Density and growth of forest stands revisited. Effect of the temporal scale of observation, site quality, and thinning

Variability of wood properties using airborne and terrestrial laser scanning

(1)Wood production in fast‐growing Eucalyptus grandis trees is highly dependent on both potassium (K) fertilization and water availability but the molecular processes underlying wood formation in response to the combined effects of these two limiting factors are still unknown (2)E. grandis trees were submitted to four combinations of K‐fertilization and water supply. Weighted gene co‐expression network analysis (WGCNA) and MixOmics‐based co‐regulation networks were used to integrate xylem transcriptome, metabolome and complex wood traits. Functional characterization of a candidate gene was performed in transgenic E. grandis hairy roots. (3)This integrated network‐based approach enabled us to identify meaningful biological processes and regulators impacted by K‐fertilization and/or water limitation. It revealed that modules of co‐regulated genes and metabolites strongly correlated to wood complex traits are in the heart of a complex trade‐off between biomass production and stress responses. Nested in these modules, potential new cell wall regulators were identified as further confirmed by the functional characterization of EgMYB137. (4)These findings provide new insights into the regulatory mechanisms of wood formation under stress conditions pointing out both known and new regulators co‐opted by K‐fertilization and/or water limitation that may potentially promote adaptive wood traits.

https://nph.onlinelibrary.wiley.com/doi/pdf/10.1111/nph.15802

A systems biology view of wood formation in Eucalyptus grandis trees submitted to different potassium and water regimes

Com o objetivo de avaliar a durabilidade natural da madeira, amostras de alburno e de cerne de Luehea divaricata (acoita-cavalo), Carya illinoinensis (nogueira-peca) e Platanus x acerifolia (platano), medindo 2,5 x 2,5 x 30,0 cm (radial x tangencial x longitudinal), foram submetidas a ensaios experimentais em um povoamento de Pinus e em campo aberto. Durante um ano, as amostras foram periodicamente pesadas e avaliadas pelo criterio de notas, para determinar o percentual de perda de massa e indice de deterioracao, respectivamente. Os resultados mostraram que, independente da especie e do tipo de lenho, o ambiente dentro da floresta e mais favoravel a deterioracao da madeira do que fora dele. Apesar da elevada correlacoes entre a perda de massa e o indice de deterioracao foram observadas variacoes na avaliacao da durabilidade da madeira entre esses criterios. Para todas as especies, a madeira proveniente do alburno foi a mais atacada. Para perda de massa nao foi observada diferenca entre as especies avaliadas, entretanto, o indice de deterioracao apontou o platano como a mais atacada. Palavras-chave: deterioracao da madeira; perda de massa; indice de deterioracao.

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Durabilidade natural da madeira de três espécies florestais em ensaios de campo natural durability of three wood species in field tests

Old trees as a natural heritage are significant components of terrestrial biodiversity, and they also play an important role in the ecosystem. An overall understanding of the distribution patterns and ecological characteristics of old trees in China’s Anhui Province will provide valuable insights into old tree conservation and scientific planning. Based on the data from 617 field collection and historical sample documents, we applied DIVA-GIS combined with the BIOCLIM model to qualitatively and quantitatively analyse the distribution patterns of old trees and their dominant climate factors for the first time. The model assessment results indicated that the area under the receiving operator curve (AUC) and kappa statistics reached 0.969 and 0.921, respectively, which indicated that the data fit the model very well and that the prediction was highly reliable. According to principal component analysis (PCA), the main bioclimatic variables influencing the distribution of old trees were as follows: water requirements, drought tolerance, preference temperature, heat resistance, cold tolerance and others. The cumulative frequency curves further confirmed that the ecological characteristics of the geographical distributing area for old trees in the study area were annual mean temperature (10.90~16.30oC), maximum temperature of warmest month (25.60~32.40oC), mean temperature of coldest quarter (0.30~4.90oC), annual precipitation (665.00~1701.00 mm), precipitation of driest month (14.00~47.00 mm) and precipitation of driest quarter (45.00~173.00 mm). The current distribution pattern of old trees was mainly affected by precipitation factors. Furthermore, this study demonstrates a new method for the conservation of old trees by virtue of GIS software and predictive models. All of these results could help establish conservation plans for old trees.

http://www.pjoes.com/pdf-110346-47188?filename=Modelling Suitable.pdf

Modelling Suitable Habitat and EcologicalCharacteristics of Old Trees Using DIVA-GISin Anhui Province, China

