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Forest fragment size and microhabitat effects on palm seed predation

Fleury, M.; Galetti, M.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 1-13
ENG
Relevância na Pesquisa
37.1%
The establishment of plant species depends crucially on where the seeds are deposited. However, since most studies have been conducted in continuous forests, not much is known about the effects of forest fragmentation on the maintenance of abiotic and biotic characteristics in microhabitats and their effects on seed survival. in this study, we evaluated the effects of forest fragmentation on the predation upon the seeds of the palm Syagrus romanzoffiana in three microhabitats (interior forest, forest edge and gaps) in eight fragments of semi-deciduous Atlantic forest ranging in size from 9.5 ha to 33,845 ha in southeastern Brazil. Specifically, we examined the influence of the microhabitat structure, fauna and fragment size on the pattern of seed predation. Fragments < 100 ha showed similar abiotic and biotic characteristics to those of the forest edge, with no seed predation in these areas. Forest fragments 230-380 ha in size did not present safe sites for S. romanzoffiana seed survival and showed high seed predation intensity in all microhabitats evaluated. In fragments larger than 1000 ha, the seed predation was lower, with abiotic and biotic differences among gaps, interior forests and forest edges. In these fragments, the survival of S. romanzoffiana seeds was related to squirrel abundance and interior forest maintenance. Based on these results...

Microhabitat use by species of the genera Bothrops and Crotalus (Viperidae) in semi-extensive captivity

Gomes, C. A.; Almeida-Santos, S. M.
Fonte: Universidade Estadual Paulista (UNESP), Centro de Estudos de Venenos e Animais Peçonhentos (CEVAP) Publicador: Universidade Estadual Paulista (UNESP), Centro de Estudos de Venenos e Animais Peçonhentos (CEVAP)
Tipo: Artigo de Revista Científica Formato: 393-398
ENG
Relevância na Pesquisa
37.26%
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Many factors influence microhabitat including climate and the occurrence of predators, prey and suitable shelters. The influence of predators in a semi-extensive breeding system is minimized due to frequent monitoring of the area. This situation enables the independent analysis of such other variables as refuges and temperature. Some specimens of the Viperidae family are kept in a semi-extensive breeding system at the Instituto Butantanitute for display and study. These animals are widely distributed in the Atlantic Forest and Cerrado, two biomes with distinct climatic characteristics. We compared the daily activity pattern and microhabitat use of the species Bothrops jararaca and Crotalus durissus terrificus. Our main questions were whether rattlesnakes and lancehead snakes respond to habitat selection differently in similar climatic conditions and if they choose similar microhabitats. Species of the genus Bothrops were frequently found under shelters regardless of the time of day. on the other hand, snakes of the genus Crotalus were frequently found sheltered during the early morning, then migrated to sunnier areas and returned to shelters in late afternoon.

Effects of microhabitat on palm seed predation in two forest fragments in southeast Brazil

Fleury, M.; Galetti, M.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 179-184
ENG
Relevância na Pesquisa
37.1%
The establishment of plants depends crucially on where seeds are deposited in the environment. Some authors suggest that in forest understory seed predation is lower than in gaps, and higher than at the forest edge. However, most studies have been carried out in large forest patches and very little is known about the effects of microhabitat conditions on seed predation in forest fragments. We evaluated the effects of three microhabitats (gaps, forest edge, and understory) on seed predation of two palm species (Euterpe edulis and Syagrus romanzoffiana) in two semi-deciduous forest fragments (230 and 2100 hat in southeast Brazil. Our objective was to test two hypotheses: (1) Low rodent abundance in small fragments as a result of meso-predator action levels leads to lower seed predation in small fragments. (2) Most mammal species in small fragments are generalists with respect to diet and habitat, so that seed predation is similar in different microhabitats (gaps, forest edge and understory) in the small fragment, but not in the larger one. The study community of small fragments is usually composed of generalist species (in diet and habitat aspects), so we expected the same rate of seed predation among microhabitats (gaps, forest edge and understory) in the tested smaller fragment. The experiment was carried out in the dry season (for E. edulis) and in the wet season (for S. romanzoffiana) in 1999. We conclude that post-dispersal seed predation in forest fragments can be directly connected with mammal communities...

