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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

Historie vegetace Chebské pánve ze sedimentárního záznamu lokality SOOS / History of vegetational development in the Cheb basin from sedimentary record of the SOOS National Nature Reserve

Suda, Tomáš January 2012 (has links)
Vegetation development in the Cheb basin ( W Czech Republic) recorded in the sediments of the SOOS ational ature Reserve This thesis focuses on palaeoecological research of quaternary sediments in the Soos National Nature Reserve (Cheb basin, NW Czech Republic). Quaternary history of this locality is poorly known, despite it is a valuable and protected area with high natural qualities. The Soos basin is also known for its unique geological record, which is expected to cover information on landscape dynamics at least during the Holocene. A lake existed in the Soos basin enabling accumulation of diatomite and peat sediments of a broad palaeoecological potential. Records were analysed with method of pollen analysis and were dated using 14C. The results of this study bring information about vegetation development in the area of Cheb basin as well as development of lake ecosystem. It also gives a new insight on lake's origin and its age. The accumulation of peat sediments started in the Preboreal period and was continuous at least until the Atlantic following with a hiatus, therefore further detection of vegetation development is impossible. The beginning of diatomite accumulation, as well as the existence of the lake goes back to the Bølling interstadial, according to radiocarbon dating. However, this...
32

Využití Biologické olympiády ve školách a zařazení vybraných úloh do výuky na gymnáziích. / Utilization of Biology Olympiad in schools and implementation of selected tasks into highschool teaching.

Dvořáková, Darina January 2012 (has links)
This thesis deals with the Biology Olympiad and remaking of selected tasks of region round. The remaked tasks can be used in highschool education. The thesis includes theoretical and practical part. The theoretical part provides general information about the Biology Olympiad (BiO), charts the achievements of Czech students in International Biology Olympiad (IBO), includes literary review of selected topics. The practical part encompass four remaked tasks of different topics: Eucaryotic cell as a mosaic, Water in life of animals, Animals' areas and their distribution, History of the flora in Czech Republic. The tasks are processed in the form of worksheets. The worksheets were tested at schools. Knowledge of students was tested by using of created pretests and posttests. The practical part also presents the result of research based on a questionnaire survey focused on the involvement of school in BiO and teachers' opinions on these topics.
33

Composição e qualidade de méis de abelha Jandaira (Melipona subnitida), efeitos estocagem e comparação com méis de Apis mellifera / Composition, quality and comparison of Jandaira (Melipona subnitida) and Apis mellifera honey

