Die Landschaften Mitteleuropas sind das Resultat einer langwierigen Geschichte menschlicher Landnutzung mit ihren unterschiedlichen, z.T. konkurrierenden Nutzungsansprüchen. Durch eine überwiegend intensive Beanspruchung haben die direkten und indirekten Auswirkungen der Landnutzung in vielen Fällen zu Umweltproblemen geführt. Die Disziplin der Landschaftsökologie hat es sich zur Aufgabe gemacht, Konzepte für eine nachhaltige Nutzung der Landschaft zu entwickeln. Eine wichtige Fragestellung stellt dabei die Abschätzung der möglichen Folgen von Landnutzungsänderungen dar.<br /> Für die Analyse der relevanten Prozesse in der Landschaft werden häufig mathematische Modelle eingesetzt, welche es erlauben die Landschaft unter aktuellen Verhältnissen oder hinsichtlich veränderter Rahmenbedingungen zu untersuchen. Die hypothetische Änderung der Landnutzung, die als Landnutzungsszenario bezeichnet wird, verkörpert eine wesentliche Modifikation der Rahmenbedingungen, weil Landnutzung maßgeblich Einfluss auf die natürlichen Prozesse der Landschaft nimmt. Während die Antriebskräfte einer solchen Änderung überwiegend von sozio-ökonomischen und politischen Entscheidungen gesteuert werden, orientiert sich die exakte Verortung der Landnutzungsänderungen an den naturräumlichen Bedingungen und folgt z.T. erkennbaren Regeln. Anhand dieser Vorgaben ist es möglich, räumlich explizite Landnutzungsszenarien zu entwickeln, die als Eingangsdaten für die Modellierung verschiedener landschaftsökologischer Fragestellungen wie z.B. für die Untersuchung des Einflusses der Landnutzung auf den Wasserhaushalt, die Erosionsgefahr oder die Habitatqualität dienen können. <br /> <br /> Im Rahmen dieser Dissertation wurde das rasterbasierte deterministische Allokationsmodell luck (Land Use Change Scenario Kit) für die explizite Verortung der Landnutzungsänderungen entwickelt. Es basiert auf den in der Landschaftsökologie üblichen räumlichen Daten wie Landnutzung, Boden sowie Topographie und richtet sich bei der Szenarienableitung nach den Leitbildern der Landschaftsplanung. Das Modell fußt auf der Hypothese, dass das Landnutzungsmuster als Funktion seiner landschaftsökologischen Faktoren beschrieben werden kann. Das Veränderungspotenzial einer Landnutzungseinheit resultiert im Modell aus einer Kombination der Bewertung der relativen Eignung des Standortes für die jeweilige Landnutzung und der Berücksichtigung von Standorteigenschaften der umliegenden Nachbarn. Die Durchführung der Landnutzungsänderung im Modell ist iterativ angelegt, um den graduellen Prozess des Landschaftswandels nachvollziehen zu können.<br /> Als Fallbeispiel für die Anwendung solcher räumlich expliziten Landnutzungsszenarien dient die Fragestellung, inwieweit Landnutzungsänderungen die Hochwasserentstehung beeinflussen. Um den Einfluss auf die Hochwasserentstehung für jede der Landnutzungskategorien &ndash; bebaute, landwirtschaftlich genutzte und naturnahe Flächen &ndash; abschätzen zu können, wird im Landnutzungsmodell luck exemplarisch für jede Kategorie ein Teilmodell für die Veränderung von Landnutzung angeboten: <br /> 1) Ausdehnung der Siedlungsfläche: Dieses Teilmodell fußt auf der Annahme, dass sich Siedlungen nur in direkter Nachbarschaft bereits bestehender Bebauung und bevorzugt entlang von Entwicklungsachsen ausbreiten. Steile Hangneigungen stellen für potenzielle Standorte ein Hemmnis bei der Ausbreitung dar. <br /> 2) Stilllegung von Grenzertragsackerflächen: Gemäß der Hypothese, dass sich die Stilllegung von Ackerflächen an der potenziellen Ertragsleistung der Standorte orientiert, werden in diesem Teilmodell alle Ackerstandorte dahingehend bewertet und die Flächen mit der geringsten Leistungsfähigkeit stillgelegt. Bei homogenen Gebietseigenschaften werden die Stilllegungsflächen zufällig auf die Ackerfläche verteilt.<br /> 3) Etablierung von Schutzgebieten in Ufer- und Auenbereichen: Ausgehend von der These, dass sich entlang von Flüssen sensible Flächen befinden, deren Schutz positive Folgen für das Leistungsvermögen der Landschaft haben kann, werden in diesem Teilmodell schützenswerte Ufer- und Auenbereiche auf derzeit landwirtschaftlich genutzten Flächen ausgewiesen. Die Größe der Schutzgebietsfläche orientiert sich an der Morphologie der umgebenden Landschaft.