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Heterogeneidade ambiental, diversidade e estrutura da comunidade harborea de um trecho da Floresta Ombrofila Densa Atlantica; Environmental heterogeneity, species diversity, and structure of the tre community in a stand of the Brazilian Atlantic Rain Forest

Andre Luis Casarin Rochelle
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 17/07/2008 PT
Relevância na Pesquisa
35.82%
A Floresta Atlântica é um ecossistema complexo, exibindo áreas com mais de 200 espécies de árvores coexistindo em um único hectare. Variações topográficas, principalmente em pequenas escalas, parecem ter forte influência sobre a diversidade, porque estão relacionadas com o processo de formação do substrato e com a disponibilidade de água e nutrientes do solo. Este trabalho investigou a relação entre variáveis microtopográficas e a estrutura da comunidade arbórea em 1 hectare de Floresta Atlântica, no Parque Estadual Serra do Mar, Ubatuba, SP. No capítulo 1, testamos as hipóteses que microvariações topográficas aumentam a diversidade de espécies arbóreas e que microhábitats côncavos possuem maior diversidade que microhábitats convexos, e no capitulo 2, que microhábitats côncavos detêm mais biomassa que microhábitats convexos devido ao predomínio de processos de sedimentação neste tipo de microrrelevo. No capítulo 3, apresentamos uma descrição fitossociológica, discutindo sua diversidade em contextos regionais e continentais. Alocamos 100 parcelas contíguas de 10 x 10 metros (S23º21?59.8??W45º05?02.8?) e etiquetamos, medimos (PAP e altura) e identificamos todas as árvores (PAP>15 cm). Para cada parcela...

Wave exposure, swimming performance, and the structure of tropical and temperate reef fish assemblages

Fulton, Christopher; Bellwood, David
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
45.67%
We examined the relationship between swimming performance, wave exposure, and the distribution patterns of labrids on temperate rocky reefs, in comparison with previous functional analyses of a tropical assemblage. Visual censuses of the distribution and

Fe and Zn effects on the Si Cycle and diatom community structure in two contrasting high and low-silicate HNLC areas

LeBlanc, K; Hare, C; Boyd, P W; Bruland, K W; Sohst, B; Pickmere, Stuart; Lohan, M C; Buck, K; Ellwood, Michael; Hutchins, D A
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
45.75%
We compared the importance of Fe, Zn and Si availability for diatom growth and silicification through microcosm enrichment experiments in two contrasting HNLC systems of the Sub-Arctic and Sub-Antarctic Pacific. The Bering Sea was characterized by low Fe

A comparison of bird communities in the anthropogenic and natural-tree fall gaps of a reduced-impact logged subtropical forest in Bolivia

Felton, Adam; Wood, Jeffrey; Felton, Annika M; Hennessey, Bennett A.; Lindenmayer, David
Fonte: Cambridge University Press Publicador: Cambridge University Press
Tipo: Artigo de Revista Científica
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35.82%
We studied bird community composition and abundance within four vegetation and disturbance categories located within selectively logged and unlogged forest in a Bolivian subtropical lowland forestry concession. The logged forest was subject to reduced-imp

Overdispersion of body size in Australian desert lizard communities at local scales only: no evidence for the Narcissus effect

Rabosky, Daniel L.; Reid, Julian; Cowan, Mark A.; Foulkes, Jeff
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
45.86%
Both local and regional processes may contribute to community diversity and structure at local scales. Although many studies have investigated patterns of local or regional community structure, few have addressed the extent to which local community struct

What makes us a community: structure, correlations, and success in scientific world

Kalinin, Sergei V.; Maksov, Artem
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 11/02/2015
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35.85%
We explore the statistical structure of scientific community based on multivariate analysis of publication (or other identifiable metrics) distribution in the author space. Here, we define community based on keywords, i.e. projecting semantic content of the documents on predefined meanings; however, more complex approaches based on semantic clustering of publications are possible. Remarkably, this simple statistical analysis of publication metadata allows understanding of internal interactions with community in general agreement with experience acquired over decades of social interaction within it. We further discuss potential applications of this approach for ranking within the community, reviewer selection, and optimization of community output.

