1,721,044 research outputs found
Managing European beech (Fagus sylvatica L.) forests for construction wood
No full textWhile the demand for construction wood is increasing, and Norway spruce faces declining area shares and increased climate-related risks, European beech has proven to offer adequate stiffness and bending strength for construction wood out of glued laminated timber (GLT). This study aims to identify the most suitable stand treatment for maximizing beech construction wood production. The research was conducted across a unique dataset of 19 long-term permanent plots, characterized by very contrasting and modern thinning methods (intense (A) and moderate (B)) and an extremely long running time (starting 1968–1971). Continuous measurements up to 2009 enabled an empirical analysis of construction timber yield during the thinning and in the remaining stands 2009. Additionally, growth and timber assortments by intended use and diameter classes were modelled based on crown projection area and diameter at breast height (DBH). A quality-based sorting, however, was neither feasible due to the available data nor required by the world’s leading manufacturer of beech construction timber (Pollmeier Massivholz GmbH & Co.KG). Results indicate that moderate thinning, combined with moderate annual diameter increment and relatively long rotation periods, maximizes the production of beech construction wood with a mid-diameter of the trunks of at least 30 cm. In contrast, intense thinning is only suitable for achieving higher target diameters. Following these recommendations the study suggests that the number of target trees could exceed current practice. These findings challenge existing literature recommendations and provide alternative management strategies for beech stands, although they contrast with guidelines for ensuring climate-stable stands
Evaluation of the forest growth simulator SILVA on dominant trees in mature mixed Silver fir–Norway spruce stands in South-West Germany
No full textForest growth simulators go beyond a mere tabulation of empirical measurements by employing biometric models that functionally describe the dependence of forest growth of the initial forest structure, growth conditions and management regime. This makes them very flexible and allows predicting growth reactions for unknown and/or complex forest growth scenarios. When simulation outcomes are to be used in silvicultural strategic planning, the results are of direct and delicate importance, and the correct simulator performance must be ascertained. This is especially so when the considered forest situation differs from the forest data used to parameterise the model (e.g. different geographical region). In this article, the forest growth simulator SILVA (version 2.2) was validated for 55 long-term experimental plots of mature mixed Silver fir–Norway spruce stands in southwest Germany (Picea abies, Abies alba). The evaluation was restricted to the upper canopy trees during the survey period 1989–2004. Following the general evaluation criteria for ecological models from [Vanclay, J.K., Skovsgaard, J.P., 1997. Evaluating forest growth models. Ecol. Mod. 98, 1–12], a specific methodology was developed to evaluate the simulated height and diameter growth on the basis of forest growth principles. The qualitative analysis proved the SILVA growth algorithms to be in accordance with physiologically based standard growth equations. The quantitative evaluation was limited by incomplete knowledge of the site conditions. To overcome this problem, the experimental plots were regarded as a “heterogeneous growth series” which allows analysing the growth behaviour in a more general way. It could be shown that for the given data set, the SILVA simulations produced an overestimation of height growth (median: +61% spruce, +12% fir), and an underestimation of diameter growth and competition sensitivity (median: −16% spruce, −70% fir). The errors partially compensated in the volume growth resulting in an overall over-/underestimation of +9% for spruce and −58% for fir (median). The unbalanced height and diameter growth cannot be compensated by a change in the site conditions because this affects both height and diameter growth either positive or negative. Hence, an adjustment of selected parameterisation values appears to offer the best solution to adapt SILVA to the considered forest situation. This approach of adaptive parameterisation is discussed against a more general background of deductive vs. inductive forest growth modelling
Assessing the relationship between height growth and molecular genetic variation in Douglas-fir (Pseudotsuga menziesii) provenances
No full textDouglas-fir (Pseudotsuga menziesii) is a conifer tree native to western North America. In central Europe, it shows superior growth performance and is considered a suitable substitute for tree species impaired in vitality due to climate change. Maintenance and improvement of growth performance in a changing environment is a main challenge for forest tree breeders. In this context, genetic variation as a factor underlying phenotypic variation, but also as the basis for future adaptation, is of particular interest. The aims of this study were to analyse (1) genetic diversity of selected Douglas-fir provenances, (2) variation in height growth among provenances, and (3) to assess the link between genetic and phenotypic variation in height growth. Genotyping was done on microsatellite loci. Effects of 'provenance', 'genotype', and 'site' on height growth were assessed by fitting mixed linear models. The most significant genetic differentiation was observed between provenances of the coastal variety, versus a provenance of the interior variety originating from British Columbia. Although genetic differentiation among provenances of the coastal variety was lower, genetic structures within this variety were identified. Moreover, genetic diversity showed a latitudinal gradient with the southernmost provenances being more diverse, probably reflecting the species' evolutionary history. The modelling approach revealed that height growth differed significantly by 'provenance', 'site', and the interaction between 'site' and 'provenance'. Additionally, this analysis showed that genetic variation captured by the genotyped microsatellite loci was significantly related to variation in height growth, providing statistical evidence for a genetic component in the observed phenotypic variation
Quantifying and mapping the ready-to-use veneer volume of European beech trees based on terrestrial laser scanning data
No full textUsing 3D point clouds obtained with terrestrial laser scanning (TLS), we automatically and non-destructively quantified and mapped the estimated veneer wood volume of standing trees in differently structured beech stands. To mitigate climate change, we need to utilise wood for long-term carbon storage in products like construction wood and for substituting building materials based on fossil fuels. As the supply of wood from Norway spruce decreases, alternative species like beech must be considered for construction purposes. We present an approach to quantify and map the volume available for veneer production in beech forests. Our method is based on point clouds derived from TLS. We studied three forest plots, each with two different treatments (moderate vs. heavy thinning), resulting in varying stand basal areas ranging from 25 m2 to 36 m2 per hectare. We fitted different configurations of veneer rolls into point clouds of tree stems, choosing the configuration that yielded the highest volume of veneer wood. Our automatic optimisation algorithm ensured no misplaced veneer rolls. At the tree level, veneer wood volume was higher in intensely thinned stands. At the stand level, overall veneer volume was higher in moderately thinned stands, whereas the overall veneer share was higher in the heavily thinned stands. The veneer volume of a tree depended on diameter at breast height, crown base height, taper and curvature depth. Our approach detects all trees in a forest potentially ready for veneer production and shows the direct volumetric outcome under bark. This enables the planning of tree selection for harvest based on adaptable requirements for the veneer production
Manipulation des Mikrobioms von Ips typographus und dessen Effekte auf die Pathogenabwehr am Beispiel von Beauveria bassiana
No full textAnalyse der raumzeitlichen Variabilität modellierter Spitzenwindgeschwindigkeiten über Wäldern Europas
No full textDetection and modeling of storm damage in forests using satellite imagery-based spatial patterns.
No full textFreilanduntersuchung zur Effizienz von SPLAT(R)Verb zum Schutz von Picea abies mit Ips typographus als Zielorganismus
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