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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

A palaeoenvironmental history of the Paroo and Warrego Regions, Australia: a multi-proxy, multi-site approach

Gayler, Lucyna Maria January 2008 (has links)
Research Doctorate - Doctor of Philosophy (PhD) / The records of environmental change in Australia’s arid zone can be greatly enriched by employing a multi-proxy approach and landscape-scale analysis. This research uses these tools to construct a palaeoenvironmental history of the Paroo/Warrego Region. While the Region’s flow regimes and water balances are characterised by medium-term (decadal) variability (Young, 1999), its hydrological records are inadequately brief. Subsequently, land and water management decisions are based on short term data, risking irreversible damage, desertification or loss of diversity. A better understanding of this highly dynamic landscape can thus improve the land and resource management outcomes. While dating was constrained by a lack of funds, the Paroo/Warrego history reconstructed from fluvial and aeolian deposits correlated well with events recorded from other inland regions of the Australian continent. In summary, this new research provided evidence of high lake water levels prior to the Last Glacial. The extreme aridity at the onset of Last Glacial caused long term drying of the lakes and mobilisation of the red sand dunes. In latter stages of the glacial phase the aridity gave way to periodic fluctuations between flood and drought events that probably lasted until 16 000 - 14 000 BP. The new climatic regime resulted in formation of gypsum lunettes and later, following reduction in gypsum supply, clay lunettes. The orientation of red sand dunes and lunettes indicates a more northerly extent of the westerlies than in modern times. Around the late Pleistocene-early Holocene boundary the climate became more stable and wetter, but still somewhat drier than during the pre-Last Glacial lacustrine phase. As a result, the region’s lakes reverted to a permanent and semi-permanent status. A strong aridity signal, comparable to the semi-regular droughts of the Last Glacial, was recorded in the Paroo/Warrego lakes during the late 1890s-1940s period of below average rainfall. It was followed by 50 years of wetter conditions with two extremely wet phases in the 1950s and the 1970s. Finally, the most recent records suggest a new drying trend. The semi-arid vegetation appears to have adapted to climate variability, with herbs and grasses expanding with the onset of wet conditions before being replaced by Chenopodiaceae as the landscape started to dry. The fresher lake basins and water courses were likely to provide refuge during prolonged arid phases and dispersal foci during intervening wetter periods, thus enabling greater flexibility in response to changes and enhancing resilience. The European land use interfered with the natural cycles and balances, leading to decrease in ground cover, suppression of fire, increase in runoff and catchment erosion, acceleration of sediment accumulation rates in wetlands, resulting in decline of their water holding capacity, and expansion of woody vegetation. The research improved the processing protocols, reference databases, and transfer of methods to enable greater sample processing efficiency and improve results. The use of multiple proxies (including biotic and abiotic components) and sites, as well as different depositional features, provided access to a broader picture of environmental change than was previously possible. It also facilitated multi-scale resolution, allowing discrimination between localised responses of individual lakes and regional trends. The full value of this research will come from informing natural resource managers, whose actions will shape the future landscapes of the Paroo and Warrego Region.
32

A palaeoenvironmental history of the Paroo and Warrego Regions, Australia: a multi-proxy, multi-site approach

Gayler, Lucyna Maria January 2008 (has links)
Research Doctorate - Doctor of Philosophy (PhD) / The records of environmental change in Australia’s arid zone can be greatly enriched by employing a multi-proxy approach and landscape-scale analysis. This research uses these tools to construct a palaeoenvironmental history of the Paroo/Warrego Region. While the Region’s flow regimes and water balances are characterised by medium-term (decadal) variability (Young, 1999), its hydrological records are inadequately brief. Subsequently, land and water management decisions are based on short term data, risking irreversible damage, desertification or loss of diversity. A better understanding of this highly dynamic landscape can thus improve the land and resource management outcomes. While dating was constrained by a lack of funds, the Paroo/Warrego history reconstructed from fluvial and aeolian deposits correlated well with events recorded from other inland regions of the Australian continent. In summary, this new research provided evidence of high lake water levels prior to the Last Glacial. The extreme aridity at the onset of Last Glacial caused long term drying of the lakes and mobilisation of the red sand dunes. In latter stages of the glacial phase the aridity gave way to periodic fluctuations between flood and drought events that probably lasted until 16 000 - 14 000 BP. The new climatic regime resulted in formation of gypsum lunettes and later, following reduction in gypsum supply, clay lunettes. The orientation of red sand dunes and lunettes indicates a more northerly extent of the westerlies than in modern times. Around the late Pleistocene-early Holocene boundary the climate became more stable and wetter, but still somewhat drier than during the pre-Last Glacial lacustrine phase. As a result, the region’s lakes reverted to a permanent and semi-permanent status. A strong aridity signal, comparable to the semi-regular droughts of the Last Glacial, was recorded in the Paroo/Warrego lakes during the late 1890s-1940s period of below average rainfall. It was followed by 50 years of wetter conditions with two extremely wet phases in the 1950s and the 1970s. Finally, the most recent records suggest a new drying trend. The semi-arid vegetation appears to have adapted to climate variability, with herbs and grasses expanding with the onset of wet conditions before being replaced by Chenopodiaceae as the landscape started to dry. The fresher lake basins and water courses were likely to provide refuge during prolonged arid phases and dispersal foci during intervening wetter periods, thus enabling greater flexibility in response to changes and enhancing resilience. The European land use interfered with the natural cycles and balances, leading to decrease in ground cover, suppression of fire, increase in runoff and catchment erosion, acceleration of sediment accumulation rates in wetlands, resulting in decline of their water holding capacity, and expansion of woody vegetation. The research improved the processing protocols, reference databases, and transfer of methods to enable greater sample processing efficiency and improve results. The use of multiple proxies (including biotic and abiotic components) and sites, as well as different depositional features, provided access to a broader picture of environmental change than was previously possible. It also facilitated multi-scale resolution, allowing discrimination between localised responses of individual lakes and regional trends. The full value of this research will come from informing natural resource managers, whose actions will shape the future landscapes of the Paroo and Warrego Region.
33

