Editorial

5 pages, 654 KiB

Open AccessEditorial

Recent Advances in Nondestructive Evaluation of Wood: In-Forest Wood Quality Assessments

by Xiping Wang

Forests 2021, 12(7), 949; https://doi.org/10.3390/f12070949 - 19 Jul 2021

Cited by 5 | Viewed by 1917

Efficient wood production and utilization requires knowing the wood quality attributes of forest resources relevant to various end uses, prescribing appropriate silvicultural treatments that positively influence wood quality, and then, at the time of harvesting, sorting and allocating standing timbers to the most [...] Read more.

Efficient wood production and utilization requires knowing the wood quality attributes of forest resources relevant to various end uses, prescribing appropriate silvicultural treatments that positively influence wood quality, and then, at the time of harvesting, sorting and allocating standing timbers to the most appropriate markets [...] Full article

(This article belongs to the Special Issue Recent Advances in Nondestructive Evaluation of Wood: In-Forest Wood Quality Assessments)

Research

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21 pages, 5188 KiB

Open AccessArticle

Using Ground Penetrating Radar (GPR) to Predict Log Moisture Content of Commercially Important Canadian Softwoods

by Isabelle Duchesne, Queju Tong and Guillaume Hans

Forests 2023, 14(12), 2396; https://doi.org/10.3390/f14122396 - 08 Dec 2023

Viewed by 837

Abstract

The non-destructive testing of wood fibre properties is crucial for informing forest management decisions and achieving optimal resource utilization. Moisture content (MC) is an important indicator of wood freshness and may reveal the presence of wood degradation. However, efficient methods are still needed [...] Read more.

The non-destructive testing of wood fibre properties is crucial for informing forest management decisions and achieving optimal resource utilization. Moisture content (MC) is an important indicator of wood freshness and may reveal the presence of wood degradation. However, efficient methods are still needed to better monitor this property along the forest–wood value chain. The objective of the study was to develop prediction models to evaluate log MC based on the propagation of ground penetrating radar (GPR) signals. A total of 165 trees representing four species (black spruce (Picea mariana (Mill.) B.S.P.), white spruce (Picea glauca (Moench) Voss), red spruce (Picea rubens Sarg.), and balsam fir (Abies balsamea (L.) Mill.)) were harvested in two regions of the province of Quebec. GPR signals were acquired in the green (fresh) state and at three subsequent drying stages. Partial least squares regression (PLSR) and locally weighted PLSR (LWPLSR) were employed to establish relationships between GPR signals (antenna frequency: 1.6 GHz) and log properties. The models were fitted on three calibration sets containing four drying stages and different species mixes. The LWPLSR models performed better than the PLSR models for predicting log MC, with a lower root mean square error (RMSEp range: 10.8%–20.2% vs. 13.0%–20.5%) and a higher R²p (0.63–0.87 vs. 0.62–0.82). Spruce-only models performed considerably better than fir-only models while multi-species models were in-between. Despite the complex anisotropy of wood and the physics of wave propagation, the GPR technology can be successfully used to estimate log moisture content, but the GPR-based MC models should be calibrated for each specific type of wood material. Full article

(This article belongs to the Special Issue Recent Advances in Nondestructive Evaluation of Wood: In-Forest Wood Quality Assessments)

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16 pages, 4295 KiB

Open AccessArticle

Design of a Tree Micro Drill Instrument to Improve the Accuracy of Wood Density Estimation

by Jianfeng Yao, Zhenyang Wu, Yili Zheng, Benqiang Rao, Zhuofan Li, Yunchao Hu and Bolin Nie

Forests 2023, 14(10), 2071; https://doi.org/10.3390/f14102071 - 17 Oct 2023

Viewed by 879

Abstract

To improve the estimation accuracy of wood density and study the linear correlation between drill feed resistance and wood density, a new micro drill instrument prototype that can simultaneously measure the rotation resistance and feed resistance of the drill needle was designed. The [...] Read more.

