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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.
1

The Vertical Stratification of the Macrobenthos in the Brazos River, Texas

Poole, Walton Charles 12 1900 (has links)
Quantification of stream macrobenthos populations has remained a perplexing problem in rivbrine ecology, despite numerous attempts at improvement. This is in part due to well documented variations in chemical and physical parameters locally and geographically, and resultant adapted macrobenthos populations. Southwood (1968) and Hynes (1970a) have reviewed the various sampling techniques developed'for the census of lotic macrobenthos populations. Needham and Usinger (1956), Chutter (1969), and others have pointed out the difficulty in obtaining adequate numbers of samples which will yield population estimates with desired statistical confidence, and still maintain some degree of sampling economy. Needham and Usinger (1956) and Gaufin et al. (1956) mentioned the "patchy" distribution of aquatic insect populations as the primary source of this difficulty. The concept of patchy distribution in insect populations was originally discussed by Andrewartha (1961). Attempts to improve confidence through improved sampling devices and techniques have led to development of numerous types of samplers. Cummins (1962) indicated that there were almost as many samplers as there were researchers.
2

Composition and structure of spider assemblages in layers of the mixedwood boreal forest after variable retention harvest

Pinzon, Jaime Unknown Date
No description available.
3

Vertical stratification and species composition of Nymphalidae butterfly assemblages in tree-fall gaps and understory in Madidi National Park, Bolivia

Skarped, Linnéa January 2014 (has links)
Rainforest is a dynamic ecosystem where species are affected by numerous biotic and abiotic factors. One important abiotic factor for many species is the availability of sunlight. The understory habitat under the closed undisturbed canopy is comparably constant with regard to sunlight and therefore also humidity and temperature. The canopy regulates the amount of sunlight that will reach the ground, which means that changes in canopy cover will change the understory environment. The main natural disturbances that affect the structure of rainforest are tree falls, that resulting in tree-fall gaps. The aim of this study was to compare the vertical stratification and species composition of fruit-feeding Nymphalidae butterflies between tree-fall gaps of different sizes and undisturbed understory in a primary rainforest in Madidi National Park, Bolivia. Fruit-baited traps were suspended at ground level (2 m) and in canopy (10-15 m) in 5 tree-fall gaps and adjacent undisturbed understory, a total of 40 traps. There were more species rich assemblages in gaps both at ground level and in canopy, compared to understory. The data show that there are different species assemblages in tree-fall gaps, undisturbed understory, canopy and at ground level. The vegetation structure affected by the amount of sun light was an important factor affecting butterfly assemblages. There was a tendency that differences among gap assemblages increased with gap size. These results indicate the importance of the mosaic pattern caused by natural tree-fall gaps, they contain specific resources that favor different butterfly assemblages.
4

Multicohort Management and LiDAR: New Forest Management Tools for Northeastern Ontario Boreal Mixedwood Bird Communities

Burrell, Michael 11 January 2010 (has links)
While traditional management of the boreal forests results in even-aged forests with low landscape scale variability, recent work has suggested that much of the eastern boreal forest of North America is subject to long natural fire return-intervals. This has led to the development of new management strategies to maintain a mosaic of even and multi-aged stands. In this context I investigated the relationships between diameter-distributions, stand age, forest structure and bird communities. Results showed weak associations of the bird community with cohort classes, but that diameter-distributions can work to succinctly describe some of the variation in stand structure and bird communities. I also explored the utility of LiDAR to measure important structural features for bird communities. Results showed that LiDAR can outperform traditional measures of stand structure at explaining bird communities at differing scales.
5

Multicohort Management and LiDAR: New Forest Management Tools for Northeastern Ontario Boreal Mixedwood Bird Communities