Pour une meilleure représentation de la diversité des biomes herbacés africains dans les modèles de végétation : apports des traits physionomiques, de l’indice de surface foliaire et des phytolithes de graminées / For a better representation of African grass biomes in vegetation models : inputs from grass physiognomic traits, leaf area index and phytoliths

Pasturel, Marine 12 March 2015 (has links)
Les biomes herbacés africains intertropicaux devraient faire face, dans un proche futur, à des changements drastiques. Les modèles dynamiques de végétation (DGVM) ont des difficultés à simuler les limites actuelles de ces biomes, notamment parce qu’ils ne prennent pas en compte la diversité des couverts herbacés en C4. Il est donc nécessaire de caractériser cette diversité floristique et physionomique afin qu’elle puisse être facilement prise en compte dans les DGVMs, et que les comparaisons modèle/données (phytolithes) soient possibles.Dans cet objectif, les traits physionomiques des graminées en C4 dominantes au Sénégal et en Afrique du Sud ont été répertoriés. Quatre groupes physionomiques ont été statistiquement discriminés. Ils varient avec la distribution spatiale des biomes et les précipitations régionales. Deux groupes sont fortement corrélés à l’indice de surface foliaire (LAI) et à la biomasse herbacée. Au Sénégal ces deux groupes sont bien différenciés par l’indice phytolithique Iph qui est un proxy des couverts herbacés intertropicaux. En Afrique du Sud, les phytolithes n’ont pas permis de tracer l’ensemble de la transition savane/steppe. Ces deux groupes physionomiques remplissent les critères nécessaires à la caractérisation de types fonctionnels de plantes (PFT). L’intégration de ces PFTs dans le modèle LPJ-GUESS améliore la simulation des biomes herbacés actuels et permet de proposer des simulations pour l’horizon 2100. Ces simulations montrent que l’augmentation de la durée de la saison sèche et de la concentration en CO2 atmosphérique devraient favoriser l’expansion simultanée des steppes et des savanes fermées aux dépens des savanes ouvertes. / Intertropical african herbaceous biomes are expected to face drastic changes in a near future. However Dynamic Global Vegetation Models (DGVMs) simulate their modern boundaries with poor accuracy, especially at the regional scale. DGVMs fail to consider the diversity of their C4 grass cover. Efforts are thus needed to characterize this floristic and physiognomic diversity in a way that can be used for enhancing DGVMs simulations, and enabling model/data (phytoliths) comparisons. For that purpose, physiognomic traits of dominant C4 grass species settled in Senegal and South Africa were listed. Four grass physiognomic groups were statistically identified. The abundance of four of them significantly varied with biome distributions and regional precipitation. Two grass physiognomic groups were additionally strongly correlated with leaf area index (LAI) and grass biomass. In Senegal, those two groups were also well traced by the Iph phytolith index which is a tropical grass cover proxy. In South Africa the limited set of phytolith data did not allow to observe the full savanna/steppe transition. The two physiognomic groups finally fulfilled the criteria required for creating Plant Functional Types (PFTs). Those new PFTs, parameterized in the LPJ-GUESS DGVM, enhanced the simulation of modern herbaceous biomes distribution in Senegal and South Africa. Simulations were additionally performed for the 2100 horizon. They evidence that the increase of both length of the dry season and atmospheric CO2 concentration should favor the simultaneous spread of steppes and closed savannas at the expense of open savannas.
34

Projeto arqueológico Alto Canoas - Paraca: um estudo da presença Jê no planalto Catarinense. / Upper Canoas Archaeological Project: A study of the Jê presence in the plateau of Santa Catarina, Brazil

Corteletti, Rafael 05 March 2013 (has links)
