Thesis (M.S.)--Oregon State University, 1996. / Typescript (photocopy). Includes bibliographical references (leaves 229-241). Also available online.

Thesis (Ph. D.)--Uppsala University, 1985. / Includes bibliographical references (p. 103-110).

Thesis (Ph. D.)--University of Wisconsin--Madison, 2002. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.) University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 27, 2007) Includes bibliographical references.

O conhecimento da fenologia é baseado nas observações de períodos de desenvolvimento da planta. Mudanças intra e interanuais na temperatura e precipitação podem influenciar diretamente as diferentes fases da fenologia, assim como as condições de umidade dos diferentes tipos de solo ao qual a vegetação está associada. O sensoriamento remoto é uma ferramenta que torna possível a aquisição de informações para análise espacial e temporal da vegetação. Este trabalho apresenta um estudo sobre as variações da resposta espectral da vegetação campestre natural na Área de Proteção Ambiental (APA) do Ibirapuitã, localizada no bioma Pampa, avaliando suas relações com os elementos do clima. Para isso, a metodologia compreendeu a coleta de dados climáticos de temperatura média do ar e precipitação pluvial; dados orbitais a partir de imagens de média resolução espacial do sensor MODIS para o período de 2000 a 2009, com posterior estimativa da correlação estatística entre estes dados. Além disso, utilizou-se o produto SRTM para auxiliar definição da grade amostral, em função da altimetria e solo. Os resultados mostraram os períodos de crescimento/desenvolvimento da vegetação campestre natural associados às estações do ano, com um período de crescimento nas estações quentes, diminuição da reflectância na região espectral do visível e aumento da reflectância no infravermelho próximo. Observou-se também, um período de senescência na estação fria do ano, onde o comportamento espectral da vegetação apresenta um aumento da reflectância na região espectral do visível e diminuição da reflectância no infravermelho próximo. As diferenças na reflectância da vegetação para cada tipo de solo foi observada para solos mais profundos, capazes de armazenar mais água. De maneira geral, verificou-se que a resposta espectral da vegetação campestre apresentou relação com as variações de temperatura média do ar e precipitação na região, respondendo às variáveis meteorológicas com um atraso aproximado de dezesseis (16) dias. Verificou-se assim que dados MODIS do infravermelho próximo, são adequados para monitorar o início da estação de máximo crescimento da vegetação campestre natural da APA do Ibirapuitã que se inicia na primavera. Este período está relacionado com a temperatura média do ar. / The knowledge of phenology is based on observations of periods of plant development. Inter-annual changes in temperature and rainfall may directly influence the different stages of phenology, as well as the moisture conditions of different soil types to which the vegetation is associated. Remote sensing is a tool which allows the acquisition of information for spatial and temporal analysis of vegetation. This work has aimed to study the variations of the natural grassland spectral response in the Ibirapuitã environmental protected area, which belongs to the Pampa biome, evaluating their relationship with the elements of climate. The methodology has consisted of collection of meteorological data, such as air temperature and rainfall, and orbital data from medium spatial resolution MODIS images, which covered the period from 2000 to 2009. It has also performed a statistical correlation among those data. In addition, a SRTM-defining product has employed as sampling grid, depending on elevation and soil. The results have showed periods of growth and development of natural grassland vegetation associated with the seasons, with a growth period during the warm seasons, and with a decrease of the reflectance in the visible spectrum and with an increase in the near infrared one. It was also observed a period of senescence during the cold season, where the spectral characteristics of the vegetation present a increase of the reflectance in the visible spectrum and with an decrease in the near infrared one. The differences in reflectance of vegetation in each soil type have showed most prominent in the deeper ones, which have a large water storage capacity. Overall, it has been observed a tight coupling between the spectral response of grassland vegetation and changes in air temperature and rainfall in the study area, so that the former has responded to the meteorological variables with a delay of approximately sixteen (16) days. Near-infrared MODIS data have been showed suitable to monitor the beginning of the season of maximum growth of natural grassland vegetation in the APA of the Ibirapuitã of which begins in spring. This period is mainly related to air temperature.