To improve the estimation accuracy of wood density and study the linear correlation between drill feed resistance and wood density, a new micro drill instrument prototype that can simultaneously measure the rotation resistance and feed resistance of the drill needle was designed. The test tree species included hard and soft broad-leaved trees and coniferous trees, and the absolute dry density of each wood sample was measured. The drill resistance data were tested by our newly proposed prototype and a Resistograph 650-SC, and four linear models were established to define the relation between drill resistance and the absolute dry density of the wood. The results showed that (1) the statistical indicators of each model for our proposed prototype were better than the corresponding indicators of the Resistograph 650-SC for three of the four species tested; (2) the coefficient of determination of the linear regression model between the feed resistance of our proposed prototype and the absolute dry density of wood was 0.946; and (3) the statistical indicators of the model that included rotation resistance and feed resistance were better than those of the model that only including rotation resistance. Although the proposed prototype produced a competitive level of accuracy and explicitly demonstrated that including feed resistance improved wood density measurement accuracy, the prototype should be considered a first iteration as further hardware design changes and in-forest performance assessments across wider diverse set of test species are required before a conclusive evaluation can be rendered. Full article

(This article belongs to the Special Issue Recent Advances in Nondestructive Evaluation of Wood: In-Forest Wood Quality Assessments)

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20 pages, 4916 KiB

Open AccessArticle

Evaluation of Softwood Timber Quality—A Case Study on Two Silvicultural Systems in Central Germany

by Kirsten Höwler, Dominik Seidel, Tobias Krenn, Dirk Berthold, Martin Ehbrecht, Jan Müller and Bettina Kietz

Forests 2022, 13(11), 1910; https://doi.org/10.3390/f13111910 - 14 Nov 2022

Cited by 1 | Viewed by 1338

Abstract

Norway spruce (Picea abies (L.) H.Karst) trees planted with high stem densities produce finely branched, solid logs but are vulnerable to extreme weather events, e.g., storms. Over the last decades spruce stands have been planted at lower stand densities, resulting in wider [...] Read more.

Norway spruce (Picea abies (L.) H.Karst) trees planted with high stem densities produce finely branched, solid logs but are vulnerable to extreme weather events, e.g., storms. Over the last decades spruce stands have been planted at lower stand densities, resulting in wider crowns, lower crown bases, and higher stand stability, but this might decrease the quality of coniferous timber due to an increased growing rate and wider annual rings. Therefore, in this case study we investigated the influence of different silvicultural treatments and stand densities on tree morphology and wood properties of 100 spruce trees up to sawn timber as the final product. Tree morphology was assessed using mobile laser scanning. Ring width analysis, wood density measurements, and the four-point bending strength test on visually graded boards were conducted to gain information on wood properties and product quality. In stands thinned from below, higher wood densities were observed due to smaller annual rings compared to stands that were thinned from above at equal annual ring widths. In addition, crown asymmetry and the height-to-diameter ratio were identified as proxies for wood density. Lastly, visually assessed quality differences between the forest stands were discerned on the examined boards. Full article

(This article belongs to the Special Issue Recent Advances in Nondestructive Evaluation of Wood: In-Forest Wood Quality Assessments)

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13 pages, 2864 KiB

Open AccessArticle

Sight versus Sound: Do Visual Assessments of Dead Standing Trees Reflect Acoustic Nondestructive Evaluations of Wood Quality?

by Tyler J. Hovde, John W. Forsman, Robert J. Ross, Mark Rudnick, Xinfeng Xie, Xiping Wang and Yvette L. Dickson

Forests 2022, 13(10), 1680; https://doi.org/10.3390/f13101680 - 13 Oct 2022

Cited by 1 | Viewed by 1209

Abstract

The forest industry typically uses visual appearance to evaluate the wood quality when salvaging dead standing trees. We investigated whether the visual appearance of white spruce (Picea glauca (Moench) Voss) defoliated by the spruce budworm (Choristoneura fumiferana (Clem.)) accurately reflects wood [...] Read more.