Nesta tese vou apresentar novos dados sobre padrões de ocupação dos Jê Meridionais e minhas interpretações sobre a história deste povo, com base em meu estudo de caso, do Alto Rio Canoas, região de Urubici, em Santa Catarina, Brasil. No planalto, os camposde altitude e a mata de araucária dominam a paisagem. Nas serrarias de Urubici, as nascentes de vários arroios e rios começam em zonas húmidas, com solos rasos e pedregosos, na área dos campos, a cerca de 1800m de altitude. Estas águas correm através de vales incisos florestados pela mata de araucária criando cachoeiras e corredeiras, que acabam por se transformar no meândrico Rio Canoas, que flui no meio de um vale largo e plano, em torno de 1000m acima do nível do mar. A montanhosa região de Urubici foi intensamente pesquisada na década de 60, mas depois disso, a pesquisa ficou estagnada. Os principais pontos deste projeto foram: Primeiro, foram revisadas e atualizadas as pesquisas anteriores, revisitando a maioria dos sítios arqueológicos mapeados na década de 60, atribuindo-lhes coordenadas geográficas, fotos e mapas, e descrições ambientais recentes. Segundo, além da visita aos sítios mapeados previamente, foi realizado um mapeamento oportunista de novos sítios, baseado em entrevistas com membros da comunidade local, o que gerou um novo mapa arqueológico da região. Terceiro, com base nessas informações e nas novas escavações em sítios específicos, iniciou-se a reflexão sobre as paisagens Jê do Sul, com o objetivo de compreender a história de longo prazo e o sistema de assentamento da tradição arqueológica Taquara-Itararé. Quarto, a partir das análises de grãos de amido de fitólitos, a partir de restos carbonizados de alimento aderidos a parede da cerâmica coletada na escavação do sítio Bonin, foram obtidos novos dados, importantíssimos para pensar novas formas de interpretação na arqueologia da tradição Taquara-Itararé. Tais análises trouxeram evidências de produção de alimentos como Zea mays, Cucurbitasp., Manihotsp., e o consumo alimentar de Phaseolussp. e Dioscoreasp. entre outros, o que, sem dúvida, é uma chave para pensar em outro tipo de organização social, mobilidade e economia para os povos proto-Jê Meridional. Em quinto lugar, no sentido de pensar uma \"estratigrafia paisagem do Jê Meridional\" um banco de dados SIG foi utilizado como uma ferramenta para criar modelos virtuais de, por exemplo, a análise visibilidade acumulada entre sítios e análise de rotas de menor custo. / In this thesis I will present new data on Southern Jêsettlement patterns, and my interpretations regarding the history of these people, based on my case study, from the Upper Canoas River, Urubici region, in Santa Catarina state, Brazil. On the highland plateau, the High Altitude Grasslands (or Campos) and the Paraná Pine Forest dominate the landscape. In the Urubici hills, various headwaters begin in wetland areas, with shallow and rocky soils, on Campos, around 1800m altitude. These waters flow through incised valleys forested by Paraná Pine and create waterfalls and rapids, which eventually turn into the meandering Canoas River that flows in the middle of a wide and flat valley, around 1000m above sea level. The mountainous Urubici region was intensively researched in the 60\'s, but after that, research wasstagnated. The main points of this project were: First, I reviewed and updated previous research, which involved relocating the sites mapped in the 60\'s, assigning them geographical coordinates, photos and maps, and improving environmental descriptions. Second, I carried out an inspection of previously recorded sites and carried out opportunistic survey, based on interviews with members of the local community, looking for new sites, and making a new archaeological map of the region. Third, based on this information and my new excavations at targeted sites, I aimed to think about the Southern Jê landscapes, with a view to understanding the long-term history and the settlement pattern of the Taquara-Itararé archaeological tradition. Fourth, starch grain and phytoliths analysis from charred food remains founded in pottery, collected at Bonin site excavation, achieved important new data for new interpretive ways on Taquara-Itararé archaeology, bringing to us food production evidences of Zea mays, Cucurbitasp., Manihotsp., and food consumption of Phaseolussp.,Dioscoreasp. and others, what is a key to think another kind of social organization, mobility and economy for southern proto-Jê people. Fifth, in a way to think the \"southern Jê landscape stratigraphy\" aGIS database were used like a tool to create virtual models of, for example, cumulative viewshed analysis and least coast pathway analysis.
35