Microhabitat and plant structure of Characeae (Chlorophyta) populations in streams from São Paulo State, southeastern Brazil

Vieira, J.; Necchi, O.
Fonte: Adac-cryptogamie Publicador: Adac-cryptogamie
Tipo: Artigo de Revista Científica Formato: 51-63
ENG
Relevância na Pesquisa
37.45%
Microhabitat distribution was investigated in five populations of Characeae (two of Chara guairensis, two of Nitella subglomerata and one of Nitella sp.) to determine the distributional patterns, the morphometric and reproductive adaptations to varying environmental conditions and niche width on a scale of few centimeters. Variations in physical variables revealed some general trends of microhabitat distribution for the Characeae populations studied, with occurrence under the following conditions: slow and narrow current velocities; substrata predominantly composed of small particle size (sand-clay); variable and generally low depths. In terms of morphological adaptations, we found some general patterns: plants with longer whorl branchlets also had longer internodes in all populations studied, whereas longer plants had also thicker axis. The former were generally associated with higher biomass (percent cover). Few correlations of morphological characters were observed with environmental variables (e.g. plant length with irradiance: negative in two populations and positive in one population). Despite the general patterns of occurrence mentioned above, our results also indicated that each population differed in its responses to environmental variables and had particular morphological and reproductive adaptations. The Characean populations occurred under a narrower range of microhabitat conditions than other macroalgae from lotic habitats...

Microhabitat and morphometric variation of two chaetophoracean (chaetophorales, chlorophyta) species in tropical streams of southeastern Brazil

Branco, Ciro Cesar Zanini; Necchi Jr., Orlando
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 169-174
ENG
Relevância na Pesquisa
37.56%
Two populations of Chaetophora elegans (Roth) C. Agardh and two of Stigeoclonium helveticum Vischer were investigated for microhabitat characteristics and morphological variation in streams of Sao Paulo State, southeastern Brazil. Different patterns of microhabitat distribution were found between species investigated. Populations of C. elegans were distributed under relatively narrow microhabitat conditions (high irradiance, low depth, moderate to high current velocity, rocky substrata and lower values of niche width) and showing little morphometric variation (colony diameter, main axis cell size, and apical branch number). Stigeoclonium helveticum occurred under more diverse microhabitat conditions, revealed by lack of significant difference between sampling units with and without the alga and wider niche width, but also exhibited relatively narrow morphometric variation (plant length, main axis cell and lateral branch cell sizes). The narrow microhabitat conditions and smaller niche width of C. elegans can explain its low abundance (percentage cover) in streams from the area studied as well as in other regions of Sao Paulo State. In contrast, the wider variation of microhabitat conditions and the higher niche widths of S. helveticum suggest that this green alga is able to grow in a high number of stream ecosystems in the region investigated...

Influência do microhabitat e da densidade e distância de vizinhos na demografia de populações espécies arbóreas; The influence of microhabitat and distance and density of neighborns on the population demography of four woody species

Carolina Bernucci Virillo
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 18/08/2010 PT
Relevância na Pesquisa
37.37%
Os mecanismos responsáveis pela alta diversidade de espécies arbóreas em florestas tropicais têm sido alvo de intenso debate na literatura, e dentre os inúmeros mecanismos propostos, dois deles têm encontrado relativo suporte empírico: a dependência de densidade e a diferenciação de nichos. O objetivo deste trabalho foi investigar a ocorrência destes mecanismos na Floresta Ombrófila Densa Atlântica, que apresenta uma enorme diversidade de espécies vegetais, que variam em abundância, e uma grande diversidade de habitats, o que faz deste bioma um local apropriado para buscar evidências da ocorrência desses mecanismos. Foi investigada a influência da densidade de coespecíficos, da vizinhança e do microhábitat na demografia de quatro espécies arbóreas, e esperava-se que estes fatores atuassem de maneira conjunta na determinação da demografia das espécies estudadas. Em cinco áreas de 0,25 ha, duas na Floresta Ombrófila Densa de Terras Baixas (TB) e três na Floresta Ombrófila Densa Submontana (SM), foram marcados e medidos os indivíduos destas espécies, e um recenso foi realizado após dois anos para obtenção de taxas de mortalidade e recrutamento. Indivíduos com PAP (perímetro a altura do peito) > 15 cm foram acompanhados mensalmente para a avaliação da fenologia reprodutiva e do incremento diamétrico. Foi avaliada a influência da densidade de indivíduos e da distância e número de vizinhos coespecíficos na demografia das espécies. Também foi avaliada a relação da demografia com habitats específicos...

