Univ., Diss.--Utrecht, 2004. / Zsfassung in engl. und niederl. Sprache.

Thesis (M.S.)--Bowling Green State University, 2005. / Document formatted into pages; contains xii, 106 p. : ill., maps. Includes bibliographical references.

Thesis (M. Sc.(Zoology))--University of Pretoria, 2006. / Includes summary. Includes bibliographical references. Available on the Internet via the World Wide Web.

Orientador: Carlos Frederico Duarte da Rocha / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-09T17:01:38Z (GMT). No. of bitstreams: 1 Miranda_JivanildoPinheiro_D.pdf: 7646850 bytes, checksum: 1b29966bda6798dfbb87bba528797710 (MD5) Previous issue date: 2007 / Resumo: Neste estudo investiguei a riqueza, composição e distribuição local da herpetofauna do Parque Nacional dos Lençóis Maranhenses (PNLM), Maranhão, Brasil. Realizei 47 expedições, totalizando 235 dias de amostragem utilizando o método de procura visual limitada por tempo. Adicionalmente, estudei a ocorrência de atropelamentos de vertebrados na rota de acesso ao parque. Assim, registrei 63 espécies da herpetofauna no PNLM, sendo 21 espécies de anuros, 12 de lagartos, 24 de serpentes, duas de anfisbenas, três de quelônios e uma de jacaré. Destas espécies, 52 (E 82,5%) ocorrem apenas na restinga. As demais espécies ocorrem no campo de dunas do parque. Em relação aos atropelamentos, realizei cerca de 10896 quilômetros de amostragem. Encontrei 206 carcaças de vertebrados atropelados, distribuídas por 55 espécies. O grupo de vertebrado mais atropelado, em número de espécies (23 espécies) e de indivíduos (69 indivíduos), foi a classe Reptilia. Apesar do PNLM ser enfatizado do ponto de vista paisagístico, este estudo mostra que seus ambientes possuem significativa riqueza de espécies da herpetofauna. Estas espécies ocorrem principalmente no ambiente de restinga, o qual corresponde a apenas 21% da área do parque. Devido a crescente visitação turística e do aumento de empreendimentos na área, é importante que ações para a conservação da restinga do PNLM sejam urgentemente implementadas / Abstract: Herpetofauna richness, composition and local distribution (sand dunes or restinga habitats) were studied in Lençóis Maranhenses National Park (LMNP), Maranhão state, northeastern Brazil. I carried out 235 days of sampling using the method of visual search limited by time. In addition, I studied road killed vertebrates in the access route to the park (a road that crosses restinga habitats). Thus, I recorded 63 species of the herpetofauna (21 anurans, 12 lizards, 24 snakes, two amphisbaenians, three turtles and an alligator) in LMNP. Fifty-two species (E 82,5%) were found only in restinga habitats. Concerning to road killed animals, I carried out 10896 km of sampling and I found 206 carcasses of vertebrates, corresponding to 55 species. Reptilia was the vertebrate class with the largest number of species (23 species) and individuals (69 individuals) killed. Overall, the great number of species occurring in restinga habitats and high incidence of reptiles road killed in the route to the park, highlight the importance of actions to improve conservation in restinga habitats, which currently comprise only 21% of the total area protected by the park / Doutorado / Ecologia / Doutor em Ecologia