<br /> <br /> Die drei Teilmodelle wurden hinsichtlich der implizierten Hypothesen mit vielen unterschiedlichen Ansätzen validiert. Das Resultat dieser intensiven Analyse zeigt für jedes Teilmodell eine zufriedenstellende Tauglichkeit. <br /> Die Modellierung der Landnutzungsänderungen wurden in drei mesoskaligen Flusseinzugsgebieten mit einer Fläche zwischen 100 und 500 km&#178; durchgeführt, die sich markant in ihrer Landnutzung unterscheiden. Besonderer Wert wurde bei der Gebietsauswahl darauf gelegt, dass eines der Gebiete intensiv landwirtschaftlich genutzt wird, eines dicht besiedelt und eines vorwiegend bewaldet ist. <br /> Im Hinblick auf ihre Relevanz für die vorliegende Fragestellung wurden aus bestehenden Landnutzungstrends die Szenarien für (1) die prognostizierte Siedlungsfläche für das Jahr 2010, (2) die möglichen Konsequenzen des EU-weiten Beschlusses der Agenda 2000 und (3) die Novelle des Bundesnaturschutzgesetzes aus dem Jahr 2001 abgeleitet.<br /> Jedes Szenario wurde mit Hilfe des Modells auf die drei Untersuchungsgebiete angewendet. Dabei wurden für die Siedlungsausdehnung in allen drei Gebieten realistische Landnutzungsmuster generiert. Einschränkungen ergeben sich bei der Suche nach Grenzertragsstilllegungsflächen. Hier hat unter homogenen Gebietseigenschaften die zufällige Verteilung von Flächen für die Stilllegung zu einem unrealistischen Ergebnis geführt. Die Güte der Schutzgebietsausweisung ist maßgeblich an die aktuelle Landnutzung der Aue und die Morphologie des Geländes gebunden. Die besten Ergebnisse werden erzielt, wenn die Flächen in den Ufer- und Auenbereichen mehrheitlich unter derzeitiger Ackernutzung stehen und der Flusslauf sich in das Relief eingetieft hat.<br /> Exemplarisch werden für jeden Landnutzungstrend die hydrologischen Auswirkungen anhand eines historischen Hochwassers beschrieben, aus denen jedoch keine pauschale Aussage zum Einfluss der Landnutzung abgeleitet werden kann.<br /> Die Studie demonstriert die Bedeutung des Landnutzungsmusters für die natürlichen Prozesse in der Landschaft und unterstreicht die Notwendigkeit einer räumlich expliziten Modellierung für landschaftsökologische Fragestellungen in der Mesoskala. / Today&prime;s landscapes in Central Europe are the result of a long history of land-use, which is characterised by many different demands. The immediate and long-term consequences of predominantly intensive land-use have led to environmental problems in many cases. Therefore it is necessary to develop strategies for the maintenance of landscape efficiency which take into account the different claims of utilisation. In this context the estimation of possible impacts of land-use changes represents an important statement of problem. <br /> For the analysis of the relevant processes within the landscape, it is common to apply mathematical models. Such models enable the investigation of the landscape under current conditions or with regard to modified boundary conditions. A hypothetic alteration of land-use, which is termed as land-use scenario, represents a substantial modification of the boundary conditions, because land-use exerts a strong influence on the natural processes of the landscape. While the driving forces are predominantly governed by socio-economical and political decisions, the exact location of land-use changes within the landscape mainly depends on the natural conditions and follows partly transparent rules. With these presumptions it is possible to develop land-use scenarios, which can serve as input data for the modelling of different questions of landscape ecology such as the influence of land-use on the water balance, the danger of erosion or the quality of habitat characteristics. <br /> In the context of this thesis the grid-based deterministic allocation model luck (Land Use Change Scenario Kit) for the allocation of land-use changes was developed. It is based upon the types of spatial data, which are commonly used in landscape ecology, such as information on land-use, soils as well as topography. The derivation of scenarios follows the approaches of landscape planning. The model is based upon the hypothesis, that land-use structure can be described as a function of its landscape ecological factors. The potential of a site to become subject to land-use changes, results from a combination of its local qualities and the site characteristics of its neighbourhood. Land-use change is realised iteratively in order to simulate the gradual process of changes in the landscape.