Utilização de microhabitat por três espécies de roedores cricetídeos em um cerrado do Brasil central

Rocha, Clarisse Rezende
Fonte: Universidade de Brasília Publicador: Universidade de Brasília
Tipo: Dissertação
PT_BR
Relevância na Pesquisa
27.65%
Dissertação (mestrado)—Universidade de Brasília, Instituto de Ciências Biológicas, Departamento de Ecologia, Programa de Pós-Graduação em Ecologia, 2007.; O objetivo deste trabalho foi analisar a utilização de microhabitat por Calomys tener, Necromys lasiurus e Thalpomys lasiotis e os fatores que mais influenciam a abundância destas três espécies de cricetídeos em áreas abertas de campo com murundus. O estudo foi realizado na Estação Ecológica de Águas Emendadas, Planaltina, DF, entre julho e setembro de 2004. Foram estabelecidas duas grades com 100 pontos de amostragem cada, em que foram colocadas armadilhas e para os quais foram registrados os dados de oito variáveis de microhabitat e das capturas dos roedores. A abundância de Calomys tener foi associada negativamente com o número de árvores e positivamente com a quantidade de gramíneas e de número de cupinzeiros. Foi encontrada diferença significativa entre as variáveis de microhabitat utilizadas por esta espécie quando comparados os machos com as fêmeas. Necromys lasiurus apresentou abundância diretamente proporcional à densidade de árvores no microhabitat. Thalpomys lasiotis apresentou associação negativa com o diâmetro de árvore e associação positiva com a variável distância da árvore mais próxima...

Microhabitat use by endangered Iberian cyprinids nase Iberochondrostoma almacai and chub Squalius aradensis

Santos, J.M.; Ferreira, M.T.
Fonte: Birkhauser Verlag Publicador: Birkhauser Verlag
Tipo: Artigo de Revista Científica
Publicado em //2008 ENG
Relevância na Pesquisa
37.37%
Research Article; Over the last decade there has been a major rise in the number of attempts at fish conservation and management as a response to the widespread degradation of aquatic ecosystems. The assessments involved are rarely planned and executed with inputs from the species life history, particularly their microhabitat use over space and time.The seasonal and sizerelated microhabitat use of two critically endangered cyprinids – the Iberian nase Iberochondrostoma almacai and Iberian chub Squalius aradensis – was examined at seven sites across four small catchments in southwest Portugal. Both species displayed nonrandom microhabitat use. In autumn, nase preferred more sheltered (>50% cover) habitats with small substrata (organic cover and silt) than in summer, while chub were found to occupy significantly fasterflowing habitats areas (>10 cm/s) with coarser substrata (>50 mm particle size) in the spring than in the rest of the year. Size-related analyses indicated that young-of-year (yoy) nase used coarser substrata (>5 mm particle size) and more exposed habitats (<50% cover) than adult nase. Adult chub, on the other hand, occupied coarser substrata (>50 mm particle size) and faster-flowing areas (>10 cm/s) than yoy and juveniles. Based on these findings...

