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"Unidades de vegetação e pastagens nativas do Pantanal da Nhecolândia, Mato Grosso do Sul" ; "Vegetation units and native pastures of Pantanal da Nhecolândia, Mato Grosso do Sul, Brazil"

Rodela, Luciana Graci
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 11/07/2006 PT
Relevância na Pesquisa
36.83%
Este estudo foi realizado na Fazenda Nhumirim, propriedade da EMBRAPA Pantanal, Nhecolândia, Pantanal do Mato Grosso do Sul. Diante da necessidade do reconhecimento dos elementos do meio ambiente natural, bem como de sua dinâmica, para a busca do equilíbrio ambiental na região, esta pesquisa teve como objetivo estudar a vegetação da Nhecolândia. A Nhecolândia é uma das mais expressivas regiões criatórias de gado de corte do Brasil. As pastagens nativas correspondem a grande variedade de unidades de vegetação, de campos a cerrados. O uso espacial e temporal dessas pastagens por bovinos, sua disponibilidade, qualidade e produtividade pecuária são influenciados pelas condições ambientais, principalmente inundações e precipitações. Para conservação e utilização sustentável dos recursos naturais e pastagens nativas no Pantanal, é de grande importância mapear as principais unidades ambientais, estabelecer unidades de vegetação/pastagens para conhecer as áreas de sobrevivência de espécies de animais, visto que o Pantanal corresponde à uma coleção de ambientes de equilibrio dinâmico frágil; a planície possui declividades baixissimas que provocam um deslocamento extremamente lento das águas, a dinâmica hídrica é particular: as chuvas e os rios abastecem os lençóis freáticos causando inundações; e a alimentação do rebanho baseia-se quase que integralmente em pastagens nativas. Tendo em vista a utilização da vegetação como pastagem...

Dinâmica da vegetação e inferências climáticas no Quaternário Tardio na região da Ilha de Marajó (PA), empregando os isótopos do carbono (12C, 13C, 14C) da matéria orgânica de solos e sedimentos; Vegetation dynamics and climatic inferences in the Late Quaternary in the Marajó Island region, employing the carbon isotopes (12C,13C,14C) of the soil and sediments organic matter

Lima, Claudia Moré de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 27/08/2008 PT
Relevância na Pesquisa
36.87%
Considerada a maior ilha flúvio-marítima do mundo, com aproximadamente 48.000 km2, a Ilha de Marajó situa-se na zona equatorial brasileira, no litoral do Estado do Pará. Apresenta dois domínios distintos relacionados a geologia e vegetação. No setor oeste dominam solos desenvolvidos sobre os sedimentos Pós Barreiras (plio-pleistocênicos) recobertos pela Floresta Amazônica, enquanto no setor leste dominam sedimentos holocênicos derivados de ambiente fluvial/estuarino atualmente desativado. Neste setor encontram-se os extensos campos naturais marajoaras. O objetivo deste trabalho consistiu em aplicar os isótopos de carbono (12C, 13C e 14C) da matéria orgânica de solos e sedimentos com o intuito de avaliar possíveis modificações nos domínios da vegetação, em termos de plantas C3 e C4, durante o Quaternário Tardio e inferir sobre suas causas. Os resultados foram associados com observações de campo e análises petrográficas, sedimentológicas, químicas, de espículas de esponjas, isótopicas de nitrogênio e bibliográficas, sendo possível distinguir três mudanças ambientais relacionadas à geologia e vegetação, no setor leste da Ilha de Marajó durante o Pleistoceno Superior (aproximadamente 16.000 anos AP) ao Holoceno. No setor central da Ilha de Marajó foram obtidas as idades mais antigas da matéria orgânica em sedimentos de um paleocanal. Neste local...

A distribuição espacial da vegetação nas feições geomorfológica da ilha da marchantaria: planície do rio Amazonas, AM/Brasil; The spatial distribution of vegetation in the geomorphological features of the island of Marchantaria: Amazon River floodplain, Amazonas/Brazil

