997 resultados para isolated trees


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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Translocation experiments showed that a woodcreeper bird species is able to move between isolated forest fragments, but this ability is limited by increasing interpatch distances. Larger distances (> 100 m) were overcome by using small stepping-stones (isolated trees), which enhance connectivity and are useful for the species conservation in fragmented landscapes.

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Linear strips of vegetation set within a less-hospitable matrix are common features of landscapes throughout the world. Depending on location, form and function, these linear landscape elements include hedgerows, fencerows, shelterbelts, roadside or streamside strips and wildlife corridors. In many anthropogenically-modified landscapes, linear strips are important components for conservation because they provide a large proportion of the remaining wooded or shrubby habitat for fauna. They may also function to provide connectivity across the landscape. In some districts, the linear strips form an interconnected network of habitat. The spatial configuration of remnant habitat (size, shape and arrangement) may influence habitat suitability, and hence survival, of many species of plant and animal in modified landscapes. Near Euroa in south-eastern Australia, the clearing and fragmentation of temperate woodlands for agriculture has been extensive and, at present, less than 5% tree cover remains, most of which (83%) occurs as linear strips along roads and streams. The remainder of the woodland occurs as relatively small patches and single isolated trees scattered across the landscape. As an assemblage, arboreal marsupials are woodland dependent and vary in their sensitivity to habitat loss and fragmentation. This thesis focusses on determining the conservation status of arboreal marsupials in the linear network and understanding how they utilise the landscape mosaic. Specifically, the topics examined in this thesis are: (1) the composition of the arboreal marsupial assemblage in linear and non-linear woodland remnants; (2) the status and habitat preferences of species of arboreal marsupial within linear remnants; and (3) the ecology of a population of the Squirrel Glider Petaurus norfolcensis in the linear network, focusing on population dynamics, spatial organisation, and use of den trees. The arboreal marsupial fauna in the linear network was diverse, and comprised seven out of eight species known to occur in the district. The species detected within the strips were P. norfolcensis, the Sugar Glider Petaurus breviceps, Common Brushtail Possum Trichosums vulpecula, Common Ringtail Possum Pseudocheirus peregrinus, Brush-tailed Phascogale Phascogale tapoatafa, Koala Phascolarctos cinereus and Yellow-footed Antechinus Antechinus flavipes. The species not detected was the Feathertail Glider Acrabates pygmaeus. Survey sites in linear remnants (strips of woodland along roads and streams) supported a similar richness and density of arboreal mammals to sites in non-linear remnants (large patches or continuous tracts of woodland nearby). Furthermore, the combined abundance of all species of arboreal marsupials was significantly greater in sites in the linear remnants than in the non-linear remnants. This initial phase of the study provided no evidence that linear woodland remnants support a degraded or impoverished arboreal marsupial fauna in comparison with the nonlinear remnants surveyed. Intensive trapping of arboreal marsupials within a 15 km linear network between February 1997 and June 1998 showed that all species of arboreal marsupial (except A. pygmaeus) were present within the linear strips. Further analyses related trap-based abundance estimates to measures of habitat quality and landscape structure. Width of the linear habitat was significantly positively correlated with the combined abundance of all arboreal marsupials, as well as with the abundance of P. norfolcensis and T. vulpecula. The abundance of T. vulpecula was also significantly positively correlated with variation in overstorey species composition, Acacia density and the number of hollow-bearing trees. The abundance of P. norfolcensis was positively correlated with Acacia density and canopy width, and negatively correlated with distance to the nearest intersection with another linear remnant. No significant variables were identified to explain the abundance of P. tapoatafa, and there were insufficient captures of the remaining species to investigate habitat preferences. Petaurus norfolcensis were resident within the linear network and their density (0.95 -1.54 ha-1) was equal to the maximum densities recorded for this species in continuous forest elsewhere in south-eastern Australia. Rates of reproduction were also similar to those in continuous forest, with births occurring between May and December, a mean natality rate of 1.9, and a mean litter size of 1.7. Sex ratios never differed significantly from parity. Overall, the population dynamics of P. norfolcensis were comparable with published results for the species in contiguous forest, clearly suggesting that the linear remnants currently support a self-sustaining, viable population. Fifty-one P. norfolcensis were fitted with radio transmitters and tracked intermittently between December 1997 and November 1998. Home ranges were small (1.3 - 2.8 ha), narrow (20 - 40 m) and elongated (322 - 839 m). Home ranges were mostly confined to the linear remnants, although 80% of gliders also utilised small clumps of adjacent woodland within farm paddocks for foraging or denning. Home range size was significantly larger at intersections between two or more linear remnants than within straight sections of linear remnants. Intersections appeared to be important sites for social interaction because the overlap of home ranges of members of adjacent social groups was significantly greater at intersections than straight sections. Intersections provided the only opportunity for members of three or more social groups to interact, while still maintaining their territories. The 51 gliders were radiotracked to 143 different hollow-bearing trees on 2081 occasions. On average, gliders used 5.3 den trees during the study (range 1-15), and changed den trees every 4.9 days. The number of den trees used by each glider is likely to be conservative because the cumulative number of den trees continued to increase over the full duration of the study. When gliders shifted between den trees, the mean distance between consecutive den sites was 247 m. Den trees were located throughout a glider's home range, thereby reducing the need to return to a central den site and potentially minimising energy expenditure. Dens were usually located in large trees (mean diameter 88.5 cm) and were selected significantly more often than expected based on their occurrence within the landscape. The overall conclusion of this thesis is that the linear network I studied provides high quality habitat for resident populations of arboreal marsupials. Important factors influencing the suitability of the linear remnants appear to be the high level of network connectivity, the location on soils of high nutrient status, the high density of large trees and an acacia understorey. In highly fragmented landscapes, linear habitats as part of the remaining woodland mosaic have the potential to be an integral component in the conservation of woodland-dependent fauna. The habitat value of linear strips of vegetation should not be underestimated.