<br /> The influence of land-use changes on flood generation serves as a case study to demonstrate the need for spatial explicit land-use scenarios. For each land-use category &ndash; built up areas, agriculturally used areas and natural/semi-natural land &ndash; the model luck offers a submodel for investigating the effect of land-use changes on flood generation: <br /> <br /> 1) Expansion of settlement area: This submodel is based upon the assumption that settlements spread only in the neighbourhood of already existing built-up areas and preferentially along infrastructural axes of development. Steep slopes inhibit the spreading on potential locations.<br /> 2) Set-aside of marginal yield sites under agricultural use: Setting-aside of arable land is based on the hypothesis that the selection of arable land to be set-aside depends on the potential yield efficiency of the locations. Within this submodel all fields under agricultural use are valued to that effect and the ones with the least productive efficiency are selected as set-aside locations. In case of homogeneous area qualities the set-aside locations are selected randomly. <br /> 3) Establishment of protected areas in waterside and ripearian areas: This submodel takes into consideration that the protection of sensitive areas along the river courses may have positive consequences for the efficiency of the landscape. Therefore this submodel establishes protection zones on waterside and ripearian sites under currently agricultural use, that might be of value for nature conservation. The size of the protection area depends on the morphology of the surrounding landscape. <br /> <br /> The three submodels were validated with respect to the implied hypotheses by the help of many different approaches. The result of this intensive analysis shows a satisfying suitability for each of the submodels.<br /> <br /> The simulation of land-use changes was carried out for three mesoscale river catchments with an area between 100 and 500 km&#178;. Special attention was paid to the fact that these areas should be markingly different in their land-use: One study area is predominantly under intensive agricultural use, one is densely populated and the third one is covered by forest in large parts of the area. <br /> With regard to their relevance to the onhand question from existing land-use trends scenarios were derived for the prognosed settlement area for the year 2010, for the possible consequences of the EU-wide agreement of Agenda 2000 and for the amending federal conservation law dating to the year 2001, which enhances the enlargement of protected areas. <br /> Each scenario was applied to the three study areas utilizing the model luck. For the expansion of the settlement areas in all three study areas realistic land-use patterns were generated. Limitations arose only in the context of the search for marginal yield fields. Here, the random distribution of areas to be set-aside under homogeneous conditions led to unrealistic results. The quality of the establishment of protected areas in waterside and ripearian areas is substantially bound to current land-use and the morphology of the area. The best results for this submodel are achieved if waterside and ripearian areas are mainly arable land and if the river has lowered its course into the morphology. <br /> The hydrological consequences are described exemplarily for each land-use trend with a historical flood event. The interpretation of the hydrographs does not allow global statements about the influence of land-use. <br /> The study demonstrates the significance of land-use pattern for the natural processes in the landscape and underlines the necessity of spatially explicit modelling for landscape ecological questions at the mesoscale.