Stramm, Klaus Martin 21 October 2011 (has links)
Objetivos Avaliar a composição e qualidade de méis de abelha Jandaira através de análises físico-químicas; avaliar se os parâmetros apresentados se encaixam nas legislações nacional e internacional para méis de Apis mellifera; analisar os efeitos de estocagens de méis de Jandaira em três diferentes temperaturas (ambiente, geladeira e freezer) e os efeitos de um ano de armazenamento de méis de Jandaira e Apis mellifera de mesma região botânica e a comparação da alteração de seus parâmetros de qualidade. Metodologia Revisão de literatura relativa aos padrões de identidade e qualidade dos méis de Apis mellifera e de abelhas sem ferrão com ênfase na Melipona subnitida. Realização das análises preconizadas pela legislação brasileira para méis de Apis mellifera nas amostras coletadas de Jandaira e Apis, além das análises qualitativas (Fiehe, Lund e Lugol), condutividade elétrica e análise dos açúcares glicose, frutose e sacarose por CLAE. Resultados As amostras de mel de Apis apresentaram-se monoflorais (pólen dominante de Althernanthera sp.) e com parâmetros dentro do preconizado pela legislação vigente, enquanto os de méis de Jandaira apresentaram-se heteroflorais (pólen de Mimosa verrucosa, Mimosa caeselpiniaefolia e Piptadenia moniliforme) a umidade (24,80%) e atividade diastásica (ausente) fora do estabelecido pela legislação vigente para os méis de Apis mellifera. A condutividade elétrica de Apis (284,00 µS.cm-1) foi superior a obtida no mel de Jandaira (102,77µS.cm-1) e a cor do mel de Apis apresentou-se mais escura (26,67 mmPfund), comparada ao mel de Jandaira (7,00 ± 0,00 mmPfund). Determinou-se maior concentração de glicose, frutose e sacarose nos méis de Apis (23,50%, 38,78% e 5,72% respectivamente) do que nos de Jandaira (21,76%, 29,21% e 4,86% respectivamente). Os parâmetros mais afetados em um ano de estocagem em temperatura ambiente foram: HMF, acidez livre, condutividade elétrica e cor. O método de estocagem que melhor conservou as características do produto foi o freezer. Conclusões Os méis de Apis mellifera e Melipona subnitida apresentam diversas diferenças em seus padrões físico-químicos, mais acentuadamente nos valores de umidade e atividade diastásica. As análises do Tempo 0 dos méis de Apis se encaixaram sem exceção nas legislações nacional e internacional vigentes, enquanto as amostras de Jandaira se encontram fora do preconizado para a umidade e atividade diastásica. Após um ano de estocagem em temperatura ambiente com incidência de luz, o mel de Apis conservou melhor suas características físico-químicas em relação ao mel de Jandaira em todos os parâmetros analisados ainda estando em conformidade com a legislação. Quando estocados em diferentes temperaturas, os méis de Jandaira conservaram melhor seus parâmetros nas condições de freezer e geladeira, enquanto sofreram alterações visíveis em temperatura ambiente. / Objectives Evaluate the quality and composition of Jandaira bee\'s honey through the use of physicochemical analyses; find out if the obtained parameters are in concordance with the Apis mellifera honey Legislations established both nationally and internationally; evaluate the effects of storage conditions for Jandaira Honey in three different temperatures (ambient, fridge and freezer) over one year, as well as the storage of Apis mellifera samples from the same botanical region over one year in ambient temperature and the comparison of both kinds of honeys and the alterations of their quality parameters. Metodology Review of the literature asserting the quality and identity parameters of Apis mellifera honey and stingless bees, with emphasis on Melipona subnitida honey. Procedure of the analyses contained in the Brazillian Legislation (2000) for Apis mellifera honey in the collected samples of Apis mellifera and Melipona subnitida honeys, as well as the qualitative analyses (Fiehe, Lund and Lugol), electric conductivity, and quantification of the glucose, fructose and sucrose sugars via HPLC. Results The Apis honey samples were classified as monofloral (Althernantera sp. as dominant pollen) and demonstrated parameters in accord with the current Legislation, while the Jandaira honey samples were classified as heterofloral (nearly even amounts of Mimosa verrucosa, Mimora caeselpinaefolia and Piptadenia moniliforme pollen) displaying moisture (24,80%) and diastase activity (null) in discordance with the established by the current legislation for Apis mellifera honeys. The Apis honey samples presented higher values of electric conductivity (284,00 µS.cm-1) than the obtained in the Jandaira honey samples (102,77µS.cm-1) as well as a darker color (26,67mmPfund) when compared to Jandaira honey (7,00mmPfund). The concentration of the glucose, fructose and sucrose sugars was higher in the Apis honeys (23,50%, 38,78% and 5,72% respectively) than in the Jandaira honey samples (21,76%, 29,21% and 4,86% respectively). The most affected parameters throughout one year of storage were HMF, free acidity, electric conductivity and color. The temperature that conserved better the original characteristics of the product was the freezer. Conclusions The Apis mellifera and Melipona subnitida honey samples displayed several differences in their physicochemical parameters, namely in moisture and diastase activity. At first (Time 0) the Apis honey samples were without exception in accord with the national and international legislations, whereas the Jandaira samples had moisture and diastase activity stray from the protocol, however, after one year of storage in ambient temperature, the Apis honey samples still was in concordance with the legislations in every analyzed parameter and had it\'s physicochemical characteristics better conserved then the Jandaira honey samples. Jandaira also had it\'s own characteristics better conserved in the fridge and freezer, when compared to the notable alterations in the ambient temperature storage.
34

Sazonalidade na disponibilidade de alimento e dinâmica de forrageamento em Scaptotrigona aff. depilis (Hymenoptera, Apidae, Meliponini) / Seasonality in food availability and foraging dynamics in Scaptotrigona aff. depilis (Hymenoptera, Apidae, Meliponini).

