Large span timber trusses are usually built with glulam. One problem with large span glulam trusses is that the connections needed to transfer the load between truss members are often complex and expensive. Another issue is transportation. Building large span trusses out of structural timber instead, could be a way of simplifying the connections and at the same time increase the degree of on-site construction and thereby solving the transportation problem.In this study, a total of 18 laboratory tests were performed with the purpose of investigating the tensile strength and the load slip behavior of different connection designs for large span structural timber trusses. Six different test groups corresponding to six different connection designs were tested. The materials used include members made of C24 timber and gusset plates made of birch plywood, aluminum, and steel. Screws were used as fasteners for five test groups and adhesive was used for one group. The influence of different reinforcement techniques including reinforcement screws and added aluminum sheets was studied.The results showed a ductile failure behavior for all test groups except for the group where adhesive was used. However, a decrease of ductility was observed for groups were aluminum sheets were used on the outsides of the mid placed plywood gusset plate. A 12-17 % increase in capacity was observed due to the presence of aluminum sheets. The reinforcement screws had no significant effect on the capacity. However, the presence of reinforcement screws did lead to a reduction in scatter both regarding capacity and stiffness.

No description available.

A major argument for incorporating deciduous tree species in coniferous forest stands is their role in the amelioration and stabilisation of biogeochemical cycles. Current forest management strategies in central Europe aim to increase the area of mixed stands. In order to formulate statements about the ecological effects of mixtures, studies at the stand level are necessary. In a mixed stand of Norway spruce (Picea abies (L.) Karst.) and silver birch (Betula pendula Roth) in the Ore Mountains (Saxony, Germany), the effects of these two tree species on chemical and microbial parameters in the topsoil were studied at one site in the form of a case study. Samples were taken from the O layer and A horizon in areas of the stand influenced by either birch, spruce or a mixture of birch and spruce. The microbial biomass, basal respiration, metabolic quotient, pH-value and the C and N contents and stocks were analysed in the horizons Of, Oh and A. Significantly higher contents of microbial N were observed in the Of and Oh horizons in the birch and in the spruce-birch strata than in the stratum containing only spruce. The same was found with respect to pH-values in the Of horizon and basal respiration in the Oh horizon. Compared to the spruce stratum, in the birch and spruce-birch strata, significantly lower values were found for the contents of organic C and total N in the A horizon. The findings of the case study indicated that single birch trees have significant effects on the chemical and microbial topsoil properties in spruce-dominated stands. Therefore, the admixture of birch in spruce stands may distinctly affect nutrient cycling and may also be relevant for soil carbon sequestration. Further studies of these functional aspects are recommended.

The aim of this study was to investigate if SI from HPR-data from harvesters and soil moisture classes from digital depth to water maps could be used to support site adaption of regenerations within stands. The study was made on pine and spruce stands in central Sweden. The number of plants/ha, plant height, growth and damage were measured at plot level and for these plots also soil moisture classes and SI were derived from digital maps and HPR. The study shows a potential using SI from HPR and depth to water maps for site adaption of regenerations and to vary tree species within stands. Variations of SI and soil moisture are important within stands regarding different tree species establishment, growth and damage. But also, for sites with medium SI were the choice between pine and spruce is not obvious and in stands with a high spread in SI.

Understanding how different processing variables influence wood welded bonds is vital if the technique will ever be used to create engineered lumber without using adhesives. A variation of vibration welding, wood welding uses pressure and friction to bond materials together. During welding, heat causes a softening in the wood, a naturally occurring composite material. This softening leads to fiber entanglement and a bond forms upon cooling. The goal of this research was to investigate several processing aspects of the wood welding procedure. A prototype wood welding machine, designed and fabricated from the ground up, was used to investigate the effects of various welding parameters using birch wood. Wood welds were evaluated on the basis of bond coverage and ultimate shear strength. Four experiments were performed: welding frequency and duration interaction, grain orientation effects, alternative welding completion metrics, and strength development over time. During the wood welding process, three distinct phenomena were repeatedly observed: smoke creation, welding residue formation, and an audible pitch change. The presence of each was recorded for every wood welded specimen and used later in additional data analysis. Investigating each of the welding phenomena was done in an attempt to better characterize when fusion was achieved at the weld interface. ImageTool, an image analysis software package, was used to investigate and quantify the often irregular bonds exposed after shear fracture. The results of the various welding variables were analyzed on the basis of shear strength and bond uniformity. From the birch samples, it was shown that better bonds result from lower welding frequencies and longer welding durations. The grain orientation analysis demonstrated that welding orientation marginally affects the average shear strength of the wood weld. The data from the alternative welding metrics suggests that welding time is not a quality indicator of welding completion (bond coverage). The strength development trials confirmed previous research; wood welds obtain most of their strength in a relatively short period of time. Douglas fir and poplar both proved to be weldable for the first time, but they were sufficiently weaker than birch. When welding was attempted with Douglas fir under similar pressures used for birch, Douglas fir samples would commonly “washboard.” With reduced welding pressure, Douglas fir formed wood welds more easily.