The Amazon rainforest is considered the world\'s largest reservoir of plant and animal biodiversity, but in recent years has been subjected to high rates of deforestation for the conversion of native areas into agricultural fields and pasture. The understanding of the effects of land-use change on soil microbial communities is essential, taking into account the importance that these organisms play in the ecosystem. In this context, this thesis evaluated the effect of these changes on microorganism communities in soils under different land-use systems. In the first study, the microbial communities were analyzed using the nextgeneration sequencing Illumina Hiseq2000, considering samples from native forest, deforested area, agriculture and pasture. From the analysis of approximately 487 million sequences was possible to show that microbial communities respond differently in each landuse system, with changes in both taxonomic and functional diversity. Also, we suggested that ecosystem function in forest soils is maintained by the abundance of microorganisms, while in disturbed areas such functioning is maintained by high diversity and functional redundancy. In the second study, we assessed the extent to which a particular plant species, i.e. soybean, is able to select the microbial community that inhabits the rhizosphere. From the metagenomic sequencing by the 454 GS FLX Titanium platform we investigated the taxonomic and functional diversities of soil and rhizosphere communities associated to soybean, and also tested the validity of neutral and niche theories to explain rhizosphere community assembly process. The results suggest that soybean selects a specific microbial community inhabiting the rhizosphere based on functional traits, which may be related to benefits to the plant, such as growth promotion and nutrition. This process of selection follows largely the niche -based theory indicating the selection power of the plant and other environmental variables in shaping the microbial community both at the taxonomic and functional level. This thesis highlights the importance of microbial ecology studies in the context of the Amazon to a better understanding of the effects of deforestation on microorganisms, and provides information that can be suitable for future development of sustainable approaches for the ecosystem use / A floresta Amazônica é considerada o maior reservatório de biodiversidade vegetal e animal do mundo, porém, nos últimos anos tem sido submetida à altas taxas de desmatamento para a conversão de áreas de mata nativa em campos de agricultura e pastagem. A compreensão sobre os efeitos dessa mudança de uso da terra sobre as comunidades microbianas do solo é fundamental, levando-se em consideração a importância que esses organismos desempenham no ecossistema. Neste contexto, este trabalho de tese avaliou o efeito dessas mudanças sobre as comunidades de micro-organismos em solos sob diferentes sistemas de uso. No primeiro estudo, as comunidades microbianas foram analisadas por meio do sequenciamento de nova geração Illumina Hiseq2000, sendo consideradas amostras de áreas de floresta nativa, área desmatada, agricultura e pastagem. A partir da análise de aproximadamente 487 milhões de sequências foi possível mostrar que as comunidades microbianas respondem diferentemente em cada sistema de uso do solo, com alterações tanto na diversidade taxonômica quanto funcional. Também, sugere-se que o funcionamento do ecossistema em solos de floresta é mantido pela abundância dos micro-organismos presentes, enquanto nas áreas alteradas esse funcionamento é mantido pela alta diversidade e redundância funcional. No segundo estudo foi avaliado até que ponto uma espécie de planta, i.e. soja, é capaz de selecionar a comunidade habitante de sua rizosfera. A partir do sequenciamento metagenômico pela plataforma 454 GS FLX Titanium da Roche foi investigado a diversidade taxonômica e funcional das comunidades de solo e rizosfera associadas à soja, e testou-se a validade das teorias neutras e de nicho para explicar o processo de formação das comunidades microbianas. Os resultados sugerem que a soja seleciona uma comunidade específica que habita sua rizosfera com base em atributos funcionais, os quais podem estar relacionados com benefícios à planta, como promoção do crescimento e nutrição. Esse processo de seleção segue a teoria de nicho, indicando o poder de seleção da planta e de outras variáveis ambientais em moldar as comunidades microbianas tanto de forma taxonômica quanto funcional. Esta tese destaca a importância de estudos em ecologia microbiana no contexto da Amazônia para uma melhor compreensão dos efeitos do desmatamento sobre os microrganismos e disponibiliza informações que podem ser futuramente utilizados para o desenvolvimento de metodologias mais sustentáveis para o uso do ecossistema

