Página 1 dos resultados de 140 itens digitais encontrados em 0.002 segundos

Coexistence of forest and savanna in an Amazonian area from a geological perspective

ROSSETTI, D. F.; ALMEIDA, S.; AMARAL, D. D.; LIMA, C. M.; PESSENDA, L. C. R.
Fonte: WILEY-BLACKWELL PUBLISHING, INC Publicador: WILEY-BLACKWELL PUBLISHING, INC
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.49%
Question: How can the coexistence of savanna and forest in Amazonian areas with relatively uniform climates be explained? Location: Eastern Marajo Island, northeast Amazonia, Brazil. Methods: The study integrated floristic analysis, terrain morphology, sedimentology and delta(13)C of soil organic matter. Floristic analysis involved rapid ecological assessment of 33 sites, determination of occurrence, specific richness, hierarchical distribution and matrix of floristic similarity between paired vegetation types. Terrain characterization was based on analysis of Landsat images using 4(R), 5(G) and 7(B) composition and digital elevation model (DEM). Sedimentology involved field descriptions of surface and core sediments. Finally, radiocarbon dating and analysis of delta(13)C of soil profile organic matter and natural ecotone forest-savanna was undertaken. Results: Slight tectonic subsidence in eastern Marajo Island favours seasonal flooding, making it unsuitable for forest growth. However, this area displays slightly convex-up, sinuous morphologies related to paleochannels, covered by forest. Terra-firme lowland forests are expanding from west to east, preferentially occupying paleochannels and replacing savanna. Slack, running water during channel abandonment leads to disappearance of varzea/gallery forest at channel margins. Long-abandoned channels sustain continuous terra-firme forests...

Influence of multi-scale landscape structure on the occurrence of carnivorous mammals in a human-modified savanna, Brazil

LYRA-JORGE, Maria Carolina; RIBEIRO, Milton Cezar; CIOCHETI, Giordano; TAMBOSI, Leandro Reverberi; PIVELLO, Vania Regina
Fonte: SPRINGER Publicador: SPRINGER
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.53%
So Paulo is the most developed state in Brazil and contains few fragments of native ecosystems, generally surrounded by intensive agriculture lands. Despite this, some areas still shelter large native animals. We aimed at understanding how medium and large carnivores use a mosaic landscape of forest/savanna and agroecosystems, and how the species respond to different landscape parameters (percentage of landcover and edge density), in a multi-scale perspective. The response variables were: species richness, carnivore frequency and frequency for the three most recorded species (Puma concolor, Chrysocyon brachyurus and Leopardus pardalis). We compared 11 competing models using Akaike`s information criterion (AIC) and assessed model support using weight of AIC. Concurrent models were combinations of landcover types (native vegetation, ""cerrado"" formations, ""cerrado"" and eucalypt plantation), landscape feature (percentage of landcover and edge density) and spatial scale. Herein, spatial scale refers to the radius around a sampling point defining a circular landscape. The scales analyzed were 250 (fine), 1,000 (medium) and 2,000 m (coarse). The shape of curves for response variables (linear, exponential and power) was also assessed. Our results indicate that species with high mobility...

Evolution of extrafloral nectaries: adaptive process and selective regime changes from forest to savanna

Nogueira, A.; Rey, P. J.; Lohmann, Lucia Garcez
Fonte: WILEY-BLACKWELL; HOBOKEN Publicador: WILEY-BLACKWELL; HOBOKEN
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.25%
Much effort has been devoted to understanding the function of extrafloral nectaries (EFNs) for antplantherbivore interactions. However, the pattern of evolution of such structures throughout the history of plant lineages remains unexplored. In this study, we used empirical knowledge on plant defences mediated by ants as a theoretical framework to test specific hypotheses about the adaptive role of EFNs during plant evolution. Emphasis was given to different processes (neutral or adaptive) and factors (habitat change and trade-offs with new trichomes) that may have affected the evolution of antplant associations. We measured seven EFN quantitative traits in all 105 species included in a well-supported phylogeny of the tribe Bignonieae (Bignoniaceae) and collected field data on antEFN interactions in 32 species. We identified a positive association between ant visitation (a surrogate of ant guarding) and the abundance of EFNs in vegetative plant parts and rejected the hypothesis of phylogenetic conservatism of EFNs, with most traits presenting K-values < 1. Modelling the evolution of EFN traits using maximum likelihood approaches further suggested adaptive evolution, with static-optimum models showing a better fit than purely drift models. In addition...