Ocorrência e significado paleoambiental do Horizonte A húmico em Latossolos / Occurrence and palaeenvironmental significance of humic horizon in Latosols (oxisols)

Calegari, Márcia Regina 17 February 2009 (has links)
A ocorrência de solos com horizonte A húmico (Ah) hiperdesenvolvido ainda é pouco entendida. Nos Latossolos com esse horizonte (Lh) ele freqüentemente é muito espesso, com baixa saturação por bases e cor escura advinda do relativamente grande acúmulo de matéria orgânica até profundidades superiores a 100 cm. Exceto para a região Sul, tais atributos estão em desconformidade com as atuais condições de clima e vegetação em que esses Lh se encontram. Objetivou-se definir variáveis ambientais que teriam influenciado na gênese desse horizonte em Latossolos, investigando-se dados de morfologia, textura, geoquímica, geomorfologia e evidências de paleoambientes. Realizou-se primeiro um estudo bibliográfico das principais características dos Lh no Brasil, em um conjunto de 39 perfis. Destes, 11 variáveis, representando atributos ambientais, químicos e granulométricos do solo foram submetidas a análises estatísticas multivariadas, para agrupá-los segundo similaridades. Três grupos foram definidos: G1 - Latossolos Brunos e Vermelhos em superfícies de cimeira da região Sul, com os mais altos teores de carbono orgânico e de Fe2O3, Ah menos espesso e mineralogia mais oxídica que os demais; G2- Latossolos Vermelho-Amarelos e Amarelos em antigas superfícies geomorfológicas da região Sudeste, associados à vegetação e clima de altitude, com valores intermediários de carbono e de mineralogia; G3 - Latossolos Vermelho-Amarelos e Amarelos com Ah mais espessos, encontrados nos níveis mais elevados de superfícies intermediárias (Depressão Periférica Paulista e Tabuleiros do Nordeste),com os menores teores de carbono e mineralogia caulinítica. Baseados nesses agrupamentos amostraram-se 30 pedons para fins de caracterização detalhada: análise total de Zr e Ti para identificar descontinuidades e técnicas isotópicas (13C,14C) aliadas a análises de fitólitos para inferir paleoambientes. Para esta análise procedimentos de extração de fitólitos foram adaptados. Nas regiões Sudeste e Nordeste o Ah teria se formado sob vegetação menos densa que a atual, como indicado pelos fitólitos e valor 13C que indicou mistura de plantas de ciclo C3 e C4 (~-22), que revelaram predomínio de plantas C3 e, na região Sul, vegetação mais aberta com predomínio de plantas C4 (~-16), indicando clima mais seco entre o Holoceno inferior e médio. A partir das datações 14C e dos valores 13C inferiu-se um empobrecimento isotópico (~-25) no Holoceno superior, sugerindo expansão da vegetação de floresta para todas as regiões, associada à clima mais úmido e quente, semelhante ao atual, nas regiões Sudeste e Nordeste e mais úmido e frio, na região Sul. Esses resultados indicaram que vegetação e climas pretéritos, associados aos materiais de origem e estabilidade do relevo, têm participação importante na geografia e nos processos de formação do material de origem e dos horizontes Ah. As relações Ti/Zr indicaram descontinuidades litológicas, fato que sugere a ação de processos de coluvionamento no espessamento dos Ah que, com isso, podem ser considerados como poligenéticos. O Ah constitui um importante registro das variações climáticas ocorridas durante o Quaternário sendo considerado como um paleossolo relictual. A integração da análise isotópica, de fitólitos, análise total de Zr e Ti, com a morfologia e análises de rotina foram bastante úteis para esclarecer a origem dos Ah desses Lh. / Thick humic A horizons (umbric epipedons) may be found in several Brazilian Latosols (well drained Oxisols - Lh). This dark colored horizon (Ah) is frequently more than 1m thick and has a large stock of soil organic matter (SOM) and differ from nearby Latosols without an Ah and on younger surfaces and do not conform with present climate and vegetation. Several hypothesis about their genesis had been raised but without a good pedogenetic understanding. This thesis aims to define environmental variables responsible for their formation. Several pedons were examined through their morphology and landscape position, and their soil materials were studied by geochemistry methods and paleoenviromental evidence by C isotope and phytolith assemblages. First, a bibliographic survey was performed to choose a set of 39 profiles were chosen to be studied on a data set where 11 noted chemical and granulometric attributes and one environmental variable were submitted to multivariate statistic analysis in order to group then according to similarities. Three groups were defined: G1 - Brown and Red Latosols from summit surfaces of the Brazilian Southern uplands (with the highest clay, organic carbon and iron oxide values, but with thinner epipedons than the others groups). G2 - Yellow-Red and Yellow Latosols, predominantly found in summit positions, remnant ancient geomorphic surfaces from the Southeast region and associated with the vegetation adapted to high altitudinal tropical climate. G3 - Red Yellow and Yellow Latosols from the Brazilian Southeastern piedmont upland surfaces and Northeastern coastal tablelands (with the thickest umbric epipedons, loamy to clayey textures, lower carbon contents, and a kaolinitic mineralogy). From this analysis 30 Lh representative pedons were field sampled to be characterized, including total Zr and Ti contents, stable carbon isotopes (13C, 14C) and phytolith analysis, in order to better understand paleo-environmental conditions they were subjected. For the phytolith extraction laboratory procedure were adapted in order to better separate and clean then from oxidic coatings. The SOM isotope data and phytolith assemblages indicated that these Ah were formed under a less dense vegetation than the present one: a probably mixture of C3 and C4 (~-22) plants, with more contribution of the C3 in the Southeast and Northeast regions, a more open (~-16, grassy), vegetation (with contribution of C4 plants) in the middle to medium Holocene indicating the presence of a drier climate in the Southern region. From the Late Holocene a more 13C depleted values (~-25) was observed, suggesting the expansion of the tropical and subtropical forests in this region, probably associate to a humid and warm climate in the Southeast and Northeast regions, and humid and cold in the Southern region. The combination of climate and vegetation late, parent material, and stability relief have played a major role in the geographic and formation of the parent material and pedogenetic horizons of these Lh, and thus they should be considered as polygenetic soils. The humic horizons constitute an important register of Holocene climate change and that they should be considered as relic paleosoils.
36

