921 resultados para Conservation of nature


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At 38 sites in the dry sclerophyll forests of south-east Queensland, Australia, hollow-bearing trees were studied to determine the effects of past forestry practices on their density, size and spatial distribution. The density of hollow-bearing trees was reduced at sites that had been altered by poisoning and ringbarking of unmerchantable trees. This was especially the case for living hollow-bearing trees that were now at densities too low to support the full range of arboreal marsupials. Although there are presently enough hollow-bearing stags (i.e., dead hollow-bearing trees) to provide additional denning and nesting opportunities, the standing life of these hollow-bearing stags is lower than the living counterparts which means denning and nesting sites may be limited in the near future. The mean diameter at breast height (DBH) of hollow-bearing stags was significantly less than that of living hollow-bearing trees. This indicated that many large hollow-bearing stags may have a shorter standing life than smaller hollow-bearing stags. Hollow-bearing trees appear to be randomly distributed throughout the forest in both silviculturally treated and untreated areas. This finding is at odds with the suggestion by some forest managers that hollow-bearing trees should have a clumped distribution in dry sclerophyll forests of south-east Queensland.

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In Australia more than 300 vertebrates, including 43 insectivorous bat species, depend on hollows in habitat trees for shelter, with many species using a network of multiple trees as roosts, We used roost-switching data on white-striped freetail bats (Tadarida australis; Microchiroptera: Molossidae) to construct a network representation of day roosts in suburban Brisbane, Australia. Bats were caught from a communal roost tree with a roosting group of several hundred individuals and released with transmitters. Each roost used by the bats represented a node in the network, and the movements of bats between roosts formed the links between nodes. Despite differences in gender and reproductive stages, the bats exhibited the same behavior throughout three radiotelemetry periods and over 500 bat days of radio tracking: each roosted in separate roosts, switched roosts very infrequently, and associated with other bats only at the communal roost This network resembled a scale-free network in which the distribution of the number of links from each roost followed a power law. Despite being spread over a large geographic area (> 200 km(2)), each roost was connected to others by less than three links. One roost (the hub or communal roost) defined the architecture of the network because it had the most links. That the network showed scale-free properties has profound implications for the management of the habitat trees of this roosting group. Scale-free networks provide high tolerance against stochastic events such as random roost removals but are susceptible to the selective removal of hub nodes. Network analysis is a useful tool for understanding the structural organization of habitat tree usage and allows the informed judgment of the relative importance of individual trees and hence the derivation of appropriate management decisions, Conservation planners and managers should emphasize the differential importance of habitat trees and think of them as being analogous to vital service centers in human societies.

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The multicopy var gene family encoding the variant surface antigen Plasmodium falciparum erythrocyte membrane protein 1 is highly diverse, with little overlap between different P. falciparum isolates. We report 5 var genes (varS1-varS5) that are shared at relatively high frequency among 63 genetically diverse P. falciparum isolates collected from 5 islands in the West Pacific region. The varS1, varS2, and varS3 genes were localized to the internal region on chromosome 4, similar to 200 kb from pfdhfr-ts, whereas varS4 and varS5 were mapped to an internal region of chromosome 7, within 100 kb of pfcrt. The presence of varS2 and varS3 were significantly correlated with the pyrimethamine-resistant pfdhfr genotype, whereas varS4 was strongly correlated with the chloroquine-resistant pfcrt genotype. Thus, the conservation of these var genes is the result of their physical linkage with drug-resistant genes in combination with the antimalarial drug pressure in the region.

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Predicting the various responses of different species to changes in landscape structure is a formidable challenge to landscape ecology. Based on expert knowledge and landscape ecological theory, we develop five competing a priori models for predicting the presence/absence of the Koala (Phascolarctos cinereus) in Noosa Shire, south-east Queensland (Australia). A priori predictions were nested within three levels of ecological organization: in situ (site level) habitat (< 1 ha), patch level (100 ha) and landscape level (100-1000 ha). To test the models, Koala surveys and habitat surveys (n = 245) were conducted across the habitat mosaic. After taking into account tree species preferences, the patch and landscape context, and the neighbourhood effect of adjacent present sites, we applied logistic regression and hierarchical partitioning analyses to rank the alternative models and the explanatory variables. The strongest support was for a multilevel model, with Koala presence best predicted by the proportion of the landscape occupied by high quality habitat, the neighbourhood effect, the mean nearest neighbour distance between forest patches, the density of forest patches and the density of sealed roads. When tested against independent data (n = 105) using a receiver operator characteristic curve, the multilevel model performed moderately well. The study is consistent with recent assertions that habitat loss is the major driver of population decline, however, landscape configuration and roads have an important effect that needs to be incorporated into Koala conservation strategies.