Aleixo, Kátia Paula 13 June 2013 (has links)
Estudos sobre a influência da variação sazonal na disponibilidade de recursos florais na coleta de pólen e néctar pelas abelhas sem ferrão são escassos na literatura devido à ausência de métodos viáveis de se quantificar o alimento armazenado nas colônias por longos períodos. O objetivo desse estudo foi avaliar o armazenamento de alimento em colônias de Scaptotrigona aff. depilis em relação a distribuição espaçotemporal dos recursos florais em uma área urbanizada na região tropical, bem como estratégias utilizadas pelas colônias no período de menor disponibilidade alimentar. De abril de 2011 a março de 2012, a estrutura da comunidade vegetal do campus da Universidade de São Paulo, cidade de Ribeirão Preto, foi avaliada sob os aspectos da composição florística e fenologia de floração para avaliar a ocorrência de sazonalidade na distribuição dos recursos florais disponibilizados para as abelhas. Concomitantemente, foi analisado qualitativamente e quantitativamente o armazenamento mensal de pólen e néctar em colônias experimentais (CEs) de S. aff. depilis, formadas a partir da remoção de colônias mães (CMs) de seus lugares originais e substituídas por caixas de madeira vazias, as CEs, em cujas as forrageiras armazenaram o alimento durante sete dias. No mesmo período de um ano, foi avaliada a produção mensal de cria nas CMs de S. aff. depilis por meio de fotografias tomadas na região da cria em intervalos de 24h durante quatro dias consecutivos. Espécies melitófilas floresceram durante o ano todo e, consequentemente, a disponibilidade de alimento para as abelhas foi contínua. A distribuição dos recursos foi sazonal, com abundância de disponibilidade na transição da estação seca com a chuvosa e na estação chuvosa. O armazenamento de alimento foi afetado pela associação entre a sazonalidade na disponibilidade de pólen e a temperatura ambiente. O pólen foi armazenado ao longo de todo o ano, ao passo que o néctar começou a ser armazenado no final da estação seca e permaneceu durante toda a estação chuvosa. Nas CEs, a maior quantidade de alimento foi armazenada na estação chuvosa, com pico no bimestre de fevereiro-março. Mesmo apresentando um hábito generalista, as forrageiras de S. aff. depilis intensificaram, espacial e temporalmente, a coleta de recursos em poucas fontes florais. As espécies Eucalyptus moluccana, E. grandis e Myracrodruon urundeuva foram preferencialmente utilizadas no armazenamento de pólen durante a estação seca, ao passo que durante a estação chuvosa apenas Schinus terebinthifolius foi a fonte preferencialmente utilizada. A sazonalidade na disponibilidade de pólen influenciou inclusive a produção de cria, a qual diminuiu na estação seca. A disponibilidade de pólen parece ser um fator central influenciando no crescimento e no desenvolvimento das colônias de S. aff. depilis. / Studies on the influence of seasonal variation in the availability of floral resources on the collection of pollen and nectar by stingless bees are scarce due to lack of methods to quantify the stored food in the colonies for long periods of time. The aim of this study was to evaluate the storage of food in colonies of Scaptotrigona aff. depilis in relation to the spatiotemporal distribution of floral resources in an urbanized area in the tropical region, as well as assess the strategies used by the colonies during periods of food scarcity. From April 2011 to March 2012, the plant community structure in the campus of Universidade de São Paulo, located in the city of Ribeirão Preto, was studied under the aspect of floristic composition and flowering phenology to evaluate the occurrence of seasonality in the distribution of floral resources available to bees. Concurrently, it was analyzed the monthly storage of pollen and nectar in experimental colonies (ECs) of S. aff. depilis formed from removal of colonies (MCs) from their original places and replaced by empty wooden boxes, the ECs, whose foragers stored food for seven days. In the same period of an year, it was evaluated the monthly brood production in MCs of S. aff. depilis through photographs taken in the brood region at intervals of 24h for four consecutive days. Melittophilous were in bloom year-round, and therefore the availability of food resources was continuous for bees. The resource distribution was seasonal, with plenty of available resources in the transition from the dry to the rainy season and in the rainy season. The storage of food was affected by the association between the seasonal availability of pollen and ambient temperature. Pollen was stored throughout the year, while the nectar started to be stored in the dry season and remained throughout the rainy season. In ECs, the largest amount of food was stored during the rainy season, peaking in February-March. Even though foragers display a generalist habit, food collection was intensified at few sources in spatiotemporal scale. The species Eucalyptus moluccana, E. grandis and Myracrodruon urundeuva were preferentially used in the storage of pollen during the dry season, while Schinus terebinthifolius was the most frequently used species during the rainy season. Seasonality in pollen availability also influenced brood production, which decreased in the dry season. The availability of pollen seems to be a central parameter influencing the growth and development of S. aff. depilis colonies.
35