The forest industry typically uses visual appearance to evaluate the wood quality when salvaging dead standing trees. We investigated whether the visual appearance of white spruce (Picea glauca (Moench) Voss) defoliated by the spruce budworm (Choristoneura fumiferana (Clem.)) accurately reflects wood quality measured using nondestructive techniques. Longitudinal and transverse acoustic velocities were measured on white spruce, representing three condition categories assessed visually, ranging from live trees to dead standing trees with signs of decay. Generalized linear models were used to determine whether there were significant differences in longitudinal and transverse acoustic velocities among the visual categories. Longitudinal velocities significantly differed between the live and poorest visual categories. Transverse velocities did not differ by visual category. We found that tree appearance provides coarse but useful insight into intrinsic wood quality. We recommend that forest managers use acoustic, non-destructive technologies on marginal trees to measure the wood quality of salvaged trees to ensure the wood is utilized for the highest and best use thereby optimizing possible values. Full article

(This article belongs to the Special Issue Recent Advances in Nondestructive Evaluation of Wood: In-Forest Wood Quality Assessments)

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18 pages, 3913 KiB

Open AccessArticle

Field Assessment of Downed Timber Strength Deterioration Rate and Wood Quality Using Acoustic Technologies

by Munkaila Musah, Javier Hernandez Diaz, Abiodun Oluseun Alawode, Tom Gallagher, Maria Soledad Peresin, Dana Mitchell, Mathew Smidt and Brian Via

Forests 2022, 13(5), 752; https://doi.org/10.3390/f13050752 - 12 May 2022

Cited by 3 | Viewed by 2021

Abstract

Hurricane and tornado events cause significant damage to high-value timber in the United States each year. Forest managers and landowners are keenly interested in finding solutions to salvage and repurpose these downed timbers before they cause pest infestations and fire outbreaks, completely losing [...] Read more.

Hurricane and tornado events cause significant damage to high-value timber in the United States each year. Forest managers and landowners are keenly interested in finding solutions to salvage and repurpose these downed timbers before they cause pest infestations and fire outbreaks, completely losing their value or increasing processing costs. To better understand the wood quality of the downed timber, we used acoustic waves techniques as a nondestructive testing approach to assess the wood degradation rate of downed trees and determine the extent of fracture and voids in the damaged regions. We periodically monitored the acoustic velocity of the downed trees for 12 consecutive months using a time of flight (TOF) acoustic method. Acoustic measurements were conducted using three different techniques—longitudinal, transverse, and off-set methods. Wood density, age, and the diameter at breast height (dbh) class measurement for southern timber (chip-n-saw for dbh 8″–11″ and sawtimber with dbh 12″ and up) were used as the predictive parameters of the downed trees. The results indicated positive relationships between dbh class, stand age, and acoustic velocity measurement (R² > 65%). The TOF acoustic velocity was indicated to potentially separate higher-stiffness timber from lower-stiffness timber in a hurricane event for structural or non-structural applications. The regression coefficient from the repeated measurements indicated that both age and diameter class strongly impacted the acoustic properties of the downed trees (p-value ≤ 0.001). The sawtimber dbh class recorded a higher acoustic velocity compared to the chip-n-saw type. Fracture, voids, and massive decay in downed trees were detected beyond the visible inspection, features that often are identified by loggers in lower quality wood; however, TOF showed a weak response in picking up incremental deterioration due to changes in specific environmental factors that affected acoustic readings. This study showed that acoustic wave methods could potentially be used as a field evaluation tool for assessing the quality of downed trees. Full article

(This article belongs to the Special Issue Recent Advances in Nondestructive Evaluation of Wood: In-Forest Wood Quality Assessments)

