The impact of a chromium smelter on pollution was evaluated by determining Cr(VI) in topsoil, grass and tree bark by electhrothermal atomic absorption spectrometry (ETAAS). It was found that bark reflected the levels of air pollution better than soil and grass due to its high accumulative ability of Cr(VI). The tree bark was contaminated with Cr(VI) by a factor of 9 than in soil. It is therefore suggested that the bark be used as an indicator of air pollution for long-term exposure. The concentration of Cr(VI) in the bark was always a fraction of the total concentration of Cr and ranges between 1.6 and 3%. The method used in the preparation of samples was validated by the analysis of certified reference materials.

In the forestry industry tree trunks are currently classified manually. The object of this thesis is to answer whether it is possible to automate this using modern computer hardware and image-classification of tree-trunks using machine learning algorithms. The report concludes, based on results from controlled experiments that it is possible to achieve an accuracy above 90% across the genuses Birch, Pine and Spruce with a classification-time per tree shorter than 500 milli seconds. The report further compares these results against previous research and concludes that better results are probable.

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This diploma thesis was focused on the community ecology of corticolous subaerial cyanobacteria and algae. Altogether 54 morphotypes were identified on the surface of the tree bark in the Nature Reserve Březina in České středohoří Mts., Czech Republic. Compared to publish data on tropical and subtropical habitats, high morphological diversity of these organisms in a temperate region was thus recognized. Coccoid green algae - most of them belonging to the class Trebouxio-phyceae - dominated. In a study focused on the algae community structure at small spatial scales (such as a single tree trunk), the temporal factors were found as the most important factor influencing the species composition. The height of a sample on trunks and type of bark roughness seemed to influence the species richness, yet the differences were not significant. The alpha-diversity and species composition of corticolous algal communities among individual trees were strongly influenced by host tree species. The pH of the bark surface also had significant impact on species composition. Generally, trees with lower pH of the bark surface (alder, spruce) had lower species richness, whereas trees with more alkaline bark surface (ash, beech, maple) had higher alpha-diversity values. Considering the generally efficient dispersal ability of...

The aim of this study was to contribute to the comprehension of the connection of element uptake in trees at the Laacher See in Germany and climatic parameters on different time scales. Understanding the relationship of certain elements in trees and temperature might enable the assignment of extraordinary high peaks in the elemental concentration, which cannot be explained by temperature, to another process as CO2 degassing of the mofettes, which are relics of the volcanic past of the lake. Beech and oak trees at the Laacher See are not growing close to their climatic distribution limit. The relationship between tree-ring width and temperature might be not distinct enough and therefore insufficient to reconstruct climate back in time based on typical dendrochronological methods. Increasing temperatures affect the production of biomass and the release of elements in the soil. These elements are taken up by roots of trees and are implemented in yearly forming tree-rings. Using elements in tree-rings is discussed to be an alternative method for the reconstruction of climate back in time. However, there is an ongoing debate about dendrochemical methods as it is still not clear how much the resolution of the results is affected by translocation of elements between tree-rings. In this study, tree-cores of living beech and oak trees, sampled 2020, have been measured using an energy dispersive x-ray fluorescence technique (ED-XRF), which is a non-destructive method for multi-element analysis. Eleven elements (Ca, Co, Cu, Cr, Ge, Fe,K, Mn, Ni, Sc, Zn) and three elemental ratios (K/Ca, Ca/Mn, Fe/Mn) have been found to show significant positive or negative correlations in the time period from 1901 to 2018 between their concentration in tree-rings and temperature. Since Cu, Ge and K also show significant correlations with temperature in 10-year periods, higher mobility between tree-rings is assumed for those elements. Low mobility is suggested for the elements Ca and Mn as their concentration in the bark and in the wood shows little correlation. Low mobility indicated by significant correlations between elements and yearly temperature or a lack ofcorrelation between the concentration in the bark and in the wood, makes elements more suitable as indicators for temperature. However, the explanation of element concentration in tree-rings is complex, as elements are influencing each other. Antagonistic behaviour has especially been observed for the elements Ca, Co, Ge, Fe, K, Mn, Ni and Sc. These elements are showing significant correlations with temperature as well, which reveals the dependency of elemental concentrations on more than one variable. Furthermore, acidic soil at the study site might be caused by elevated CO2 concentrations, which originate from mofettes. Increasing concentrations of Fe and Ca in tree-rings give indication for decreasing soil pH. Acidification is a contrary process to temperature increase, as it generally reduces the microbial activity and therefore the availability of nutrients.

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