Vegetation and climate during Weichselian ice free intervals in northern Sweden : Interpretations from fossil and modern pollen records

Hättestrand, Martina January 2008 (has links)
<p>In this thesis the Weichselian history of northern Sweden is investigated, with emphasis on vegetation and climate during ice-free intervals. The main method used has been pollen analysis of sediments from pre-Late Weichselian landforms. To interpret fossil pollen assemblages, comparisons with modern pollen spectra were made. Modern pollen data were retrieved through monitoring of annual pollen deposition at seven sites in northern Sweden, from the boreal forest to above the present forest-line of birch. Eight years of pollen monitoring is described and put in a larger context through comparison with monitoring data from Iceland, Svalbard, Norway and Finland. A study of sediment cores from the Riipiharju esker shows evidence of two ice free phases during the Weichselian glacial; Tärendö I and Tärendö II. The Tärendö II ice free interval includes large climatic shifts, previously not recognized, from relatively warm conditions with <i>Betula</i> as the dominating pollen taxon to cold conditions with dominance of <i>Artemisia</i> and Gramineae and back to warmer conditions again. Correlation alternatives of the north Swedish ice free intervals Tärendö I and II are: 1/ Brörup (MIS 5c; c. 105-93 ka BP) and Odderade (MIS 5a; c. 85-74 ka BP), respectively, or 2/ Odderade and early Middle Weichselian time (MIS 3; c. 59-40 ka BP). Of these, alternative 2 is regarded as the most likely. Interstadial sediments deposited in a Veiki moraine plateau during downwasting of a pre-Late Weichselian ice sheet include only <i>Betula</i> dominant pollen spectra, showing that the climate during formation of the Veiki moraine was relatively warm. According to stratigraphical correlation there are three possible alternatives for Veiki moraine formation. Either it was formed during 1/ early Tärendö I, 2/ early Tärendö II, or 3/ late Tärendö II. Alternative 3 implies growth of an intermediate ice sheet reaching the eastern limit of Veiki moraine distribution during the cold phase of Tärendö II.</p>
36

Vegetation and climate during Weichselian ice free intervals in northern Sweden : Interpretations from fossil and modern pollen records

