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Precommercial thinning could be a valuable tool for climate change adaptation, as it can promote stand diversity while increasing productivity. Softwood and hardwood stands are usually thinned following different methods, and we lack recommendations for application in mixedwood stands. We evaluated the effects of precommercial thinning on the growth and composition of balsam fir (Abies balsameaL.)–birch stands dominated by paper and yellow birch (Betula papyrifera Marsh. and Betula alleghaniensis Britt.), comparing methods and production objectives (systematic release-softwood, systematic release-mixedwood, crop-tree release-mixedwood, and crop-tree release-hardwood) in Québec (Canada). Precommercial thinning increased tree-level and stand-level growth, especially for both birches. Compared to the non-thinned control, thinning increased tree diameter at breast height annual increments by 60%–107%, with similar results among modalities. Thinning changed initial stand composition, but mixedwood production plots composition was similar to that of the control 15 years after treatment. Promoting diversity is often perceived to be made at the expense of wood production. Our results suggest that we can obtain both increased growth and maintain diversity. Precommercial thinning is currently suggested as an adaptation tool that can foster drought resistance. Based on our study, we suggest it could serve another purpose in climate-adapted forest management, that is, maintaining diversity and thus increasing resilience to disturbances. [ABSTRACT FROM AUTHOR]

Ecosystem management requires good knowledge of preindustrial ecosystems and their dynamics. However, in most regions of Québec, the original forested landscape has been altered by human activities. To validate the ecosystem management conducted in the lower Mauricie region, the preindustrial landscape of the high hills of the lower Saint-Maurice region was characterized from the study of 18 historical forest surveys conducted by the pulp and paper industry in the early 20th century. The analysis of these surveys showed the predominance of irregular mature stands. Two-thirds of these stands were of mixedwood type, while a very small proportion was of hardwood type. Softwood volume was mainly constituted of balsam fir (Abies balsamea (L.) Mill.) and red (Picea rubens Sarg.) and black spruces (Picea mariana (Mill.) BSP). Lastly, the analysis of these inventories showed the occurrence, in the preindustrial landscape, of a mixed disturbance regime, where severe fires and insect outbreaks coexisted with gap dynamics. From a broader perspective, we can fully appreciate with this study the importance and usefulness for ecosystem management of conserving forest inventory archives, because in many cases they are the only references to the preindustrial landscape. [ABSTRACT FROM AUTHOR]

An in-depth understanding of the response of wood under compression/densification calls for characterization of strain distribution over the wood. Recently, an image processing technique has been used for strain evaluation on wood, as the traditional devices are not able to measure irregularly distributed strain field. Unfortunately, the classic image correlation algorithm is rather time consuming and could take up to days to compute the final result. In this paper, an improved image correlation algorithm with linearly changed searching region during the correlation seeking is presented. The processing speed is increased by over 1800 times while keeping the high accuracy of the displacement measurement. In addition, full feasibility tests were conducted on balsam fir ( (L.) Mill.) and eastern white pine ( L.) samples. The results demonstrate the high robustness, efficiency, and accuracy of the proposed method. [ABSTRACT FROM AUTHOR]

Numerous crown parameters (e.g., leaf area index, diameter, height, volume) can be obtained via the analysis of tree crown photographs. In all cases, parameter values are functions of the position of the crown outline. However, no standardized method to delineate crowns exists. To explore the effect of different outlines on tree crown descriptors, in this case crown openness (CO), and facilitate the adoption of a standard method free of user bias, we developed the program Crown Delineator that automatically delineates any outline around tree crowns following predetermined sensibility settings. We used different outlines to analyze tree CO in contrasting settings: using saplings from four species in young boreal mixedwood forests and medium-sized hybrid poplar trees from a low-density plantation. In both cases, the estimated CO increases when calculated from a looser outline, which had a strong influence on understory available light simulations using a forest simulator. These results demonstrate that the method used to trace crown outlines is an important step in the determination of CO values. We provide a much-needed computer-assisted solution to help standardize this procedure, which can also be used in many other situations in which the delineation of tree crowns is needed (e.g., competition and crown shyness). [ABSTRACT FROM AUTHOR]

The predictions of properties for wood disc average are seldom reported, and they are important for sorting out logs based on their quality. The minimum near infrared (NIR) spectra required to predict wood disc average properties would also be of critical importance. In this study, calibration and prediction models for wood disc average properties were developed using NIR spectral data for balsam fir (Abies balsamea (L.) Mill.) and black spruce (Picea mariana (Mill.) B.S.P.) samples collected from 14 different sites across Newfoundland, Canada. The calibration was done against area-weighted average wood properties determined by SilviScan. NIR spectra were collected in 18 mm increments from the radial-longitudinal face of green and oven-dried samples. Results showed that using NIR spectra from three spots per wood strip was sufficient for the modeling and prediction for density and module of elasticity (MOE). The coefficients of determination ranged from 0.76 (MOE of green wood samples) to 0.88 (density of oven-dried wood samples). However, the microfibril angle (MFA) cannot be well predicted from either green wood or oven-dried wood NIR spectra. Our results further showed that the NIR spectra collected from oven-dried wood samples gave better calibration and prediction than those collected from green wood samples. Les prédictions des propriétés moyennes des disques de bois sont rarement présentées, bien qu'elles soient importantes pour trier les billes en fonction de leur qualité. Les spectres minimum dans le proche infrarouge (PIR) qui sont nécessaires pour prédire les propriétés moyennes des disques de bois ont aussi une importance cruciale. Dans cette étude, des modèles de prédiction et de calibration des propriétés moyennes des disques de bois ont été développés à partir de données spectrales PIR d'échantillons de sapin baumier (Abies balsamea (L.) Mill.) et d'épinette noire (Picea mariana (Mill.) B.S.P.) prélevés dans 14 sites différents couvrant l'ensemble de la province de Terre-Neuve, au Canada. La calibration a été effectuée à partir des propriétés moyennes du bois déterminées à l'aide de SilviScan et pondérées par la superficie. Les spectres PIR ont été obtenus à tous les 18 mm le long de la face longitudinale-radiale d'échantillons verts et anhydres. Les résultats ont démontré que l'utilisation des spectres PIR provenant de trois points par barrette de bois était suffisante pour modéliser et prédire la densité et le module d'élasticité (MOE). Les coefficients de détermination variaient de 0,76 (MOE d'échantillons de bois à l'état vert) à 0,88 (densité d'échantillons de bois à l'état anhydre). Cependant, les spectres PIR du bois vert ou anhydre ne sont pas adéquats pour prédire l'angle des microfibrilles (AMF). Nos résultats ont de plus montré que les spectres PIR des échantillons de bois à l'état anhydre permettent d'obtenir une meilleure calibration et de faire de meilleures prédictions que ceux des échantillons de bois à l'état vert. [ABSTRACT FROM AUTHOR]