Influence of mechanical damage on the condition of trees (original) (raw)
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The Effect of Mechanical Bark Damage on the Volume Increment of Trees
Radovi Šumarskog fakulteta Univerziteta u Sarajevu, 2021
UDK: 630*232:582.475(497.6) It is well known that mechanical damage to trees, caused by felling and removal of timber from the forest, has multiple negative effects on the quality of the stock and the health of the forests as well as the volume increment. In Bosnia and Herzegovina there were no significant analises of volume increment loss due to bark damage of the trees. In this paper, a direct relationship between the significant damage to the bark of the stem and the size of the volume increment of individual trees was determined. Original data recorded during the Second National Forest Inventory in Bosnia and Herzegovina (2006-2009), within the accesible high economical forests was used. These forests cover a total area of 1.329.500 ha. Data on measured trees was taken from every fourth sample plot (one from cluster). 18.546 trees were selected, on which the 10-year increment of brest diameter (DBH) was measured and significant mechanical damage was recorded (LOJO et al., 2008)....
Folia Forestalia Polonica, 2015
The study was conducted to perform a comparative analysis of the mechanical properties of wood samples derived from oaks in the Krotoszyn Plateau, which depend on the health state of the trees. Strength parameters of oak wood were calculated for selected diseased and healthy trees (according to the Roloff classification). The study was conducted by a modified method described in the standard Polish Norm PN EN 408+ A1: 2012. For testing, prior selection of wood samples showed that more wood samples of diseased trees compared with those of healthy oaks did not fulfil the Polish standard requirements. According to the method used, the average results of strength tests of timber structures from healthy oaks exhibited higher strength parameters than those of the diseased trees.
Mechanical Properties of Green Wood and Their Relevance for Tree Risk Assessment
Arboriculture & Urban Forestry
In a biological context, the mechanical properties as elasticity and strength of green wood, particularly as measured in the axial direction, influence the stability of trees against static loads (e.g., snow, ice, rain) and dynamic loads (i.e., wind). Extensive collections of data on mechanical properties are listed in three different catalogs edited in Canada, Great Britain, and the United States. A statistical analysis shows that the density of the wood is a major predictor for the mechanical properties as measured in axial direction. In this respect, conifers from temperate zones and deciduous trees both from temperate and tropical zones do not differ significantly from each other. A common, nearly linear relation between the modulus of elasticity and the density at 50% moisture content is found. Relationships between strengths in bending, compression, and shear and green wood density have ordinary least squares scaling exponents around 1.2, but can almost equally well be approxi...
Destructive and non-destructive evaluation of seven hardwoods and analysis of data correlation
Holzforschung, 2014
Wood physical and mechanical properties in seven tropical hardwood species viz., Acacia auriculiformis A. Cunn. ex Benth., Artocarpus hirsutus Lamk., Artocarpus heterophyllus Lamk., Swietenia macrophylla King, Xylia dolabriformis Benth., Hevea braziliensis (H.B.K.) M. A.), and Tectona grandis L.f. have been studied by means of destructive and non-destructive techniques (NDT). Mechanical strength properties and specific gravity were evaluated by conventional methods. NDT was carried out by a Pilodyn and Treesonic Microsecond Timer (TMT) to measure a steel pin penetration depth into wood and dynamic MOE, respectively. In focus was the question, whether NDT data are suitable predictors for physical and mechanical properties of the indicated hardwood species. Dynamic MOE obtained by TMT correlated strongly positive with all the strength properties studied, except shearing stress. TMT data also correlated very well to static bending MOE and MOR. A linear relationship was found between Pi...