Burrell, Michael 11 January 2010 (has links)
While traditional management of the boreal forests results in even-aged forests with low landscape scale variability, recent work has suggested that much of the eastern boreal forest of North America is subject to long natural fire return-intervals. This has led to the development of new management strategies to maintain a mosaic of even and multi-aged stands. In this context I investigated the relationships between diameter-distributions, stand age, forest structure and bird communities. Results showed weak associations of the bird community with cohort classes, but that diameter-distributions can work to succinctly describe some of the variation in stand structure and bird communities. I also explored the utility of LiDAR to measure important structural features for bird communities. Results showed that LiDAR can outperform traditional measures of stand structure at explaining bird communities at differing scales.
6

Aspectos da ecologia trÃfica e distribuiÃÃo vertical de uma populaÃÃo de Dendropsophus gr. Microcephalus (Anura, Hylidae) em uma area de mata de tabuleiro litorÃneo do Nordeste brasileiro. / Aspects of trophic ecology and microhabitat use (vertical distribution) of a population of Dendropsophus gr. microcephalus (Anura, Hylidae) in a forest area of the coastal tableland Brazilian Northeast

PatrÃcia de Menezes Gondim 30 August 2012 (has links)
Neste trabalho foram realizados estudos sobre a dieta e a estratificaÃÃo vertical em D. gr. microcephalus em uma Ãrea de tabuleiro litorÃneo do nordeste brasileiro. Em relaÃÃo à dieta, foram identificados os principais itens alimentares, a ocorrÃncia de variaÃÃo sexual, ontogenÃtica e estacional quanto Ãs presas consumidas, bem como a relaÃÃo do comprimento e volume destas com o comprimento rostro-cloacal e a largura da mandÃbula. Quanto à estratificaÃÃo vertical, foram analisadas possÃveis diferenÃas sexuais, ontogenÃticas e estacionais na altura de empoleiramento. Os trabalhos de campo ocorreram mensalmente de marÃo atà dezembro de 2011, totalizando dez meses de coletas, obtendo-se uma amostra total de 229 indivÃduos (177 machos, 52 fÃmeas). Foram quantificadas 464 presas distribuÃdas em 15 categorias, sendo Diptera, Coleoptera, Araneae e Hemiptera os principais itens consumidos, composiÃÃo alimentar encontrada na maioria das espÃcies do gÃnero. O predomÃnio de dÃpteros na composiÃÃo alimentar aponta Dendropsophus como um grupo importante de biocontroladores de insetos prejudiciais. FÃmeas apresentaram valores maiores do que machos em relaÃÃo ao comprimento rostro â cloacal (CRC), largura da mandÃbula e massa corpÃrea, sendo largura da mandÃbula a responsÃvel pelas diferenÃas sexuais e ontogenÃticas quando relacionada com comprimento e volume dos itens consumidos. Quanto à variaÃÃo estacional, comprimento e volume dos itens alimentares tiveram valores maiores durante a estaÃÃo chuvosa, sugerindo uma abundÃncia maior de presas nesse perÃodo. A altura de empoleiramento em D. gr. microcephalus foi semelhante ao encontrado em outras espÃcies do gÃnero. Adultos se empoleiraram em alturas inferiores, enquanto jovens alcanÃaram alturas maiores, diferenÃas que estÃo relacionadas com a largura da mandÃbula e, possivelmente, com CRC e massa corpÃrea. EstratificaÃÃo vertical devido a variaÃÃes estacionais pode estar ligada a fatores abiÃticos como temperatura, umidade relativa do ar e/ou vento, porÃm, outros estudos devem ser realizados para confirmar a relaÃÃo desses fatores, nÃo sà com as variaÃÃes estacionais, mas tambÃm com as variaÃÃes sexuais e ontogenÃticas. / In this work, it was studied the diet and vertical stratification in D. gr. microcephalus in an area of coastal tableland of northeastern Brazil. Regarding diet, it was identified the main food items, the occurrence of sexual, ontogenetic and seasonal variation in relation to the consumed prey, as well as the ratio of length and volume of these with the snout-vent length and jaw width. As for the vertical stratification, it was analyzed possible sex, ontogenetic and seasonal time differences for perch height. The field work took place monthly from March to December 2011, totalizing ten months of collections, obtaining a sample of 229 individuals (177 males, 52 females). It was quantified 464 prey distributed in 15 categories, being Diptera, Coleoptera, Araneae e Hemiptera the main items consumed,food composition found in most species of the genus. The predominance of Diptera in dietary composition points out Dendropsophus as an important group of biocontrol of harmful insects. Females had higher values than males in relation to snout-vent length (SVL), jaw width (JW) and body mass, being jaw width the responsible for the sexual and ontogenetic differences when related to length and volume of items consumed. With regard to seasonal variation, length and volume of food items were greater during the rainy season, suggesting a greater abundance of prey during this period. The height of perch D. gr. microcephalus was similar to that found in other species of the genus. Adults perched at lower altitudes, while youngsters have reached greater heights, differences that are related to the jaw width and possibly to the SVL and body mass. Vertical stratification due to seasonal variations may be linked to abiotic factors such as temperature, relative humidity and / or wind; however, further studies should be conducted to confirm the relationship of these factors, not only with seasonal variations, but also with sexual and ontogenetic variations.
7