Microhabitat preferences of Biomphalaria pfeifferi and Lymnaea natalensis in a natural and a man-made habitat in Southeastern Tanzania

Utzinger,Jürg; Tanner,Marcel
Fonte: Instituto Oswaldo Cruz, Ministério da Saúde Publicador: Instituto Oswaldo Cruz, Ministério da Saúde
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2000 EN
Relevância na Pesquisa
37.37%
Schistosoma mansoni is an important human parasitic disease which is widespread throughout Africa. As Biomphalaria pfeifferi snails act as intermediate host, knowledge of their population ecology is an essential prerequisite towards understanding disease transmission. We conducted a field study and assessed the density and microhabitat preferences of B.pfeifferi in a natural habitat which was a residual pool of a river. Repeated removal collecting revealed a density of 26.6 [95% confidence interval (CI): 24.9-28.3] snails/m2. B.pfeifferi showed microhabitat preferences for shallow water (depths: 0-4cm). They were found most abundantly close to the shoreline (distances: 0-40cm), and preferred either plant detritus or bedrock as substratum. Lymnaea natalensis, a snail which may act as a host for human Fasciola gigantica, also occurred in this habitat with a density of 34.0 (95% CI: 24.7-43.3) snails/m2, and preferred significantly different microhabitats when compared to B.pfeifferi. Microhabitat selection by these snail species was also investigated in a man-made habitat nearby, which consisted of a flat layer of concrete fixed on the riverbed, covered by algae. Here, B.pfeifferi showed no preference for locations close to the shoreline...

Microhabitat de Habia rubica (Vieillot) e Trichothraupis melanops (Vieillot) (Aves, Emberizidae, Thraupinae), em uma floresta atlântica do sul do Brasil

Fávaro,Fernando de Lima; Anjos,Luiz dos
Fonte: Sociedade Brasileira de Zoologia Publicador: Sociedade Brasileira de Zoologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2005 PT
Relevância na Pesquisa
37.37%
Este estudo identifica quais variáveis caracterizam os microhabitats de Habia rubica (Vieillot, 1817) e Trichothraups melanops (Vieillot, 1818) e verifica o padrão de abundância dessas espécies em relação aos parâmetros de microhabitat. Análise de componentes principais mostrou as variáveis de microhabitat mais importantes para cada espécie. O microhabitat de H. rubica foi caracterizado pelo estrato médio aberto e sub-bosque denso e rico em samambaias, arvoretas, herbáceas e cipós; esta espécie apresentou maior abundância nos locais ricos em tais variáveis. Para T. melanops, as variáveis mais importantes foram samambaias, arbustos, arvoretas, herbáceas, cipós, árvores de grande porte e quantidade de árvores com briófitas; a abundância desta espécie não foi relacionada com a densidade dessas variáveis talvez devido aos seus hábitos generalistas.

Abundância, microhabitat e repartição ecológica de papa-formigas (Passeriformes, Thamnophilidae) na bacia hidrográfica do rio Tibagi, Paraná, Brasil

Lopes,Edson V.; Volpato,Graziele H.; Mendonça,Luciana B.; Fávaro,Fernando de L.; Anjos,Luiz dos
Fonte: Sociedade Brasileira de Zoologia Publicador: Sociedade Brasileira de Zoologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2006 PT
Relevância na Pesquisa
37.1%
Neste estudo a riqueza e a abundância de Thamnophilidae foram avaliadas e correlacionadas com parâmetros ambientais em quatro áreas de floresta da bacia do rio Tibagi (B1, M1, A1 e A2) dispostas em um gradiente ambiental. Em cada área, foi caracterizada a vegetação e, para cada espécie, foram analisados: 1) o microhabitat, 2) a distribuição espacial e 3) o tempo investido em cada local de forrageio. O número de espécies foi semelhante entre as áreas, contudo, em B1 foi registrada maior abundância. A vegetação desta área apresentou valor de correlação relativamente baixo quando comparada as outras três, que apresentaram valores maiores entre si. Emaranhados de cipó em todos os estratos, estrato médio e superior denso e ocorrência de clareiras foram variáveis representativas na área B1. Estrato médio denso foi representativo para cinco espécies. Por outro lado, emaranhados de cipó no estrato superior e ausência de estrato inferior denso se destacaram apenas para duas espécies. A distribuição espacial, o tempo investido em cada local de forrageio e a seleção de microhabitats variaram entre as espécies. Esses foram fatores importantes na repartição ecológica das espécies analisadas neste estudo.