O conhecimento da fenologia é baseado nas observações de períodos de desenvolvimento da planta. Mudanças intra e interanuais na temperatura e precipitação podem influenciar diretamente as diferentes fases da fenologia, assim como as condições de umidade dos diferentes tipos de solo ao qual a vegetação está associada. O sensoriamento remoto é uma ferramenta que torna possível a aquisição de informações para análise espacial e temporal da vegetação. Este trabalho apresenta um estudo sobre as variações da resposta espectral da vegetação campestre natural na Área de Proteção Ambiental (APA) do Ibirapuitã, localizada no bioma Pampa, avaliando suas relações com os elementos do clima. Para isso, a metodologia compreendeu a coleta de dados climáticos de temperatura média do ar e precipitação pluvial; dados orbitais a partir de imagens de média resolução espacial do sensor MODIS para o período de 2000 a 2009, com posterior estimativa da correlação estatística entre estes dados. Além disso, utilizou-se o produto SRTM para auxiliar definição da grade amostral, em função da altimetria e solo. Os resultados mostraram os períodos de crescimento/desenvolvimento da vegetação campestre natural associados às estações do ano, com um período de crescimento nas estações quentes, diminuição da reflectância na região espectral do visível e aumento da reflectância no infravermelho próximo. Observou-se também, um período de senescência na estação fria do ano, onde o comportamento espectral da vegetação apresenta um aumento da reflectância na região espectral do visível e diminuição da reflectância no infravermelho próximo. As diferenças na reflectância da vegetação para cada tipo de solo foi observada para solos mais profundos, capazes de armazenar mais água. De maneira geral, verificou-se que a resposta espectral da vegetação campestre apresentou relação com as variações de temperatura média do ar e precipitação na região, respondendo às variáveis meteorológicas com um atraso aproximado de dezesseis (16) dias. Verificou-se assim que dados MODIS do infravermelho próximo, são adequados para monitorar o início da estação de máximo crescimento da vegetação campestre natural da APA do Ibirapuitã que se inicia na primavera. Este período está relacionado com a temperatura média do ar. / The knowledge of phenology is based on observations of periods of plant development. Inter-annual changes in temperature and rainfall may directly influence the different stages of phenology, as well as the moisture conditions of different soil types to which the vegetation is associated. Remote sensing is a tool which allows the acquisition of information for spatial and temporal analysis of vegetation. This work has aimed to study the variations of the natural grassland spectral response in the Ibirapuitã environmental protected area, which belongs to the Pampa biome, evaluating their relationship with the elements of climate. The methodology has consisted of collection of meteorological data, such as air temperature and rainfall, and orbital data from medium spatial resolution MODIS images, which covered the period from 2000 to 2009. It has also performed a statistical correlation among those data. In addition, a SRTM-defining product has employed as sampling grid, depending on elevation and soil. The results have showed periods of growth and development of natural grassland vegetation associated with the seasons, with a growth period during the warm seasons, and with a decrease of the reflectance in the visible spectrum and with an increase in the near infrared one. It was also observed a period of senescence during the cold season, where the spectral characteristics of the vegetation present a increase of the reflectance in the visible spectrum and with an decrease in the near infrared one. The differences in reflectance of vegetation in each soil type have showed most prominent in the deeper ones, which have a large water storage capacity. Overall, it has been observed a tight coupling between the spectral response of grassland vegetation and changes in air temperature and rainfall in the study area, so that the former has responded to the meteorological variables with a delay of approximately sixteen (16) days. Near-infrared MODIS data have been showed suitable to monitor the beginning of the season of maximum growth of natural grassland vegetation in the APA of the Ibirapuitã of which begins in spring. This period is mainly related to air temperature.