USO DE ESTRATO VERTICAL POR PEQUENOS MAMÍFEROS EM FLORESTA DE GALERIA E CERRADÃO NO SUDOESTE DO BRASIL / USE OF VERTICAL STRATUM OF SMALL MAMMALS IN GALLERY FOREST AND CERRADÃO SOUTH-WESTERN OF THE BRAZIL

Lopes, Wellington Hannibal 15 November 2009 (has links)
Studies on vertical stratification of small mammals in the Cerrado biome are scarce and, therefore, this study has the aim to check the community composition of small mammals in relation to the vertical stratum utilization in gallery forest and cerradão of south-western Brazil. The captures were carried out during the months of August/September, November/December 2006 and February/March, May/June 2007. The traps were set in three transaction lines with 10 capture stations each one. Each station had a trap on the ground, other in the understory (2.0 to 3.0 m in height) and another in the canopy (8 to 10 m) in each environment, totalling 60 stations.. With an effort of 3600 traps-night 11 species of small mammals were captured, which were distributed differentially regarding the environments and the utilization of the vertical strata. Species presented habitat high segregation on physiognomies, only Rhipidomys macrurus presented in two environments. As for use of vertical strato for the Correspondence analysis Caluromys philander was the only notable in the canopy, Cryptonanus agricolai, Marmosa murina and, Oecomys bicolor were in the understory, and Gracilinanus agilis and Nectomys rattus were only sampled on the ground. In relation the faunistic and environments parameters formed two groups, where C agricolai and G. Agilis were associated to cerradão, dry season and number of tree and C. philander, M. Murina, N. rattus and O. bicolor were associated to gallery forest, stratification, number of branch and lianas. The Cerrado biome presents distinct fauna of small mammals associated with the two main forest physiognomies in it: gallery forest and cerradão. The utilization of traps in different strata increased the species richness, showing that they are distributed in different vertical strata of the forest, utilizing the complexity of the environment which enables them to coexist. / Estudos sobre estratificação vertical por pequenos mamíferos no Cerrado são escassos. Este estudo objetivou verificar a composição da comunidade de pequenos mamíferos em relação à utilização do estrato vertical em áreas de floresta de galeria e cerradão no sudoeste do Brasil. As capturas foram realizadas durante os meses de agosto/setembro, novembro/dezembro de 2006 e fevereiro/março, maio/junho de 2007. As armadilhas foram dispostas em três transecções com 10 estações de captura cada, sendo que cada estação compreendeu uma armadilhas no solo, uma no subbosque (2,0 a 3,0 m de altura) e uma no dossel (8 a 10 m) em cada ambiente, totalizando 60 estações de capturas. Com um esforço de 3600 armadilhas-noite foram capturadas 11 espécies de pequenos mamíferos, que estiveram distribuídas diferencialmente em relação aos ambientes e à utilização do estrato vertical. As espécies apresentaram forte segregação de hábitat, onde apenas Rhipidomys macrurus esteve presente nos dois ambientes. Quanto ao uso do estrato vertical, pela análise de Correspondência, Caluromys philander foi a única espécie que se destacou no dossel, Cryptonanus agricolai, Marmosa murina, e Oecomys bicolor, e se destacaram no sub-bosque, e Gracilinanus agilis e Nectomys rattus se destacaram ao nível do solo. Em ralação aos parâmetros faunísticos e ambientais formaram-se dois grupos , onde C. agricolai e G. agilis estiveram associados ao cerradão, estação seca e número de árvores e C. philander, M. murina, N. rattus e O. bicolor estiveram associados a floresta de galeria, estratificação, número de ramos e número de lianas. O bioma Cerrado apresenta distintas faunas de pequenos mamíferos associadas às duas formações florestais: floresta de galeria e o cerradão. A utilização de armadilhas em diferentes estratos aumenta a riqueza de pequenos mamíferos, mostrando que as espécies estão distribuídas em diferentes camadas verticais da floresta, utilizando a complexidade do ambiente o que possibilita a coexistência de um número maior de espécies.
8