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 Putrajaya is a model city planned with concepts of a "city in the garden" and an "intelligent city" in the tropics. This study presents the behaviour of the surface temperature and the heat island effect of Putrajaya. Findings show that heat island intensity is 2 °C on average at nighttime and negligible at daytime. But high surface temperature values were recorded at the main boulevard due to direct solar radiation incident, street orientation in the direction of northeast and southwest and low building height-to-street width ratio. Buildings facing each other had cooling effect on surfaces during the morning and evening hours; conversely, they had a warming effect at noon. Clustered trees along the street are effective in reducing the surface temperature compared to scattered and isolated trees. Surface temperature of built up areas was highest at noon, while walls and sidewalks facing northwest were hottest later in the day. Walls and sidewalks that face northwest were warmer than those that face southeast. The surface temperatures of the horizontal street surfaces and of vertical façades are at acceptable levels relative to the surface temperature of similar surfaces in mature cities in subtropical, temperate and Mediterranean climates. © 2014 Springer-Verlag Wien.

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Six microsatellite loci were used to quantify the mating system of two small fragmented populations (Selviria - SEL and Aparecida do Tabuado APT, Mato Grosso do Sul State) and isolated trees in pastures, of the bat-pollinated tropical tree Hymenaea stignocarpa, growing in the Center-west region of Brazil. In SEL population, seeds were collected from 11 mother-trees; in APT, from three trees and, in the case of isolated trees, from six individuals growing at least 500 m apart in pastures. To investigate if there are differences on mating system between trees in populations and isolated trees, trees from populations were pooled as a group and, likewise, the isolated trees were pooled to another group. The outcrossing rate was higher in the populations ((t) over cap (m)=0.873) than in isolated trees ((t) over cap (m)=0.857), but the difference was not significant. Significant and high differences between multi-locus and single-locus outcrossing rate were detected in populations ((t) over cap (m)-(t) over cap (s)=0.301, P<0.05) and isolated trees (<(t)over cap>(m)-(t) over cap (s) = 0.276, P < 0.05), suggesting mating between relatives. Higher paternity correlation was observed in trees from population (<(r)over cap>(p)=0.636) than in isolated trees ((r) over cap (p)=0.377), indicating the occurrence of some correlated matings and that part of offspring are full-sibs. It was not observed increased in self-fertilization rate in isolated trees in pastures. In general terms, the unique observed difference in mating system between populations and isolate trees was the high rate of correlated matings in trees from populations, due probably to the small distance among coespecifics and the pollinator behavior, visiting near trees.

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To investigate the movement of seeds transported by fruit-eating birds in an agricultural, fragmented landscape of the Atlantic forest of southeast Brazil, I asked which bird species are the main seed dispersers in such environment, and how they use the available habitats (small forest fragments, forest thickets, live fences, isolated trees, and active pastures) where they are most likely to drop the seeds they swallow the relative importance of fruit-eating birds as seed vectors was evaluated based on the number of fruit species eaten, the number of visits, and visitation rate to fruiting plants. Habitat use was accessed by recording the habitats where birds were seen or heard during walks conducted throughout the study area. Sixteen plant species were observed during 308.3 plant-hours. Forty-one bird species were observed eating fruits in a total of 830 visits to fruiting plants. Sayaca Tanagers (Thraupis sayaca) and Pale-breasted Thrushes (Turdus leucomelas) ate the greatest number of fruit species, were the most frequent plant visitors in terms of number and rate of visits, and had a broad range of habitat use. These two species and the Rusty-margined Guan (Penelope superciliaris), which is able to swallow large fruits with large seeds that smaller bird species cannot cat, likely have a great contribution to the movement of seeds throughout this highly degraded landscape.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Molecular markers have gradually replaced morphological markers in population studies. The advantages of molecular markers are the speed and precision of evaluations, mainly for long cycle cultures, where determinate traits can take years to manifest. The principle objectives of this research were to assess variability and genetic distances in four generations of Eucalyptus urophylla and provide data that help with the continued improvement of these materials. The populations can be found at the Experimental Forestry Sciences Station, Anhembi, SP, belonging to the College of Agriculture Luiz de Queiroz of São Paulo University. The initial base population was introduced by seeds collected in indonesia and designated P0 generation. The subsequent segregated generations, derivatives of recombination starting with open pollination, were designated P1, P2, and P3. One hundred and seventy four individual trees representing the four generations were analysed. The RAPD technique allowed the identification of 86 loci that were analysed with the Jaccard Coefficient, generating a genetic similarity matrix, permitting the estimation of genetic distances. The genetic distance of generation PO was 0.3338333, P1 was 0.336824, P2 was 0.40000, and P3 was 0.381093. In percentage terms the genetic distances between individuals grew in relation to base population, being 0.15% for generation P1, 18.93% for P2, and 13.31% for P3. This shows an increase in genetic variability with the advance of the program, despite the selective processes. From this came the belief that the initial base population was resulting from seed collection from isolated trees. These populations, although going through successive selections, had a high cross efficiency through satisfactory pollination, which then permitted genetic variation to increase, the outcome of effective recombination between individuals. Generations P2 and P3 gave a better perspective for the continuance of the improvement program due to the high number of different groups with standard genetic distances of 35%. The selections made between the diverse genetic groups allowed the efficient use of genetic variability evaluation.