Microhabitat occupation by birds in a restinga fragment of Paraná coast, PR, Brazil

Pedroso Junior,Nelson Novaes
Fonte: Instituto de Tecnologia do Paraná - Tecpar Publicador: Instituto de Tecnologia do Paraná - Tecpar
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2003 EN
Relevância na Pesquisa
37.1%
Studies were carried out to characterize microhabitat occupation by birds in a restinga fragment of Paraná coast. Were described 14 microhabitats occupied in different manners for 64 species of birds. Based on the results, could be suggested that this conspicuous class of vertebrates, together with the other elements that integrate the restinga, serve as a component to attract and stimulate the interest for the comprehension and necessity of conservation by the visitors of such ecosystem.

Microhabitat use by species of the genera Bothrops and Crotalus (Viperidae) in semi-extensive captivity

Gomes,CA; Almeida-Santos,SM
Fonte: Centro de Estudos de Venenos e Animais Peçonhentos - CEVAP, Universidade Estadual Paulista - UNESP Publicador: Centro de Estudos de Venenos e Animais Peçonhentos - CEVAP, Universidade Estadual Paulista - UNESP
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2012 EN
Relevância na Pesquisa
37.26%
Many factors influence microhabitat including climate and the occurrence of predators, prey and suitable shelters. The influence of predators in a semi-extensive breeding system is minimized due to frequent monitoring of the area. This situation enables the independent analysis of such other variables as refuges and temperature. Some specimens of the Viperidae family are kept in a semi-extensive breeding system at the Butantan Institute for display and study. These animals are widely distributed in the Atlantic Forest and Cerrado, two biomes with distinct climatic characteristics. We compared the daily activity pattern and microhabitat use of the species Bothrops jararaca and Crotalus durissus terrificus. Our main questions were whether rattlesnakes and lancehead snakes respond to habitat selection differently in similar climatic conditions and if they choose similar microhabitats. Species of the genus Bothrops were frequently found under shelters regardless of the time of day. On the other hand, snakes of the genus Crotalus were frequently found sheltered during the early morning, then migrated to sunnier areas and returned to shelters in late afternoon.

Microhabitat selection in two small temperate zone snakes, Storeria dekayi and Storeria occipitomaculata

Guy, Jayda
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN
Relevância na Pesquisa
37.37%
Microhabitat selection involves choosing distinct habitat characteristics that can affect an organism’s survival and reproduction. Thermoregulatory behaviour also impacts the physiological processes of an ectotherm and thus ultimately fitness. My study investigates the northern populations of Storeria dekayi (the northern brown snake) and Storeria occipitomaculata (the red-bellied snake), how they select their microhabitat and how this in turn relates to their thermoregulatory needs. To do this I compared microhabitat characteristics and temperatures of occupied microsites to unoccupied microsites. I then compared these findings to thermal profiles of artificial cover elements made out of concrete. I found that large cover elements (which includes rocks, logs, and scrap metal) were the main indicators of the snakes’ presence. Temperatures underneath these cover elements that were within the optimal temperature range were selected for. Also larger cover elements afford temperatures within the optimal body temperature range of Storeria for longer periods of time than smaller cover elements. These findings underpin the importance of the temperature of a microsite and that the dimensions of a cover element affect these temperatures. Overall...

Microhabitat Selection by Marine Mesoconsumers in a Thermally Heterogeneous Habitat: Behavioral Thermoregulation or Avoiding Predation Risk?