Insect Communities and Multicohort Stand Structure in Boreal Mixedwood Forests of Northeastern Ontario

Barkley, Erica Patricia 16 December 2009 (has links)
Current forest management in boreal northeastern Ontario results in young, even-aged forests; however, fire history research has found old stands with multiple cohorts of trees are common, supporting the value of Multi-cohort Management. I investigated relationships between insect communities and stand live-tree diameter distribution, cohort class and structure. Results showed that variation in abundances of Carabidae, Diapriidae, Diptera and Hymenoptera were not strongly predicted by cohort class. The concept showed greater strength when parameters of live-tree diameter distributions were used. Forest structure, not age, was important for all communities, including heterogeneity of understory and/or overstory vegetation. Trap height was a strong predictor of aerial insect community structure, with insect abundance higher in the understory than in the canopy. In summary, a more diversified classification approach which includes important habitat features in addition to simple characterization of diameter distributions should be considered to better assess forest structural variation and management.
9

Insect Communities and Multicohort Stand Structure in Boreal Mixedwood Forests of Northeastern Ontario

Barkley, Erica Patricia 16 December 2009 (has links)
Current forest management in boreal northeastern Ontario results in young, even-aged forests; however, fire history research has found old stands with multiple cohorts of trees are common, supporting the value of Multi-cohort Management. I investigated relationships between insect communities and stand live-tree diameter distribution, cohort class and structure. Results showed that variation in abundances of Carabidae, Diapriidae, Diptera and Hymenoptera were not strongly predicted by cohort class. The concept showed greater strength when parameters of live-tree diameter distributions were used. Forest structure, not age, was important for all communities, including heterogeneity of understory and/or overstory vegetation. Trap height was a strong predictor of aerial insect community structure, with insect abundance higher in the understory than in the canopy. In summary, a more diversified classification approach which includes important habitat features in addition to simple characterization of diameter distributions should be considered to better assess forest structural variation and management.
10

Estratificação vertical da comunidade de morcegos (mammalia, chiroptera) em uma área de Mata Atlântica no nordeste do Brasil