A Mata Atlântica sofreu e ainda sofre forte pressão antrópica. Atualmente, ocupa no Estado de São Paulo o equivalente a 15% de sua cobertura original. O rio Paraíba do Sul é um dos mais importantes rios da Floresta Atlântica, localizado na região mais desenvolvida do país. Há uma falta de investigações aprofundadas sobre a estruturação e o funcionamento desse rio e de outros rios localizados nessa floresta, como rios de 1ª ordem, que são extremamente importantes, pois conseguem conectar o ambiente terrestre com os rios maiores. Assim, esse trabalho objetivou investigar a distribuição de C e N e outras variáveis físico-químicas nos principais rios localizados na Bacia do Alto Paraíba do Sul: o Rio Paraíba do Sul (RPS) e seus formadores, os rios Paraibuna (RPB) e Paraitinga (RPT), além de investigar a composição química de pequenos rios localizados nas áreas preservadas da Mata Atlântica, comparando-os com os rios de 3ª ordem, e também verificar como a conversão de floresta a pastagem afeta a distribuição de carbono e nitrogênio nesses riachos. Foram realizadas coletas mensais de água durante fevereiro de 2012 a janeiro de 2013, onde foram verificados os valores de pH, condutividade elétrica, oxigênio dissolvido e temperatura, além da determinação das concentrações de nitrogênio dissolvido total, nitrogênio inorgânico dissolvido, nitrogênio orgânico dissolvido, nitrato, amônio, carbono orgânico dissolvido e carbono inorgânico dissolvido. Foi amostrado, também o material particulado em suspensão nos rios de 3ª ordem e o sedimento de fundo em alguns desses rios, onde foram realizadas análises de ?13C e ?15N, conteúdos de C e N e relação C:N. Quase a totalidade das amostras de amônio apresentaram concentrações abaixo do limite de detecção. Os resultados encontrados mostram diferenças estatísticas entre o rio Paraibuna e os rios Paraitinga e Paraíba do Sul, no que se refere aos valores de condutividade elétrica, oxigênio dissolvido, temperatura, nitrato, nitrogênio dissolvido total e carbono inorgânico dissolvido. Esses rios apresentaram valores de nitrato, nitrogênio inorgânico, nitrogênio orgânico, nitrogênio dissolvido total, carbono inorgânico dissolvido, pH, condutividade elétrica, oxigênio dissolvido e temperatura diferentes dos rios de 1ª ordem. Entre rios de floresta e pastagem as variáveis carbono inorgânico dissolvido, condutividade elétrica e temperatura foram diferentes. Esses resultados sugerem que o rio Paraibuna difere-se dos outros rios de 3ª ordem, provavelmente porque 55% da área total de sua bacia é ocupada por floresta, enquanto os rios Paraitinga e Paraíba do Sul apresentam grande parte de suas bacias ocupada por pastagem, 57% e 42%, respectivamente. Entretanto, esses rios não apresentam características de rios extremamente alterados, como é o caso de outros rios do estado de São Paulo, localizados em áreas urbanas ou de cana-de-açúcar, que são muito mais impactantes que pastagens. Tanto os rios de 3ª ordem quanto os rios de 1ª ordem apresentam pastagens subutilizadas e que não recebem fertilizantes ou insumos, fazendo, dessa maneira, com que os rios de pastagem não apresentem características tão diferentes dos rios de floresta / The Atlantic Forest suffered and continues suffering anthropogenic pressure. Nowadays, it occupies 15% of its original coverage in the state of São Paulo. The Paraíba do Sul River is one of the most important rivers of the Atlantic Forest, located in the most developed region of the country. There is a lack of deeper studies of the structure and functioning of this and other rivers of this forest, as first order rivers, that are extremely important, because they can connect terrestrial environment to larger rivers. Therefore, the present study aimed to investigate the distribution of C and N and other physicochemical variables of the main rivers located at the Alto Paraíba do Sul Basin: the Paraíba do Sul River (RPS) an its formers, the Paraibuna (RPB) and Paraitinga (RPT) rivers, also investigating the chemical composition of small rivers located in preserved areas of Atlantic Forest, comparing them with third order rivers, and also focused on the verification of how the conversion of forest to pasture affects the distribution of carbon and nitrogen in these streams. Monthly samples of water were taken from February 2012 to January 2013, for verification of pH, electrical conductivity, dissolved oxygen and temperature values, plus the determination of total dissolved nitrogen, inorganic dissolved nitrogen, organic dissolved nitrogen, nitrate, ammonium, organic dissolved carbon and inorganic dissolved carbon concentrations. Suspended particulate material of the 3rd order rivers and their bottom sediment were sampled, for determination of ?13C, ?15N and C and N content, besides the C:N ratio. The majority of ammonium samples presented concentrations below detection limit. The results show significant statistical differences between the Paraibuna and the Paraitinga and Paraiba do Sul rivers, concerning the values of electrical conductivity, dissolved oxygen, temperature, nitrate, total dissolved nitrogen and inorganic dissolved carbon. These 3rd order rivers presented nitrate, inorganic nitrogen, organic nitrogen, total dissolved nitrogen and dissolved inorganic carbon concentrations, plus pH, electrical conductivity, dissolved oxygen and temperature values different from 1st order rivers. Among the forest and pasture rivers the dissolved inorganic carbon concentration, electrical conductivity and temperature values were different. The results suggest that the Paraibuna River differs from the other two 3rd order rivers, probably because 55% of its total basin area is covered with forest, while the Paraitinga and Paraiba do Sul rivers present a great part of their basin area occupied with pastures, 57% and 42%, respectively. Nevertheless, these rivers did not present characteristics of extremely altered rivers, which is the reality of other rivers of the State of São Paulo, located in urban or sugar cane crop areas, which can cause much more impacts to rivers than pasture. The 3rd and 1st order rivers present sub utilized pasture that do not receive fertilizers, thereby, being the probable cause why pasture rivers are not so different from the forest rivers

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