920 resultados para native communities


Relevância:

100.00% 100.00%

Publicador:

Resumo:

The present study shows the distribution of alien fish species in tropical lakes in the middle Doce river basin, southeastern Brazil, obtained from a rapid assessment program. The causes for their introductions were sport-fishing improvement in some specific lakes and aquaculture in the studied basin. Presently, these species have a wide distribution occurring in 41 of the 54 lakes studied, representing an actual threat to regional native fish community. The natural connection among lakes and streams during the rainy season and the dispersal mediated by local people are the main invasion agents for alien fishes. The success of these invaders is probably due to absence of pre-existing effective competitors or top-predators in the invaded communities. We consider that the eradication of alien fishes by means of the available management tools may be very difficult due to the large number of lakes invaded and to the wide spectrum of lake conditions and resources exploited by these alien species. We recommend the use of environmental education as a tool to stop the human-mediated dispersion of aliens and to improve conservation of native fish community in lakes where these alien species are not present yet. © 2004 Instituto de Ciências Biológicas - UFMG.

Relevância:

70.00% 70.00%

Publicador:

Resumo:

Schinus terebinthifolius Raddi (Schinus) is an invasive exotic species widely found in disturbed and native communities of Florida. This species has been shown to displace native species as well as alter community structure and function. The purpose of this study was to determine if the growth and gas exchange patterns of Schinus, under differing salinity conditions, were different from native species. Two native upland glycophytic species (Rapanea punctata and Randia aculeata) and two native mangrove species (Rhizophora mangle and Laguncularia racemosa) were compared with the exotic. Overall, the exotics morphologic changes and gas exchange patterns were most similar to R. mangle. Across treatments, increasing salinity decreased relative growth rate (RGR), leaf area ratio (LAR) and specific leaf area (SLA) but did not affect root/shoot ratios (R:S). Allocation patterns were however significantly different among species. The largest proportion of Schinus biomass was allocated to stems (47%), resulting in plants that were generally taller than the other species. Schinus also had the highest SLA and largest total leaf area of all species. This meant that the exotic, which was taller and had thinner leaves, was potentially able to maintain photosynthetic area comparable to native species. Schinus response patterns show that this exotic exhibits some physiological tolerance for saline conditions. Coupled with its biomass allocation patterns (more stem biomass and large area of thin leaves), the growth traits of this exotic potentially provide this species an advantage over native plants in terms of light acquisition in a brackish forested ecosystem.

Relevância:

70.00% 70.00%

Publicador:

Resumo:

Non-native predators may have negative impacts on native communities, and these effects may be dependent on interactions among multiple non-native predators. Sequential invasions by predators can enhance risk for native prey. Prey have a limited ability to respond to multiple threats since appropriate responses may conflict, and interactions with recent invaders may be novel. We examined predator–prey interactions among two non-native predators, a recent invader, the African jewelfish, and the longer-established Mayan cichlid, and a native Florida Everglades prey assemblage. Using field enclosures and laboratory aquaria, we compared predatory effects and antipredator responses across five prey taxa. Total predation rates were higher for Mayan cichlids, which also targeted more prey types. The cichlid invaders had similar microhabitat use, but varied in foraging styles, with African jewelfish being more active. The three prey species that experienced predation were those that overlapped in habitat use with predators. Flagfish were consumed by both predators, while riverine grass shrimp and bluefin killifish were eaten only by Mayan cichlids. In mixed predator treatments, we saw no evidence of emergent effects, since interactions between the two cichlid predators were low. Prey responded to predator threats by altering activity but not vertical distribution. Results suggest that prey vulnerability is affected by activity and habitat domain overlap with predators and may be lower to newly invading predators, perhaps due to novelty in the interaction.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Long-term assessments of species assemblages are valuable tools for detecting species ecological preferences and their dispersal tracks, as well as for assessing the possible effects of alien species on native communities. Here we report a 50-year-long study on population dynamics of the four species of land flatworms (Platyhelminthes, Tricladida, Terricola) that have colonized or become extinct in a 70-year-old Atlantic Forest regrowth remnant through the period 1955-2006. On the one hand, the two initially most abundant species, which are native to the study site, Notogynaphallia ernesti and Geoplana multicolor have declined over decades and at present do not exist in the forest remnant. The extinction of these species is most likely related with their preference for open vegetation areas, which presently do not exist in the forest remnant. On the other hand, the neotropical Geoplaninae 1 and the exotic Endeavouria septemlineata were detected in the forest only very recently. The long-term study allowed us to conclude that Geoplaninae 1 was introduced into the study area, although it is only known from the study site. Endeavouria septemlineata, an active predator of the exotic giant African snail, is originally known from Hawaii. This land flatworm species was observed repeatedly in Brazilian anthropogenic areas, and this is the first report of the species in relatively well preserved native forest, which may be evidence of an ongoing adaptive process. Monitoring of its geographic spread and its ecological role would be a good practice for preventing potential damaging effects, since it also feeds on native mollusk fauna, as we observed in lab conditions.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