Fortes, Mircia Ribeiro
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 07/10/2014 PT
Relevância na Pesquisa
36.83%
Estudos biogeomorfológicos integrando a geomorfologia fluvial, neotectônica e a vegetação foram aplicados na ilha da Marchantaria, com a finalidade de analisar a distribuição da vegetação de várzea nas feições geomorfológicas. A planície do rio Amazonas é um mosaico de feições morfológicas de dimensões espaciais ora menores, ora maiores tais como ilhas, bancos arenosos, furos, paranás e lagos, que pela dinâmica fluvial estão continuamente se modificando. No canal do rio Amazonas, a ilha da Marchantaria, situada no baixo curso do rio Solimões motiva relevante interesse, tendo em vista a sua evolução areal nos últimos quarenta anos, bem como, a sua proximidade ao Encontro das Águas de Manaus EAM. A partir do arranjo dos elementos neotectônicos que condicionam as formas quaternárias atuais da ilha foram identificadas duas unidades estruturais distintas: Depósito Aluvial Subrecente (DASr) e Depósito Aluvial Recente (DAR). Também, foram definidas as unidades morfossedimentares holocênicas: feições espiras de meandro e barras de soldamento. A distribuição espacial da vegetação sobre as diferentes elevações do terreno foram agrupadas em duas unidades: vegetação lenhosa e vegetação herbácea. Os resultados mostram que: a) a vegetação distribui-se espacialmente nos diferentes níveis tectono-topográficos; b) a erosão fluvial...

Avaliação da vegetação como indicadora de áreas suscetíveis a escorregamentos na Serra do Mar em Caraguatatuba (SP); Evaluation of vegetation as an indicator of landslide susceptibility in the Serra do Mar in Caraguatatuba (SP)

Portela, Viviane Dias Alves
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 02/09/2014 PT
Relevância na Pesquisa
36.89%
Apesar de a vegetação ser considerada fator controlador de escorregamentos, os estudos que a discutem como indicador destes processos são escassos. O sensoriamento remoto, por meio dos índices de vegetação, apresenta potencial ainda não explorado para subsidiar os estudos entre vegetação e escorregamentos. Assim, o objetivo deste trabalho é avaliar a vegetação como indicador de áreas suscetíveis a escorregamentos. A área escolhida para a pesquisa é o trecho da Serra do Mar no município de Caraguatatuba, litoral norte do Estado de São Paulo. A escolha desta área remete ao evento de 1967 no qual houve escorregamentos generalizados nas escarpas da Serra do Mar que culminaram em inúmeras mortes e perdas materiais. Para a realização da pesquisa foram gerados os índices de vegetação NDVI, Simple Ratio, ReNDVI, VIg e PSRI. Os índices de vegetação foram correlacionados às cicatrizes de escorregamentos e com os seguintes parâmetros topográficos: declividade, hipsometria, orientação de vertentes e curvatura em planta. Para isso foi utilizada a distribuição da razão de área afetada por cicatrizes em cada índice de vegetação (Vcic). Os resultados demonstraram que os índices de vegetação foram eficientes ao identificar as áreas com cicatrizes além de aludir que a maior densidade de vegetação visualizada pelo NDVI e...

Influência da estrutura espacial e da vegetação sobre a assembléia de aves em remanescentes campestres no sul do Brasil; Influence of spatial and vegetation structure on the bird assemblage in grassland patches in Southern Brazil

Camilotti, Vagner Luis
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
36.87%
Esse estudo teve como objetivo investigar os fatores estruturantes das taxocenoses de aves que utilizam remanescentes de vegetação campestre na região da Fronteira Oeste do Rio Grande do Sul. Através desse estudo busquei compreender os efeitos da estrutura espacial dos remanescentes (área, formato e proximidade entre remanescentes) e também os efeitos exercidos pela estrutura do habitat no uso desses pelas aves campestres. Amostrei quantitativamente por pontos de contagem a avifauna em 21 manchas de vegetação campestre com diferentes áreas, formas e estrutura da vegetação. Utilizei ferramentas de sensoriamento remoto para avaliar a estrutura espacial dos remanescentes e caracterizei o habitat dessas manchas através de medidas da estrutura da vegetação. Utilizei o método analítico de partição da variância através de análises de regressão múltipla e análise de correlação canônica parciais para quantificar a porção da variância explicada por cada grupo de variáveis (estrutura da vegetação e estrutura espacial dos remanescentes) na variação total da abundância, composição e riqueza da avifauna nas manchas. Registrei um total de 33 espécies de aves campestres, sendo três dessas categorizadas em algum grau de ameaça de extinção: Circus cinereus...