Hättestrand, Martina January 2008 (has links)
In this thesis the Weichselian history of northern Sweden is investigated, with emphasis on vegetation and climate during ice-free intervals. The main method used has been pollen analysis of sediments from pre-Late Weichselian landforms. To interpret fossil pollen assemblages, comparisons with modern pollen spectra were made. Modern pollen data were retrieved through monitoring of annual pollen deposition at seven sites in northern Sweden, from the boreal forest to above the present forest-line of birch. Eight years of pollen monitoring is described and put in a larger context through comparison with monitoring data from Iceland, Svalbard, Norway and Finland. A study of sediment cores from the Riipiharju esker shows evidence of two ice free phases during the Weichselian glacial; Tärendö I and Tärendö II. The Tärendö II ice free interval includes large climatic shifts, previously not recognized, from relatively warm conditions with Betula as the dominating pollen taxon to cold conditions with dominance of Artemisia and Gramineae and back to warmer conditions again. Correlation alternatives of the north Swedish ice free intervals Tärendö I and II are: 1/ Brörup (MIS 5c; c. 105-93 ka BP) and Odderade (MIS 5a; c. 85-74 ka BP), respectively, or 2/ Odderade and early Middle Weichselian time (MIS 3; c. 59-40 ka BP). Of these, alternative 2 is regarded as the most likely. Interstadial sediments deposited in a Veiki moraine plateau during downwasting of a pre-Late Weichselian ice sheet include only Betula dominant pollen spectra, showing that the climate during formation of the Veiki moraine was relatively warm. According to stratigraphical correlation there are three possible alternatives for Veiki moraine formation. Either it was formed during 1/ early Tärendö I, 2/ early Tärendö II, or 3/ late Tärendö II. Alternative 3 implies growth of an intermediate ice sheet reaching the eastern limit of Veiki moraine distribution during the cold phase of Tärendö II.
37

Antibacterial Activity and Factors Impacting Antibacterial Stability of Southwestern Ontario Honey

Pask, Jessica 22 August 2013 (has links)
This thesis presents results from a two part, prospective study using honey collected from Guelph and surrounding area in southwestern Ontario. The first part determined the antibacterial of honey by collecting 26 samples of honey over two summers (2011-2012) and conducting microbroth and agar dilution assays and comparing the results to those of the criterion standard, Medihoney™ (100% manuka honey paste). Some honey samples from southwestern Ontario had antibacterial activity that was not significantly different from that of Medihoney™. The second part evaluated the effects of storage and gamma irradiation on the antibacterial activity of highly antibacterial honeys. It was found that storage for 8 months at 4°C and -20°C reduced the antibacterial activity of honey. The antibacterial activity of honey was not altered after gamma irradiation. / Pet Trust Fund
38

Pollen based Inferences of Post-glacial Vegetation and Paleoclimate Change on Melville Peninsula, Nunavut, Canada

Iamonaco, John-Paul 08 December 2011 (has links)
Pollen analysis of a sediment core from Lake SP02, Melville Peninsula, Nunavut, Canada provides a ~6300 year record of post-glacial vegetation and climate change. Dominant local and regional taxa identified include Cyperaceae, Ericaceae, Artemisia, Salix, and Oxyria. Fossil pollen assemblages, pollen accumulations rates, and variations in sediment organic matter, indicate a period of optimal Holocene warmth between 5300-3900 yr BP, followed by a prolonged period of Neoglacial cooling, as well as a period of relative warmth between 1300-1000 yr BP, interpreted as evidence for the Medieval Warm Period. Variations in pollen abundances and accumulations during the 20th century suggest a response to recent warming that is unprecedented since deglaciation of the Peninsula. Comparisons of the timing and rates of multi-scale climate variations for Melville Peninsula with adjacent sites reveal a potential late Holocene shift in the boundary separating continental and maritime climate regions in the eastern Canadian Arctic.
39

Pollen based Inferences of Post-glacial Vegetation and Paleoclimate Change on Melville Peninsula, Nunavut, Canada

Iamonaco, John-Paul 08 December 2011 (has links)
Pollen analysis of a sediment core from Lake SP02, Melville Peninsula, Nunavut, Canada provides a ~6300 year record of post-glacial vegetation and climate change. Dominant local and regional taxa identified include Cyperaceae, Ericaceae, Artemisia, Salix, and Oxyria. Fossil pollen assemblages, pollen accumulations rates, and variations in sediment organic matter, indicate a period of optimal Holocene warmth between 5300-3900 yr BP, followed by a prolonged period of Neoglacial cooling, as well as a period of relative warmth between 1300-1000 yr BP, interpreted as evidence for the Medieval Warm Period. Variations in pollen abundances and accumulations during the 20th century suggest a response to recent warming that is unprecedented since deglaciation of the Peninsula. Comparisons of the timing and rates of multi-scale climate variations for Melville Peninsula with adjacent sites reveal a potential late Holocene shift in the boundary separating continental and maritime climate regions in the eastern Canadian Arctic.
40