Ocorrência e significado paleoambiental do Horizonte A húmico em Latossolos / Occurrence and palaeenvironmental significance of humic horizon in Latosols (oxisols)

Márcia Regina Calegari 17 February 2009 (has links)
A ocorrência de solos com horizonte A húmico (Ah) hiperdesenvolvido ainda é pouco entendida. Nos Latossolos com esse horizonte (Lh) ele freqüentemente é muito espesso, com baixa saturação por bases e cor escura advinda do relativamente grande acúmulo de matéria orgânica até profundidades superiores a 100 cm. Exceto para a região Sul, tais atributos estão em desconformidade com as atuais condições de clima e vegetação em que esses Lh se encontram. Objetivou-se definir variáveis ambientais que teriam influenciado na gênese desse horizonte em Latossolos, investigando-se dados de morfologia, textura, geoquímica, geomorfologia e evidências de paleoambientes. Realizou-se primeiro um estudo bibliográfico das principais características dos Lh no Brasil, em um conjunto de 39 perfis. Destes, 11 variáveis, representando atributos ambientais, químicos e granulométricos do solo foram submetidas a análises estatísticas multivariadas, para agrupá-los segundo similaridades. Três grupos foram definidos: G1 - Latossolos Brunos e Vermelhos em superfícies de cimeira da região Sul, com os mais altos teores de carbono orgânico e de Fe2O3, Ah menos espesso e mineralogia mais oxídica que os demais; G2- Latossolos Vermelho-Amarelos e Amarelos em antigas superfícies geomorfológicas da região Sudeste, associados à vegetação e clima de altitude, com valores intermediários de carbono e de mineralogia; G3 - Latossolos Vermelho-Amarelos e Amarelos com Ah mais espessos, encontrados nos níveis mais elevados de superfícies intermediárias (Depressão Periférica Paulista e Tabuleiros do Nordeste),com os menores teores de carbono e mineralogia caulinítica. Baseados nesses agrupamentos amostraram-se 30 pedons para fins de caracterização detalhada: análise total de Zr e Ti para identificar descontinuidades e técnicas isotópicas (13C,14C) aliadas a análises de fitólitos para inferir paleoambientes. Para esta análise procedimentos de extração de fitólitos foram adaptados. Nas regiões Sudeste e Nordeste o Ah teria se formado sob vegetação menos densa que a atual, como indicado pelos fitólitos e valor 13C que indicou mistura de plantas de ciclo C3 e C4 (~-22), que revelaram predomínio de plantas C3 e, na região Sul, vegetação mais aberta com predomínio de plantas C4 (~-16), indicando clima mais seco entre o Holoceno inferior e médio. A partir das datações 14C e dos valores 13C inferiu-se um empobrecimento isotópico (~-25) no Holoceno superior, sugerindo expansão da vegetação de floresta para todas as regiões, associada à clima mais úmido e quente, semelhante ao atual, nas regiões Sudeste e Nordeste e mais úmido e frio, na região Sul. Esses resultados indicaram que vegetação e climas pretéritos, associados aos materiais de origem e estabilidade do relevo, têm participação importante na geografia e nos processos de formação do material de origem e dos horizontes Ah. As relações Ti/Zr indicaram descontinuidades litológicas, fato que sugere a ação de processos de coluvionamento no espessamento dos Ah que, com isso, podem ser considerados como poligenéticos. O Ah constitui um importante registro das variações climáticas ocorridas durante o Quaternário sendo considerado como um paleossolo relictual. A integração da análise isotópica, de fitólitos, análise total de Zr e Ti, com a morfologia e análises de rotina foram bastante úteis para esclarecer a origem dos Ah desses Lh. / Thick humic A horizons (umbric epipedons) may be found in several Brazilian Latosols (well drained Oxisols - Lh). This dark colored horizon (Ah) is frequently more than 1m thick and has a large stock of soil organic matter (SOM) and differ from nearby Latosols without an Ah and on younger surfaces and do not conform with present climate and vegetation. Several hypothesis about their genesis had been raised but without a good pedogenetic understanding. This thesis aims to define environmental variables responsible for their formation. Several pedons were examined through their morphology and landscape position, and their soil materials were studied by geochemistry methods and paleoenviromental evidence by C isotope and phytolith assemblages. First, a bibliographic survey was performed to choose a set of 39 profiles were chosen to be studied on a data set where 11 noted chemical and granulometric attributes and one environmental variable were submitted to multivariate statistic analysis in order to group then according to similarities. Three groups were defined: G1 - Brown and Red Latosols from summit surfaces of the Brazilian Southern uplands (with the highest clay, organic carbon and iron oxide values, but with thinner epipedons than the others groups). G2 - Yellow-Red and Yellow Latosols, predominantly found in summit positions, remnant ancient geomorphic surfaces from the Southeast region and associated with the vegetation adapted to high altitudinal tropical climate. G3 - Red Yellow and Yellow Latosols from the Brazilian Southeastern piedmont upland surfaces and Northeastern coastal tablelands (with the thickest umbric epipedons, loamy to clayey textures, lower carbon contents, and a kaolinitic mineralogy). From this analysis 30 Lh representative pedons were field sampled to be characterized, including total Zr and Ti contents, stable carbon isotopes (13C, 14C) and phytolith analysis, in order to better understand paleo-environmental conditions they were subjected. For the phytolith extraction laboratory procedure were adapted in order to better separate and clean then from oxidic coatings. The SOM isotope data and phytolith assemblages indicated that these Ah were formed under a less dense vegetation than the present one: a probably mixture of C3 and C4 (~-22) plants, with more contribution of the C3 in the Southeast and Northeast regions, a more open (~-16, grassy), vegetation (with contribution of C4 plants) in the middle to medium Holocene indicating the presence of a drier climate in the Southern region. From the Late Holocene a more 13C depleted values (~-25) was observed, suggesting the expansion of the tropical and subtropical forests in this region, probably associate to a humid and warm climate in the Southeast and Northeast regions, and humid and cold in the Southern region. The combination of climate and vegetation late, parent material, and stability relief have played a major role in the geographic and formation of the parent material and pedogenetic horizons of these Lh, and thus they should be considered as polygenetic soils. The humic horizons constitute an important register of Holocene climate change and that they should be considered as relic paleosoils.
37