Vaudo, Jeremy J.; Heithaus, Michael R.
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica Formato: application/pdf
Relevância na Pesquisa
37.45%
Habitat selection decisions by consumers has the potential to shape ecosystems. Understanding the factors that influence habitat selection is therefore critical to understanding ecosystem function. This is especially true of mesoconsumers because they provide the link between upper and lower tropic levels. We examined the factors influencing microhabitat selection of marine mesoconsumers – juvenile giant shovelnose rays (Glaucostegus typus), reticulate whiprays (Himantura uarnak), and pink whiprays (H. fai) – in a coastal ecosystem with intact predator and prey populations and marked spatial and temporal thermal heterogeneity. Using a combination of belt transects and data on water temperature, tidal height, prey abundance, predator abundance and ray behavior, we found that giant shovelnose rays and reticulate whiprays were most often found resting in nearshore microhabitats, especially at low tidal heights during the warm season. Microhabitat selection did not match predictions derived from distributions of prey. Although at a course scale, ray distributions appeared to match predictions of behavioral thermoregulation theory, fine-scale examination revealed a mismatch. The selection of the shallow nearshore microhabitat at low tidal heights during periods of high predator abundance (warm season) suggests that this microhabitat may serve as a refuge...

Utilização do microhábitat e comportamento de duas espécies de lagartos do gênero Tropidurus numa área de Caatinga no Monumento Natural Grota do Angico

Santana, Daniel Oliveira; Faria, Renato Gomes; Ribeiro, Adauto de Souza; Oliveira, A. C. F.; Souza, B. B.; Oliveira, D. G.; Santos, E. D. S.; Soares, F. A. M.; Gonçalves, F. B.; Calasans, H. C. M.; Vieira, H. S.; Cavalcante, J. G.; Marteis, L. S.; Aschof
Fonte: Universidade Federal de Sergipe Publicador: Universidade Federal de Sergipe
Tipo: Artigo de Revista Científica
PT_BR
Relevância na Pesquisa
37.56%
Um estudo sobre os padrões de comportamento e utilização do microhábitat por Tropidurus semitaeniatus e Tropidurus hispidus foi conduzido em área de caatinga no Monumento Natural Grota do Angico, Poço Redondo, Sergipe, nos leitos dos riachos Angico 1 e Angico 2 com afloramentos rochosos, sujeito a chuvas concentradas durante período curto do ano, onde T. semitaeniatus e T. hispidus ocorrem simpatricamente. A metodologia utilizada foi a de busca ativa, no período entre 10:00 h e 14:00 h, com todo o caminho percorrido sendo sistematicamente vistoriado. Os espécimes encontrados foram observados através do método animal focal com observação durante cinco minutos para registro dos comportamentos realizados. Além disso, foram registradas informações como horário, atividade, microhábitat e condições do tempo e da exposição dos lagartos. Calculou-se a largura de nicho utilizando o índice de diversidade de Simpson. Durante o período de estudo as duas espécies apresentaram-se ativas, com distribuição uniforme e exposição ao mosaico, sol e sombra, provavelmente para evitar superaquecimento, o que poderia causar desarranjos fisiológicos ou até mesmo a morte. Com relação à atividade e substratos utilizados...

Microhabitat selection and co-occurrence of Pachistopelma rufonigrum Pocock (Araneae, Theraphosidae) and Nothroctenus fuxico sp. nov. (Araneae, Ctenidae) in tank bromeliads from Serra de Itabaiana, Sergipe, Brazil

Dias,Sidclay Calaça; Brescovit,Antonio D.
Fonte: Sociedade Brasileira de Zoologia Publicador: Sociedade Brasileira de Zoologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2004 EN
Relevância na Pesquisa
37.45%
Microhabitat selection and co-occurrence of Pachistopelma rufonigrum Pocock (Theraphosidae) and Nothroctenus fuxico sp. nov. (Ctenidae), in tank bromeliads were investigated. Thermal conditions, inside and outside the plants, were measured in order to verify if the temperature of the water that accumulates inside the plant affects the behavior of these species. Measurements of foliar parameters were taken in order to evaluate if and how plant structure affects spider abundance and microhabitat selection. Apparently, differences in plant structure do not affect either spider abundance or microhabitat selection. No microhabitat preference was observed and co-ocurrence of both species was a random event. In addition, notes on the distribution range of P. rufonigrum and the description of N. fuxico sp. nov. from State of Sergipe, Brazil are presented.