The Brazilian plantation forestry is well known for high yields. Such yields are not necessarily linked with acceptable wood quality. Pine plantations are an important source of timber in Brazil, and although pulp and paper production plays a dominant role, there is an increasing need for sawtimber, and even high-quality timber is in demand. The impacts of crown thinning on ring width, ring density and juvenile–mature wood of loblolly pine trees were analysed. The experimental design included no thinning, an extreme release from competition, and two practice-oriented variants with moderate and heavy thinnings. X-ray microdensitometry provided ring width and density for 1197 rings and 44 trees. Mean ring width at 1.3 m height varied from 6 to 9 mm, reaching a maximum of 22 mm during the first 3–6 years regardless of thinning intensity. Only occasional differences were verified in ring densities produced from the different thinning variants. The transition from juvenile to mature wood occurred between 13 and 17 years of age. From the analysis of wood density, extreme and early thinning delayed the production of mature wood in ~ 4 years compared with non-thinned or practice-oriented thinned stands. At the same harvest age, thinning had no effect on wood density. However, harvest age itself was a determinant for obtaining wood of higher density. Altogether, results indicated that regarding current market demands no constraints related to the analysed wood characteristics are to be expected, even if extreme thinning regimes are applied.

Wood density of loblolly pine trees as affected by crown thinnings and harvest age in southern Brazil

Araucaria angustifolia (Bertol.) Kuntze is a native tree species of major importance in southern Brazil. It is a regional symbol due to its iconic shape and stature in the landscape; its wood was once economically important and its seeds are an important source of food for the fauna and are presently used in regional cuisine. Despite its importance and apparent abundance, the species is facing extinction mainly as a result of unregulated exploitation and deforestation. This study catalogued the remaining individuals in order to add to the body of knowledge available on A. angustifolia, a species that has become rare across its historic range. The circumference at breast height (1.30 m), the total height, and the tree volume were measured (3,529 araucarias). We catalogued trees with a large diameter measuring them in loco over three years involving a journey of more than 6,800 km. The volumes of these old trees are very large, ranging from 38.2 m3 to 106.6 m3. The largest A. angustifolia individual is located in the state of Santa Catarina and measures 3.25 m in diameter. The giant araucarias with > 2.00 m in diameter are rare and only 13 individuals could be found in southern Brazil; a priority action at the governmental level is to recognize and preserve these monumental trees and together with a need for a public policy of drawing up specific inventories of large trees.

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The last giant Araucaria trees in southern Brazil

Loblolly pine is widely planted in southern Brazil. Despite its major relevance for the forestry sector, knowledge about its radial growth at different height levels is scarce—it is unprecedented for trees subjected to crown thinning. The following questions were answered: (1) how many competitors should be removed to favour the radial growth of potential crop trees? and (2) how long does it take to detect enhanced growth rates along the stem and how long do the effects last? The research design included four thinning treatments where competitor trees were removed in different intensities starting at age 5 years. At age 30 years, 20 trees from each thinning treatment were selected, of which cross-sectional discs were taken at 1.3 m, 25, 50 and 75% of commercial height. The removal of one competitor tree per potential crop tree is not sufficient to increase radial growth immediately after thinning—two competitors need to be removed. Growth responses were detected immediately at the tree base (1.3 m), but took ~ 3 and ~ 8 years to be detectable at 25% (~ 8 m) and 50% (~ 15 m) of commercial height. Positive influences on growth rate following thinning take longer to be detectable upwards in the stem than at the trees base. However, once present, enhanced growth rates last longer at higher levels than at the tree base.

Influence of crown thinning on radial growth pattern of Pinus taeda in southern Brazil

The Weibull function, a continuous probability distribution, is widely used for diameter distribution modelling, in which parameter estimation performance is affected by stand attributes and fitting methods. The Weibull cumulative distribution function is nonlinear, and classical fitting methods may provide a not optimal solution. Invoking the use of artificial intelligence by metaheuristics is reasonable for this optimisation task. Therefore, aimed and compared (1) the metaheuristics genetic algorithm and simulated annealing performance over the moment and percentile methods; (2) the hybrid strategy merging the metaheuristics tested and the percentile method and, (3) the metaheuristics fitness functions under basal area and density errors. A long-term experiment in a Pinus taeda stand subjected to crown thinning was used. According to our findings, all methods have a similar performance, independent of the thinning regimes and age. The pattern of the estimated parameters tends to be acceptable, as b increases over time and c increases after thinning. Overall, our findings suggest that methods based on metaheuristics have a higher precision than classical methods for estimating Weibull parameters. According to the classification test, the methods that involved simulated annealing stood out. The hybrid method involving this metaheuristic also stood out, with accurate estimates. Classical methods showed the poorest performance, and we therefore suggest the use of simulated annealing due to its faster processing time and high-quality solution.

Mário Dobner

Papers

Wood density of loblolly pine trees as affected by crown thinnings and harvest age in southern Brazil

The last giant Araucaria trees in southern Brazil

Influence of crown thinning on radial growth pattern of Pinus taeda in southern Brazil

Appropriate search techniques to estimate Weibull function parameters in a Pinus spp. plantation

Meteorological effects on 30-years-grown Pinus taeda under a gradient of crown thinning intensities in southern Brazil