The main goal of this diploma thesis was to find and quantify the connection between coherence, entropy, polarimetric angle alpha obtained from Sentinel-1 radar data and grass cutting/pastures. The research was carried out in the area of the Krkonoše national park. To assemble and validate applied methodology, field data was collected 5 times. Hourly rainfall data from Czech hydrometeorological institute was available, but it did not have to be used - no rainfalls were recorded at the time of data acquisitions. Dependence between mowing and the value of coherence has been confirmed. After mowing, median coherence was higher than before mowing. The results were similar to VH as well as VV polarization. Coherence on polygons remained higher after 12-24 days. In total, two different data acquisition geometries (ascending and descending) were examined. The results in both cases were similar. For polarimetric parameters, no correlation between polarimetric parameters and grass mowing or pasture has been confirmed. Keywords: radar, SAR, Sentinel-1, coherence, polarimetry, grass mowing

Prescribed burning is a commonly used wildlife management tool. While most of the available data have evaluated short term effects of fire on wildlife (< 3 years), the present study addresses longer term effects (0 to 7 years). This enables a more thorough investigation of fire management affects on herpetofaunal communities at the landscape level. Ten sites, stratified by 0 to 7 years post-burn, were randomly selected on Big Oaks National Wildlife Refuge in southeastern Indiana and monitored for 2 field seasons. Within each site, several trapping methods were utilized including a sampling array of drift fences, pitfall traps, single and double ended funnel traps, PVC pipes, and cover boards. Burning caused immediate stand level effects and changed vegetation characteristics, which affected the species assemblages of herpetofauna and small mammals. Data collected identified the spatial and temporal variables that explained the patterns of occurrence and abundance of herpetofaunal species and small mammal species, and how community vegetation characteristics such as structure, resource availability, and plant species assemblages, correlated with and affected those patterns. Burn regimes of 2-5 years were found to be optimal when managing herpetofauna and small mammals. Constrictor coluber priapus and Peromyscus leucopus were captured frequently in the study area and the effects of a properly timed prescribed burn could have positive effects on the numbers of generalist species. Akaike information criterion was used to determine the habitat variables that were most important in habitat selection of the herpetofaunal and small mammal classes and species. While this study was limited to one wildlife refuge, in the central hardwoods its findings may have ramifications for herpetofauna in other areas where prescribed fire can be used as a management tool.

O Pampa é um bioma do tipo savana exclusivo da região Neotropical, situado na porção sul da América do Sul, cobrindo a Argentina, o Uruguai e o Brasil. O clima é quente temperado e úmido, com temperaturas anuais que variam de 0° C no inverno e mais de 24° C no verão. Os grandes distúrbios no Pampa se iniciaram a cerca de 300 anos com a chegada da colonização Europeia na região e o advento da agricultura, silvicultura, manejo sem controle pelo fogo e a criação de gado, leiteiro e de corte. Apesar de contribuir para a falta de heterogeneidade vegetal e perda na diversidade de fauna, a pecuária ainda é extensivamente indicada como manejo sustentável do Pampa. Com pesquisas e trabalhos por vezes mais focados no aumento da produtividade do rebanho que na manutenção da biodiversidade, a conservação do Pampa vem sendo negligenciada. O monitoramento de diferentes metodologias de pastejo, tradicional, em mosaico e exclusão total do gado, se faz necessário para um maior entendimento de como a diversidade de plantas e animais se comportam nestes sistemas. Para isso, são necessários bons modelos ecológicos para testes de hipóteses e diferentes manejos, o que sustenta a utilização de aranhas para estes estudos. Aranhas são rápidas colonizadoras, ótimas dispersoras, predadoras generalistas, além de estarem estritamente relacionadas à estrutura vegetal. Suscetíveis a impactos bióticos e abióticos, aranhas são ótimas medidoras de qualidade ambiental e, sendo de fácil amostragem, podem ser envolvidas em estudos sobre diversidade de espécies e indivíduos. Para tanto, este estudo foi realizado na APA do Ibirapuitã, na Campanha do Rio Grande do Sul, Brasil. Seis parcelas, de