The purpose of this study is to gain some first insights into the role of burst-like turbulent motions in sediment suspension over a sandy channel bed, during typical conditions of strong sediment transport with active bedforms. The focus is the suspension mechanism that maintains sizeable sediment concentrations away from the bed, where much of the downstream transport occurs, rather than entrainment at the sediment boundary itself. Flow components downstream and normal to the mean boundary, along with the output of an optical suspended sediment sensor, were monitored 1 m above the bed. The main study data were collected in a 10 m deep channel of the Fraser River near Mission, British Columbia, Canada. Velocities averaged 1.4 m/s at the surface and 0.9 m/s at the sensors, where mean suspended sediment concentrations were 500 mg/l; decimetre height small dunes on the backs of larger, metre amplitude dunes covered the channel bed. Many hours of data were recorded at 5 Hz, allowing multi-second scale turbulent motions as well as multi-minute oscillations to be resolved in both the velocity and turbidity records. Burst-like "ejection and inrush" motions were identified, producing a high degree of intermittency in momentum exchange: 80% of the mean Reynolds stress at the 1 m level is produced during 12% of the record duration. The burst recurrence period appears to be significantly greater than predicted by applying the conventional outer flow scaling in this environment. It is hypothesised that the non-uniform shear and pressure gradient conditions over the various scales of bedforms on the river floor may somehow affect mean burst periodicity, modifying the recurrence scaling developed over flat boundaries. The determination of a burst recurrence timescale from one-point data is inherently imprecise however and, as elsewhere, a continuous variation of return periods with relative magnitude of extreme (u'v') events is observed. The optical turbidity (OBS) time series reveals that these intermittent burst-like motions are, as expected, very important in vertically mixing sediments across the 1 m level in the flow; for example violent ejections, occurring only 1% of the time and contributing some 10% to mean turbulent momentum flux, appear to account for 6% of the total vertical sediment flux. The statistical association between the momentum and sediment mixing efficiencies of any ejection appears to be only moderately strong, however; very intense suspension can be associated with rather "weak" ejections (in terms of stress), and vice-versa. Differences between momentum and sediment mixing effects of a given ejection may partly be related to the "crossing trajectories effect"; sand grains continually fall out of the eddies that bear them, so the momentum and sediment "contents" of an eddy at 1 m off the bed are not perfectly linked. Turbulent sediment suspension is, like momentum exchange, a highly intermittent process in itself. After selecting turbulent events only for suspension efficiency, the largest ones, occupying only 5% of the time, contribute approximately one half of the total vertical sediment flux. There is no indication that the conventional scaling of burst recurrence corresponds to the occurrence of any distinctive event level for suspension. Interestingly, burst-like turbulent motions are not the only flow oscillations contributing to suspension in the high flow conditions of the study. Multi-minute period flow perturbations at 1 m off the bed significantly assist burst-scale turbulent motions in driving the upward sediment mixing. In summary, turbulent mixing of both momentum and sediment at 1 m over a typical sandy river bed is dominated by intermittent, intense "burst-like" events. However, the extrapolation of intermittent "bursting" concepts and structural constants from small-scale laboratory flows to the larger fluvial environment may be misleading. / Arts, Faculty of / Geography, Department of / Graduate

Geochemistry has been used to determine the provenance and diagenetic history of eolian sandstone deposits. However, the grain size, sorting, cementation, and detrital composition of eolian units can change along dune foreset laminae. The purpose of this study was to test for consistent trends of compositional change along dune foresets. Such trends could increase the quality of geochemical sampling of eolian sandstones and possibly aid in estimating the original height of ancient sand dunes. XRF data was gathered for both major and trace elements from the Pennsylvanian to Permian Weber Sandstone, Early Jurassic Navajo Sandstone, and modern Coral Pink Sand Dunes of southern Utah. Data was plotted using both 2-dimensional scatter plots and 3-dimensional principal components analysis (PCA) plots. The PCA plots proved to be the most informative and suggest that there are no consistent, statistically significant geochemical trends within or between the three units sampled. However, this study found that PCA was able to show significant geochemical differences between the three units sampled, even when they are all dominated by a single mineral (>90% quartz). The Weber Sandstone had the most varied composition, and dunes within the unit could be highly dissimilar to each other. The Navajo Sandstone had less overall geochemical variability than the Weber Sandstone, and individual dunes were similar to each other. The modern Coral Pink Sand Dunes had much less compositional variation than either of the other two units, and dunes in this unit were very similar to each other.