Sensoriamento remoto aplicado na analise da cobertura vegetal das reservas de desenvolvimento sustentavel Amana e Mamiraua; Remote sensing applied in vegetation analysis of Amana and Mamiraua sustainable-use protected areas

Gustavo Manzon Nunes
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 04/03/2008 PT
Relevância na Pesquisa
36.85%
O conhecimento da biodiversidade amazônica, em especial o relacionado à sua cobertura vegetal, tem sido alvo de amplos estudos envolvendo a investigação de seus processos ecológicos-evolutivos e o seu funcionamento como um conjunto integrado e complexo de unidades biológicas. O desenvolvimento de tecnologias e metodologias no campo do Sensoriamento Remoto, cada vez mais vem se tornando essencial na análise, discriminação e monitoramento de vastas áreas dominadas pela Floresta Tropical. Esta tese buscou avaliar os aspectos relacionados à potencialidade das imagens dos sensores Moderate Resolution Imaging Spectroradiometer (MODIS)/Terra, Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER)/Terra e Synthetic Aperture Radar (SAR)/R99-B, para a discriminação de fitofisionomias existentes nas Reservas de Desenvolvimento Sustentável Amanã e Mamirauá (RDSA e RDSM). A partir de processamentos realizados com os dados do sensor MODIS, Produto MOD13 - Índices de Vegetação EVI (Enhanced vegetation ÍNDEX) e NDVI (Normalized Difference Vegetation Index), foi avaliado o comportamento sazonal/temporal de quatro fitofisionomias existentes nas RDSA e RDSM, entre os anos de 2004 e 2005. Com este estudo, foi possível concluir que (i) os índices de vegetação foram sensíveis às características estruturais e fisionômicas do geossistema estudado; (ii) o EVI apresentou a melhor resposta para a discriminação de fitofisionomias...

Integration of landsat TM and SPOT HRG Images for vegetation change detection in the Brazilian Amazon.

LU, D.; BATISTELLA, M.; MORAN, E.
Fonte: Photogrammetric Engineering & Remote Sensing, v. 74, n. 4, p. 421-430, 2008. Publicador: Photogrammetric Engineering & Remote Sensing, v. 74, n. 4, p. 421-430, 2008.
Tipo: Artigo em periódico indexado (ALICE)
PT_BR
Relevância na Pesquisa
36.85%
Traditional change detection approaches have been proven to be difficult in detecting vegetation changes in the moist tropical regions with multitemporal images. This paper explores the integration of Landsat Thematic Mapper (TM) and SPOT High Resolution Geometric (HRG) instrument data for vegetation change detection in the Brazilian Amazon. A principal component analysis was used to integrate TM and HRG panchromatic data. Vegetation change/non-change was detected with the image differencing approach based on the TM and HRG fused image and the corresponding TM and HRG multispectral images into thematic maps with three coarse land-cover classes: forest, non-forest vegetation, and non-vegetation lands. A hybrid approach combining image differencing and post-classification comparison was used to detect vegetation change trajectories. This research indicates promising vegetation chance trajectories. This research indicates promising vegetation change techniques especially for vegetation gain and loss, even if very limited reference data are available.; 2008

Analysis and modelling of the flood pulse and vegetation productivity response in floodplain wetlands

Powell, Susan Jennifer
Fonte: Universidade Nacional da Austrália Publicador: Universidade Nacional da Austrália
Tipo: Thesis (PhD); Doctor of Philosophy (PhD)
EN_AU
Relevância na Pesquisa
36.87%
This thesis aims to develop a conceptual understanding of the flooding patterns and vegetation response of large floodplain wetlands and to develop an inundation and vegetation response model for water management. Applicable to a range of floodplain wetland systems, the conceptual node-network approach was developed in relation to the Gwydir wetlands, NSW, Australia. The Gwydir floodplains and wetlands occur in a dryland setting and are reliant on flows from the upstream catchment that has substantial water resource development. The Gwydir wetlands include a range of ecological values and are listed under international agreements for the protection of wetlands and migratory waterbirds. The challenge of understanding flooding patterns in the Gwydir wetlands are common to other floodplain systems where shallow inundation, rapid vegetation growth and canopy cover may preclude the assessment of open water flooding from conventional remote sensing techniques. To characterise the flooding patterns a multi-temporal decision tree approach was developed. Based on classification of flooding as open water or from the subsequent high vigour vegetation response, the method uses remotely sensed vegetation indices to map a range of flood events. The results are summarised into homogenous patches with respect to flood frequency and connectivity. Using the patch analysis and assessment of connectivity between the patches and channels...