In recent years, concern has grown over the consequences of global warming. The arctic region is thought to be particularly vulnerable to increasing temperatures, and warming is occurring here substantially more rapidly than at lower latitudes. Consequently, assessments of the state of the Arctic are a focus of international efforts. For the terrestrial Arctic, large datasets are generated by remote sensing of above-ground variables, with an emphasis on vegetation properties, and, by association, carbon fluxes. However, the terrestrial component of the carbon (C) cycle remains poorly quantified and the below-ground distribution and stocks of soil C can not be quantified directly by remote sensing. Large areas of the Arctic are also difficult to access, limiting field surveys. The scientific community does know, however, that this region stores a massive proportion (although poorly quantified, soil C stocks for tundra soils vary from 96 to 192 Gt C) of the global reservoir of soil carbon, much of it in permafrost (900 Gt C), and these stocks may be very vulnerable to increased rates of decomposition due to rising temperatures. The consequences of this could be increasing source strength of the radiatively forcing gases carbon dioxide (CO2) and methane (CH4). The principal objective of this project is to provide a critical evaluation of methods used to link soil C stocks and fluxes at the usual scales spanned by the field surveys (centimetre to kilometre) and remote sensing surveys (kilometre to hundreds of kilometres). The soil C distribution of two sub-arctic sites in contrasting climatic, landscape/geomorphologic and vegetation settings has been described and analysed. The transition between birch forest and tundra heath in the Abisko (Swedish Lapland) field site, and the transition between mire and birch forest in the Kevo (Finnish Lapland) field site span several vegetation categories and landscape contexts. The natural variability of below-ground C stocks (excluding coarse roots > 2 mm diameter), at scales from the centimetre to the kilometre scale, is high: 0.01 to 18.8 kg C m-2 for the 0 - 4 cm depth in a 2.5 km2 area of Abisko. The depths of the soil profiles and the soil C stocks are not directly linked to either vegetation categories or Leaf Area Index (LAI), thus vegetation properties are not a straightforward proxy for soil C distribution. When mapping soil or vegetation categories over large areas, it is usually necessary to aggregate several vegetation or soil categories to simplify the output (both for mapping and for modelling). Using this approach, an average value of 2.3 kg C m-2 was derived both for soils beneath treeless areas and forest understorey. This aggregated value is potentially misleading, however, because there is significant skew resulting from the inclusion of exposed ridges (with very low soil C stocks) in the ‘treeless’ category. Furthermore, if birch trees colonise tundra heath and other ‘open’ plant communities in the coming decades, there will likely be substantial shifts in soil C stocks. This will be both due to direct climate effects on decomposition, but also due to changes in above- and below-ground C inputs (both in quantity and quality) and possibly changes in so-called root ‘priming’ effects on the decomposition of existing organic matter. A model of soil respiration using parameters from field surveys shows that soils of the birch forest are more sensitive to increases in mean annual temperature than soils under tundra heath. The heterogeneity of soil properties, moisture and temperature regimes and vegetation cover in ecotone areas means that responses to climate change will differ across these landscapes. Any exercise in upscaling results from field surveys has to indicate the heterogeneity of vegetation and soil categories to guide soil sampling and modelling of C cycle processes in the Arctic.

No description available.

