Academic literature on the topic 'Wood accumulation'

Transported large wood (LW) in rivers may block at river infrastructures such as bridge piers and pose an additional flood hazard. An improved process understanding of LW accumulations at bridge piers is essential for a flood risk assessment. Therefore, we conducted a field study at the River Glatt in Zurich (Switzerland) to analyze the LW accumulation process of single logs at a circular bridge pier and to evaluate the results of previous flume experiments with respect to potential scale effects. The field test demonstrated that the LW accumulation process can be described by an impact, rotation, and separation phase. The LW accumulation was described by combining two simplified equilibria of acting forces and moments, which are mainly a function of the pier diameter, pier roughness, and flow properties. We applied the resulting analytic criterion to the field data and demonstrated that the criterion can explain the behavior of 82% of the logs. In general, the field observations confirmed previous results on the LW accumulation probability in the laboratory, which supports the applicability of laboratory studies to investigate LW–structure interactions.

A novel experimental setup for the laboratory was designed in order to investigate large woody debris accumulations and their influence on hydraulic flow conditions and channel morphology at a river cross-section. Real wood and mobile gravel bedload material were used to simulate morphodynamic interactions in a headwater stream, based on a New Zealand prototype river. The survey methodology employs Structure from Motion techniques, using an advanced multi-camera-array. In this study we present the experimental setup and initial results from our first experiments. With this research project we aim to investigate the dynamics of jam initiation and the characteristic evolution of the jam, for a given discharge, sediment load, and distribution of woody material. Furthermore, this study will elaborate more practical and efficient methodologies for observing wood jams, both in the laboratory and in the field. The project expands current knowledge about interaction processes between flow, sediment and woody debris, which are presently poorly understood and still represent a gap in research.

It is shown that the chemical composition of the litter falls and wood of deciduous and coniferous trees is different. On the background of aerotechnogenic pollution, accumulation of individual heavy metals, an increase in ash content was noted. There was revealed the anthropogenic dynamics of the accumulation of heavy metals in the wood of trees: the maximum number during the period of diesel traction; as the railway site is electrified, the accumulation of elements decreases. The obtained data can be recommended to be used for phytoremediation at sites subject to pollution. The obtained data will be the basis for assessing the phytoextractive potential of woody plants, in diagnosing aero-technogenic pollution of the environment, solving the problem of reducing environmental risks, as well as during the modernization and planning of environmental measures in the field of railway infrastructure.

It is well known that wood structural members can stand a relatively heavy load in the short term but will gradually get weaker if the load is applied for a longer period. This phenomenon is caused by the damage accumulation effect in wood and should be appropriately considered during the design of timber structures. Although various formulation methods (also known as classical models) have been proposed to evaluate the damage accumulation effect in wood, the calibration of model parameters is very time-consuming. Our work proposes a novel method to deal with the damage accumulation effect in wood that involves the application of machine learning algorithms. The proposed algorithm considers a multi-objective optimization process with a combination of goodness-of-fit and complexity. Long-term experimental data of typical wood species are used for developing the machine learning based damage accumulation model. Compared with existing pre-formulated models, our model managed to reduce the complexity of the model structure and give sufficiently accurate and unbiased predictions. This study aims to provide a novel tool for evaluating the damage accumulation in wood structural members, and the proposed model can further support the life-cycle performance assessment of timber structures under long-term service scenarios.

The amount and annual net accumulation of above-ground dead woody material were quantified in a tropical deciduous forest in western Mexico. Three plots were located within a small watershed (16 ha) and distributed along a 150-m-elevation gradient (Upper, Middle and Lower plot). Total amount of above-ground dead phytomass (fine + coarse) was 27.2 Mg ha-1. Coarse dead category (branches + logs) made up 70.6% (19.2 Mg ha-1) of the total. The rest comprised the fine fraction, which was lying on the forest floor as surface litter. Of the total coarse dead woody mass, 70.8% was standing, hanging or still attached to live trees (13.6 Mg ha-1). Dead wood net accumulation was 6.6 Mg ha-1 y-1; 58% of this was coarse woody material and the rest comprised the fine litterfall fraction. The amount of standing, hanging/attached dead branches (2-20 cm circumference) varied significantly among plots, with the highest value in the Upper plot. Dead wood net accumulation was similar between the Upper and Middle plots, and significantly higher than the Lower plot. Compared to the intact canopy, the removal of dead mass (hanging/attached dead branches and standing dead logs) caused a significant decrease in throughfall nutrient concentration and nutrient flux by this pathway.

Relevance. The native forests can be recognized as endangered formations of the European North of Russia. They are benchmarks of forest sustainability for comparative assessment with forests of other origin and use, what determines the relevance of research on their structural features. The purpose of the research is to conduct a comparative assessment of dynamic processes in the native forests of spruce formations of the southern taiga subzone of various successional positions (phases of dynamics) in the time trend of their development. Material and methods. Native spruce forests of different ages of the southern taiga subzone of the Central Forest Biosphere Reserve (Tver region) and the Kologrivsky Forest Reserve (Kostroma region) were researched various dynamic characteristics and successional position — climax, demutation, digressive. In the biogeocenoses of the sample areas, the age of trees and the presence of rot were determined, age series were built, the volumes of trees in age generations were calculated. All the tree fractions of the analyzed spruce forests were arranged in one time series: stands, current tree fall and deadfall — from retrospective values (– 60 years) to prospective values of the age limit of trees of the first generations of stands (+ ~ 300 years). The processes of dynamics of volumes of the wood fraction of native spruce forests of various successional positions in a long time space with different rates of accumulation and decomposition of wood biomass are described. Results and discussion. The processes of accumulation of biomass and the formation of age structures of biogeocenosis are 4 to 7 times slower than the processes of decomposition of the dying biomass of woody decay. Wood-destroying fungi of the saprotrophic complex “adjust” the activity of the decomposition process of wood decay to the dynamics of wood accumulation by the stand, maintaining the balance of accumulation and decomposition of woody biomass in the forest community. The correlation dependence of the increase in the values of tree infestation with wood-destroying fungi in age generations with an increase in their age is expressed in correlation coefficients from r — 0.89 at mr — 0.07 and t — 11.8 (spruce grove 1) to 0.99 at mr — 0.004 and t — 245 (spruce grove 4). The connection in both cases is very high, almost functional, which can be interpreted as a pattern. Conclusion. In native virgin forests, the balance of reproducible and decomposable wood is preserved as one of the most important criteria for the sustainable functioning of forest communities. This position can be regarded as an important fact of the evolutionary functional structure of forests.