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13 pages, 5572 KiB

Open AccessArticle

A Comparison of Radial Wood Property Variation on Pinus radiata between an IML PD-400 ‘Resi’ Instrument and Increment Cores Analysed by SilviScan

by Geoffrey M. Downes, Jonathan J. Harrington, David M. Drew, Marco Lausberg, Phillip Muyambo, Duncan Watt and David J. Lee

Forests 2022, 13(5), 751; https://doi.org/10.3390/f13050751 - 12 May 2022

Cited by 6 | Viewed by 5232

Abstract

Mature age Pinus radiata D. Don trees were sampled across nine sites in northern New South Wales, Australia, that were expected, based on site quality and inventory metrics, to exhibit significant variation in productivity and wood quality. Twenty trees per site were harvested [...] Read more.

Mature age Pinus radiata D. Don trees were sampled across nine sites in northern New South Wales, Australia, that were expected, based on site quality and inventory metrics, to exhibit significant variation in productivity and wood quality. Twenty trees per site were harvested and 13 mm diameter, pith-to-bark increment cores were extracted from three trees per site from eight of the nine sites for SilviScan analysis. Outerwood increment cores were collected from all trees for basic density measurement. The same trees were also sampled using an IML PD400 (Resi) instrument. Radial mean properties of wood basic density derived from Resi traces were found to correlate strongly with the mean density data derived from SilviScan analyses and from increment cores. The Resi-derived basic density of 10 mm radial segments was strongly correlated with SilviScan measures of basic density averaged at similar intervals. Full article

(This article belongs to the Special Issue Recent Advances in Nondestructive Evaluation of Wood: In-Forest Wood Quality Assessments)

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16 pages, 1829 KiB

Open AccessArticle

Thinning Influences Wood Properties of Plantation-Grown Eucalyptus nitens at Three Sites in Tasmania

by Vilius Gendvilas, Geoffrey M. Downes, Mark Neyland, Mark Hunt, Peter A. Harrison, Andrew Jacobs, Dean Williams and Julianne O’Reilly-Wapstra

Forests 2021, 12(10), 1304; https://doi.org/10.3390/f12101304 - 24 Sep 2021

Cited by 2 | Viewed by 2530

Abstract

Thinning of forestry plantations is a common silviculture practice to increase growth rates and to produce larger dimension logs. The wood properties, basic density and stiffness, are key indicators of the suitability of timber for particular purposes and ultimately determine timber value. The [...] Read more.

Thinning of forestry plantations is a common silviculture practice to increase growth rates and to produce larger dimension logs. The wood properties, basic density and stiffness, are key indicators of the suitability of timber for particular purposes and ultimately determine timber value. The impact of thinning operations on wood properties is, therefore, of considerable interest to forest growers and timber producers. To date, studies examining the impact of thinning on wood properties have produced variable results and understanding the consistency of the effects of thinning treatments across various sites for important plantation species is limited. Two non-destructive assessment techniques, drilling resistance and acoustic wave velocity, were used to examine the impact of thinning on basic density and stiffness in 19–21-year-old plantation grown Eucalyptus nitens across three sites. Commercial thinning to 300 trees ha⁻¹ decreased the stiffness of standing trees and this effect was consistent across the sites. Reduction in stiffness due to thinning ranged from 3.5% to 11.5%. There was no difference in wood properties between commercially and non-commercially thinned trees to 300 trees ha⁻¹ and no difference in wood properties when thinned to 500 trees ha⁻¹. Basic density was not affected by thinning. The site had significant effects on both basic density and stiffness, which were lowest at the highest precipitation and highest elevation site. The results indicate that wood properties are influenced both by silviculture and site environmental differences. This knowledge can be used for the better management of E. nitens resources for solid wood production. Full article

(This article belongs to the Special Issue Recent Advances in Nondestructive Evaluation of Wood: In-Forest Wood Quality Assessments)

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