um hectare cada, foram distribuídas em pares em três fazendas. Cada par é constituído de uma parcela com pastejo, demarcadas apenas por estacas, onde o gado tem livre acesso, e uma parcela sem pastejo, cercadas desde Agosto de 2012 onde o pastejo do gado foi excluído por completo. A principal expectativa principal é que a abundancia, riqueza, biomassa e composição de aranhas serão diferentes quando áreas com e sem pastejo são comparadas forem comparados. As amostragens foram realizadas com o uso de armadilhas de queda do tipo “Pitfall traps” nas primaveras de 2011, 2012 e 2013, e sazonalmente no outono (maio), inverno (setembro) e primavera (novembro) de 2015 e verão (fevereiro) de 2016 para a captura de aranhas de hábito epígeo. Para análises estatísticas, Testes T, ANOVA e ANOSIM foram realizadas. Linyphiidae e Lycosidae foram as famílias mais abundantes e ricas em todas as coletas realizadas. Os resultados obtidos em 2011, 2012 e 2013 não demonstraram diferença significativa na fauna de aranhas, abundância e riqueza quando áreas com e sem pastejo foram comparadas. Contudo, os resultados apresentaram valores maiores nas áreas com pastejo quando comparando com áreas sem pastejo. Em 2015/2016 a abundância e a riqueza de aranhas também não foram significativamente diferentes nos dados coletados, contudo, os valores brutos também apresentaram maiores abundância e riqueza em áreas com pastejo do que nas sem pastejo. Analisando-se as estações como um todo, juntando áreas com e sem pastejo, o verão foi a estação com mais riqueza geral. Contudo, analisando as áreas com e sem pastejo separadamente, o inverno foi a estação mais rica e abundante em cada uma destas áreas. Apesar dos resultados anteriores, as espécies mais abundantes demonstraram diferença significativa em suas abundancias em cada estação do ano quando áreas com e sem pastejo foram comparados. A biomassa das aranhas não foi significativamente diferente para todos os anos entre áreas com e sem pastejo, com valores maiores em áreas com pastejo. Entretanto, espécies mais abundantes demonstraram diferenças significativas em sua biomassa sazonalmente nos anos de 2015 e 2016, com valores maiores em áreas com pastejo. Áreas com e sem pastejo ainda se mantém similares mesmo após quase quatro anos de exclusão do gado em termos de abundância total de aranhas. Apenas aranhas mais abundantes demonstram diferença entre áreas com e sem pastejo em termos de abundância e biomassa. / Pampa is a savanna-like biome, exclusively of Neotropical region, lying in southern part o South America, covering Argentina, Uruguay and Brazil. The climate is hot temperate and humid, with annual temperatures ranging of 0° C in winter and higher than 24° C in summer. The increase of disturbance at Pampa began around 300 years after Europian colonization and the advent of agriculture, silviculture, uncontrolled fire management and creation of dairy and beef cattle. Even livestock causing loss of vegetal heterogeneity and fauna diversity, it is a widely recommended methodology for sustainable management of Pampa. With studies more focused in forage properties and beef production than diversity maintenance, the Pampa conservation has been neglected. Monitoring different livestock methodologies are necessary to improve knowledge of how diversity of plants and animals change during this impact. Thus, using great ecological models, like spiders, are necessary to test hypotheses and different managements. Spiders are quick settlers, great dispersers, generalist predators and are much correlated with vegetal structure. Susceptible to biotic and abiotic impacts, spiders are great environmental quality meters, being easy to sample and to measure abundance, diversity and richness. This study was conduct at Ibirapuitã River Environmental Federal Protection Area “Área de Proteção Ambiental – APA do Rio Ibirapuitã” in Rio Grande do Sul state, Brazil. Six plots, of one hectare each, were distributed in pars in three farms. Each pair is constituted of a closed plot, a fenced plots since August 2012, with total exclusion of cattle graze; and a opened plot with only poles in the corners to demarcate the place, and cattle have free access for graze. Our main expectative is that abundance, richness, biomass and composition of arenofauna will be different when grazed and ungrazed areas were compared. Ground dwelling spiders were sampled with Pitfall traps in springs of 2011, 2012 and 2013, and seasonally in autumn (May), winter (September) and spring (November) 2015 and summer (February) 2016. Statistical analyses were performed using Stundents’ Test, ANOVA and