Evidence that creation of a Pinus radiate plantation in south-eastern Australia has reduced habitat for frogs

Parris, Kirstem M; Lindenmayer, David
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
35.7%
Loss and fragmentation of habitat resulting from the clearing of forests for agriculture and urban development threaten the persistence of thousands of species worldwide. The clearing of native forest to plant a monoculture of exotic trees may also reduce and fragment the habitat available for indigenous plants and animals. Metacommunity theory suggests that the species richness of a community in a patch of habitat will increase with patch size but decrease with patch isolation. We investigated whether replacement of native Eucalyptus forest with a plantation of Pinus radiata has reduced and fragmented habitat for frogs, leading to a lower species richness of frog communities in the pine plantation and in small and/or isolated remnant patches of native forest. We surveyed frogs at 60 sites at streams and wetlands in the pine plantation, remnant patches of native forest surrounded by pines, and adjacent areas of contiguous native forest near Tumut in New South Wales, Australia. Only two of eight species of frogs were recorded in the pine plantation, and regression modelling indicated that streams and wetlands in the pines supported fewer frog species than those in remnant patches or the intact native forest. In addition, species richness tended to be higher at wide...

Australian forest plantations: an overview of industry, environmental and community issues and benefits.

Gaztanaga, Enrique; Keenan, Rodney; Kanowski, Peter; Stanton, Richard
Fonte: Institute of Foresters of Australia Publicador: Institute of Foresters of Australia
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
35.74%
Australia has over 1.5 million ha of plantation forests. Governments and industry share a goal of doubling this area by 2020, with most new plantations to be established on previously-cleared agricultural land. Plantations currently supply over half of the raw material required by the forest products industry and also provide a range of environmental and social services. The ownership and management structure of Australian forest plantations and plantation-based forest industries has changed considerably over the past decade, and plantation growing, processing and marketing sectors are becoming increasingly globalised. This paper reviews the major forces driving development of forest plantations in Australia and the key policy and management issues to be considered if plantations are to meet varied expectations of the Australian community. Our assessment is based on papers and discussion at the 'Prospects for Australian Forest Plantations 2002' conference. The wide-ranging papers to the conference considered opportunities for Australia's forest plantations and plantation-based industries in changing global wood markets. They discussed alternative and emerging markets for wood and other plantation products and environmental services...

Impact of soil warming and shading on colonisation and community structure of arbuscular mycorrhizal fungi in roots of a native grassland

Heinemeyer, A; Ridgway, Karen; Edwards, Everard; Benham, D; Young, Peter J; Fitter, Alastair H.
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
55.88%
Arbuscular mycorrhizal (AM) fungi have a major influence on the structure, responses and below-ground C allocation of plant communities. Our lack of understanding of the response of AM fungi to factors such as light and temperature is an obstacle to accurate prediction of the impact of global climate change on ecosystem functioning. In order to investigate this response, we divided a grassland site into 24 plots, each either unshaded or partly shaded with soil either unheated or heated by 3°C at 2 cm depth. In both short-term studies in spring and autumn, and in a 1-year-long study, we measured root length colonization (LRC) by AM and non-AM fungi. For selected root samples, DNA sequences were amplified by PCR with fungal-specific primers for part of the small sub-unit (SSU) rRNA gene. In spring, the total LRC increased over 6 weeks from 12% to 25%. Shading significantly reduced AM but increased non-AM fungal colonization, while soil warming had no effect. In the year-long study, colonization by AM fungi peaked in summer, whereas non-AM colonization peaked in autumn, when there was an additive effect of shading and soil warming that reduced AM but increased non-AM fungi. Stepwise regression revealed that light received within the 7 days prior to sampling was the most significant factor in determining AM LRC and that mean temperature was the most important influence on non-AM LRC. Loglinear analysis confirmed that there were no seasonal or treatment effects on the host plant community. Ten AM fungal sequence types were identified that clustered into two families of the Glomales...

Residential Space and Collective Interest Formation in Beijings Housing Disputes

Tomba, Luigi
Fonte: Cambridge University Press Publicador: Cambridge University Press
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
45.67%
This article investigates the interest structure that leads to collective conflicts over the protection of private property in middle-class residential compounds in Beijing. The departure from a work-unit dominated social landscape means that work and residence are now de-linked and the new private residential compounds create communities of consumers, not of producers. Individual status is formed in the context of local socialization patterns in the neighbourhoods at least as much as in the workplace. Based on fieldwork in Beijing's residential compounds in 2002 and 2003, this article highlights the importance of spatial factors in determining the formation of collective interests and argues that the enclosed residential spaces of the gated communities are providing both a catalyst for the autonomous mobilization of collective resources and new social units for the Chinese state to govern an increasingly complex society.

