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Les sols forestiers constituent un réservoir considérable d’éléments nutritifs disponibles pour soutenir la productivité forestière. Ces sols contiennent aussi une quantité, encore inconnue à ce jour, d’éléments traces biodisponibles provenant de sources anthropiques ou naturelles. Or, plusieurs de ces éléments recèlent un potentiel toxique pour les organismes vivants. Ainsi, la quantification de la concentration et du contenu total en éléments traces des sols forestiers s’avère nécessaire afin d’évaluer les impacts des perturbations sur la qualité des sols. Les objectifs de ce projet de recherche sont: 1) de mesurer le contenu total en éléments traces en phase solide (Ag, As, Ba, Cd, Ce, Co, Cr, Cu, Mn, Ni, Pb, Rb, Se, Sr, Tl, V, Y, Zn) des divers horizons de sols d’écosystèmes forestiers du Québec méridional; 2) d’établir des liens significatifs entre la fraction soluble dans l’eau des éléments traces et les propriétés des horizons de sols et; 3) d’évaluer le rôle de la proximité d’un centre urbain sur les contenus en éléments traces. Pour répondre à ces objectifs, quatre profils de sols situés dans la région de St-Hippolyte et deux situés dans la région de Montréal furent échantillonnés jusqu'à l'atteinte du matériel parental. Les résultats de ce projet de recherche ont révélé que le contenu total en éléments traces présents dans les profils de sols se retrouve en grande partie dans les fragments grossiers du sol. Il a été démontré que la teneur en carbone organique, les complexes organométalliques et les oxydes de fer et d’aluminium dictent la distribution en profil de la majorité des éléments traces étudiés. Finalement, il fut prouvé que la région de Montréal présente des niveaux de contamination en éléments traces (Ag, As, Ba, Cu, Mn, Pb, Rb, Se, Sr, Tl et Zn) supérieurs à ceux rencontrés dans les Laurentides. / Forest soils represent an important stock of nutrients available to sustain forest productivity. They also contain an amount, still unknown, of trace elements inherited from natural or anthropogical sources. Many of these trace elements can be toxic to living organisms. Thereby, quantification of the concentration and the total content of trace elements in forest soils is necessary to asses the impact of these elements on soil quality. The specific objectives of this research project are: 1) to measure the total content of trace elements in solid phase (Ag, As, Ba, Cd, Ce, Co, Cr, Cu, Mn, Ni, Pb, Rb, Se, Sr, Tl, V, Y, Zn) of various soil horizons in two forest ecosystems of southern Quebec, 2) to establish significant correlations between the bioavailable fraction (water-soluble) of trace elements and soil horizons properties and 3) to compare the trace element stock of two Canadian Shield’s forest soil with those of similar soils situated in the Montreal area. To achieve these goals four soil profiles situated in the pristine region of St-Hippolyte and two in the urban area of Montréal, were excavated down to the parent material. The results of this research have established that the trace element’s total stock is mainly concentrated in coarse fragments of the soil. Multivariate statistical analyses revealed significant links between organic carbon, organometallic complexes as well as Fe-Al oxides and the distribution of trace element in soil profiles. Finally, it was proved that Montreal’s soil contained more trace element (Ag, As, Ba, Cu, Mn, Pb, Rb, Se, Sr, Tl et Zn) than Canadian Shield’s soils.

The aim of this diploma thesis was to carry out an analysis of current use of horses in forestry within the South Bohemian region. The diploma thesis contains a brief introduction to the breeding of cold-blooded horses in the Czech Republic, the conditions for breeding cold-blooded horses, the basics of training and harnessing of cold-blooded horses, a description of work done by the horse in a forest and last but not least the thesis presents the issue of causing damage on forest vegetation, soil and soil water while gathering wood. The analysis of common use of horses in forestry has been carried out via the survey method and personal visits. Evaluation and subsequent information analysis was carried out with the focus on the economic side of using horses in forestry and on the estimate of the perspective of their further use. Simplified maps of the South Bohemian Region are a part of the diploma thesis, portraying stables where there are working horses being boarded and capturing possible locations where horses may be used for forestry purposes.

Nitrogen availability and transformation in acidified and N saturated soils of Czech (The Bohemian Forest, Ore Mountains) and Ukraine (Pop Ivan massif) mountain forest ecosystems were investigated. The study was primarily focused on the role of microbial immobilization in soil N retention. The study was based on field measurements (ion exchange resins), analyses of selected soil biochemical and microbial characteristics, and on laboratory experiments (15N labelling).