This paper reports the first attempt of characterizing various physical, mechanical and chemical properties of Quiscal fibres, used by the native communities in Chile and investigating the influence of atmospheric dielectric barrier discharge plasma treatment on various properties such as diameter and linear density, fat, wax and impurity%, moisture regain, chemical elements and groups, thermal degradation, surface morphology, etc. According to the experimental observations, Quiscal fibre has lower tenacity than most of the technical grade natural fibres such as sisal, hemp, flax, etc., and plasma treatment at optimum dose improved its tenacity to the level of sisal fibres. Plasma treatment also reduced the amount of fat, wax and other foreign impurities present in Quiscal fibres as well as removed lignin and hemicellulose partially from the fibre structure. Plasma treatment led to functionalization of Quiscal fibre surface with chemical groups, as revealed from attenuated total reflection spectroscopy and also confirmed from the elemental analysis using energy dispersive Xray technique and pH and conductivity measurements of fibre aqueous extract. The wetting behavior of Quiscal fibre also improved considerably through plasma treatment. However, untreated and plasma treated Quiscal fibres showed similar thermal degradation behavior, except the final degradation stage, in which plasma treated fibres showed higher stability and incomplete degradation unlike the untreated fibres. The experimental results suggested that the plasma treated Quiscal fibres, like other technical grade natural fibres, can find potential application as reinforcement of composite materials for various industrial applications.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

This paper reports the first attempt of characterizing several physical, mechanical and chemical properties of Quiscal fibres, usually used by the native communities in Chile and on investigations concerning the influence of atmospheric dielectric barrier discharge (DBD) plasma treatment on various properties such as diameter and linear density, percent of impurity, moisture regain, chemical elements and groups, thermal degradation, surface morphology, among others.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Many prairie restoration projects are hampered by a lack of knowledge on how to restore the high diversity found in prairies, while at the same time preventing the establishment of a large weedy component. Methods are needed to increase diversity and abundance of native species while minimizing exotic species invasions in both 1) newly planted restorations and 2) established restorations. We established an experiment in Story and Monona counties in 2005 to determine the effects of different native cover crop species and timing of seeding on the establishment of new prairie restorations. We found that adding a 30-species prairie mix in early spring led to diverse native communities, but adding the mix in the late summer or the following year after cover crops established led to low diversity communities dominated by exotics. The identity of cover crops affected communities less than timing of seed additions. A second seed addition added to ash after a spring fire in the seventh year (Monona County site) increased recruitment from the prairie mix slightly, but the increase was not enough to cause convergence in the treatments. Surprisingly, the second seed addition increased diversity only in communities that were already the most diverse (i.e., in plots seeded with the prairie mix in early spring before cover crops established). These results imply that 1) cover crops are not effective for establishing prairie and 2) over seeding into established plots may not be an easy and efficient way to increase native recruitment and lower weedy species abundances. Therefore, focusing on establishing high levels of recruitment and diversity and excluding weedy species during the critical time early in establishment should be a priority for new projects.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

La présente thèse offre une analyse critique du phénomène du suicide en milieu autochtone en s’appuyant notamment sur les croyances sur la mort et sur les rituels funéraires actuels dans la communauté atikamekw de Manawan, dans la région de la Mauricie, au Québec. L’objectif de la recherche est de comprendre la représentation de la mort volontaire chez les Atikamekw à partir des conceptions locales et de tracer un portrait anthropologique de la situation du suicide de cette communauté. La question du suicide en milieu autochtone étant un sujet sensible et difficile à aborder, nous avons choisi d’associer à notre recherche anthropologique, des discussions interdisciplinaires sur les approches sur le suicide, sur la mort et sur le deuil, tout en portant un regard sur les aspects historiques de la relation entre les Atikamekw et l’État-nation canadien. Le principe théorique retenu pour cette thèse est celui selon lequel chaque Atikamekw est perçu comme un agent de sa culture, qualifié à reconnaître sa propre situation politique et historique et habilité à proposer des changements sur le plan social et politique. L’ethnographie réalisée dans le cadre de cette recherche vise également à donner une intelligibilité empirique au phénomène du suicide et aux nouvelles pratiques funéraires à Manawan, tout en étant préoccupé par les liens établis entre les événements du suicide, le contexte historique et la situation actuelle de la communauté de Manawan. Une attention particulière est portée aux aspects sociaux qui y sont liés, comme la question de l’âge, du genre, des relations familiales et sociales, de la consommation d’alcool et de drogues, de l’accessibilité à l’éducation, des relations intergénérationnelles et de la relation entre les membres de la communauté et les professionnels qui travaillent.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