Non-detection errors in a survey of persistent, highly-detectable vegetation species

Clarke, K.; Lewis, M.; Brandle, R.; Ostendorf, B.
Fonte: Kluwer Academic Publ Publicador: Kluwer Academic Publ
Tipo: Artigo de Revista Científica
Publicado em //2012 EN
Relevância na Pesquisa
36.87%
Rare, small or annual vegetation species are widely known to be imperfectly detected with single site surveys by most conventional vegetation survey methods. However, the detectability of common, persistent vegetation species is assumed to be high, but without supporting research. In this study, we evaluate the extent of false-negative errors of perennial vegetation species in a systematic vegetation survey in arid South Australia. Analysis was limited to the seven most easily detected persistent vegetation species and controlled for observer skill. By comparison of methodologies, we then predict the magnitude of non-detection error rates in a second survey. The analysis revealed that all but one highly detectable perennial vegetation species was imperfectly detected (detection probabilities ranged from 0.22 to 0.83). While focussed in the Australian rangelands, the implications of this study are far reaching. Inferences drawn from systematic vegetation surveys that fail to identify and account for non-detection errors should be considered potentially flawed. The identification of this problem in vegetation surveying is long overdue. By comparison, non-detection has been a widely acknowledged, and dealt with, problem in fauna surveying for decades. We recommend that...

Mapping the wetland vegetation communities of the Australian Great Artesian Basin springs using SAM, MTMF and spectrally segmented PCA hyperspectral analyses

White, D.C.; Lewis, M.M.
Fonte: ISPRS Publicador: ISPRS
Tipo: Conference paper
Publicado em //2012 EN
Relevância na Pesquisa
36.85%
The Australian Great Artesian Basin (GAB) supports a unique and diverse range of groundwater dependent wetland ecosystems termed GAB springs. In recent decades the ecological sustainability of the springs has become uncertain as demands on this iconic groundwater resource increase. The impacts of existing water extractions for mining and pastoral activities are unknown. This situation is compounded by the likelihood of future increasing demand for extractions. Hyperspectral remote sensing provides the necessary spectral and spatial detail to discriminate wetland vegetation communities. Therefore the objectives of this paper are to discriminate the spatial extent and distribution of key spring wetland vegetation communities associated with the GAB springs evaluating three hyperspectral techniques: Spectral Angle Mapper (SAM), Mixture Tuned Matched Filtering (MTMF) and Spectrally Segmented PCA. In addition, to determine if the hyperspectral techniques developed can be applied at a number of sites representative of the range of spring formations and geomorphic settings and at two temporal intervals. Two epochs of HyMap airborne hyperspectral imagery were captured for this research in March 2009 and April 2011 at a number of sites representative of the floristic and geomorphic diversity of GAB spring groups/complexes within South Australia. Colour digital aerial photography at 30 cm GSD was acquired concurrently with the HyMap imagery. The image acquisition coincided with a field campaign of spectroradiometry measurements and a botanical survey. To identify key wavebands which have the greatest capability to discriminate vegetation communities of the GAB springs and surrounding area three hyperspectral data reduction techniques were employed: (i) Spectrally Segmented PCA (SSPCA); (ii) the Minimum Noise Transform (MNF); and (iii) the Pixel Purity Index (PPI). SSPCA was applied to NDVI-masked vegetation portions of the HyMap imagery with wavelength regions spectrally segmented for the VIS-NIR (450-1...

Recent palynological spectra from the Planalto region of the Serra Geral, Rio Grande do Sul, Brazil: Reconstruction of contemporary vegetation - a case study; Rezente Pollenspektren der Planalto-Region der Serra Geral, Rio Grande do Sul/ Brasilien: Rekonstruktion der rezenten Vegetation - Eine Fallstudie

Kriegel, Kerstin
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
EN
Relevância na Pesquisa
36.85%
The relationships between vegetation and recent palynomorphs are examined along a areal of 8000 km² in the state of Rio Grande do Sul, South Brazil. This areal is located between Caxias do Sul (NW) and Cambará do Sul (NE), and Canela/Gramado (SW) and the CPCN Pró-Mata (Centro de Pesquisas e Conservação da Natureza Pró-Mata, SE). Local plant communities of semi-deciduous and deciduous forests, Araucaria forests, Capões, gallery forests, Capoeiras, grasslands (Campos) and anthropogenic affected areas were sampled for palynological analysis and plant identification. The distribution of these communities can be related to the equivalent specific regional environmental parameters such as topography, temperature and moisture. The palynomorphs of eighty-five surface-soil samples were classified using TILIA and raster interpolation method ArcGIS 8/ArcMap for visualisation of counted pollen and spore data, cluster analysis and were ordinated using Principal Component Analysis (PCA). Results indicate that the plant communities sampled have distinct pollen and spore assemblages: Araucaria forests are characterised by Dicksonia sellowiana; semi-deciduous and deciduous forests are characterised by Cyatheaceae; Capões are characterised by Podocarpus sp....