Reconstitui??o paleoambiental utilizando uma abordagem multi-proxy em um registro de turfeira tropical de montanha, Minas Gerais, Brasil

Costa, Camila Rodrigues 09 March 2018 (has links)
Data de aprova??o retirada da vers?o impressa do trabalho. / ?rea de concentra??o: Produ??o Vegetal. / Submitted by Jos? Henrique Henrique (jose.neves@ufvjm.edu.br) on 2018-08-14T22:18:43Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) camila_rodrigues_costa.pdf: 5661319 bytes, checksum: b9deab885dfc53d90534a8a979f8d00d (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2018-10-05T19:35:26Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) camila_rodrigues_costa.pdf: 5661319 bytes, checksum: b9deab885dfc53d90534a8a979f8d00d (MD5) / Made available in DSpace on 2018-10-05T19:35:26Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) camila_rodrigues_costa.pdf: 5661319 bytes, checksum: b9deab885dfc53d90534a8a979f8d00d (MD5) Previous issue date: 2018 / Funda??o de Amparo ? Pesquisa do estado de Minas Gerais (FAPEMIG) / As turfeiras s?o ambientes de transi??o entre os ecossistemas terrestres e aqu?ticos, formados pela acumula??o sequencial de mat?ria org?nica. Extremamente sens?veis as mudan?as nos padr?es de precipita??o e temperatura, as turfeiras s?o consideradas verdadeiros arquivos da evolu??o do ambiente ao seu redor. Nas depress?es das ?reas dissecadas da Serra do Espinha?o Meridional, Minas Gerais, ocorrem ambientes propicios para forma??o de turfeiras. Dentre elas encontra-se a turfeira do Rio Preto (18?14'5,25"S e 43?19'7,24" WGS, 1.593 m.s.m) inserida no Parque Estadual do Rio Preto. A turfeira do Rio Preto ? colonizada por diferentes fisionomias do Bioma Cerrado principalmente o Campo ?mido e Campo Rupestre, sendo encontrados ainda redutos de Floresta Estacional Semidecidual (Cap?es de Mata). O objetivo deste trabalho foi reconstituir as mudan?as paleoambientais ocorridas desde o final do Pleistoceno Tardio. Para isto foi utilizada uma abordagem multi-proxy, consistindo em estratigrafia do perfil do solo da turfeira, an?lises palinol?gicas, de is?topos est?veis (13C e 15N), de composi??o geoqu?mica e data??es radiocarb?nicas. A idade mais antiga, obtida da base do testemunho, foi de 23.037 anos cal. AP, indicando que a forma??o da turfeira se deu a partir do Pleistoceno Tardio. A partir da an?lise conjunta dos proxys foi poss?vel inferir cinco principais fases de mudan?as paleoambientais: RP-I, entre ~ 23.037 e 13.500 anos cal. AP, clima bastante ?mido e frio, possibilitando a presen?a de indicadores de Floresta Montana e o empobrecimento do sinal isot?pico. Este foi um per?odo de bastante instabilidade na bacia hidrogr?fica da turfeira, inferida pelo alto teor de Si, indicador de sinal de material mineral local; RP-II, entre ~13.500 e 11.700 anos cal. AP, ligeiro aumento da temperatura e queda na umidade levando a redu??o de indicadores de clima frio e a expans?o da vegeta??o campestre. No entanto as condi??es ainda eram mais ?midas e frias que as atuais, e a ind?cios de diminui??o do sinal de material mineral local; RP-III, entre ~11.700 e 8.500 anos cal. AP, tend?ncia de aumento da temperatura e diminui??o da umidade em conjunto com a mudan?a da vegeta??o de plantas C3 para C4, causando a forte retra??o das Floresta Estacional Semidecidual e Floresta Montana, em conjunto aumento do fluxo de sinal de material mineral local; RP-IV, entre ~8.500 e 7.000 anos cal. AP, condi??es de clima ainda mais seco e quente, causando o desaparecimento dos indicadores de clima frio, retra??o do Campo ?mido e expans?o do Campo Rupestre. Per?odo de bastante estabilidade da bacia hidrogr?fica da turfeira, sugerido pelo baixo conte?do de material mineral; RP-V, de 7.000 anos cal. AP at? o presente, clima era novamente mais ?mido e temperaturas mais amenas, semelhante ?s condi??es atuais, aumento na acumula??o