Coleção de referência de silicofitólitos da flora do Sudoeste do Paraná: subsídios para estudos paleoambientais / Collection of reference of silicophytoliths the flora of the Southwest Paraná: subsidies for studies paleoenvironmental

Raitz, Edenilson 28 March 2012 (has links)
Made available in DSpace on 2017-07-10T17:31:20Z (GMT). No. of bitstreams: 1 Edenilson_Raitz_parte1.pdf: 6176309 bytes, checksum: 0b9b9558d2a9e917ab11d7d142d99d3e (MD5) Previous issue date: 2012-03-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Phytoliths bodies are of amorphous silica (SiO2.nH20) produced during the vegetative cycle and plant death after the production can be incorporated into the soil/sediment, and may remain there for extended periods of time. For an analysis consistent fitolítica is necessary to compare the sets of phytoliths found in soil and the collections of references phytoliths extracted from existing plants. The problem is there is no reference collection available for the Southwest region of Paraná and in Brazil, so there is no possibility of comparisons difficult paleoenvironmental reconstructions through this proxy. In order to minimize the lack of information on the production of phytoliths by vegetation of Brazil was made a reference collection of phytoliths from phytophysionomies Mixed Ombrophylous Forest and grassland, both located in the Southwest of Paraná State. This collection consists of 30 families, 57 genera and 75 species. In the floristic survey of FOM Lauraceae, Myrtaceae, Poaceae, and Fabaceae Pteridaceae families have greater representation of species. The vegetation of the grassland had a high representation of Poaceae, Asterceae, Cyperaceae, and Lauraceae. It was found that the production of Late Gray (fraction that contains the phytoliths) decrease of herbaceous to woody phytophysionomies in both. Only two (Araucaria angustifolia and Rapanea gardneriana) of 71 species analyzed did not produce identifiable phytoliths in the leaves. The production of phytoliths in different strata varied in similar proportions in the FOM and the field, especially in stratum A, because the presence of grass species that contributed to high amount of morphotypes short-cells (bilobate, cross and saddle, rondel and conical) in two forest types. While the layers B, C, D and redundancy Epiphytes presented to each other for producing morphotypes blocky, tabular, globular, cylindric and irregular cells by species. The production of phytoliths in the FOM morphological differ in quantity significantly from conjuto produced by species of the grassland, since grasses produce more biomineralizations than eudicotyledonous. The analysis fitolítica the first 40 cm of soil under the FOM revealed a change in vegetation type, evolving from a opened vegetation to more closed forest (current). It was possible to deduce that this change has occurred as a result of past human action. Similar trend was found in the soil analysis of the grassland, that is, moved from grassland to grassland clean of this dirty again to grassland clean, change occurred due to the abandonment of the field and return of site anthropogenic activities. The degradation of two morphotypes differed in physiognomy. The morphotypes found in soil under the FOM showed the lowest degradation compared to the grassland. The set of two soils revealed significant patterns that differentiate the two forest types, showing that different vegetation units can be discriminated by the signatures phytolitic produced by them. These results reinforce the utility of using phytoliths as significant indicators to distinguish vegetation units dominated by field and/or forest, even in a short period of time, thus demonstrating the potential of phytoliths analysis for paleoecological reconstruction in southern Brazil. / Fitólitos são corpos de sílica amorfa (SiO2.nH20), produzidos ao longo do ciclo vegetativo das plantas e após a morte das produtoras podem ser incorporados ao solo/sedimentos, podendo permanecer ali por longos períodos de tempo. Para uma análise fitolítica consistente é necessária a comparação entre os conjuntos de fitólitos encontrados no solo e as coleções de referências de fitólitos extraídos de plantas atuais. O problema consiste em não haver coleção de referência disponível para a região Sudoeste do Paraná e do Brasil, logo, não existem possibilidades de comparações, dificultando a reconstrução paleoambiental por meio deste proxy. Visando minimizar a carência de informações sobre a produção de fitólitos pela vegetação do Brasil foi elaborada uma coleção de referência de fitólitos da fitofisionomias Floresta Ombrófila Mista e do Campo, ambas localizadas no Sudoeste do Estado do Paraná. Esta coleção é composta por 30 famílias, 57 gêneros e 75 espécies. No levantamento florístico da FOM as famílias Lauraceae, Myrtaceae, Poaceae, Pteridaceae e Fabaceae apresentam maior representatividade de espécies. A vegetação do Campo apresentou elevada representatividade de espécies de Poaceae, Asterceae, Cyperaceae e Lauraceae. Constatou-se que a produção de Cinza Final (fração que contém os fitólitos) diminuem do estratos herbáceo para o arbóreo nas duas fitofisionomias. Somente duas (Araucaria angustifolia e Rapanea gardneriana) das 71 espécies analisadas não produziram fitólitos identificáveis nas folhas. A produção de fitólitos nos diferentes estratos variou em proporções similares na FOM e no Campo, principalmente no estrato A, devido presença de espécies de gramíneas que contribuiram com elevada quantidade de morfotipos short-cells (bilobate, cross e saddle, rondel e conical) nas duas fitofisionomias. Enquanto que os estratos B, C, D e Epífitas apresentaram redundância entre si pela produção de morfotipos blocky, tabular, globular, cylindric, irregular cells pelas espécies. A produção morfológica de fitólitos na FOM diferiu em quantidade, significativamente em relação ao conjuto produzido pelas espécies do Campo, pois as gramíneas produzem mais biomineralizações do que as eudicotiledôneas. A análise fitolítica dos primeiros 40 cm de solo sob a FOM revelou mudança no tipo de vegetação, evoluindo de uma vegetação mais aberta para floresta mais fechada (atual). Foi possível elocubrar que esta mudança tenha ocorrido em decorrência da ação antrópica passada. Tendência similar foi encontrada na análise do solo do Campo, isto é, passou de Campo limpo para Campo sujo e deste, novamente para Campo limpo, mudança ocorrida devido ao abandono da área e retorno das atividades antrópicas locais. A degradação dos morfotipos diferenciou nas duas fitofisionomia. Os morfotipos encontrados no solo sob a FOM apresentaram menor índice de degradação se comparado ao do Campo. O conjunto dos dois solos revelaram padrões significativos que diferenciam as duas fitofisionomias, mostrando que diferentes unidades de vegetação podem ser discriminadas pelas assinaturas fitolíticas por elas produzidas. Estes resultados reforçam a utilidade de usar fitólitos como indicadores significativos para diferenciar unidades de vegetação dominada por Campo e/ou Floresta, mesmo em curto período de tempo, demonstrando assim, o potencial da análise de fitólitos para a reconstrução paleoecológica na região Sul do Brasil.
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Coleção de referência de silicofitólitos da flora do Sudoeste do Paraná: subsídios para estudos paleoambientais / Collection of reference of silicophytoliths the flora of the Southwest Paraná: subsidies for studies paleoenvironmental