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Soil compaction has been becoming one of the main impacts caused by the activities of mechanized harvesting. The weight and movement of machines at the time of cutting and loading of timber combined with the not appropriate moisture condition of the soil are the main causes of soil structural degradation, observed mainly by changes in soil physical properties. Thus, this study aimed to identify soil compaction caused due to forest harvesting stages of Pinus taeda L. performed on three different soil moistures. A study in the city of Quedas do Iguaçu in southwestern Paraná was carried out in pine stands of Araupel S/A company. The research was assessed as completely randomized in and sub-subdivide plots with five replications. The eighteen treatments consisted of the interaction of three factors, namely: moisture (rainy day harvesting and 3 and 7 days after rain); harvesting operations (machine traffic (MT); no machine traffic (NMT) and timer landing (TL)); and time of collection (before and after harvest), being major plot, subdivided plots, and sub-subdivided plots in time, respectively. Soil under a native forest adjacent to the experiment was evaluated to infer on the changes caused to the soil regarding its cultivation and management. Results indicated that the difference in soil moisture represented by the different days of harvest after a rain did not influence differently the soil compaction. On the other hand, harvesting operations (MT, NMT and TL) impacted soil to a depth of 10 cm causing compaction on the traffic lines of the machines, while the eventual falling trees at the time of cutting and timber landing did not cause changes in density, macroporosity and resistance to penetration. The residual biomass from forest harvesting was essential to minimize soil compaction caused by machinery traffic that was close to the maximum. Comparison of physical parameters of soil under native forest and pine stand showed that planting and management of soils covered by natural forests alter the physical properties of the surface until 30 cm of depth. / A compactação vem se tornando um dos principais impactos causados ao solo pelas atividades de colheita florestal mecanizada. O peso e a movimentação das máquinas no momento do corte e extração da madeira, aliada à condição de umidade do solo imprópria para tal são as principais causas da degradação estrutural do solo, verificada principalmente por alterações em suas propriedades físicas. Nesse sentido, este trabalho objetivou identificar a compactação causada devido às etapas de colheita florestal de Pinus taeda L. realizada em três diferentes umidades do solo. O estudo foi realizado no município de Quedas do Iguaçu, em povoamento da empresa Araupel S/A. A pesquisa foi avaliada como delineamento inteiramente casualizado em parcelas sub-subdivididas, com dezoito tratamentos e cinco repetições. Os tratamentos foram compostos pela interação de três fatores, sendo eles: umidade (colheita em dia de chuva, três dias após a chuva e sete dias após a chuva), operações de colheita (com passagem de máquinas (CP), sem passagem de máquinas (SP) e estaleiro (E), e a ocasião de coleta (antes e depois da colheita), sendo respectivamente, parcela principal, parcelas subdivididas e parcelas sub-subdivididas no tempo. O solo sob uma floresta nativa adjacente ao experimento foi avaliado para inferir sobre as alterações provocados no solo pelo cultivo e manejo do mesmo. Os resultados obtidos indicam que a diferença de umidade no solo, representada pela colheita em diferentes números de dias após uma chuva, não influenciou de maneira diferenciada na compactação do solo. Por outro lado, as operações de colheita (CP, SP e E) impactaram o solo até a profundidade de 10 cm, causando a compactação nas linhas de tráfego das máquinas, enquanto que a eventual queda de árvores no momento do corte e o empilhamento de toras não provocaram alterações na densidade, macroporosidade e resistência a penetração. A biomassa residual da colheita florestal foi essencial para minimizar a compactação do solo causada pelo tráfego das máquinas que foi próxima da máxima. A comparação de parâmetros físicos do solo sob mata nativa e povoamento de pinus mostrou que o cultivo e manejo de solos que um dia foram cobertos por florestas naturais provoca alterações nas propriedades físicas do solo da superfície até 30 cm de profundidade.