Nunes, Hannah Larissa de Figueiredo Loureiro 17 July 2013 (has links)
Made available in DSpace on 2015-04-17T14:55:28Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 3149838 bytes, checksum: 6e2cd7d8e4cf2d23dbee3a492349788e (MD5) Previous issue date: 2013-07-17 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The Neotropical bat fauna stands out for presenting a high trophic and morphological diversity, which can comprise around 50% of mammal species associated with forests. Among the factors that could possibly allow the existence of this complex fauna, we highlight: the diversity of feeding strategies, the activity patterns, the seasonal variaton in the composition of bat communities and the vertical stratification. The present study aimed to analyze the vertical structure and composition of the bat fauna in an Atlantic forest area. The study was conducted between the months of april 2012 and march 2013, in the Reserva Biológica Guaribas (Sema 3), municipality of Rio Tinto, Paraiba. Three sample nights were performed monthly, with mist nets armed in the same position, placed in the understory and canopy (about 15 meters high), opened for 12 hours every night. Additionally, were performed active search for refuges and, during the last five months of sampling, we used three mobile mist nets set at the understory, opened for six hours every night. The total amount of sampling effort was 92.092 h.m2. From all methodologies, 1.760 individuals were captured, belonging to four families and 23 species, among wich we highlight the first record of Molossops temminckii for the state of Paraiba. The average estimated bat richness (Chao 1, Jack 1, Jack 2, Bootstrap) was 25.3±1.3 species. We observed the existence of vertical stratification, through multivariate analysis (PERMANOVA), with eight species (Artibeus lituratus, Artibeus planirostris, Cynomops planirostris, Glossophaga soricina, Molossops temminckii, Phyllostomus discolor, Platyrrhinus lineatus e Sturnira lilium) significantly more abundant in the canopy than in understory. No species showed a significant preference toward the understory. Besides the difference in species composition, abundance and richness were higher in the canopy. An analysis of variance showed no significant difference between the species capture time, except for Dermanura cinerea. We also found significant and positive correlations between total richness and abundance of Artibeus planirostris with the average monthly rainfall of the last five years for the city of Rio Tinto. / A quiropterofauna Neotropical se destaca por apresentar uma alta diversidade trófica e morfológica, podendo abranger em torno de 50% da mastofauna associada às florestas. Entre os fatores que, possivelmente, permitem a existência de uma fauna tão complexa, destacam-se: a diversidade de estratégias alimentares, os padrões no horário de atividade, a variação sazonal na composição das comunidades de morcegos e a estratificação vertical. O presente estudo teve como objetivos analisar a estrutura vertical e a composição da comunidade de morcegos em uma área de Mata Atlântica. O estudo foi desenvolvido entre os meses de abril de 2012 e março de 2013, na Reserva Biológica Guaribas (Sema 3), município de Rio Tinto, Paraíba. Foram realizadas três noites de coletas mensais, com redes fixas dispostas no sub-bosque e dossel florestal (em torno de 15m de altura), abertas por 12 horas a cada noite. Adicionalmente, foram realizadas buscas por abrigos e, durante os últimos cinco meses de amostragem, foram utilizadas três redes de sub-bosque móveis, abertas por seis horas a cada noite. O esforço total foi de 92.092 h.m2. A partir de todas as metodologias utilizadas, foram capturados 1.760 indivíduos, pertencentes a quatro famílias e 23 espécies, dentre as quais destaca-se o primeiro registro de Molossops temminckii para o estado da Paraíba. A estimativa média da riqueza de espécies (Chao 1, Jack 1, Jack 2 e Bootstrap) foi de 25.3±1.3 espécies. Foi observada a existência de estratificação vertical, através da análise multivariada (Permanova), sendo oito espécies (Artibeus lituratus, Artibeus planirostris, Cynomops planirostris, Glossophaga soricina, Molossops temminckii, Phyllostomus discolor, Platyrrhinus lineatus e Sturnira lilium) significativamente mais abundantes no dossel do que no sub-bosque. Nenhuma espécie mostrou preferência significativa pelo sub-bosque. Além da diferença na composição de espécies, a abundância e a riqueza foram maiores no dossel. Uma análise de variância não demonstrou diferença significativa entre os horários de captura das espécies, exceto para Dermanura cinerea. Foram também encontradas correlações significativas e positivas entre a riqueza total de espécies e a abundância de Artibeus planirostris com a precipitação média mensal dos últimos cinco anos para a cidade de Rio Tinto.

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