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No description available.

Pollen analysis of lake sediments was used to reconstruct the postglacial vegetation history of Hippa Island (53°31'50” N, 132°58'24” W), located on the exposed west coast of Haida Gwaii (Queen Charlotte Islands) on the northern British Columbia coast. A 3.55 m sediment core was extracted from Hippa Lake, a small, shallow lake on Hippa Island. Five radiocarbon ages were obtained on organic-rich sediment. A linear age-depth model estimated the base of the sediment core to be 14,000 cal yr BP (12,000 14C yr BP). Pollen and spores extracted from sediment subsamples (1 cm3) taken along the length of the core were identified and counted to a minimum sum of 500 pollen and spores, except for four basal samples, which had low pollen concentrations. Hippa Island’s vegetation history shares broad similarities to other vegetation records from Haida Gwaii and elsewhere along the British Columbia coast; however, climate fluctuations are not well recorded by the predominantly mesic pollen assemblages. The late-glacial period (14,000–13,500 cal yr BP; 12,000–11,400 14C yr BP) records a diverse herb-dominated vegetation community composed of Cyperaceae, Artemisia, Salix, and many other herbs. Transition to Pinus woodland by 13,250 cal yr BP (11,250 14C yr BP) is followed by increases in Alnus viridis and Alnus rubra, and the arrival of Picea. A decrease in Pinus and minor increases in ferns and herbs coincide with the Younger Dryas cold period; however, regression to tundra or increased Tsuga mertensiana, which characterized Younger Dryas cooling at other sites along the north Pacific coast, did not occur on Hippa Island. After 11,000 cal yr BP (9750 14C yr BP), a sharp change in vegetation occurs with Pinus, Alnus viridis, and Cyperaceae being replaced by Picea, Tsuga heterophylla and Lysichiton americanus. Despite well-documented evidence of a warmer and drier interval during the early Holocene, the composition of the mesic vegetation communities on Hippa Island was relatively stable during this time. Increases in Cupressaceae after 6000 cal yr BP (5300 14C yr BP) suggest increasing precipitation in the mid-Holocene. Modern mixed Cupressaceae-Picea-T. heterophylla forest formed by 4500 cal yr BP (4000 14C yr BP). / Graduate

Peat from a treeless "barrens" of the forest-tundra transition has been studied by the method or pollen analysis. The frequencies of various fossil pollens at successively greater depths of the peat deposits have been determined and presented in pollen diagrams, whose use is discussed in the study or the characteristics, vegetational history and development of the terrain. Illustrated with photographs of the terrain and photomicrographs of microfossils. / Thesis / Master of Arts (MA)

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This thesis considers some of the main issues surrounding the quantitative models that have been developed to reconstruct vegetation from pollen assemblages. Conducted within a pine dominated woodland, a palynologically difficult landscape, to determine vegetation changes over the late Holocene the results highlight the complexities of undertaking such studies in these contexts. Pollen productivity estimates were calculated from moss samples over the woodland using complete sets and derived subsets to detect influences of sampling design on resultant model output. Differences in the PPE sets were compared using reconstructions from simulation models in comparison to observed vegetation patterns. The results indicate that both parameter calculation and model reconstructions were influenced by the landscape form and composition. Sensitivity of the models to such small variations in parameter values heightens the need for robust data generation and increased investigation to controlling factors on pollen productivity. Performance of the reconstruction models experienced variation with respect to deposition basin size and site specific characteristics. Overall, the regional reconstructions proved to generate more confident estimates of vegetation cover whilst local scale reconstructions were subject to greater variability. Comparison of the quantitative modelling to standard interpretation and the modern analogue approach shows contrasts between the results obtained with respect to limitations associated with each method and the time frames, recent (ca. 100 years) and longer (ca. 3000 years), over which they were applied. Consequently, no one quantitative approach could be identified as being superior as site specific variations were recognised in relation to the most suitable approach. In response, a hierarchical technique is proposed to utilise the benefits of each technique and to obtain detailed information to strengthen interpretations. However, it is stressed study specific constrains that determine the available resources will influence the ability to fully apply this composite approach.