Modeling count data of rare species: some statistical issues

Cunningham, Ross; Lindenmayer, David
Fonte: Ecological Society of America Publicador: Ecological Society of America
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
45.74%
Most species abundance data show that a small number of species contribute the vast majority of individuals to a community. Thus, most taxa in a community are uncommon or rare. Yet such species will frequently be of ecological, conservation, or management interest. Data for uncommon or rare species will be presence/absence data or counts of abundance that contain a greater number of zero observations than would be predicted using standard, unimodal statistical distributions. Such data are generally referred to as zero-inflated data and require specialized methods for statistical analysis. Statistical approaches to modeling zero-inflated data include nonstandard mixture models; two-part, conditional models; and birth process models. In this paper, we briefly summarize two of these methods and illustrate the two-part, conditional approach to the problem of modeling count data with extra zeros. An advantage of this approach includes separate fits and separate interpretations of both components of count data; that is to say, the presence/absence component and the abundance component (given presence) can be analyzed separately. This can be valuable not only for simplicity, but also such a two-step method may assist ecological understanding in cases where the basis for species presence might be separated from the underlying reasons affecting the population size of that species at those sites where it is present. We present two case studies of the application of the two-part conditional model for modeling count data with extra zeros. One deals with modeling relationships between counts of the rare and endangered arboreal marsupial...

Structural and floristic characteristics of some monodominant and adjacent mixed rainforests in New Caledonia

Read, Jennifer; Jaffre, T; Godrie, E; Hope, Geoffrey; Veillon, J
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
45.7%
Nothofagus spp. dominate the upper canopy of some rainforests on ultramafic soils in New Caledonia. These monodominant forests typically occur within, or contiguous with, larger areas of mixed-canopy rainforest. In this study the structure, diversity and

The Reality of Ecological Assemblages: A Palaeo-ecological Puzzle

Sterelny, Kim
Fonte: Kluwer Academic Publishers Publicador: Kluwer Academic Publishers
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
35.75%
Ecological communities, I argue, are objective units of nature if they have structure that regulates their membership. Evidence of such structure in contemporary ecology is scant, but the palaeoecological phenomenon of co-ordinated stasis is a prima facie example of internal regulation. I argue that no individualist attempts to explain away the appearance of internal regulation succeeds. But no internalist model is fully satisfactory, either, in explaining the contrast between pre and post Pleistocene ecology.

Determination of the impact of continuous defoliation of Lolium perenne and Trifolium repens on bacterial and fungal community structure in rhizosphere soil

Clayton, Stephen; Clegg, C D; Murray, P J; Gregory, Patricia
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
75.89%
To determine the effects of defoliation on microbial community structure, rhizosphere soil samples were taken pre-, and post-defoliation from the root tip and mature root regions of Trifolium repens L. and Lolium perenne L. Microbial DNA isolated from samples was used to generate polymerase chain reaction-denaturing gradient gel electrophoresis molecular profiles of bacterial and fungal communities. Bacterial plate counts were also obtained. Neither plant species nor defoliation affected the bacterial and fungal community structures in both the root tip and mature root regions, but there were significant differences in the bacterial and fungal community profiles between the two root regions for each plant. Prior to defoliation, there was no difference between plants for bacterial plate counts of soils from the root tip regions; however, counts were greater in the mature root region of L. perenne than T. repens. Bacterial plate counts for T. repens were higher in the root tip than the mature root region. After defoliation, there was no effect of plant type, position along the root or defoliation status on bacterial plate counts, although there were significant increases in bacterial plate counts with time. The results indicate that a general effect existed during maturation in the root regions of each plant...

Composition, structure, light attenuation and nutrient content of the understorey vegetation in a Eucalyptus sieberi regrowth stand 6 years after thinning and fertilisation.