Effet de la végétation sur la variabilité de la profondeur de dégel à petite échelle dans un paysage de tourbières en forêt boréale dans les Territoires du Nord-Ouest

Higgins, Kellina Leslie
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
FR
Relevância na Pesquisa
36.85%
Afin de mieux comprendre les effets des changements climatiques sur le pergélisol, il s’avère essentiel d’obtenir une meilleure connaissance des facteurs physiques et biologiques l’influençant. Même si plusieurs études font référence à l’influence de la végétation sur le pergélisol à grande échelle, l’effet de la végétation sur la profondeur du front de dégel du pergélisol à l’échelle de mètres, tel qu’exploré ici, est peu connu. L’étude s’est effectuée dans une forêt boréale tourbeuse dans la zone à pergélisol discontinu au sud des Territoires du Nord-Ouest (N61°18’, O121°18’). Nous avons comparé la profondeur de dégel aux mesures du couvert végétal suivantes : densité arborescente, couvert arbustif, indice de surface foliaire et présence de cryptogames (lichens et bryophytes). Nous avons trouvé qu’une plus grande densité arborescente menait à une moins grande profondeur de dégel tandis que le couvert arbustif (<50cm de hauteur) n’avait aucune influence. De plus, la profondeur de dégel dépendait de l’espèce des cryptogames et des microformes. Cette recherche quantifie l’influence de la végétation par strate sur la dégradation du pergélisol. Ultimement, les résultats pourront être pris en considération dans la mise en place des modèles...

The effect of climate change on tropical rainforest vegetation pattern

Ostendorf, B.; Hilbert, D.; Hopkins, M.
Fonte: Elsevier Science BV Publicador: Elsevier Science BV
Tipo: Artigo de Revista Científica
Publicado em //2001 EN
Relevância na Pesquisa
36.88%
The effect of climatic change on tropical vegetation is of global and regional concern because of the high biodiversity and the potential feedback to the carbon, water, and nutrient cycles. One of the most critical aspects for assessing broad-scale consequences of climate change is our understanding of how vegetation may change. Models relating vegetation and environmental conditions can be developed for large regions. For a simple application of static models of vegetation–environment relationships, one would have to assume that the probability of species (or vegetation) occurrence conditional on environmental conditions is constant in time (abbreviated as the POCEC assumption). This assumption is critical and difficult. In this paper, we evaluate how the spatial arrangement of forest pattern may constrain vegetation change as predicted by a spatially static artificial neural network (ANN) model. We have relaxed the POCEC assumption by subjoining a spatially dynamic component based on the cellular automata approach. The ANN model quantifies a most suitable forest type based on the conditional probability of vegetation in the environmental space, whereas the cellular automata model imposes spatial constraints on the transition to the best-suited type. We adapt the cellular automata algorithm to successively increase spatial constraints...

Mapping and evaluation of the state of conservation of the vegetation in and surrounding the Chapada Diamantina National Park, NE Brazil

Funch,Roy Richard; Harley,Raymond Mervyn; Funch,Ligia Silveira
Fonte: Instituto Virtual da Biodiversidade | BIOTA - FAPESP Publicador: Instituto Virtual da Biodiversidade | BIOTA - FAPESP
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2009 EN
Relevância na Pesquisa
36.85%
The Chapada Diamantina National Park (CDNP) was created in the midst of a densely populated area, and significant sections of the reserve are still undergoing processes of natural regeneration after intensive diamond mining activities were initiated in the mid-1800's. An up-to-date vegetation map was needed in order to indicate the types and distribution of regional vegetation assemblages in an easily interpretable manner and at an appropriate planning scale that could be easily consulted by decision makers and other interested groups at all levels of conservation (and development) planning. A vegetation map of the Chapada Diamantina National Park, and the areas immediately surrounding it, was prepared that: 1) delimits, describes, and maps the regional vegetation assemblages; 2) provides an indication of the degree of conservation of the mapped vegetation; 3) develops this information in a format that facilitates continued updating and revision as more information becomes available, enabling the monitoring of the evolution of the Park lands, and; 4) presents this information in a manner that can be easily interpreted and used for planning, management and conservation purposes. The resulting vegetation map revealed intensive anthropogenic disturbances in forested...