Le chlorométhane (CH3Cl) est un composé organique volatile responsable de plus de 15 % de la dégradation de l’ozone stratosphérique due aux composés chlorés. Il est produit majoritairement par les plantes vivantes ou en décomposition. Les bactéries capables d’utiliser le CH3Cl comme source de carbone pour leur croissance peuvent jouer un rôle de filtre dans les émissions de CH3Cl vers l'atmosphère. Ce processus biologique reste à quantifier dans l'environnement, notamment pour les sols forestiers considérés comme un puits majeur de ce composé.Dans les études environnementales, le gène cmu A est utilisé comme biomarqueur de la dégradation bactérienne du CH3Cl. Il code une chlorométhane méthyltransférase essentielle à la croissance bactérienne avec le CH3Cl parla voie cmu (pour chloromethane utilisation), la seule caractérisée à ce jour. Mon projet de thèse avait un double objectif : i) l’approfondissement des connaissances de l’adaptation au CH3Cl chez une bactérie méthylotrophe modèle, Methylobacterium extorquens CM4; ii) l’exploration de la diversité des bactéries CH3Cl-dégradantes de sols forestiers. L’étude RNAseq chez la souche CM4 a montré que la croissance avec le CH3Cl s'accompagne de différences dans la transcription de 137 gènes de son génome (6.2 Mb) par rapport à sa croissance sur le méthanol (CH3OH). Les gènes de la voie cmu, ainsi que d’autres gènes impliqués dans le métabolisme de cofacteurs essentiels à l’utilisation du CH3Cl par cette voie et eux aussi portés par le plasmide pCMU01 de la souche, en font partie. Les paralogues de ces gènes localisés sur le chromosome ne sont quant à eux pas différentiellement exprimés. En revanche, d’autres gènes du chromosome, potentiellement impliqués dans l’excrétion de protons produits lors de la déshalogénation (hppA), la régénération du NADP+ (pnt), ou le métabolisme du cofacteur tétrahydrofolate(gènes gcvPHT), le sont. L’étude de la diversité des bactéries CH3Cl-dégradantes de sol forestier de la réserve naturelle de Steigerwald (Allemagne) a été réalisée sur des microcosmes par une approche de « Stable Isotope Probing ». Les microorganismes capables d’assimiler le CH3Cl marqué au [13C] incorporent cet isotope lourd du carbone dans leur ADN. L'analyse des séquences amplifiées par PCR des gènes codant l’ARN 16S des fractions d'ADN enrichies en [13C] a permis de mettre en évidence de nouveaux phylotypes, du genre Methylovirgula et de l’ordre des Actinomycetales, distincts de ceux auxquelles les souches dégradant le CH3Cl isolées jusqu'ici sont affiliées. En revanche, les séquences du gène cmuA et d’autres gènes du métabolisme méthylotrophe obtenues par PCR à partir de l'ADN enrichi en [13C] sont très proches de celles des souches CH3Cl-dégradantes connues. Les résultats obtenus suggèrent ainsi que des bactéries ayant acquis par transfert horizontal les gènes de dégradation de la voie cmu ou ne possédant pas de gène cmuA contribuent au filtrage biologique du CH3Cl des sols forestiers. A l'avenir, le couplage de différentes méthodes moléculaires et des approches culturales visera à découvrir de nouvelles voies microbiennes de l’utilisation du CH3Cl, et à caractériser l’abondance et la diversité des métabolismes impliqués dans la dégradation du CH3Cl dans les sols et d'autres compartiments environnementaux. / Chloromethane (CH3Cl) is a volatile organic compound responsible for over 15% of stratospheric ozone degradation due to chlorinated compounds. It is mainly produced by living and decaying plants. Bacteria utilizing CH3Cl as sole carbon and energy source for growth were shown to be involved in the filtering of CH3Cl emissions to the atmosphere. This biological process remains to be quantified in the environment, especially for forest soil, a major CH3Cl sink. The cmuA gene is used as a biomarker of bacterial CH3Cl degradation in environmental studies. It encodes a CH3Cl methyltransferase essential for bacterial growth by the cmu (chloromethane utilization) pathway for growth with CH3Cl and the only one characterized so far. My thesis project had a double aim: i) In depth studies of CH3Cl adaptation of a model methylotrophic bacterium, Methylobacterium extorquens strain CM4; ii) Exploration of bacterial CH3Cl-utilizers in forest. An RNAseq study of strain CM4 has shown that growth with CH3Cl leads to a difference of transcription of 137 genes in its 6.2 Mb genome compared to growth with methanol (CH3OH). Among those, genes of the cmu pathway and other genes involved in the metabolism of essential cofactors for CH3Cl utilization by this pathway, are all plasmid pCMU01-encoded. Paralogous genes located on the chromosome were not differentially expressed. On the other hand, other chromosomal genes potentially involved in extruding protons generated during CH3Cl deshalogenation (hppA), NADP+ regeneration (pnt), or in the cofactor tetrahydrofolate metabolism (gcvPHT) were differentially expressed. The diversity of CH3Cl-degrading bacteria in forest soil of the German natural park of Steigerwald was studied in microcosms using stable isotope probing. Microorganisms able to assimilate labeled [13C]- CH3Cl incorporate this heavy carbon isotope in their DNA. Sequence analysis of the PCR-amplified 16S RNA encoding gene from [13C]-DNA fractions uncovered phylotypes of the genus Methylovirgula and of the order of the Actinomycetales, which were not associated with bacterial CH3Cl degradation so far. In contrast, PCR-amplified sequences of cmuA and other genes of methylotrophic metabolism were closely related to known CH3Cl-degrading isolates. These results suggest that bacteria containing genes of the cmu pathway acquired by horizontal gene transfer as well as bacteria lacking the cmu pathway contribute to biological filtering of CH3Cl in forest soil. Future experiments coupling molecular and culture methods will aim to discover new CH3Cl-degrading pathways and to characterize the abundance and diversity of CH3Cl-degradation metabolism in soil and other environmental compartments.