The most frequent agents of damages of trees at the sample plots in Serbia
Sustainable Forestry: Collection, 2014
The papers presents the results of the monitoring of damages at 130 sample plots in the grid 16x16 kilometers, which has been continuously conducted in Serbia since 2003. The causes of the damages on the trees can be the consequence of the activity of the series of the adverse agents and owning to it the research of the most significant agents of the damages was made. All damages were classified in the paper by species and types of agents. The occurrence of the mass desiccation of oak forests is to a great extent result of the presence of the agents of powdery mildew. As the example of the use of the data from the database, the spatial arrangement of the plots with the pedunculate oak (which is our most sensitive species) was determined, as well as the infection of them by the powdery mildew. The strongest attack was reported during 2005 and 2006, when 79.3 % and 77.6% of the observed trees was infected. The critical month for the occurrence of the intensive infections by the powdery mildew in Serbia is the first half of July, which is important for the creation of the programmes aimed at the protection.
Mechanical properties of wood examined by semi-destructive devices
Materials and Structures, 2014
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Annals of Forest Science
& Key message Mechanical acclimation of young poplars (Populus tremula × Populus alba, INRA 717-1B4) submitted to periodic stem bending is mainly driven by compressive strains. Flexure wood and compressive flexure wood exhibit higher mechanical resilience and lower mechanical damage. & Context It is well known that thigmomorphogenesis modulates tree growth and the anatomical structure of wood. However, nothing is known about the mechanical behaviour of the tissues of fresh wood formed under mechanical stimulation. & Aims We investigated the elastic and plastic properties of the fresh wood of young poplar trees (Populus tremula × Populus alba, INRA 717-1B4) submitted to periodic controlled stem bending that mimics the mechanical effect of wind. & Methods For a set of trees, we applied symmetrical bending treatments, which led to the formation of "flexure wood". For another set of trees, asymmetrical bending treatments, including compression (or tension) only, were applied and generated specific wood formation: "compressive flexure wood" and "tensile flexure wood". We investigated the elastic and plastic properties of these woods at the stem and at the local tissue levels. & Results The results revealed that fresh wood formed under compressive treatments is more resistant to damage (damage reduced by 44%) and a higher mechanical resilience (+ 33%), suggesting that this tissue is able to withstand higher mechanical strains than "normal wood". This improvement could explain the higher mechanical strength of the stem to bending (+ 42%). & Conclusion When trees experience repetitive mechanical stimulations, they adjust the plastic plastic behaviour of their wood in a way that improves the mechanical safety. This demonstrates the adaptive benefit of the mechanical acclimation of trees.
Effect of Dimensional Variables on the Behavior of Trees for Biomechanical Studies
Applied Sciences
The dimensional variables of trees play an important role in biomechanical studies that seek to estimate the risk of falls, since they influence their biomechanical behavior in relation to the forces to which they are subjected, and therefore, their safety factor. The aim of this research is to evaluate the effect of dimensional variables of trees on their mechanical behavior. A finite-element model was used to perform linear static analysis. The wood from the tree was considered clean, and the architectural model was based on dimensional variables of species commonly used in urban afforestation in São Paulo, Brazil. Different slenderness, tapering, height, and load level were used to analyze the tree mechanical behavior. The numerical-simulation model facilitates the evaluation of the influence of dimensional parameters of trees on deflections and stresses. The behavior of the deflections varies according to height, diameter, and loading level. Since the model considers the geometr...
Forests
Wood properties have an influence on the safety around the tree itself as well as on actual possibilities of using wood. The article focuses on the wood properties of the Norway spruce (Picea abies (L.) Karst.) in reference to the time since the tree has decayed. The study was conducted among mature tree stands of spruce in Białowieża Forest, where over the last 10 years there has been a weakening of spruce tree stands due to water deficiency which has contributed to the gradation of the European spruce bark beetle (Ips typographus). The study focused on spruce wood of living and healthy specimens as well as the wood of standing trees which has decayed between one and five years before the sample was collected. The findings indicate a gradual decrease in wood properties as time passed since the physiological decay of the tree. Significant differences in the decrease of mechanical wood properties have been observed in trees which had been decayed for 3 years and they should be consid...