Spatial Analysis of Chimpanzee Habitat Quality Based on Vegetation Food Availability in Gombe National Park, Tanzania

Zhong, Ying
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Masters' project
Publicado em 24/04/2015 EN_US
Relevância na Pesquisa
36.99%
Chimpanzee (Pan troglodytes) is an Endangered species listed in IUCN Red List with a most recently estimated total population ranging approximately from 172700 to 299700. In east Africa, habitat loss and degradation resulting from agriculture development is the major cause of population decline. Gombe National Park is one among few remaining habitats for chimpanzees in East Africa. The park has been well-protected and maintained high vegetation cover compared to its surrounding environment. Given its importance to the chimpanzee’s diet, the vegetation cover defines the spatial variation of chimpanzee habitat quality. The aim of this project is to evaluate chimpanzee habitat quality for Gombe National Park by mapping the spatial variation of vegetation food availability, for the ultimate goal of supporting chimpanzee habitat conservation planning and studies of chimpanzee feeding behavior and ecology. Two sections of work were done to achieve this goal: vegetation species distribution modeling and vegetation cover mapping: Vegetation Species Distribution Modeling Vegetation food availability is a significant determinant of chimpanzee habitat quality. Different food resources can be of significant difference in indicating habitat quality due to chimpanzee’s feeding preference. Therefore...

Coastal Plain Pond Vegetation Patterns: Tracking Changes Across Space and Time

ODea, Claire
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação
Publicado em //2010
Relevância na Pesquisa
36.88%

Coastal plain ponds are an understudied and threatened wetland ecosystem with many unique environmental attributes. Research in these ponds can investigate species-environment relationships, while simultaneously providing ecosystem-specific information crucial to their continued conservation and management. This dissertation explores patterns in coastal plain pond vegetation composition and species-environment relationships across space, through time, and in the seed bank and standing vegetation.

In a two-year field study at 18 coastal plain ponds across the island of Martha's Vineyard, Massachusetts, I investigated species-environment relationships within and among ponds. I identified vegetation species presences and abundances within 1 m2 quadrats, which ran continuously along transects established perpendicular to the water's edge. Species data were analyzed against local and landscape-scale environmental data. I also conducted a one-year seed bank study in which sediments from four coastal plain ponds were incubated in growth chambers and composition was compared to the standing vegetation. One hundred and thirty-four plant species were identified during vegetation sampling and 38 species were identified from incubated sediments.

I found significant compositional change across space in response to environmental gradients...

Spatial Patterns in Dryland Vegetation and the Significance of Dispersal, Infiltration and Complex Topography

Thompson, Sal
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação Formato: 10762285 bytes; application/pdf
Publicado em //2010 EN_US
Relevância na Pesquisa
36.88%

Drylands, comprising arid and semi-arid areas and the dry subtropics, over some 40% of the world's land area and support approximately 2 billion people, including at least 1 billion who depend on dryland agriculture and grazing. 10-20% of drylands are estimated to have already undergone degradation or desertification, and lack of monitoring and assessment remains a key impediment to preventing further desertification. Change in vegetation cover, specifically in the spatial organization of vegetation may occur prior to irreversible land degradation, and can be used to assess desertification risk. Coherent spatial structures arise in the distribution of dryland vegetation where plant growth is localized in regular spatial patterns. Such "patterned vegetation" occurs across a variety of vegetation and soil types, extends over at least 18 million ha, occurs in 5 continents and is economically and environmentally valuable in its own right.

Vegetation patterning in drylands arises due to positive feedbacks between hydrological forcing and plant growth so that the patterns change in response to trends in mean annual rainfall. Mathematical models indicate that vegetation patterns collapse to a desertified state after undergoing a characteristic set of transformations so that the condition of a pattern at any point in time can be explicitly linked to ecosystem health. This dissertation focuses on the mathematical description of vegetation patterns with a view to improving such predictions. It evaluates the validity of current mathematical descriptions of patterning for the specific case of small-scale vegetation patterns and proposes alternative hypotheses for their formation. It assesses the significance of seed dispersal in determining pattern form and dynamics for two cases: vegetation growing on flat ground with isotropic patterning...

