23-fold reduction in the damage caused by bats if nets are applied correctly. There is still a need to monitor orchards over several seasons and to test non-lethal bat deterrence methods more widely.

Modulus of elasticity of Norway spruce saw logs vs. structural lumber grade

2006 ◽  
Vol 64 (4) ◽  
pp. 273-279 ◽  
Author(s):  
Jacob Edlund ◽  
Håkan Lindström ◽  
Fredrik Nilsson ◽  
Marco Reale
Keyword(s):  
Norway Spruce ◽  
Modulus Of Elasticity ◽  
Structural Lumber ◽  
Lumber Grade

scholarly journals Does the Prevalence of Obesity Affect the Demand for Soft Drinks? Evidence from Cross-Country Panel Data

2022 ◽  
Vol 19 (2) ◽  
pp. 938
Author(s):  
Fabrizio Ferretti ◽  
Michele Mariani ◽  
Elena Sarti
Keyword(s):  
Nutrition Education ◽  
Least Squares Method ◽  
Soft Drink ◽  
Soft Drinks ◽  
Market Demand ◽  
Reverse Causality ◽  
Soft Drink Consumption ◽  
Variable Approach ◽  
Prevalence Of Obesity ◽  
The Impact

The impact of soft drinks on obesity has been widely investigated during the last decades. Conversely, the role of obesity as a factor influencing the demand for soft drinks remains largely unexplored. However, understanding potential changes in the demand for soft drinks, as a result of changes in the spread of obesity, may be useful to better design a comprehensive strategy to curb soft drink consumption. In this paper, we aim to answer the following research question: Does the prevalence of obesity affect the demand for soft drinks? For this purpose, we collected data in a sample of 97 countries worldwide for the period 2005–2019. To deal with problems of reverse causality, an instrumental variable approach and a two-stage least squares method were used to estimate the impact of the age-standardized obesity rate on the market demand for soft drinks. After controlling for several demographic and socio-economic confounding factors, we found that a one percent increase in the prevalence of obesity increases the consumption of soft drinks and carbonated soft drinks by about 2.37 and 1.11 L per person/year, respectively. Our findings corroborate the idea that the development of an obesogenic food environment is a self-sustaining process, in which obesity and unhealthy lifestyles reinforce each other, and further support the need for an integrated approach to curb soft drink consumption by combining sugar taxes with bans, regulations, and nutrition education programs.

scholarly journals Benefits of implementing IT tools and procedures for the estimation and measurement uncertainty in testing laboratories

2020 ◽  
Vol 2 (7) ◽  
pp. 317-323
Author(s):  
Maria Cristina Dijmarescu
Keyword(s):  
Measurement Uncertainty ◽  
Rapid Expansion ◽  
Market Demand ◽  
Destructive Testing ◽  
Continuous Increase ◽  
Testing Laboratories ◽  
Quality Of Products ◽  
The Impact ◽  
Non Destructive

Destructive and non-destructive testing of materials present a rapid expansion given by the increase in market demand caused by the desire to obtain an increasingly better quality of products. The continuous increase in quality demands leads directly to the need to implement and modernize the techniques, methods, and equipment used for quality control. Consequently, the need for product testing services has a rapid growth. This paper presents the strength and weaknesses of implementing IT tools for the estimation of the measurement uncertainty in testing laboratories and the impact of these tools on the economic part

scholarly journals The impact of FDI on environmental technology innovation from the perspective of environmental regulation

2020 ◽  
Vol 206 ◽  
pp. 02001
Author(s):  
Ziting Wei
Keyword(s):  
Environmental Regulation ◽  
Technology Innovation ◽  
Negative Impact ◽  
Positive Impact ◽  
Inhibitory Effect ◽  
Market Demand ◽  
Environmental Technology ◽  
Industrial Enterprises ◽  
Threshold Regression Model ◽  
The Impact

Based on the perspective of environmental regulation, this paper selects panel data of 30 provinces in China from 2011 to 2016, establishes Hansen panel threshold regression model, and investigates the impact of FDI on environmental technology innovation of industrial enterprises in China under the threshold of environmental regulation. The results show that FDI has a significant inhibitory effect on the environmental technological innovation of industrial enterprises; the effect has a significant dual threshold of environmental regulation, with the intensity of environmental regulation across the threshold, the negative impact of FDI gradually weakened; market demand and industry scale have a significant positive impact, the role of technological progress is not significant. The findings of this paper provide a certain reference for the rational use of environmental regulation policies, the maximization of FDI technology spillover, the promotion of environmental technology innovation of industrial enterprises, and the realization of “win-win” of environment and economy.

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