Soil erosion by water is a main form of land degradation worldwide. The problem has been addressed, among others, in the United Nations Sustainability Goals. However, for mitigation of erosion consequences and adequate management of affected areas, reliable information on the magnitude and spatial patterns of erosion is needed. Although such need is often addressed by erosion modelling, precise erosion monitoring is necessary for the calibration and validation of erosion models and to study erosion patterns in landscapes. Conventional methods for quantification of rill erosion are based on labour-intensive field measurements. In contrast, remote sensing techniques promise fast, non-invasive, systematic and larger-scale surveying. Thus, the main objective of this study was to develop and evaluate automated and transferable methodologies for mapping the spatial extent of erosion rills from a single acquisition of remote sensing data. Data collected by an uncrewed aerial vehicle was used to deliver a highly detailed digital elevation model (DEM) of the analysed area. Rills were classified by two methods with different settings. One approach was based on a series of decision rules applied on DEM-derived geomorphological terrain attributes. The second approach utilized the random forest machine learning algorithm. The methods were tested on three agricultural fields representing different erosion patterns and vegetation covers. Our study showed that the proposed methods can ensure recognition of rills with accuracies between 80 and 90% depending on rill characteristics. In some cases, however, the methods were sensitive to very small rill incisions and to similar geometry of rills to other features. Additionally, their performance was influenced by the vegetation structure and cover. Besides these challenges, the introduced approach was capable of mapping rills fully automatically at the field scale and can, therefore, support a fast and flexible assessment of erosion magnitudes.

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Understanding of carbon cycling in coniferous forests that represent a large carbon sink is crucial for our understanding of natural processes under global climate change. Recognition of fungi as fundamental decomposers can contribute to this understanding. Fungi are able to decompose numbers of substrates and possess a variety of enzymes to do so In this study I present litter decomposing fungi in mountain spruce forest from national park Šumava. The aim of my thesis was to follow succession and community changes of fungi from the early stages of decomposition of Picea abies needles until degradation of organic matter in the organic horizon of the soil. This aim was accomplished partly by recording the extracellular enzyme production of fungi in different stages of decomposition from needles attached to the twigs of a fallen tree to a litter material in later stages of decomposition on the soil surface. In addition to testing of fungi on their natural substrata - needle litter, enzyme activities were also measured in laboratory agar cultures, which allow comparison of diverse fungi with different origins. Enzyme activities were aimed at enzymes decomposing cellulose and compounds found in litter. Although ecology of endophytic and saprothrophic fungi suggest differences in enzyme production, these...

The aim of the diploma thesis was to evaluate the content of soil organic carbon in the area of Novohradsko. Soil organic carbon was monitored in its stable (SOC) and labile (WSOC) form, followed by the total organic carbon stock (Cpool). These soil parameters were determined in soils of different land cover types (forest, arable land, grassland) in the area formed by the catchments of Pasecký, Bedřichovský, Váčkový and Veverský stream. Data obtained in 2001, 2007 and 2014 were statistically analysed and the comparison of the data from different catchments was conducted. The results show the impact of different land use on the amount of soil organic carbon. In general, a higher amount of soil organic carbon were found in soils of grassland and forest soils, whereas a lower amounts were found in arable land. The comparison and the time development analysis show that there is a trend of the increase in quantity of stable fraction of soil organic carbon in all categories of land cover over the whole monitored period. The opposite trend of a continuous decrease over the whole of the monitored period in all categories of land cover was observed in amounts of labile fraction of soil organic carbon. It can be said that there is an increase in the stock of a stable fraction of soil organic carbon due to lower losses of the labile fraction of soil organic carbon in forest soils, arable soils and soils of grassland.