Late quaternary vegetation dynamics and human impact on Alexander Selkirk Island, Chile

Haberle, Simon
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.88%
Aim: To reconstruct the history of vegetation and environments using pollen, charcoal and sediment analysis, and to identify the timing and nature of climate change and human impact on the vegetation of a remote Pacific island. Location: Cerro de Los Inocentes, 1000 m above sea level, Alexander Selkirk Island (33°45′S, 80°45′W), Chile. The westernmost island of the Juan Fernandez Archipelago, south-east Pacific Ocean. Methods: A 150-cm long sediment core comprising 87 cm dark brown peat overlying 63 cm of yellow grey clay was extracted from a shallow depression on the southern slopes of Cerro de Los Inocentes. Pollen, charcoal, sediment and accelerator mass spectrometry radiocarbon analyses were used to construct a record of vegetation change through time. Numerical analysis of multispecies data allowed the classification of fossil assemblages into distinct pollen zones. Results: Pollen and spores are preserved throughout the sediment with high concentrations coinciding with the beginning of organic sediment accumulation at around 800014C yr BP. Prior to 800014C yr BP, the deposition of clays, presumably from upslope erosion, occurred in a landscape sparsely vegetated by grasses, ferns and Pernettya rigida heath, including several plants that are only found 100-200 m above the site today (Zone CI-1). After 800014C yr BP...

Relationships among fire frequency, rainfall and vegetation patterns in the wet-dry tropics of northern Australia: an analysis based on NOAA-AVHRR data

Spessa, Allan; McBeth, B; Prentice, Iain Colin
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.87%
Aim To quantify the regional-scale spatio-temporal relationships among rainfall, vegetation and fire frequency in the Australian wet-dry tropics (AWDT). Location Northern Australia: Cape York Peninsula, central Arnhem, central Kimberly, Einasleigh Uplands, Gulf Fall Uplands and northern Kimberley. Methods Monthly 'fraction of photosynthetic active radiation absorbed by green vegetation' (fAPAR) was decomposed into monthly evergreen (EG) and monthly raingreen (RG) components using time-series techniques applied to monthly normalized difference vegetation index (NDVI) data from Advanced Very High Resolution Radiometer (AVHRR) imagery. Fire affected areas were independently mapped at the same spatio-temporal resolution from AVHRR imagery. Weather station records were spatially interpolated to create monthly rainfall surfaces. Vegetation structural classes were derived from a digitized map of northern Australian vegetation communities (1:1,000,000). Generalized linear models were used to quantify relationships among the fAPAR, EG and RG signals, vegetation structure, rainfall and fire frequency, for the period November 1996-December 2001. Results The fAPAR and EG signals are positively correlated with annual rainfall and canopy cover, notably: EGclosed forest > EG open heathland > EGopen forest > EG woodland > EGopen woodland > EG low woodland > EGlow open woodland > EG open grassland· Vegetation height and fAPAR are positively correlated...

Vegetation of the Hantam-Tanqua-Roggeveld subregion, South Africa. Part 1: fynbos biome related vegetation

Van Der Merwe,Helga; Van Rooyen,Margaretha W.; Van Rooyen,Noel
Fonte: Koedoe Publicador: Koedoe
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2008 EN
Relevância na Pesquisa
36.85%
The Succulent Karoo Hotspot stretches along the western side of the Republic of South Africa and Namibia. A lack of botanical information on the Hantam-Tanqua-Roggeveld area of the Succulent Karoo Hotspot was identified during the SKEP (Succulent Karoo Ecosystem Plan) process. A grant from CEPF (Critical Ecosystem Partnership Fund) funded a study to produce a vegetation map of the area to serve as baseline for ecosystem management. Vegetation surveys were conducted over an area of more than three million hectares from August to October 2004. Two major floristic units were identified, namely the Fynbos Biome related (Mountain Renosterveld) and Succulent Karoo Biome related units. An analysis of the floristic data of the predominantly Mountain Renosterveld vegetation unit is presented in this paper. Three associations were identified, which were subdivided into nine subassociations, one of which contains four variants. The vegetation units are described in terms of their species composition and their relationships with the physical environment. A vegetation map is provided depicting the geographical distribution of the different vegetation types. The main threat to the vegetation of the region identified by the farming community was a lack of infrastructure.