de turfa, possibilitando o reaparecimento dos indicadores de Floresta Montana e Floresta Estacional Semidecidual junto com a retra??o do Campo, e diminui??o da entrada de material mineral. Flutua??es no clima influenciaram fortemente as mudan?as na paleovegeta??o e na estrutura sedimentar do registro da turfeira do Rio Preto. Devido ? import?ncia das turfeiras, n?o s? como arquivo de mudan?as paleoambientais, mas tamb?m pelos seus servi?os ambientais (armazenamento de ?gua e de carbono), estes ambientes precisam ser melhores protegidos. / Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Produ??o Vegetal, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2018. / The peatlands are transitional environments between terrestrial and aquatic ecosystems, formed by the sequential accumulation of organic matter. Extremely sensitive to changes in precipitation and temperature patterns, peatlands are real archives of the evolution of the environment around them. In Serra do Espinha?o Meridional, Minas Gerais State, Brazil, in depressions of the dissected areas occurs an environment conducive to formation of peatlands. Among them the peatland of Rio Preto (18?14'5,25"S e 43?19'7,24" WGS, 1.593 m.s.m), located in the Rio Preto State Park. The area is colonized by different vegetation physiognomy of the Cerrado Biome, mainly Rupestre Fields and Wet Fields, beyond of redoubts of Semidecidual Stationary Forests, called Capon Forests. The area is colonized by different vegetation physiognomy of the Cerrado Biome, mainly Rupestre Fields and Wet Fields, beyond of redoubts of Semidecidual Stationary Forests, called Capon Forests. The objective of this work was to reconstruct the paleoenvironmental changes that have occurred since the Late Pleistocene. The work was constituted by the application of a multi-proxy approach, such as peatland soil stratigraphy, palynological analyzes, stable isotopes (13C and 15N), geochemical composition analyzes and 14C dating. The oldest age obtained at the base of the peatland profile was 23.037 cal. years BP, indicating that the formation of the peatland occurred during the Late Pleistocene. In this study it was possible to infer five main stages of paleoenvironmental changes: RP-I ~23.000-13.500 cal. years BP, very cold climate and very humid, presence of Montana Forest indicators and impoverishment of the isotopic signal, period of instability in hydrographic basin of the peatland; RP-II ~13.500-11.700 cal. years BP, small increase in temperature and decreased humidity, reduction of the indicators of cold climate and the expansion of the field vegetation, however the climatic conditions were more humid and cooler than the current, decrease of the entrance of local mineral material; RP-III ~11.700-8.500 cal. years BP, trend of increased temperature and decreased humidity, change in vegetation from C3 to C4 plants, reduction of the Semideciduous Seasonal Forest and Mountain Forests, increased flow of local mineral material; RP-IV ~8.500-7.000 cal. years BP, drier and hotter weather, causing the disappearance of the indicators of cold weather, retraction of the Wet Field and expansion of Rupestre Field. Period of very stability in the watershed of the peatland; RP-V 7.000 cal. years BP until present, increased humidity and decrease in temperature, as current conditions, increased accumulation of peat, reappearance of the indicators of Montana Forest and Seasonal Semideciduous Forest and retraction of the Field, decrease of regional and local dust. Fluctuations in the climate influenced changes in paleovegetation and the sedimentary structure of the peatland Rio Preto. Given the value of peatlands as archives of paleoenvironmental changes and their environmental functions, these environments need to be better protected.

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