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Report published in the Proceedings of the National Conference on "Education in the Information Society", Plovdiv, May, 2013

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The goal of this project was to explore activism, attitudes, and imagery connecting Black churchgoers in Miami, Florida and the natural environment. The research approach was qualitative, began as exploratory research, and used the techniques of snowball sampling, participant observation, and semi-structured interviews. Three case studies representing various socio-economic levels, denominations, participant education levels, and environmental facets were chosen for in-depth ethnographic research. There are three major findings in the research. First, there is a link between the preservation of Black history and the preservation of the environment among Black churchgoers, who feel strong connections to a sense of place, rural life, and the past. However their work is strongly directed to bring about benefits for people and the environment in the present and the future. Second, public access to public lands is a basic and important right espoused by these Black churchgoing activists. Third, the vocabulary used by Black churchgoing activists regarding the natural environment differs from today's “mainstream” environmentalists. The concept of “beauty” is pivotal to Black appreciation of and activism toward the environment and is reminiscent of the early environmental protection movement in the United States and conservationists such as John Muir. These findings concerning how Black spirituality relates to the environment adds to the sparse literature on the subject, and provides for potential linkages between Blacks and “mainstream” environmental groups to benefit both parties. An understanding of the connections between Black spirituality and perceptions of the environment should facilitate the development of better programs to improve and protect the environment. Environmental projects may also address the social and economic needs of Black communities, churches, and congregations, as well as the ecosystem. ^

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In this article, I offer an institutional history of the ecosystem concept, tracing shifts in its meaning and application as it has become the key organizing principle for the Everglades restoration program in Florida. Two institutional forms are analyzed here: (1) quasigovernmental organizations, a term I use to describe interagency science collaboratives and community stakeholder organizations, and (2) government bureaucracies, which are the administrative agencies tasked with Everglades restoration planning and implementation. In analyzing these knowledge trajectories, I both document the complex networks of relations that facilitate the ecosystem’s emergence as an object of knowledge and examine the bureaucratic claims to authority that circumscribe the ecosystem’s transformation into policy.

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The development of the ecosystem approach and models for the management of ocean marine resources requires easy access to standard validated datasets of historical catch data for the main exploited species. They are used to measure the impact of biomass removal by fisheries and to evaluate the models skills, while the use of standard dataset facilitates models inter-comparison. North Atlantic albacore tuna is exploited all year round by longline and in summer and autumn by surface fisheries and fishery statistics compiled by the International Commission for the Conservation of Atlantic Tunas (ICCAT). Catch and effort with geographical coordinates at monthly spatial resolution of 1° or 5° squares were extracted for this species with a careful definition of fisheries and data screening. In total, thirteen fisheries were defined for the period 1956-2010, with fishing gears longline, troll, mid-water trawl and bait fishing. However, the spatialized catch effort data available in ICCAT database represent a fraction of the entire total catch. Length frequencies of catch were also extracted according to the definition of fisheries above for the period 1956-2010 with a quarterly temporal resolution and spatial resolutions varying from 1°x 1° to 10°x 20°. The resolution used to measure the fish also varies with size-bins of 1, 2 or 5 cm (Fork Length). The screening of data allowed detecting inconsistencies with a relatively large number of samples larger than 150 cm while all studies on the growth of albacore suggest that fish rarely grow up over 130 cm. Therefore, a threshold value of 130 cm has been arbitrarily fixed and all length frequency data above this value removed from the original data set.

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The Caribbean genus Pseudophoenix (Arecaceae) has its center of taxonomic diversity in Hispaniola (Haiti and the Dominican Republic). Three species (P. ekmanii, P. lediniana, and P. vinifera) are restricted to this island. In this thesis I investigated the population genetic diversity and structure of Pseudophoenix using ten microsatellite loci. Results showed homozygote excess and high inbreeding coefficients in all populations across all polymorphic loci. Overall, there was high differentiation among populations. Results from the Bayesian and Neighbor Joining cluster analyses identified groups that were consistence with currently accepted species delimitation. We included the only known population of an undescribed morph from the Dominican Republic that has been suggested to represent a new species. Results from the cluster analyses suggested that this putative species is closely related to P. sargentii from Turk and Caicos. Our study provided insights pertinent to the conservation genetics and management of this genus in Hispaniola.