"Da cultura à natureza - um estudo do cosmos e da ecologia dos enawene-nawe" ; From culture to nature: A study of the cosmos and ecology of the Enawene-Nawe

Santos, Gilton Mendes dos
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 27/04/2006 PT
Relevância na Pesquisa
36.27%
Esta tese é um estudo da ecologia e da cosmologia dos Enawene-Nawe, povo de língua Aruak, habitante da Amazônia Meridional, na faixa de transição entre o Cerrado e a Floresta Tropical. Sua abordagem está voltada para a interface cultura/natureza e, com base no material etnográfico, examina a hipótese de que a cultura é a condição genérica e primeira, e a natureza um momento particular e secundário, resultado de um processo de diferenciação da cultura – concepção diametralmente oposta à teoria evolutiva, típica do pensamento científico moderno. ; This thesis is a study of the ecology and cosmology of the Enawene-Nawe, people of the Aruak language, inhabitants of the southern Amazon, in the transitional region between the savanna and the tropical forest. The study explores the interface culture/nature and, based upon ethnographic material, examines the hypothesis that culture is a generic and primary condition and nature a particular moment and secondary, the result of a process of cultural differentiation – a concept diametrically opposed to the theory of evolution, typical of modern scientific thinking.

Unidades demonstrativas de restauração ecológica através de técnicas nucleadoras: Floresta Estacional Semidecidual, Cerrado e Restinga; Ecological Restoration Demonstrative Units using Nucleation Techniques: Seasonal Semidecidual Forest, Brazilian Savanna and Coastal Plain Vegetation

Bechara, Fernando Campanhã
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 06/07/2006 PT
Relevância na Pesquisa
36.44%
Refazer ecossistemas de forma artificial representa um desafio de iniciar um processo de sucessão o mais semelhante possível aos processos naturais. A recuperação ambiental tem se baseado no modelo da silvicultura tradicional, plantandose árvores sob espaçamento 3 x 2 m, em área total, com altos insumos de implantação/manutenção, e gerando-se bosques desenvolvidos em altura, porém com baixa diversidade de formas de vida e regeneração. Técnicas nucleadoras de restauração formam microhabitats em núcleos propícios para a chegada de uma série de espécies de todas as formas de vida, que num processo de aceleração sucessional, irradiam diversidade por toda a área. As técnicas foram implantadas em áreas piloto de um hectare, denominadas “Unidades Demonstrativas” (UDs). As UDs foram montadas em Floresta Estacional Semidecidual (Capão Bonito-SP), Cerrado (Santa Rita do Passa Quatro-SP) e Restinga (Florianópolis-SC). Na primeira UD, com um ano de idade, as técnicas nucleadoras introduziram 1.603 mudas de 148 espécies nativas, dentre 84 espécies arbóreas (883 mudas), 12 arbustivas (124 mudas), 30 herbáceas (242 mudas), 20 trepadeiras (260 mudas) e 2 bromeliáceas (3 mudas), além de 94 mudas de hábito indeterminado. Entre as espécies...

Impacto da invasão e mecanismos de regeneração natural do cerradão em áreas ocupadas por Pteridium arachnoideum (kaulf.) Maxon (Dennstaedtiaceae) no sudoeste do Estado de São Paulo; Impact and regeneration mechanism after invasion by Pteridium arachnoideum (Kaulf.) Maxon (Dennstaedtiaceae) in savanna woodland areas, southwestern São Paulo State