Informações sobre as plantas visitadas pelas abelhas para a obtenção de recursos alimentares são importantes para conhecimento básico de padrões ecológicos e também para a aplicação desse conhecimento na polinização de plantas cultivadas. Por isso, faz-se necessário não somente conhecer quais plantas são fontes de pólen, néctar e/ou óleo para as abelhas, mas também analisar e compreender como essas plantas são utilizadas. Pode-se, então, estudar o uso dos recursos alimentares em diferentes escalas biológicas: individual, populacional ou comunitária. Nesse contexto, estudando-se espécies de abelhas solitárias coletoras de óleo, este trabalho objetivou compreender como indivíduos de duas populações de Epicharis dejeanii (Centridini) do litoral paulista contribuem para o nicho trófico da espécie. A sobreposição/partição dos recursos alimentares também foi estudada para populações de três espécies de Tetrapedia: T. curvitarsis, T. diversipes e T. rugulosa em uma área de cerrado. Aplicando-se a metodologia de análise polínica do resíduo pós-emergencial dos ninhos-armadilha aliada a um levantamento florístico-fenológico das plantas da área, observou-se que as três espécies de Tetrapedia estudadas ao longo de um ano são generalistas. Apesar disso, concentram suas coletas em poucas espécies de plantas, especialmente em espécies do gênero Croton (Euphorbiaceae). O mesmo padrão foi observado para as populações de E. dejeanii estudadas no litoral paulista: muitas plantas são visitadas, mas poucas intensamente exploradas. Neste caso, os tipos polínicos mais utilizados pertencem às famílias Melastomataceae, Myrtaceae e Malpighiaceae, com destaque para o tipo Tibouchina (Melastomataceae). Para todas as espécies de abelhas estudadas, Malpighiaceae foi a única família de plantas visitadas para a obtenção de óleo floral, que é utilizado na construção e no aprovisionamento de células de cria. As duas populações estudadas de E. dejeanii eram compostas por indivíduos generalistas e especialistas. Mas, os tipos polínicos utilizados pelos indivíduos especialistas estão contemplados na dieta dos indivíduos generalistas. Isso indica que a população provavelmente compartilha um mesmo ranking de fontes de recursos preferidas / Information about which plants are visited by bees for gathering food resources is important for basic understanding of ecological patterns and also for applying this knowledge in crop pollination. Therefore, it is necessary to know the plant species that provide pollen, nectar and/or oil for the bees, as well as analyze and understand how these plants are used by them. For this, we can study the use of food resources at different biological scales: individual, population or community level. Within this context, studying solitary oil-collecting bees, this study aimed to understand how individuals of Epicharis dejeanii (Centridini) from two populations of São Paulo Coast contribute to the trophic niche of this species. The overlap/partition of food resources was also studied in a Cerrado area, using populations of three species of Tetrapedia: T. curvitarsis, T. diversipes and T. rugulosa. Through the method of pollen analysis of post-emergency residues from trap-nests, combined with floristic and phenological surveys of plants from the area, we found that the three species of Tetrapedia studied over one year are generalists. Despite this, the bees concentrated their collections in just a few plant species, especially in the genus Croton (Euphorbiaceae). The same pattern was observed in populations of E. dejeanii of the São Paulo Coast, where many plants are visited, but only a few are intensively exploited. In this case, pollen types intensively used belong to Melastomataceae, Myrtaceae and Malpighiaceae, highlighting the Tibouchina kind (Melastomataceae). For all studied bees, Malpighiaceae was the only plant family visited for floral oil gathering, an essential resource for the construction and provisioning of brood cells. Regarding E. dejeanii, the two populations studied were composed of generalist and specialist individuals, being the pollen types used by specialist individuals included in the diet of the generalist ones. These results indicate that the population probably shares the same ranking of preferred sources

Objective of the theses was to determine the botanical origin of bee-collected pollens using pollen analysis. The beehive, from where the pollen came from, is located in Hlavatce, which is 20 km far from České Budějovice. Bee-collected polens was obtained via pollen trap, which was put on the beehive once a week for 24 hours between 17th March to 6th June 2017. Pollens were dried, sorted according to the color shades, and the partial color samples were weighed on the analytical scales. The pollen analysis took place at a microscope magnification of 400x. The characteristics of exine (sculpture) and quantity and type of apertures were observed. The size of the grain, which was measured always in 50 pollen grains, helped to classify the plant species. Using the Shannon-Wiener Diversity Index, the bee's preferences were assessed in individual samples. The work is supplemented with photos of selected pollen grains.

