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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

Seasonal and Diurnal Patterns of Spatial Spread, Grouping Dynamics and Influence of Resources on a Free-Ranging Cattle Herd in a Semi-Arid Rangeland in South Texas, USA

Cheleuitte-Nieves, Christopher 2011 August 1900 (has links)
Knowledge of scale-dependent factors that affect the distribution of ungulate herds, such as cattle, is essential for the development of more accurate predictive models of animal movement and the management of sustainable agriculture. Our objectives were to evaluate the seasonal and diurnal patterns of herd spread, explore grouping dynamics, and the influence of dominance ranks, seasonal changes in forage biomass, use of shade, water and supplemental feed areas on cattle distribution. Positional and activity information of eleven free-ranging Bonsmara, Bos taurus, cows were obtained at five minute intervals using Global Positioning System collars. We conducted a total of 12 trials each of three weeks from August 2007 to August 2009 in a 457ha shrub-dominated savanna in South Texas. Spread was obtained by calculating the average Euclidean distance of individuals to the center of the herd. The association software package, ASSOC1, was used to analyze spatio-temporal interactions. Normalized Difference Vegetation Index, an indicator of available forage biomass, was calculated using satellite imagery. Number of GPS fixes was used as an indicator of animal use of shade patches and water and supplemental feeding areas. In this semi-arid environment, herd spread was greatest and subgroup division occurred during summer when forage biomass was high. Herd spread was the least and shade patches were used more during winter when forage biomass was low. Throughout the year spread was smallest and use of shade patches highest during the midday period compared to other periods of the day. Location of individuals in the center of the herd was not associated with their dominance ranking. There was no significant overall pattern of seasonal changes in cattle use of water and supplemental feeding areas. Seasonal forage availability and shade patches seem to have a greater influence on herd dispersion patterns and grouping dynamics than any effect of social dominance. Herd distribution is likely related to changes in forage biomass and temperature fluctuations which drive compensatory night-time feeding and thermoregulatory actions. Accurate ethological studies of herds depend on our ability to understand herd dynamics at multiple scales that affect and are relevant to animal's response to the landscape.
2

Restauração florestal versus referência ecológica: utilização de indicadores ecológicos em ambientes ciliares na Floresta Ombrófila Mista / Forest restoration versus ecological reference: use of ecological indicators in riparian environments in Araucaria Forest

Stedille, Lilian Iara Bet 18 July 2016 (has links)
Submitted by Claudia Rocha (claudia.rocha@udesc.br) on 2017-12-08T12:33:43Z No. of bitstreams: 1 PGEF16MA062.pdf: 2473191 bytes, checksum: cbe6e188be2f3f4cf384e50b2938078b (MD5) / Made available in DSpace on 2017-12-08T12:33:43Z (GMT). No. of bitstreams: 1 PGEF16MA062.pdf: 2473191 bytes, checksum: cbe6e188be2f3f4cf384e50b2938078b (MD5) Previous issue date: 2016-07-18 / PROMOP / The forest succession is a way to restore disturbed forest. Measure taken to to the of permanent preservation areas (PPA’s) adequacy, mainly riparian, wood-producing farms in the Santa Catarina Plateau South region. Since the need for monitoring of these environments the main objective of this study was to investigate the passive restoration in riparian forest on Poço Grande and Campo de Dentro farms, with the main focus for the survey of the tree composition. Only on the Poço Grande farm has further study, envolvento environmental compartmentalization in forest "reference" ecological formed by fragments into more advanced successional stage and locations in passive "restoration". Where it was included natural regeneration, seed bank, the presence of grasses (Ocellochloa rudis (Nees) Zuloaga & Morrone and Merostachys multiramea Hack), soil and canopy. The results of the first chapter indicates that compartmentalization on the farm Poço Grande showed that the sites in "restoration" have lower density values, basal area, evenness among arboreal, and greater participation of pioneers and autocóricos individuals. In the second chapter between 23 variables, the existence of an ecological gradient of diversity (Shannon index of tree) standing out among the other variables involved. The second gradient formed is related to the presence of O. rudis and higher soil pH and effective cation exchange capacity, even without a relationship with a sector, may influence the formation of a dense layer of biomass. The tree composition of Poço Grande and Campo de Dentro farms for years of assessment 2011 and 2016, has among the species most phytosociologic position. Between evaluated the sampled species follow the same pattern of ecological groups and dispersal syndromes, with high participation of zoochorous. Since the Poço Grande farm, a decrease in the share of late side individuals and increase climax individuals. Inside the Campo de Dentro farm was an 15 16 increase in the proportion of pioneering individuals and decrease among individuals climax. In both farms there was an increase of individuals with syndrome zoochoric dispersion and a decrease of anemochorous and autocóricos. The methodology of passive restoration proved to be a promising alternative in locations with favorable landscape. Indicates continuing the monitoring / A sucessão florestal é uma maneira de restaurar florestas alteradas. Medida adotada para para a adequação de áreas de preservação permanente (APP), principalmente ciliares, em fazendas produtoras de madeira na região do Planalto Sul Catarinense. Visto a necessidade de monitoramento destes ambientes o objetivo principal deste trabalho foi investigar a restauração passiva nas áreas ciliares das fazendas Poço Grande e Campo de Dentro, com enfoque principal para o levantamento da composição arbórea. Apenas na fazenda Poço Grande tem-se um estudo mais aprofundado, envolvento a setorização ambiental, em floresta de “referência” ecológica formada por fragmentos em estádio sucessional mais avançado e, locais em “restauração” passiva. Onde incluiu-se o levantamento da regeneração natural, banco de sementes, presença de gramíneas (Ocellochloa rudis (Nees) Zuloaga & Morrone e Merostachys multiramea Hack), solos e dossel. Os resultados do primeiro capítulo indicam que a setorização na fazenda Poço Grande evidenciou que os locais em “restauração” apresentam menores valores de densidade, área basal, equabilidade entre adultos, e maior participação de indivíduos pioneiros e autocóricos. No segundo capítulo entre 23 variáveis analisadas, a existência de um gradiente ecológico de diversidade (índice de Shannon de árboreas) sobressaindo-se entre as demais variáveis envolvidas. O segundo gradiente formado está relacionado a presença de O. rudis, com maiores valores de pH do solo e capacidade de troca catiônica efetiva, que mesmo sem uma relação com algum setor, pode influênciar pela formação de uma densa camada de biomassa. Ao avaliar a composição arbórea das fazendas Poço Grande e Campo de Dentro, para os anos de avaliação 2011 e 2016, tem-se a manutenção das espécies de maiores valores de importância. Entre os anos avaliados as espécies seguem o mesmo padrão de grupos ecológicos e síndromes de dispersão, com elevada participação de zoocó 11 12 ricas. Sendo que na fazenda Poço Grande, ocorreu diminuição na participação dos indivíduos secundários tardios e, aumento de indivíduos clímax. Na fazenda Campo de Dentro ocorreu aumento na proporção de indivíduos pioneiro e diminuição entre os indivíduos clímax. Em ambas fazendas se verificou um aumento de indivíduos com síndrome de dispersão zoocórica e, uma diminuição de anemocóricos e autocóricos. A metodologia da restauração passiva mostrou-se como uma alternativa promissora em locais com paisagem favorável. Indica-se dar continuidade ao monitoramento

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