Guerin, Natalia
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 15/03/2010 PT
Relevância na Pesquisa
46.49%
As samambaias do gênero Pteridium caracterizam-se pelas largas frondes e por um sistema de rizomas subterrâneos que possibilita sua rápida expansão. Apresentam elevada produção de biomassa ao longo do ano, que aumenta a incidência de incêndios, e ainda liberam substâncias químicas consideradas alelopáticas. Atualmente, são conhecidas como plantas-problema, pois vêm se expandindo e ocupando grandes áreas em diversas partes do mundo, causando impacto econômico e ecológico. Nesse contexto, este estudo teve por objetivo geral a compreensão do impacto da invasão por Pteridium arachnoideum sobre a vegetação de cerrado e a elucidação dos mecanismos por meio dos quais vem sendo lentamente revertido o processo de invasão na área de estudo. Para tanto, analisamos áreas de cerradão invadidas há mais de quatro décadas na Estação Ecológica de Assis (EEcA), no sudoeste do estado de São Paulo. Analisamos a composição florística e estrutura da comunidade em uma área invadida dentro da EEcA. Avaliamos os componentes do estrato arbóreo e regenerante da comunidade, a fim de verificar quais as espécies que conseguiram ultrapassar as barreiras físicas e químicas impostas pela presença da samambaia. Para tanto, comparamos a vegetação da área invadida com uma área adjacente não invadida...

Ecologia e controle da invasão de Pinus elliottii no campo cerrado; Ecology of invasion and management of slash pine in a Brazilian savanna

Abreu, Rodolfo Cesar Real de
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 28/05/2013 PT
Relevância na Pesquisa
36.54%
Os impactos negativos que as espécies invasoras causam aos ecossistemas naturais ou seminaturais são noticiados há pelo menos seis décadas em diferentes partes do mundo. Diversos estudos têm sido realizados visando diagnosticar o processo de invasão, conhecer a ecologia das espécies invasoras e gerar subsídios para o manejo, controle ou erradicação daquelas que causam problemas. No Brasil, a invasão de ecossistemas naturais começou a ser estudada recentemente e muito conhecimento ainda precisa ser gerado para basear a tomada de decisões sobre o problema. Este estudo teve por objetivo descrever o processo de invasão do Cerrado por Pinus elliottii e buscar técnicas de manejo viáveis ecológica e economicamente para o controle da invasora. O estudo foi realizado na Estação Ecológica de Santa Bárbara, no munícipio de Águas de Santa Bárbara, São Paulo, em duas frentes de pesquisa: uma para estudar a ecologia da espécie invasora, e a outra para verificar qual seria a técnica de controle mais vantajosa ecológica e economicamente. O estudo de ecologia baseou-se na amostragem de cinco blocos de 10 parcelas, cada uma com área de 10 x 10 m, para o estudo de plantas nativas com altura a partir de 50 cm e, dentro de cada parcela...

Composição e sazonalidade de borboletas frugívoras no cerrado, com ênfase na relação fenológica entre Eunica bechina (Nymphalidae: Biblidinae) e sua planta hospedeira Caryocar brasiliense (Caryocaraceae); Composition and seasonality of fruit-feeding butterflies in the cerrado savanna, with emphasis on the phenological relationship between Eunica bechina (Nymphalidae: Biblidinae) and its host plant Caryocar brasiliense (Caryocaraceae)

Danilo Germano Muniz da Silva
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 27/05/2011 PT
Relevância na Pesquisa
46.41%
Em muitos ambientes tropicais, estações chuvosas se alternam com períodos de seca. A estação seca é um período de menor disponibilidade e qualidade nutricional de folhas, sendo, portanto, um período desfavorável para insetos herbívoros e gerando as oscilações sazonais em suas populações. O cerrado é um bioma neotropical sazonal, que inclui formações de savana (cerrado sensu stricto), e onde o clima se caracteriza por uma estação quente e chuvosa de outubro a abril e uma fria e seca de maio a setembro. A produção de folhas novas se concentra geralmente na estação chuvosa, tornando este um período favorável para muitos insetos herbívoros tais como as borboletas. Em seu estágio larval, as borboletas são herbívoros vorazes cujas populações comumente oscilam de acordo com a disponibilidade de folhas adequadas ao desenvolvimento dos imaturos. Borboletas podem ser divididas funcionalmente em duas guildas: as que se alimentam em sua forma adulta do néctar de flores, e aquelas que se alimentam dos líquidos oriundos de frutos em decomposição, seiva de árvores, carcaças de animais e excrementos. As espécies do segundo grupo são conhecidas como borboletas frugívoras. A guilda de borboletas frugívoras tem sido amplamente utilizada em estudos de ecologia de comunidades devido à facilidade de captura usando armadilhas com iscas de fruta fermentada...