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Isolated trees in pastures are now often, due to increasing devastation of forested areas, important feeding places for migratory or generalist birds. These trees serve both as food sources and as deposition sites for seeds from fruits consumed in neighboring areas. The objective of this study was to identify the avian consumers of the fruits of Cytharexyllum myrianthum trees in open pastures and describe their feeding behavior and how it influences seed dispersion. Forty two hours of observations included 198 feeding bouts of nine bird species. Turdus leucomelas (Muscicapidae) was the main consumer (28% of fruit consumption), swallowing the entire fruit. Next, was Tyrannus melancholicus (Tyrannidae, 23%), which may be the most efficient seed disperser of C. myrianthum because it regurgitates the seeds on sites far from the parent tree.

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Six microsatellite loci were used to quantify the mating system of two small fragmented populations (Selviria - SEL and Aparecida do Tabuado - APT, Mato Grosso do Sul State) and isolated trees in pastures, of the bat-pollinated tropical tree Hymenaea stignocarpa, growing in the Center-west region of Brazil. In SEL population, seeds were collected from 11 mother-trees; in APT, from three trees and, in the case of isolated trees, from six individuals growing at least 500 m apart in pastures. To investigate if there are differences on mating system between trees in populations and isolated trees, trees from populations were pooled as a group and, likewise, the isolated trees were pooled to another group. The outcrossing rate was higher in the populations (t̂ m= 0.873) than in isolated trees (t̂ m=0.857), but the difference was not significant. Significant and high differences between multi-locus and single-locus outcrossing rate were detected in populations (t̂ m- t̂ s=0.301, P<0.05) and isolated trees (t̂ m- t̂ s=0.276, P<0.05), suggesting mating between relatives. Higher paternity correlation was observed in trees from population (r̂ p=0.636) than in isolated trees (r̂ p=0.377), indicating the occurrence of some correlated matings and that part of offspring are full-sibs. It was not observed increased in self-fertilization rate in isolated trees in pastures. In general terms, the unique observed difference in mating system between populations and isolate trees was the high rate of correlated matings in trees from populations, due probably to the small distance among coespecifics and the pollinator behavior, visiting near trees.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Os meios urbanos são espaços cada vez mais edificados, compactos e com solos impermeabilizados, onde a ausência ou reduzida presença de espaços verdes é uma realidade. Os elementos arbóreos, qualquer que seja a sua disposição, ganham cada vez mais significado enquanto representantes do meio natural na conservação da qualidade e conforto de vida nas cidades. Este trabalho desenvolveu-se a partir do tema das árvores em meio urbano, tendo por base os benefícios das árvores nas cidades, a sua distribuição espacial e o estado de conservação deste tipo de património. O principal fio condutor passou pela concepção do inventário do Património Arbóreo da cidade de Portalegre, com recurso às novas tecnologias da informação, nomeadamente os Sistemas de Informação Geográfica, capaz de se integrar nos sistemas homólogos do Município de Portalegre. O inventário à escala do perímetro urbano da cidade de Portalegre contabilizou 2087 elementos arbóreos localizados em áreas públicas, dos quais 1500 são árvores de folha caduca e 587 são perenifólias. Registou-se um elevado índice de diversidade para aquela área, cerca de 705 árvores/km2, embora as árvores estejam distribuídas de forma heterogénea pelo território considerado, percebendo-se com isso as zonas de carência de arborização. Com este inventário foi ainda possível conceber uma avaliação económica segundo a Norma de Granada, de 13 árvores isoladas e uma alameda com 38 indivíduos, assim como propor a classificação destes elementos a Árvores de Interesse Público. Anseia-se que este trabalho seja um documento informativo e sensibilizador de todo o público em geral, mas principalmente que se assuma como uma ferramenta útil aos responsáveis pelos espaços verdes da cidade de Portalegre.