Effects of trap position, trap history, microhabitat and season on capture probabilities of small mammals in a wet eucalypt forest

Cunningham, Ross; Lindenmayer, David; MacGregor, Chris; Barry, Simon C; Welsh, Alan
Fonte: CSIRO Publishing Publicador: CSIRO Publishing
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
37.1%
In this study, we use data drawn from a series of trapping events on four 0.5-ha trapping grids surveyed in the wet eucalypt forests of central Victoria, south-astern Australia, to identify relationships between capture probabilities and several factors of interest for three species of small mammals that are common throughout the forests of this region: the agile antechinus (Antechinus agilis), the dusky antechinus (Antechinus swainsonii) and the bush rat (Rattus fuscipes). The design of our study - four regular trapping grids - generated spatio-temporal data with binary responses and many covariates. We used powerful and relatively new statistical methodology to deal with the spatio-temporal dependence patterns in the data - analytical problems that are common in trapping data such as these modelled here. Although A. agilis, A. swainsonii and R. fuscipes are among the best studied mammals in Australia, our data analysis produced new perspectives on their probability of being captured. In particular, we quantified how capture probability is affected by trap position within a trapping grid, day of capture in a sequence of trapping days, history of trap occupancy over time by different species and sexes of those species, time of the year or season...

Habitat models for the four-fingered skink(Carlia tetradactyla) at the microhabitat and landscape scale (submitted)

Fischer, Joern; Lindenmayer, David; Cowling, Ann
Fonte: CSIRO Publishing Publicador: CSIRO Publishing
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
37.26%
A spatially nested experimental design was used to survey reptiles in a sheep- and cattle-grazing landscape in southern New South Wales, Australia. Sixteen landscape units were chosen on the basis of their aspect, topography and amount of tree cover. Across these landscape units, 288 pitfall traps were established at 144 plots arranged in 48 sites. Each plot was searched for reptiles and pitfall-trapped in two separate survey periods. The four-fingered skink (Carlia tetradactyla) was the most commonly encountered reptile species, and detailed statistical habitat models were constructed for this species. The four-fingered skink responded to both landscape scale and microhabitat variables. The species was more likely to be detected in landscape units characterised by a high amount of tree cover. Adults were most likely to inhabit microhabitats dominated by box- or gum-type eucalypts, with a moderate amount of canopy cover and with a large number of spiders. Juveniles were most likely to inhabit microhabitats with a moderate amount of weed invasion where shrubs were present. Finally, the four-fingered skink was more likely to be found at sites with at least two other co-occurring small reptile species. Body condition and tail loss of adult skinks were not related to the habitat or microhabitat where a given individual was found. The results are discussed in relation to current herpetological research...

The effects of food presentation and microhabitat upon resource monopoly in a ground-foraging ant (Hymenoptera: Formicidae) community

McGlynn,Terrence P; Eben Kirksey,S
Fonte: Revista de Biología Tropical Publicador: Revista de Biología Tropical
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2000 EN
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In Neotropical wet forests several species of omnivorous, resource-defending ants, live and forage in close proximity to one another. Although the forest floor is heterogeneous in microhabitat and food quantity, little is known about the impact of microhabitat and food variation upon resource monopoly among ants. We investigated how food type and microhabitat influence food monopoly in resource-defending ants in old-growth tropical wet forest in the Caribbean lowlands of Costa Rica. We measured several microhabitat characteristics at 66 points in a 0.5 hectare plot, and baited each point with two categories of tuna bait. These baits were presented in "split" and "clumped" arrangements. We measured the frequency of bait monopoly by a single species, as well as the number of recruited ant foragers at a bait. Out of five common species, two (Wasmannia auropunctata and Pheidole simonsi) more frequently monopolized one bait type over the other, and one (P. simonsi) recruited more ants to the split baits. We then considered the recruitment response by all ant species in the community. We found that the frequency of monopoly, sharing, and the absence of ants at a given point in the rainforest differed with bait type. The frequency of monopoly was associated with microhabitat type in two out of eight microhabitat variables (leaf litter depth and palms); variation in two other types (canopy tree distance and leafcutter ant trails) was associated with changes in forager number. In at least two ant species...