Feeding habits of fish from a stream in the savanna of Central Brazil, Araguaia Basin

Melo,Cesar Enrique de; Machado,Francisco de Arruda; Pinto-Silva,Vangil
Fonte: Sociedade Brasileira de Ictiologia Publicador: Sociedade Brasileira de Ictiologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2004 EN
Relevância na Pesquisa
36.25%
The objective of the present study was to determine the composition of the diet of fish and its relation to the condition of canopy along a stream in the savanna of Central Brazil. Fish were collected monthly from April 1994 to March 1995. A total of 3872 individuals belonging to 82 species were captured and 1606 of them had their stomach content analysed. Allochthonous resources were widely used by fish. Although some fish groups do present generalist habits, most of the species can be included in well-defined trophic groups. Piscivores were abundant only during the flooding season when they occupied the stream looking for food and reproduction sites. Deforestation of the riparian forest has negative effects on the fish populations that depend on allochthonous resources. Lack of vegetation near the mouth of the river allows sand accumulation on the bottom of the stream and destruction of important microhabitats used as feeding and shelter, a fact that excluded some species from this site.

Trophic structure of a fish community in Bananal stream subbasin in Brasília National Park, Cerrado biome (Brazilian Savanna), DF

Schneider,Mariana; Aquino,Pedro De Podestà Uchôa de; Silva,Maria Júlia Martins; Fonseca,Claudia Padovesi
Fonte: Sociedade Brasileira de Ictiologia Publicador: Sociedade Brasileira de Ictiologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2011 EN
Relevância na Pesquisa
36.25%
The aim of this study was to determine the trophic structure of the fish community in the Bananal stream subbasin, which belongs to a well-preserved Cerrado area (Brazilian Savanna) in Brasília National Park, Brazil. We also evaluated the influence of environmental variations in the diet of fish species. Four samples were taken in each 30 m long established transect, two in the rainy season and two in the dry season. A total of 1,050 stomachs of the 13 most abundant species were analyzed. A total of 36 food items were consumed, where 24 were autochthonous, 8 allochthonous, and 4 of undetermined origin. Non-metric multidimensional scaling (NMDS) analysis, in addition to the results of frequency of occurrence and abundance charts, was used to determine four groups of feeding guilds: detritivores, omnivores (tending toward herbivory and invertivory), invertivores and piscivores. Around 69% of the volume of resources consumed was allochthonous, which proves the importance of the resources provided by riparian vegetation. The contribution of autochthonous and allochthonous items in the diet differed due to seasonality for Aspidoras fuscoguttatus, Astyanax sp., Characidium xanthopterum, Hyphessobrycon balbus, Kolpotocheirodon theloura, Moenkhausia sp....

Ticks on birds in a savanna (Cerrado) reserve on the outskirts of Uberlândia, Minas Gerais, Brazil

Pascoal,Jamile de Oliveira; Amorim,Marcus do Prado; Martins,Maria Marlene; Melo,Celine; Silva Júnior,Eurípedes Luciano da; Ogrzewalska,Maria; Labruna,Marcelo Bahia; Szabó,Matias Pablo Juan
Fonte: Colégio Brasileiro de Parasitologia Veterinária Publicador: Colégio Brasileiro de Parasitologia Veterinária
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2013 EN
Relevância na Pesquisa
36.41%
We report tick infestations on birds, in the environment and on domestic animals in a non-forested phytophysiognomy, the savanna-like Cerrado sensu stricto, in a natural reserve on the outskirts of the urban area of Uberlândia, Minas Gerais, Brazil. Overall, 238 birds within 50 species, 15 families and six orders were caught. Passeriformes were the most numerous, with 216 birds (90.75%), among which 22 had ticks (n = 31). Within this order, the prevalence of tick infestation was 10.2%, and the abundance and mean intensity were 0.14 and 1.41, respectively. Only immature ticks of the species Amblyomma nodosum were found on the birds. The tick species found both on animals (Rhipicephalus sanguineus, Rhipicephalus (Boophilus) microplus, Amblyomma cajennense and Dermacentor nitens) and in the environment (Amblyomma dubitatum, Rhipicephalus (B.) microplus and Amblyomma cajennense) were as expected. This difference in tick species between the environment and birds possibly occurred because the sampling of the environment was limited to the ground. This study also highlights the importance of the diverse microenvironments used by ticks and hosts in the same area and the complex ecology of bird-tick relationships. Ecological and epidemiological aspects of the findings are discussed.