The nineteenth century in Germany posed a repressive environment for-women as they were defined as inferior to men and forced into the subservient roles of housewives and mothers. This thesis examines the portrayal of femininity in three contemporary writers of the period, Louise Aston, Charlotte Birch-Pfeiffer and Louise von Francois. The first chapter endeavors to situate the writers in their social environment. It examines the mechanics that supported the patriarchal system, such as socializing women through education and categorizing them as inferior to justify and support their traditional roles. Chapters two, three, and four respectively deal with each author, presenting an introduction to their particular conditions and a brief summary of their lives. Following this, the individual tests are analyzed for their portrayal of femininity. These writers' visions of femininity differ greatly. Aston, whose career spanned the revolution of 1848, openly promotes liberal-humanist ideas and advocates the emancipation of women. Her heroines bear male an female traits and rise to positions of power and leadership. Birch-Pfeiffer's women are strong and independent. She frequently reverses the traditional gender roles. However, she upholds the moral code of her time, including the idea of the woman as exemplar of chastity and virtue . Francois idealizes the traditional role of women. However, she elevates that role by extolling motherhood and marital fidelity as supreme virtues. Despite these differences, there are similarities. All three writers offer an alternative picture of femininity despite this adherence, to a greater or lesser degree, to the traditional values of their time. In addition, they all criticize the patriarchal structures of society, revealing their discontent more or less openly. Finally, their portrayal of femininity was in each case based on their particular circumstances of the individual writers lives. Aston exploited the revolutionary times to present a strong claim for female emancipation; Birch- Pfeiffer, in need o f money, adapted strongly to the taste of her audience, finding in turn, interested recipients for her ideas; and Francois, a very private and proud person, chose to upgrade the women's role within the tradition, in attempt to avoid public attention. Within their circumstances, each one of the authors presented the best possible version of femininity as an alternative to traditional values.

Aim of the work: to explain possibilities of natural birch regeneration if clearcut areas, to detect main influencing factors and their intensity. Object of the work: Clearcut areas from 1996, 1999 and 2002 of site types Lfs and Lds of Pakruojis State Forest Enterprise. Methods: for analysis of regeneration quality, rectangular sample plots were selected. They were placed in the clearcut areas 20, 40 and 60 metres from their western edge. The density, height and age of sapling according to tree species was determined. Saplings were evaluated according to their growth conditions: prepared or unprepared soil. Dependence of saplings density on the stand from western side as well as dependence saplings density and height on precedent stand was investigated. Research data was processed using methods of dispersive and regression analysis. Results: it was determined, that regeneration of birch depends on site type and precedent stand, soil preparation, stand from western site of the clearcut. Soil preparation, stand from western site of the clearcut have the biggest influence on birch saplings density. Height of birch saplings depends on soil preparation and soil type. Distance from stand edge have no influence on birch natural regeneration.

Sewage sludge could be used in forestry as enrichment of soil properties. It is also expected that sewage sludge which is rich in phosphorus, nitrogen and organic material can enhance the growth of tree seedlings in poor soils. Our study was performed in Taruskos experimental forest site in Panevezys region. The experimental site amended with industrial sewage sludge ten years ago was afforestated with birch and pine seedlings. The aim of our thesis is to evaluate the influence of sewage sludge to trees development after long time period. To reach our goal we have assessed three aspects: i) amended with sewage sludge and control (untreated) soil properties, ii) biomass and morphological parameters (functional traits) of trees in control and amended with sewage sludge sites, iii) Cu, Cd and Pb concentrations in both soil and tree compartments. In modelling part was used Phyto DSS model for evaluation heavy metals accumulation rate in tree seedlings and biomass growth. In the end of our study we suggest tree functional traits which could be used to evaluate sewage sludge application positive and negative aspects. In addition, we excepted one tree specie which planting in contaminated site would be the most economically and environmentally relevant. Thesis structure: Introduction; Heavy metals and tree growth; Methodology of soil and trees measurements; Results and analysis; Soil – tree system modeling; Conclusions and suggestions; references. Thesis consist of: 76 p. text... [to full text] / Tiriamojo darbo pagrindinis tikslas įvertinti pušų ir beržų augimo ypatumus augant nuotekų dumblu patręštoje vietoje. Atlikti beržų ir pušų medelių palyginamieji tyrimai nuotekų dumblu patręštoje vietoje su medeliais augusiais natūraliomis sąlygomis. Taip pat įvertintas dirvožemio bei medelių užterštumas sunkiaisiais metalais. Atliktas modeliavimas su Phyto DSS programa ir įvertintas sunkiųjų metalų kaupimąsis medžiuose bei biomasės prieaugis. Darbo gale pateiktos rekomendacijos kokius medelių funkcinius parametrus pasirinkti vertinant nuotekų dumblo panaudojimo teigiamasias bei neigiamasias savybes. Taip pat išskirta medžių rūšis, kurios auginimas užterštoje teritorijoje būtų efektyvesnis tiek aplinkosauginiu tiek ekonominiu požiūriu. Darbą sudaro 8 dalys: Įvadas; Sunkieji metalai ir medžių augimas; Dirvožemio ir medžių tyrimų metodika; Rezultatai ir jų analizė; Dirvožemio – medžio sistemos modeliavimas, Išvados ir siūlymai; Literatūros sąrašas. Darbo apimtis – 76 p. teksto be priedų, 44 iliustr., 16 lent., 90 bibliografiniai šaltinių. Atskirai pridedami darbo priedai.