ANOSIM. Linyphiidae and Lycosidae were the most abundant and richer families. Results of 2011, 2012 and 2013 were no significant different in spider abundance and richness when grazed and ungrazed plots were compared. However, raw data suggest higher values of abundance in grazed areas than ungrazed ones. In 2015/2016 samples, spider abundance and richness were not significant different between grazed and ungrazed areas. Raw data suggest that grazed areas abundance and richness was higher than in ungrazed though. Although summer was the richer season in general, winter was the richer season separately in grazed and ungrazed areas. Despite the previous results, abundance of the most abundant species were significant different between grazed and ungrazed areas in general and in each season. Spider biomass was not significant different in any year when grazed and ungrazed areas were compared. However, biomass of most abundant species were significant different seasonally and in each season in 2015/2016. Grazed and ungrazed areas are still very similar even after almost four years of cattle exclusion in terms of spider abundance and biomass. Only most abundant species demonstrate a significant difference between grazed and ungrazed areas in terms of abundance and biomass, with higher values in grazed plots.

Doctor of Philosophy / Department of Geography / Douglas Goodin / Quantitative remote sensing provides an effective way of estimating and mapping vegetation characteristics over an extensive area. The spatially explicit distribution of canopy vegetative properties from remote sensing imagery can be further used for studies of spatial patterns and processes in grassland systems. My research focused on remote sensing of grassland vegetation characteristics and its applications to spatial analysis of grassland dynamics involving interactions between pyric herbivory and vegetation heterogeneity. In remote sensing of vegetation characteristics, (1) I estimated the foliar pigments and nutritional elements at the leaf level using hyperspectral data. The foliar pigments, chlorophylls and carotenoids, were retrieved by inverting the physical radiative transfer model, PROSPECT. The nutritional elements were modeled empirically using partial least squares (PLS) regression. Correlations were found between the leaf pigments and nutritional elements. This provided insight into the use of pigment-related vegetation indices as a proxy of the plant nutritional quality. (2) At the canopy level, I assessed the use of the broadband vegetation indices, normalized difference vegetation index (NDVI) and green-red vegetation index (GRVI), in detecting vegetation quantity (LAI) and quality (leaf and canopy chlorophyll concentrations). The relationships between vegetation indices and vegetation characteristics were examined in the physical model, PROSAIL, and validated by a field dataset collected from a tallgrass prairie. NDVI showed high correlations with LAI and canopy chlorophylls. GRVI performed even better than NDVI in estimating LAI. A new index GNVI (green-red normalized vegetation index) that combined NDVI and GRVI was proposed to extract leaf chlorophyll concentration. These findings showed the potential of using broadband vegetation indices from multispectral remote sensors to monitor vegetation quantity and quality over a wide spatial extent. In the spatial analysis, I examined interactions between pyric herbivory and grassland heterogeneity at multiple scales from the remote sensing imagery. (3) At a coarse, watershed level, I evaluated effects of fire and large herbivores on the spatial distribution of canopy nitrogen. It was found that the interactive effects of fire and ungulate grazing were present in the watersheds burnt in spring, where a high level of ungulate grazing reduced vegetation density, but promoted canopy heterogeneity. Two grazer species, bison and cattle, were compared. Differences in the vegetation canopy between sites with bison and cattle were observed, which may be related to differences in the grazing intensity, forage behavior and habitat selection between the two grazer species. (4) At a fine, patch level (30 m), bison forage pattern was examined associated with canopy nitrogen heterogeneity. Bison preference for patches with high canopy nitrogen was evident in May. Later in June – September, bison tended to avoid sites with high canopy nitrogen. Vegetation heterogeneity showed significant influences on bison habitat selection in June. Bison preferred sites with low variance in canopy nitrogen, where the patch types were highly aggregated and equitably proportioned.