Bauhus, Juergen; Aubin, I; Messier, Christian; Connell, Matthew
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
45.78%
In this study, we investigated the effects of commercial thinning and fertiliser application 6 years after treatment on the structure, composition, and nutrient concentrations of understorey vegetation in a Eucalyptus sieberi regrowth forest in East Gippsland. The stand was thinned at age 26 years, reducing the basal area by ca. 50% and lowering the stocking from ca. 1350 to ca. 250 stems ha-1. Whereas the species diversity and richness of the understorey were not significantly affected by the treatments, thinning promoted the abundance of herbaceous species, and fertilisation increased the proportion of ground ferns such as Pteridium esculentum. Fertilisation with 100 kg N ha-1 and 100 kg P ha-1 decreased the foliage N concentration in Tetrarrhena juncea and Gonocarpus teucrioides, and increased the foliage P concentrations in four of the five most frequent species. This suggested that the understorey was more limited by P than by N. The photosynthetically active radiation above the understorey was 41% of that in the open in thinned stands and 32-34% in unthinned stands, showing that 6 years after thinning the canopy density had not yet returned to pre-treatment levels. However, light attenuation within the understorey did not differ among treatments...

Estimating mixtures of leaf functional types using continental-scale satellite and climatic data

Berry, Sandra Lee; Roderick, Michael
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
35.72%
Aim Recent research has shown that much of the variability in leaf gas exchange and leaf longevity can be related to variations in the surface : volume ratio of leaves. The aim of this paper was to develop a theoretical framework and a practical method to extend that result to the vegetation at the continental scale. The study was conducted in Australia. We propose that vegetation is composed of a mixture of three basic leaf types, 'turgor' (T), 'mesic' (M) and 'sclerophyll' (S) leaves. Changes in the relative proportions of T, M and S leaves within a vegetation type are visualized using a ternary diagram and differences in vegetation structure are shown to be easily mapped onto the ternary diagram. We estimate the proportions of T, M and S leaves using readily available data. The total amount of PAR absorbed by the vegetation (fPAR) is estimated using continental-scale satellite observations. The total fPAR is then decomposed into that absorbed by T, M and S leaves. The relative absorption of PAR by T leaves is estimated from the temporal dynamics in the satellite signal, while the relative proportions of M and S leaves are estimated using climatic (solar radiation, rainfall) data. When the availability of light, nutrients and water were near-optimal...

Fire and succession in the ultramafic maquis of New Caledonia

McCoy, S; Jaffre, T; Rigault, F; Ash, Julian
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
35.75%
Aim: This study investigates the role of fire and post fire succession in determining the structure and composition of vegetation on ultramafic iron crust soils. Location: The study was conducted in the Plaines des Lacs region of southern New Caledonia. Methods: A survey was made of eighty-eight sites, recording floristic composition, trunk size-class distributions, regeneration after fire, growth ring counts of Dacrydium araucarioides (Podocarpaceae) and historical information on past fires. Floristic data was ordinated using multidimensional scaling and an index of succession based on structural and historical information. A transition matrix model was developed to predict the effect of fire frequency on vegetation composition. Results: The vegetation is undergoing postfire succession from maquis to forest, after about 75 years, and eventually to rainforest. Gymnostoma deplancheanum has a key role as an early colonist that produces shade, the bulk of the litter, and forms nitrogen fixing nodules with Frankia sp. However, the open canopy of Gymnostoma and slow litter decay creates flammable conditions. Though many species resprout from rootstocks, only thirty-nine persist through fires while 114 others colonize at later successional stages...

Effects of within- and between-patch processes on community dynamics in a fragmentation experiment

Davies, K; Melbourne, B; Margules, Chris
Fonte: Ecological Society of America Publicador: Ecological Society of America
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
55.87%
The effects of the experimental fragmentation of native eucalypt forest on the beetle community were tested, in a controlled, replicated, long-term experiment. Included in our design were three fragment sizes, fragment edge and interior sites, and sites in the surrounding exotic pine plantation matrix. We followed 325 species through 28 sampling periods over seven years, including two years pre-fragmentation. We examined effects of fragmentation on four attributes of community structure: (1) species richness, (2) species composition, (3) relative abundance, and (4) the changes in occurrence of all species individually by the traits of rarity, degree of isolation (dispersal ability), and trophic group. We also considered how changes in these attributes altered community dynamics (turnover). We used both community-level and species-level responses to determine the relative importance of processes acting at the within-patch and between-patch scales. At the within-patch scale there were two findings. (1) There was no evidence of an increase in the extinction rate on fragments, as was hypothesized. Neither species richness nor the occurrence of rare species declined on fragments compared to continuous forest. (2) Edge effects altered species occurrences and abundances on fragments compared to continuous forest. There was evidence of two edge effects...