Seasonal variation of ground spiders in a Brazilian Savanna

Mineo,Marina Farcic; Del-Claro,Kleber; Brescovit,Antonio Domingos
Fonte: Sociedade Brasileira de Zoologia Publicador: Sociedade Brasileira de Zoologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2010 EN
Relevância na Pesquisa
36.37%
The Brazilian Savanna Ecoregion (Cerrado) is one of the richest biomes in the world, with a characteristic highly seasonal climate a dry season between May and September and a rainy season from October through April. Ground-dwelling spiders from three Cerrado phytophysiognomies, "campo cerrado", "cerrado" and "cerradão", were sampled using pitfall traps during two years, totaling 111 species and 3,529 individuals. The abundance of individuals and species richness was higher during the wet season. Fifty-eight species were captured exclusively during that period, whereas only nineteen were restricted to the dry season. Only two species were found in all samples. The number of juveniles was higher than the number of adults in all phytophysiognomies and in all species during both seasons. The highest abundance was registered in October and the lowest in April. Overall sex ratio was male-biased in all vegetation types sampled. Distinct climate variables affected the abundance of spiders depending on sex, age and vegetal physiognomy where they were sampled. This study involved the longest sampling of spider abundance and diversity on the ground of a Brazilian Savanna.

Biome-specific effects of nitrogen and phosphorus on the photosynthetic characteristics of trees at a forest-savanna boundary in Cameroon

Ferreira Domingues, Tomas; Ishida, F. Yoko; Feldpausch, Ted R.; Grace, John; Meir, Patrick; Saiz, Gustavo; Sene, Olivier; Schrodt, Franziska; Sonké, Bonaventure; Taedoumg, Herman; Veenendaal, Elmar M.; Lewis, Simon; Lloyd, Jon
Fonte: Springer Berlin Heidelberg Publicador: Springer Berlin Heidelberg
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
36.53%
Photosynthesis/nutrient relationships of proximally growing forest and savanna trees were determined in an ecotonal region of Cameroon (Africa). Although area-based foliar N concentrations were typically lower for savanna trees, there was no difference in photosynthetic rates between the two vegetation formation types. Opposite to N, area-based P concentrations were—on average—slightly lower for forest trees; a dependency of photosynthetic characteristics on foliar P was only evident for savanna trees. Thus savanna trees use N more efficiently than their forest counterparts, but only in the presence of relatively high foliar P. Along with some other recent studies, these results suggest that both N and P are important modulators of woody tropical plant photosynthetic capacities, influencing photosynthetic metabolism in different ways that are also biome specific. Attempts to find simple unifying equations to describe woody tropical vegetation photosynthesis-nutrient relationships are likely to meet with failure, with ecophysiological distinctions between forest and savanna requiring acknowledgement.

Spatial Pattern Enhances Ecosystem Functioning in an African Savanna

Doak, Daniel F.; Brody, Alison K.; Jocqué, Rudy; Palmer, Todd M.; Pringle, Robert Mitchell
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
36.62%
The finding that regular spatial patterns can emerge in nature from local interactions between organisms has prompted a search for the ecological importance of these patterns. Theoretical models have predicted that patterning may have positive emergent effects on fundamental ecosystem functions, such as productivity. We provide empirical support for this prediction. In dryland ecosystems, termite mounds are often hotspots of plant growth (primary productivity). Using detailed observations and manipulative experiments in an African savanna, we show that these mounds are also local hotspots of animal abundance (secondary and tertiary productivity): insect abundance and biomass decreased with distance from the nearest termite mound, as did the abundance, biomass, and reproductive output of insect-eating predators. Null-model analyses indicated that at the landscape scale, the evenly spaced distribution of termite mounds produced dramatically greater abundance, biomass, and reproductive output of consumers across trophic levels than would be obtained in landscapes with randomly distributed mounds. These emergent properties of spatial pattern arose because the average distance from an arbitrarily chosen point to the nearest feature in a landscape is minimized in landscapes where the features are hyper-dispersed (i.e....