The implementation of anti-drug policies that focus on illicit crops in the Andean countries faces many significant obstacles, one of which is the cultural clash it generates between the main stakeholders. On the one hand one finds the governments and agencies that attempt to implement crop substitution and eradication policies and on the other the peasant and natives communities that have traditionally grown and used coca or those peasants who have found in coca an instrument of power and political leverage that they never had before. The confrontation about coca eradication, alternative development and other anti-drug policies in coca growing areas transcends drug related issues and is part of a wider and deeper confrontation that reflects the long-term unsolved conflicts of the Andean societies. All Andean countries have stratified and fragmented societies in which peasants and Indians have been excluded from power. In Bolivia, Ecuador and Peru most peasants belong to native communities many of which have remained segregated from “white” society. The mixing of the races (mestizaje) in Colombia occurred early during the Conquest and Colony. Those of Indian descent became subservient to the Spanish and Creoles. The society that evolved was (and still is) highly hierarchical, authoritarian, and has subjacent racist values. The resulting political system has been exclusionary of large portions of the population. Among Indian communities coca has been used for millennia and its use has become an identity symbol of their resistance against what may be looked at as foreign invasion. “The Andean Indian chews coca because that way he affirms his identity as son and owner of the land that yesterday the Spaniard took away and today the landowner keeps away from him. To chew coca is to be Indian...and to quietly and obstinately challenge the contemporary lords that descend from the old encomenderos and the older conquistadors” (Vidart, 1991: 61, author’s translation). In Andean literature on illegal drugs as well as in seminars, colloquia and other meetings where drug policies are debated, complaints are frequently expressed about the treatment of coca in the same category as cocaine, heroin, morphine amphetamines and other “hard” drugs. The complainants assert that “coca is not cocaine” and that it is unfair to classify coca, a nature given plant which has been used for millennia in the Andes without significant negative effects on users, in the same category as man made psychotropic drugs. They also argue that coca has manifold social and religious meanings in indigenous cultures, that coca is sacred and that the requirement of the1961 Single Convention demanding that Bolivia and Peru completely eradicate coca within 25 years is limiting Indigenous communities in their freedom to practice their religions. In most debates about drug interdiction, the views of those who oppose that approach are not accepted as legitimate. Indeed, “prohibitionists” demonize drugs and those who oppose drug policies in Latin America frequently demonize the United States as the imperialist power that imposes them. This dual polarization is a main obstacle to establish a meaningful policy debate aimed at broadening the policy consensus necessary for successful policy implementation. This essay surveys the status of coca in the United Nations Conventions, explains why it is confusing, and how a few changes would eliminate some of the sources of conflict and help organize and control licit coca markets in the Andes. The current disorganized and weakly controlled legal coca market in Peru has been analyzed to demonstrate its deficiencies and to illustrate possible improvements in international drug control policies.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Este trabalho apresenta um estudo sobre as políticas de educação escolar e saúde indígena no Brasil, buscando verificar a presença das tendências de modificação observadas nas políticas sociais do país, a partir das décadas de 1980 e 1990: descentralização das políticas para as esferas subnacionais de governo; criação de mecanismos de participação da sociedade civil nos processos decisórios; estabelecimento de parcerias com instituições privadas para a provisão de serviços públicos; institucionalização de canais de controle; alteração no conteúdo das políticas e ampliação de seu alcance. O estudo foi realizado a partir de uma análise comparativa das duas políticas no nível federal e no nível local de governo. A análise no nível local foi realizada a partir do estudo de caso do Parque Indígena do Xingu. Buscou-se verificar, na trajetória das políticas, a influência dos fatores relacionados aos processos de Redemocratização e Reforma do Estado, das dinâmicas próprias das áreas de saúde e educação, da questão indígena e da agenda estatal indigenista. A partir da análise, verificamos, no nível federal, um avanço na legislação de ambos os campos, comparado com os princípios existentes antes da Constituição Federal de 1988. No que se refere à legislação, a educação escolar indígena apresenta-se mais consolidada quando comparada à saúde que ainda apresenta muitas indefinições. No Parque Indígena do Xingu percebemos uma inflexão nas duas políticas, a partir da década de 1990, que passam a buscar um crescente protagonismo indígena e a valorização de uma abordagem intercultural. No Xingu estes avanços foram resultado, sobretudo, da iniciativa das comunidades indígenas da região, em parceria com a Universidade Federal de São Paulo, na área da saúde, e com o Instituto Socioambiental, na área da educação, e com recursos, a principio, de fundações internacionais.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)