Floristic-structural variations of a tree community associated to edge distance in a forest patch in “Planalto Sul Catarinense” region; VARIAÇÕES FLORÍSTICO-ESTRUTURAIS DA COMUNIDADE ARBÓREA ASSOCIADAS À DISTÂNCIA DA BORDA EM UM FRAGMENTO FLORESTAL NO PLANALTO SUL-CATARINENSE

Pscheidt, Francieli; UDESC; Rech, Carla Carolina Chini; UDESC; Missio, Francieli de Fátima; UDESC; Bento, Marco Antonio; UDESC; Buzzi Junior, Fernando; UDESC; Ansolin, Roni Djeison; UDESC; Bonazza, Marcelo; UDESC; Aguiar, Manoela Drews; FURB; Silva, Ana
Fonte: FUPEF DO PARANÁ Publicador: FUPEF DO PARANÁ
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; Artigo Avaliado pelos Pares Formato: application/pdf
Publicado em 08/08/2014 POR
Relevância na Pesquisa
35.85%
Com o propósito de comparar a organização florístico-estrutural de uma comunidade de espécies arbóreas nos setores de borda e interior em um fragmento de Floresta Ombrófila Mista localizado no município de Lages, SC, foi realizado um levantamento vegetacional em cinco transeções de 100 x 20 m, subdivididas em parcelas de 10 x 20 m, perpendiculares à borda do fragmento. Todas as árvores com circunferência na altura do peito (CAP) ≥ 15,7 cm foram mensuradas (CAP e altura) e determinadas. Os dados foram analisados por meio do índice de valor de importância (IVI), da análise de correspondência retificada (DCA), da análise de variância multivariada não paramétrica (NPMANOVA), dos valores médios de abundância, área basal, altura, riqueza, diversidade e equabilidade e da frequência de indivíduos em classes de diâmetro e altura. Apesar de tanto o setor borda quando o interior apresentarem Araucaria angustifolia (Bertol.) Kuntze e Lithraea brasilisiensis Marchand entre as espécies de maior IVI, houve substituição nas demais posições de IVI, que refletiu na variação da organização da comunidade entre os setores (p = 0,022), também observada na DCA. Em relação aos valores médios das demais variáveis mensuradas...

Dicksonia sellowiana and Araucaria angustifolia phorophyte influence on the vascular epiphyte community in Araucaria Forest.; INFLUÊNCIA DOS FORÓFITOS Dicksonia sellowiana e Araucaria angustifolia SOBRE A COMUNIDADE DE EPÍFITOS VASCULARES EM FLORESTA COM ARAUCÁRIA

Becker, Diego Fedrizzi Petry; Universidade Feevale; Müller, Andressa; Universidade Feevale; Schmitt, Jairo Lizandro; Universidade Feevale
Fonte: FUPEF DO PARANÁ Publicador: FUPEF DO PARANÁ
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; Artigo Avaliado pelos Pares Formato: application/pdf
Publicado em 06/03/2015 POR
Relevância na Pesquisa
35.91%
We analyzed the influence of moisture and pH substrate of Araucaria angustifolia (Bertol.) Kuntze e Dicksonia sellowiana Hook. on the richness, composition and community structure of vascular epiphytes within the Araucaria Forest. In order to study the epiphytic community, 20 phorophytes of A. angustifolia and D. sellowiana were selected in one hectare of Araucaria Forest. The phorophytes were divided equally into four intervals of one meter each. Araucaria angustifolia showed 20 species, while D. sellowiana 11. Means of species per host tree were significantly higher in D. sellowiana than for A. angustifolia. The moisture and pH of phorophyte types differ statistically and the most relation was observed between moisture and epiphytic ferns richness. Principal coordinates analysis showed well-defined groupings for phorophyte types and floristic heterogeneity among height intervals. Blechnum acutum (Desv.) Mett. occupied both phorophytes and had the highest importance values, demonstrating high ecological tolerance. The results show that moisture was the factor with the highest influence in the epiphytic community structure, especially for the ferns. ; Foi verificada a influência da umidade e do pH do substrato de Araucaria angustifolia (Bertol.) Kuntze e de Dicksonia sellowiana Hook. sobre a riqueza...