Raitz, Edenilson 28 March 2012 (has links)
Made available in DSpace on 2017-05-12T14:42:50Z (GMT). No. of bitstreams: 1 Edenilson_Raitz_parte1.pdf: 6176309 bytes, checksum: 0b9b9558d2a9e917ab11d7d142d99d3e (MD5) Previous issue date: 2012-03-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Phytoliths bodies are of amorphous silica (SiO2.nH20) produced during the vegetative cycle and plant death after the production can be incorporated into the soil/sediment, and may remain there for extended periods of time. For an analysis consistent fitolítica is necessary to compare the sets of phytoliths found in soil and the collections of references phytoliths extracted from existing plants. The problem is there is no reference collection available for the Southwest region of Paraná and in Brazil, so there is no possibility of comparisons difficult paleoenvironmental reconstructions through this proxy. In order to minimize the lack of information on the production of phytoliths by vegetation of Brazil was made a reference collection of phytoliths from phytophysionomies Mixed Ombrophylous Forest and grassland, both located in the Southwest of Paraná State. This collection consists of 30 families, 57 genera and 75 species. In the floristic survey of FOM Lauraceae, Myrtaceae, Poaceae, and Fabaceae Pteridaceae families have greater representation of species. The vegetation of the grassland had a high representation of Poaceae, Asterceae, Cyperaceae, and Lauraceae. It was found that the production of Late Gray (fraction that contains the phytoliths) decrease of herbaceous to woody phytophysionomies in both. Only two (Araucaria angustifolia and Rapanea gardneriana) of 71 species analyzed did not produce identifiable phytoliths in the leaves. The production of phytoliths in different strata varied in similar proportions in the FOM and the field, especially in stratum A, because the presence of grass species that contributed to high amount of morphotypes short-cells (bilobate, cross and saddle, rondel and conical) in two forest types. While the layers B, C, D and redundancy Epiphytes presented to each other for producing morphotypes blocky, tabular, globular, cylindric and irregular cells by species. The production of phytoliths in the FOM morphological differ in quantity significantly from conjuto produced by species of the grassland, since grasses produce more biomineralizations than eudicotyledonous. The analysis fitolítica the first 40 cm of soil under the FOM revealed a change in vegetation type, evolving from a opened vegetation to more closed forest (current). It was possible to deduce that this change has occurred as a result of past human action. Similar trend was found in the soil analysis of the grassland, that is, moved from grassland to grassland clean of this dirty again to grassland clean, change occurred due to the abandonment of the field and return of site anthropogenic activities. The degradation of two morphotypes differed in physiognomy. The morphotypes found in soil under the FOM showed the lowest degradation compared to the grassland. The set of two soils revealed significant patterns that differentiate the two forest types, showing that different vegetation units can be discriminated by the signatures phytolitic produced by them. These results reinforce the utility of using phytoliths as significant indicators to distinguish vegetation units dominated by field and/or forest, even in a short period of time, thus demonstrating the potential of phytoliths analysis for paleoecological reconstruction in southern Brazil. / Fitólitos são corpos de sílica amorfa (SiO2.nH20), produzidos ao longo do ciclo vegetativo das plantas e após a morte das produtoras podem ser incorporados ao solo/sedimentos, podendo permanecer ali por longos períodos de tempo. Para uma análise fitolítica consistente é necessária a comparação entre os conjuntos de fitólitos encontrados no solo e as coleções de referências de fitólitos extraídos de plantas atuais. O problema consiste em não haver coleção de referência disponível para a região Sudoeste do Paraná e do Brasil, logo, não existem possibilidades de comparações, dificultando a reconstrução paleoambiental por meio deste proxy. Visando minimizar a carência de informações sobre a produção de fitólitos pela vegetação do Brasil foi elaborada uma coleção de referência de fitólitos da fitofisionomias Floresta Ombrófila Mista e do Campo, ambas localizadas no Sudoeste do Estado do Paraná. Esta coleção é composta por 30 famílias, 57 gêneros e 75 espécies. No levantamento florístico da FOM as famílias Lauraceae, Myrtaceae, Poaceae, Pteridaceae e Fabaceae apresentam maior representatividade de espécies. A vegetação do Campo apresentou elevada representatividade de espécies de Poaceae, Asterceae, Cyperaceae e Lauraceae. Constatou-se que a produção de Cinza Final (fração que contém os fitólitos) diminuem do estratos herbáceo para o arbóreo nas duas fitofisionomias. Somente duas (Araucaria angustifolia e Rapanea gardneriana) das 71 espécies analisadas não produziram fitólitos identificáveis nas folhas. A produção de fitólitos nos diferentes estratos variou em proporções similares na FOM e no Campo, principalmente no estrato A, devido presença de espécies de gramíneas que contribuiram com elevada quantidade de morfotipos short-cells (bilobate, cross e saddle, rondel e conical) nas duas fitofisionomias. Enquanto que os estratos B, C, D e Epífitas apresentaram redundância entre si pela produção de morfotipos blocky, tabular, globular, cylindric, irregular cells pelas espécies. A produção morfológica de fitólitos na FOM diferiu em quantidade, significativamente em relação ao conjuto produzido pelas espécies do Campo, pois as gramíneas produzem mais biomineralizações do que as eudicotiledôneas. A análise fitolítica dos primeiros 40 cm de solo sob a FOM revelou mudança no tipo de vegetação, evoluindo de uma vegetação mais aberta para floresta mais fechada (atual). Foi possível elocubrar que esta mudança tenha ocorrido em decorrência da ação antrópica passada. Tendência similar foi encontrada na análise do solo do Campo, isto é, passou de Campo limpo para Campo sujo e deste, novamente para Campo limpo, mudança ocorrida devido ao abandono da área e retorno das atividades antrópicas locais. A degradação dos morfotipos diferenciou nas duas fitofisionomia. Os morfotipos encontrados no solo sob a FOM apresentaram menor índice de degradação se comparado ao do Campo. O conjunto dos dois solos revelaram padrões significativos que diferenciam as duas fitofisionomias, mostrando que diferentes unidades de vegetação podem ser discriminadas pelas assinaturas fitolíticas por elas produzidas. Estes resultados reforçam a utilidade de usar fitólitos como indicadores significativos para diferenciar unidades de vegetação dominada por Campo e/ou Floresta, mesmo em curto período de tempo, demonstrando assim, o potencial da análise de fitólitos para a reconstrução paleoecológica na região Sul do Brasil.
39

Late Quaternary Landscape Evolution and Environmental Change in Charwell Basin, South Island, New Zealand