Environmental filters play an important role in plant community assembly. Evaluating spatial variation in functional traits across environmental gradients may help determine the environmental filters that play a role in community assembly and how plant communities respond to prevailing environmental conditions. In this study, we evaluated spatial variation in leaf traits (size, thickness, specific area and dry matter content) of coastal sand dune plant communities across 16 sites along a precipitation gradient in the Yucatan Peninsula. We described community-wide trait variation in terms of dispersion and dominant values across the gradient in order to answer the following questions: Which environmental filters explain variation in leaf traits? What ecological strategies, in terms of leaf economics, do these environmental filters favour? Mean specific leaf area and dispersion in leaf thickness tended to be lower in drier sites, suggesting that plants invest more biomass per leaf (a conservative strategy) and become more succulent as aridity increases. Contrary to expectation, leaf size increased with proximity to the coastline and dry matter content was significantly greater in the wettest region. Therefore, variation in these leaf traits content cannot be explained by the precipitation gradient. We have shown that predictable variation in some functional leaf traits can be found, even at small scales within the same vegetation zone in coastal sand dunes. Our study supports the notion that variation in water availability can be an important driver of functional trait distribution in the plant communities of some arid environments.

Insects fulfill important roles within all ecosystems, including deserts, and interact directly and indirectly with the endemic and endangered species at the Ash Meadows National Wildlife Refuge (AMNWR). Here I investigate the variability of species richness, diversity, abundance and community composition of four insect groups between stabilized sand dune habitats, unstabilized sand dune habitats and non-sand dune habitats. The insects examined in this thesis include antlions (Myrmeleontidae), bees (Apiformes), darkling beetles (Tenebrionidae) and velvet ants (Mutillidae). As the impact and interactions of two of the insect groups, antlions and velvet ants, are largely unknown within any ecosystem, this thesis also includes a faunal study of velvet ants at AMNWR and their spatial and temporal variation at the refuge. Generalized linear mixed models were used to identify significant differences in richness, diversity and abundance for each insect group between the stabilized sand dune, unstabilized sand dune and non-sand dune habitats. Species richness differed between habitats for antlions, beetles and velvet ants over the study period. Diversity differed between habitats for antlions and beetles, and abundance differed between habitats for all groups over the study period. Nearly every habitat supported some unique species. The faunal survey of velvet ants revealed minor variation in flight times between species and a unique pattern of temporal niche partitioning in one species. Habitat preferences were observed for seven of 42 velvet ant species at AMNWR. In a comparison of the diversity of velvet ants between AMNWR and the Nevada Test Site (NTS), six velvet ant species that occurred at the NTS were not found at AMNWR. Diagnoses and a key are provided for the velvet ants of AMNWR. This thesis increases the number of known terrestrial invertebrates at the refuge and provides a comparison of terrestrial insect distribution and habitat use at AMNWR. These investigations contribute to the goals and objectives of the U. S. Fish and Wildlife Service to obtain basic inventories and understand the terrestrial habitat use of invertebrates at AMNWR.

The objectives of this investigation are as follows: 1) review the existing hydrogeologic data for the San Luis Valley, the Great Sand Dunes Monument, and Medano Creek; 2) review the surface-water data that have been collected on Medano Creek; 3) collect or review previously collected water-level data obtained in the area of lower Medano Creek and correlate them with the surface-water data; 4) conduct constant-head permeameter tests on sand samples collected near the ground surface along lower Medano Creek; 5) produce a conceptual model of lower Medano Creek; and 6) produce a numerical model of lower Medano Creek that will predict the effect that a lowering of the regional water table could have on the terminus of flow of Medano Creek. The complex hydrogeologic conditions under lower Medano Creek have been approximated with three homogeneous and anisotropic layers. A complex system of confining layers is represented by a single low-hydraulic-conductivity layer in the middle. Numerical-modeling results suggest that the location of the terminus of flow in Medano Creek will recede significantly in response to a lowering of the regional water table, possibly by as much as 21,000 feet (6,400 meters) if the regional water table is lowered 150 feet (46 meters). These results indicate the qualitative effect that a lowering of the regional water table would have on lower Medano Creek, but they cannot be considered to be precise quantitative predictions. The results should be regarded with caution due to the paucity of data available.

This research formulated a recent geologic history of the Clatsop Plains dating from 3500 years BP to present. Research consisted of geomorphic mapping, near-surface stratigraphic evaluation, carbon dating and subsurface interpretation of available data.