Key Message: The automatic detection of tree-ring boundaries and other anatomical features using image analysis has progressed substantially over the past decade with advances in machine learning and imagery technology, as well as increasing demands from the dendrochronology community. This paper presents a publicly available dataset of 64 annotated images of transverse sections of commercially grown Pinus taeda L. trees from northern Uruguay, presenting 17 to 24 annual rings. The collection contains several challenging features for automatic ring detection, including illumination and surface preparation variation, fungal infection (blue stains), knot formation, missing bark or interruptions in outer rings, and radial cracking. This dataset can be used to develop and test automatic tree ring detection algorithms. The dataset presented here was used to develop the Cross-Section Tree-Ring Detection (CS-TRD) method, an open-source automated ring-detection algorithm for cross-sectioned images. Dataset access at https://doi.org/10.5281/zenodo.15110647. Access to the metadata describing the data set: https://metadata-afs.nancy.inra.fr/geonetwork/srv/fre/catalog.search#/metadata/5fdbd411-9ae1-4ce6-8ef0-cdfa2fbd7a6a.

This work describes a Tree Ring Detection method for complete Cross-Sections of Trees (CS-TRD) that detects, processes, and connects edges corresponding to the tree's growth rings. The method relies on edge detection, and its parameters are set to default values and can be adjusted as needed. The only required input is the location of the biological center of the tree, the pith, which can be marked manually or using an automatic detection algorithm. CS-TRD achieves an F-Score of 91% in the UruDendro dataset (of Pinus taeda) and 97% in the Kennel dataset (of Abies alba) without specialized hardware requirements.

Understanding how thinning strategies impact wood quality and quantity for different purposes is of interest, given that plantation management is often based on parameters that require validation under varying growth conditions. Planted forests for solid purposes in the northern region of Urugay, western Argentina and South of Brazil are usually managed in initial stockings ranging from 800 to 1200 trees·ha⁻¹ depending on the use of clones or seeds. Subsequent thinnings are applied (at plantation ages varying from 3 to 11 years) up to final stockings of around 200 trees·ha⁻¹. This study evaluated contrasting thinning regimes applied early in the crop cycle, with an initial tree density of 840 trees·ha⁻¹. Two thinning treatments were applied at 1.5 and 7.3 years, reducing tree densities to 700–400 and 400–100 trees·ha⁻¹, respectively. Growth analyses were conducted from 1.5 to 20.8 years, considering total height, diameter at breast height, individual volume, total and commercial volume per hectare, mean annual increase, and current annual increase. At the final harvest, contrasting tree densities of 100, 250, and 400 trees·ha⁻¹ were sampled to assess wood density and mechanical properties (bending and compression on small-scale clear samples). Individual growth and wood properties were related to a Stand Density Index to understand the effect of competition on these values. The results identified thinning regimes that resulted in the most significant individual and per-hectare growth (both in thinning and clear felling) and the optimal harvest time under specific growth conditions. We assessed the proportions of commercial logs for sawmill and pulp uses, providing valuable inputs for subsequent economic analyses of thinning regimes aiming for the most convenient combination of wood products. Wood’s physical and mechanical properties were relatively little affected by contrasting levels of competition between trees; therefore, the choice of silvicultural system will depend on production and economic criteria.

This study investigates the performance of phenol–formaldehyde adhesives containing Eucalyptus lignin as an extender in their formulation. A commercial phenol–formaldehyde resin was used, and five different types of lignin were tested: (1) kraft lignin precipitated with carbon dioxide, (2) kraft lignin precipitated with sulfuric acid, (3) soda lignin precipitated with hydrochloric acid, (4) soda lignin precipitated with sulfuric acid, and (5) a second soda lignin where the wood underwent a phosphoric acid extraction process prior to alkaline extraction. The lignins were used both unmodified and activated through three different processes: hydroxymethylation, phenolysis in an acidic medium, and alkaline phenolysis. Adhesives were formulated with substitution percentages of the base resin ranging from 10% to 60%, in addition to a reference adhesive that contained no lignin. Wooden test specimens were manufactured to determine the tensile shear strength. Results indicate that best performance is achieved when lignins are activated through hydroxymethylation and when soda lignin is used. Under optimal conditions, it is possible to replace at least 45% of the base resin with activated Eucalyptus soda lignin, which represents a reduction of at least 30% in the cost of the final adhesive. This substitution results in a 46% increase in adhesive strength compared to the base adhesive (without lignin). These findings suggest that the valorization Eucalyptus soda lignin could have significant economic and environmental benefits.

Approximately 1–2% of the wood processed for pulp production is converted into sawdust and pinchips, which are commonly burned for energy in industries that already produce excess power. This material, juvenile wood only containing sapwood, poses challenges for its valorization. This study explores the extraction of polyphenols from Eucalyptus wood residues generated by a pulp industry in Uruguay, aiming to evaluate their suitability as partial replacements in phenol-formaldehyde (PF) adhesives. Using solid-liquid extraction with sodium hydroxide and sodium sulfite, the extractions conditions were optimized through an experimental design considering sodium hydroxide and sodium sulfite charges, along with temperature as variables. The extracts were characterized based on phenolic content, condensed tannins content, antioxidant activity, and Stiasny number, to assess the adhesive potential. Adhesives formulated with 10%, 20%, and 30% PF resin substitution demonstrated a progressive reduction in tensile shear strength, with the 10% substitution achieving acceptable strength. While higher substitution levels compromised adhesive performance, the results suggest that formulation adjustments may improve performance at moderate substitution ratios. Furthermore, the high antioxidant capacity of the extracts opens up potential for their use in other high-value applications where natural antioxidants are increasingly sought after as safer and more sustainable alternatives to synthetic additives. Graphical abstract

To understand how the thinning strategies impacts on wood quality and quantity for different purposes is of interest, considering that the management of plantations is carried out with parameters that have yet to be validated for different growth conditions. This work evaluated contrasting thinning regimes applied early at two moments of the crop cycle. With an initial population of 840 trees.ha-1, two thinning with populations ranging from 700 to 400, and from 400 to 100 trees.ha-1 were applied at 1.5 and 7.3 years, respectively. Growth analyses were carried out from the ages of 1.5 to 20.8 years considering: total height, diameter at breast height, individual volume, total and commercial volume per hectare, mean annual increase and current annual increase. At final age, contrasting populations of 100, 250 and 400 trees.ha-1 were sampled to assess wood density, and mechanical properties (bending and compression on small scale clear samples). The values of individual growth and wood properties are related to a Stand Density Index to understand the effect of competition on those values. The results allow us to identify the thinning schemes that record the most significant individual and per-hectare growth (both in thinning and clear felling) and the optimal harvest time under specific growth conditions. We assessed the proportions of commercial logs for sawmill and pulp uses, providing valuable inputs for a subsequent economic analysis of thinning regimes seeking for the most convenient combination of wood products. Wood's physical and mechanical properties assessed were barely affected by contrasting levels of competition between trees, therefore the decision of the silvicultural system to implement will depend on production and economic criteria.