Influence of habitat on the reproductive ecology of the Amazonian palm, Mauritia flexuosa, in Roraima, Brazil

Khorsand Rosa, Roxaneh
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
36.49%
Although Mauritia flexuosa (Arecaceae) plays a pivotal role in the ecology and economy of the Amazon, and occurs in a variety of habitats, little is known about the influence of habitat on the reproductive biology of this palm. My dissertation focuses on the reproductive biology of M. flexuosa in three habitats in Roraima, Brazil: undisturbed forest, undisturbed forest-savanna ecotone, and savanna disturbed by plantations of the exotic tree, Acacia mangium. First, I calculated sex ratios and linked precipitation patterns with phenology. Sex ratios were female-biased. Precipitation was negatively associated with flowering, and positively associated with fruiting. Habitat appears to have no significant influence on phenology of M. flexuosa, although short-term climate variation may affect phenology of this species. Second, I examined floral biology, observed floral visitors, and performed exclusion experiments to determine the pollination system of M. flexuosa. Fruit set did not differ significantly between the visitor exclusion treatment and the control, but was significantly lowest in the wind + visitor exclusion treatment, suggesting that this dioecious palm is anemophilous, independent of habitat. Third, I identified the abiotic and biotic factors explaining variation in fruit mass...

Postcards from the past: charting the landscape-scale conversion of tropical Australian savanna to closed forest during the 20th century

Brook, B.; Bowman, D.
Fonte: Kluwer Academic Publ Publicador: Kluwer Academic Publ
Tipo: Artigo de Revista Científica
Publicado em //2006 EN
Relevância na Pesquisa
36.53%
Repeated sequences of digitised and geo-referenced historical aerial photography provide a powerful means of understanding landscape change. We use this method to demonstrate a landscape wide expansion of closed forest (42% increase in total coverage) in the Australian monsoon tropics over the past five decades. Retrospective habitat suitability models (HSI) of closed forest derived using four landscape measures (drainage distance, slope angle, aspect and elevation) for imagery taken in 1947 correctly forecast the subsequent spatial distribution of the expansion, with topographic fire protection primarily determining the closed-forest distribution. The dynamics of the closed forest-savanna boundary were predicted accurately by generalised linear models, with closed-forest expansion in fire-protected sites along forest edges and regression in the more fire-prone areas. Two factors may plausibly explain the expansion of closed forests. First, eco-ethnographic records stress the skilful use of fire by Aboriginal people in protecting isolated and locally resource-rich closed-forest patches. Second, the recent global increase in atmospheric CO2 may be changing the competitive balance between savanna and forest by enabling C3 trees to grow fast enough to escape the fire trap presented by flammable C4 grasses.; The original publication can be found at www.springerlink.com

The evolution of shelter: ecology and ethology of chimpanzee nest building

Stewart, Fiona Anne
Fonte: University of Cambridge; Department of Biological Anthropology Publicador: University of Cambridge; Department of Biological Anthropology
Tipo: Thesis; doctoral; PhD
EN
Relevância na Pesquisa
36.37%
Human beings of all cultures build some form of shelter, and the global distribution of Homo sapiens depends on this basic trait. All great apes (chimpanzee, bonobo, gorilla, and orangutan) build analogous structures (called nests or beds) at least once a day throughout their adult lives, which suggests that this elementary technology was present before the hominid lines separated. This thesis investigates the variability and function of specifically wild chimpanzee shelters. I compared characteristics of chimpanzee nests, nesting trees, nest shape, and architecture in two savanna-dwelling populations on opposite sides of Africa: Fongoli, Senegal, and Issa, Tanzania. Savanna habitats are the most extreme habitats in which chimpanzees survive today, and may represent a similar environment to that in which early hominins evolved in the Plio-Pleistocene (Chapter 2). Investigating variation in nest-building within and between these two extreme habitats made it possible to tackle hypotheses of the shelter function of nests (Chapter 3). The influence of environment, specifically the role of protection from disease vectors and fluctuating temperatures, was assessed through a novel experiment in which I slept overnight in arboreal chimpanzee nests and on the bare earth (Chapter 4). To assess whether or not nests serve as an anti-predation function...