Hughes, Matthew William January 2008 (has links)
Charwell Basin is a 6 km-wide structural depression situated at the boundary between the axial ranges and faulted and folded Marlborough Fault Zone of north-eastern South Island, New Zealand. The basin contains the piedmont reach of the Charwell River, and a series of late Quaternary loess-mantled alluvial terraces and terrace remnants that have been uplifted and translocated from their sediment source due to strike-slip motion along the Hope Fault which bounds the basin to its immediate north. The aim of this study was to provide an interdisciplinary, integrated and holistic analysis of late Quaternary landscape evolution and environmental change in Charwell Basin using terrain analysis, loess stratigraphy, soil chemistry and paleoecological data. The study contributes new understanding of New Zealand landscape and ecosystem responses to regional and global climatic change extending to Marine Isotope Stage (MIS) 6, and shows that climatically-forced shifts in biogeomorphic processes play a significant role in lowland landscape evolution. Morphometric analysis of alluvial terraces and terrace remnants of increasing age demonstrated geomorphic evolution through time, with a decrease in extent of original planar terrace tread morphology and an increase in frequency of steeper slopes and convexo-concave land elements. Paleotopographic analysis of a &gt150 ka terrace mantled by up to three loess sheets revealed multiple episodes of alluvial aggradation and degradation and, subsequent to river abandonment, gully incision prior to and coeval with loess accumulation. Spatial heterogeneity in loess sheet preservation showed a complex history of loess accumulation and erosion. A critical profile curvature range of -0.005 to -0.014 (d2z/dx2, m-1) for loess erosion derived from a model parameterised in different ways successfully predicted loess occurrence on adjacent slope elements, but incorrectly predicted loess occurrence on an older terrace remnant from which all loess has been eroded. Future analyses incorporating planform curvature, regolith erosivity and other landform parameters may improve identification of thresholds controlling loess occurrence in Charwell Basin and in other South Island landscapes. A loess chronostratigraphic framework was developed for, and pedogenic phases identified in, the three loess sheets mantling the &gt150 ka terrace. Except for one age, infrared-stimulated luminescence dates from both an upbuilding interfluve loess exposure and colluvial gully infill underestimated loess age with respect to the widespread Kawakawa/Oruanui Tephra (KOT; 27,097 ± 957 cal. yr BP), highlighting the need for improvements in the methodology. Onset of loess sheet 1 accumulation started at ca. 50 ka, with a break at ca. 27 ka corresponding to the extended Last Glacial Maximum (eLGM) interstadial identified elsewhere in New Zealand. Loess accumulation through MIS 3 indicates a regional loess flux, and that glaciation was not a necessary condition for loess generation in South Island. Loess accumulation and local alluvial aggradation are decoupled: the youngest aggradation event only covers ~12 kyr of the period of loess sheet 1 accumulation. Older local aggradation episodes could not be the source because their associated terraces are mantled by loess sheet 1. In the absence of numerical ages, the timing of L2 and L3 accumulation is inferred on the basis of an offshore clastic sediment record. The upbuilding phase of loess sheet 2 occurred in late MIS 5a/MIS 4, and loess sheet 3 accumulated in two phases in MIS 5b and late MIS 6. Biogenic silica data were used to reconstruct broad shifts in vegetation and changes in gully soil saturation status. During interglacial/interstadial periods (MIS 1, early MIS 3, MIS 5) Nothofagus¬-dominated forest covered the area in association with Microlaena spp grasses. Lowering of treeline altitude during glacial/stadial periods (MIS 2, MIS 3, MIS 5b, late MIS 6) led to reduction in forest cover and a mosaic of shrubs and Chionochloa spp, Festuca spp and Poa spp tussock grasses. Comparison of interfluve and gully records showed spatial heterogeneity in vegetation cover possibly related to environmental gradients of exposure or soil moisture. A post-KOT peak in gully tree phytoliths corresponds to the eLGM interstadial, and a shift to grass-dominated vegetation occurred during the LGM sensu stricto. Diatoms indicated the site became considerably wetter from ca. 36 ka, with peak wetness at ca. 30, 25 and 21 ka, possibly due to reduced evapotranspiration and/or increased precipitation from a combination of strengthened westerly winds and increased cloudiness, or strengthened southerly flow and increased precipitation. Human influence after ca. 750 yr BP led to re-establishment of grassland in the area, which deposited phytoliths mixed to 30 cm depth in the soil. A coupled gully colluvial infilling/vegetation record showed that sediment flux during the late Pleistocene was ~0.0019 m3 m-1 yr-1 under a shrubland/grassland mosaic, and Holocene sediment flux was ~0.0034 m3 m-1 yr-1 under forest. This increase of 60% through the last glacial-interglacial transition resulted from increased bioturbation and down-slope soil transport via root growth and treethrow, which formed a biomantle as evidenced by slope redistribution of the KOT. These results contrast with sediment transport rates and processes hypothesised to occur contemporaneously in adjacent mountain catchments. This suggests that intraregional biogeomorphic processes can differ significantly depending on topography and geological substrate, with different landscapes responding in unique ways to the same climate shifts. Analysis of Quaternary terrestrial landscape evolution in non-glaciated mountainous and lowland areas must therefore consider spatial and temporal heterogeneity in sediment fluxes and underlying transport processes.
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Dental Calculus: Combining Current Methods in the Study of Diet and Mouth Use Activities Among Neolithic and Early Bronze Age Hunter-Gatherers of the Cis-Baikal, Siberia

2015 June 1900 (has links)
The utility of dental calculus as a proxy for diet and mouth use is explored for the Middle Holocene Cis-Baikal region of Central Siberia based on two methods: a macroscopic analysis of severity and a microscopic analysis of particles within deposits. The study area was inhabited by two culturally and biologically distinct cultures, the Early Neolithic (EN) Kitoi culture (8,000 to 7,000/6,800 cal B.P.) and the Late Neolithic-Early Bronze Age (LN-EBA) Isakovo-Serovo-Glaskovo (ISG) cultural complex (6,000/5,800 to 4,000 cal B.P.), separated by a period of cultural transition marked by a cessation in formal cemetery use. Data were collected from four cemetery sites, two dating to the EN and two dating to the LN-EBA. Nonparametric testing of calculus severity revealed that, for adult males and juveniles, lakeshore populations displayed greater affinity to each other than to their contemporaneous cultural counterpart populations living along riverine systems in the Angara River Valley. Trends within the EN cemetery Shamanka II contrasted to the other cemetery populations, with noticeably larger deposits in anterior quadrants and significant sexual distinctions. The proportion of protein to carbohydrates consumed is known to influence calculus formation, but both cultural groups lived on a diet based predominately on meat sources so dietary ratios alone do not adequately explain the differences distinguished. A complex multifactorial model involving microregional differences in resources/environment, foraging patterns, individual variation, and dental wear patterns provides at least a partial explanation for the results observed. A wide range of particles were recovered during the microscopic analysis of calculus, albeit in low concentrations. The low starch grain counts were consistent with a diet based predominately on meats but still provide some of the first direct evidence for plant consumption in the Cis-Baikal, including possible plant processing by cooking or grinding based on damage evident on the grains. Other particles recovered may provide evidence of mouth use activities or palaeoenvironmental influences. Together, the two components of this analysis offer strong evidence that dental calculus is a useful tool for reconstructing hunter-gatherer lifeways but also highlight the limitations of conducting this type of research on previously excavated and potentially contaminated material.

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