Informações sobre as plantas visitadas pelas abelhas para a obtenção de recursos alimentares são importantes para conhecimento básico de padrões ecológicos e também para a aplicação desse conhecimento na polinização de plantas cultivadas. Por isso, faz-se necessário não somente conhecer quais plantas são fontes de pólen, néctar e/ou óleo para as abelhas, mas também analisar e compreender como essas plantas são utilizadas. Pode-se, então, estudar o uso dos recursos alimentares em diferentes escalas biológicas: individual, populacional ou comunitária. Nesse contexto, estudando-se espécies de abelhas solitárias coletoras de óleo, este trabalho objetivou compreender como indivíduos de duas populações de Epicharis dejeanii (Centridini) do litoral paulista contribuem para o nicho trófico da espécie. A sobreposição/partição dos recursos alimentares também foi estudada para populações de três espécies de Tetrapedia: T. curvitarsis, T. diversipes e T. rugulosa em uma área de cerrado. Aplicando-se a metodologia de análise polínica do resíduo pós-emergencial dos ninhos-armadilha aliada a um levantamento florístico-fenológico das plantas da área, observou-se que as três espécies de Tetrapedia estudadas ao longo de um ano são generalistas. Apesar disso, concentram suas coletas em poucas espécies de plantas, especialmente em espécies do gênero Croton (Euphorbiaceae). O mesmo padrão foi observado para as populações de E. dejeanii estudadas no litoral paulista: muitas plantas são visitadas, mas poucas intensamente exploradas. Neste caso, os tipos polínicos mais utilizados pertencem às famílias Melastomataceae, Myrtaceae e Malpighiaceae, com destaque para o tipo Tibouchina (Melastomataceae). Para todas as espécies de abelhas estudadas, Malpighiaceae foi a única família de plantas visitadas para a obtenção de óleo floral, que é utilizado na construção e no aprovisionamento de células de cria. As duas populações estudadas de E. dejeanii eram compostas por indivíduos generalistas e especialistas. Mas, os tipos polínicos utilizados pelos indivíduos especialistas estão contemplados na dieta dos indivíduos generalistas. Isso indica que a população provavelmente compartilha um mesmo ranking de fontes de recursos preferidas / Information about which plants are visited by bees for gathering food resources is important for basic understanding of ecological patterns and also for applying this knowledge in crop pollination. Therefore, it is necessary to know the plant species that provide pollen, nectar and/or oil for the bees, as well as analyze and understand how these plants are used by them. For this, we can study the use of food resources at different biological scales: individual, population or community level. Within this context, studying solitary oil-collecting bees, this study aimed to understand how individuals of Epicharis dejeanii (Centridini) from two populations of São Paulo Coast contribute to the trophic niche of this species. The overlap/partition of food resources was also studied in a Cerrado area, using populations of three species of Tetrapedia: T. curvitarsis, T. diversipes and T. rugulosa. Through the method of pollen analysis of post-emergency residues from trap-nests, combined with floristic and phenological surveys of plants from the area, we found that the three species of Tetrapedia studied over one year are generalists. Despite this, the bees concentrated their collections in just a few plant species, especially in the genus Croton (Euphorbiaceae). The same pattern was observed in populations of E. dejeanii of the São Paulo Coast, where many plants are visited, but only a few are intensively exploited. In this case, pollen types intensively used belong to Melastomataceae, Myrtaceae and Malpighiaceae, highlighting the Tibouchina kind (Melastomataceae). For all studied bees, Malpighiaceae was the only plant family visited for floral oil gathering, an essential resource for the construction and provisioning of brood cells. Regarding E. dejeanii, the two populations studied were composed of generalist and specialist individuals, being the pollen types used by specialist individuals included in the diet of the generalist ones. These results indicate that the population probably shares the same ranking of preferred sources

Questions remain regarding the impacts of late-Holocene human activities and environmental change on landscapes of the Caribbean islands. This dissertation examined the long-term environmental history of two sites in the northern Caribbean primarily through the analysis of proxy data sources contained in sediment cores. At Laguna Alejandro, a coastal lagoon in the southwestern Dominican Republic, we interpreted, from sediment lithology and stable oxygen isotope data, at least ten storm events over the past 1,000 years, producing the first long record of storm activity from the island. During the Little Ice Age (1400−1800 CE), we interpreted an increased frequency of hurricane landfalls at the study site with longer ecosystem recovery times and decreased fire activity versus during earlier, more moist periods of the late-Holocene. At Freshwater Pond, an inland pond on Barbuda, we interpreted vegetation disturbance from presence of disturbance pollen taxa and biomass burning near the pond from abundance of macroscopic (>125 µm) charcoal from sediments representing ~150 BCE–1250 CE, with consistency of burning and human history on the island informed by the archaeological record suggesting fire activity was primarily due to Pre-Columbian inhabitants. Microscopic charcoal analysis indicated that extra-local burning, primarily island-wide, continued until ~1610 CE then declined, possibly reflecting a change in land-use practices by Europeans who entered the region in 1492 CE and established a permanent settlement on the island in the 1660s. My study on modern pollen from surface soils and sediments, the first from lowland seasonally-dry vegetation of the Greater Antilles, informed our ideas on vegetation-pollen representation in different plant communities, including tropical dry forest, thorn forest, mangrove, mudflat, and lagoon. My modern pollen results also aided in the interpretation of stratigraphic pollen in the study of nearby L. Alejandro’s sediments and revealed changes in floristic composition at the study site through time. Pollen of maize (Zea mays) and Prosopis juliflora in sediments representing ~1760 CE document human subsistence agriculture and disturbance to tropical dry forest in the watershed. / PHD