Extracting structural vegetation components from small-footprint waveform LiDAR data in savanna ecosystems

McGlinchy, Joseph
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
46.44%
Research groups at Rochester Institute of Technology and Carnegie Institution for Science are focusing on characterization of savanna ecosystems using data collected from the Carnegie Airborne Observatory (CAO), which integrates high spatial resolution imaging spectroscopy and waveform light detection and ranging (LiDAR) data. This component of the larger RIT ecosystem project evaluated the extraction of waveform features from the small-footprint waveform LiDAR data and their ability to explain structural variation across differing land cover types by way of bare ground cover, woody, and herbaceous biomass estimation. The combination of nanosecond digitization of the backscattered signal and fine spatial resolution allowed for the extraction of structural information embedded within the waveform at the sub-object level. Signal processing approaches subsequently were used to combine measurements within a composite footprint size of sub-meter and above. The ability of the waveform features to estimate the level of bare ground coverage for a single pixel was verified by comparing grayscale maps of the features to imagery and abundance map combinations of spectral endmembers. The ability of above-ground waveform features to explain the woody and herbaceous field measurements was evaluated statistically by forward selection regression models...

Soil Microbial Biomass And Activity In A Cork Oak Savanna

Maria C. Caldeira; David Fangueiro; Xavier Lecomte; Miguel N. Bugalho; João P. Coutinho; João S. Pereira
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Poster
Relevância na Pesquisa
36.37%
Cork oak savannas are composed by a sparse tree canopy (30-70 trees/ha) and a grassland understory predominantly composed of C3 annuals that survive the hot and dry Mediterranean summers as seeds in the soil. Microbial communities can be more or less efficient at converting organic substrates into microbial biomass carbon depending on the quantity and quality of organic matter inputs. The cork oak savannas have two distinct types of plant litter that can affect soil microbial biomass and activity differently: herbaceous litter and the more recalcitrant woody plant litter resulting from the trees. Spatial variability of soil microbial biomass and activity due to the tree-grassland component of cork oak savannas were evaluated in order to better understand the soil carbon dynamics of these systems. To quantify changes in soil microbial biomass and activity, measurements were performed in a Cork oak savanna in Southern Portugal. At this site 8 plots were randomly established under mature cork oak trees and paired with 8 open grassland plots. During one year soil cores (0-10 cm) were monthly collected at each site for measuring soil microbial biomass C and other eco-physiology parameters. Results/Conclusion Soil microbial biomass carbon (Cmic) and nitrogen (Nmic) were always higher under the tree canopy than in the open grasslands. Organic carbon (Corg) was also higher under the tree canopies. The Cmic/Corg ratio relates to the microbial activity and its potential to mineralize organic substances. The Cmic/Corg ratio was lower under the tree canopies than in the open grasslands. Less microbial biomass was supported per unit of Corg. Basal activity was always higher under the canopy than in the open grassland. Trees scattered in the savanna function as islands inducing larger soil microbial communities and higher basal activity under the canopies. Lower Cmic/Corg ratio under the tree canopies suggests a more recalcitrant nature of the litter and a decrease in relative availability of organic matter under the trees.

Feeding ecology of Ara ararauna (Aves, Psittacidae) at firebreaks in western Cerrado, Brazil

Tubelis, Dárius Pukenis
Fonte: Universidade Federal de Santa Catarina Publicador: Universidade Federal de Santa Catarina
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; Formato: application/pdf
Publicado em 01/01/2009 POR
Relevância na Pesquisa
36.41%
http://dx.doi.org/10.5007/2175-7925.2009v22n2p105This study aimed to identify food items of the Blue-and-yellow Macaw (Ara ararauna) flocks foraging at firebreaks in western Cerrado, Brazil. Also, I discuss ecological aspects of macaw feeding activities at firebreaks. Two 3,500ha portions of Emas National Park were selected for observations. The sites were mosaics of woodland savanna and shrubby grassland, crossed and bordered by firebreaks and adjacent unsealed roads. A total of 76 foraging flocks of macaws were recorded at firebreaks between September 2006 and February 2007. Seven plant species were identified as food items. Seeds of a shrub species (Anacardium humile) were the most often consumed resource. Parts of other plant species were sometimes consumed. Macaws perched in tree canopies to consume their young apical parts, young leaves, flowers and parts of branches. The frequency of consumption of parts of shrubs was significantly higher than that of trees. At Emas National Park, numerous Blue-and-yellow Macaw flocks are attracted to firebreaks mainly by fruiting A. humile patches. Their foraging activities often damage reproductive and young parts of shrubs and trees.