997 resultados para Forest roads


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This paper develops a model of a forest owner operating in an open-city environment, where the rent for developed land is increasing concave in nearby preserved open space and is rising over time reflecting an upward trend in households’ income. Thus, our model creates the possibility of switching from forestry to residential use at some point in the future. In addition it allows the optimal harvest length to vary over time even if stumpage prices and regeneration costs remain constant. Within this framework we examine how adjacent preserved open space and alternative development constraints affect the private landowner´s decisions. We find that in the presence of rising income, preserved open space hastens regeneration and conversion cuts but leads to lower density development of nearby unzoned parcels due to indirect dynamic effects. We also find that both a binding development moratorium and a binding minimum-lot-size policy can postpone regeneration and conversion cut dates and thus help to protect open space even if only temporarily. However, the policies do not have the same effects on development density of converted forestland. While the former leads to high-density development, the latter encourages low-density development.

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This paper aims at building a theoretical framework to examine the impact of development pressure on private owner’s forest management practices, namely, on regeneration and conversion cut dates. As the rent for developed land is rising over time, our model creates the possibility of switching from forestry to residential use at some point in the future, thus departing from the Faustmann’s traditional setup. Comparative statics results with respect to stumpage prices, regeneration costs and urban growth parameters are provided. The results obtained depend on the impact on the opportunity cost of holding the stand and the impact on the opportunity cost of holding the land, generalizing Faustmann’s unambiguous results.

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Dissertation submitted in partial fulfillment of the requirements for the Degree of Master of Science in Geospatial Technologies.

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The phlebotomine sandfly fauna of a primary forest reserve at Morretes (eastern Paraná State) was studied, using CDC-like light traps, one night per month, at canopy and ground level, between April 1995 and March 1996. A total of 3,106 insects were collected, identified as belonging to nine species. Lutzomyia ayrozai and Lu.geniculata were predominant, seven other species also being present. Monthly mean temperature, rainfall and the temperature of the collection night significantly influenced the numbers of Lu. ayrozai while the two first factors influenced the numbers of Lu. geniculata, besides the collected quantities of females of the two species. The influence of the factors on Lu. ayrozai numbers was more immediate than in those of Lu. geniculata. Numbers of both species and of the females of Lu. geniculata collected in different seasons, but not at the different heights, varied significantly. Differences between the behaviour of Lu. ayrozai in Morretes and in other regions could be attributed to environmental differences and/or to regional variations in the species, which could constitute species complexes. Hourly variations of collections were different in the species and seasons.

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A positive coefficient of association (affinity) between Runchomyia reversa and Anopheles cruzii and high (0.38) index were observed, probably due to the similar breeding places (bromeliads) and to landing habits. Furthermore, a high (0.92) index of association between Oc. scapularis and Wyeomyia incaudata, with low coefficient of association was observed.

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Mosquitoes (22 species) (0.5%) and Runchomyia reversa (5%) biting humans in the morning in Florianópolis, State of Santa Catarina, were significantly more common below than above waist and all Wyeomyia incaudata were collected below the waist. Short trousers are not recommended, unless using repellents.

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Climate change is emerging as one of the major threats to natural communities of the world’s ecosystems; and biodiversity hotspots, such as Madeira Island, might face a challenging future in the conservation of endangered land snails’ species. With this thesis, progresses have been made in order to properly understand the impact of climate on these vulnerable taxa; and species distribution models coupled with GIS and climate change scenarios have become crucial to understand the relations between species distribution and environmental conditions, identifying threats and determining biodiversity vulnerability. With the use of MaxEnt, important changes in the species suitable areas were obtained. Laurel forest species, highly dependent on precipitation and relative humidity, may face major losses on their future suitable areas, leading to the possible extinction of several endangered species, such as Leiostyla heterodon. Despite the complexity of the biological systems, the intrinsic uncertainty of species distribution models and the lack of information about land snails’ functional traits, this analysis contributed to a pioneer study on the impacts of climate change on endemic species of Madeira Island. The future inclusion of predictions of the effect of climate change on species distribution as part of IUCN assessments could contribute to species prioritizing, promoting specific management actions and maximizing conservation investment.

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The first reported case of an accident with Bothriopsis taeniata in Brazil is described. The victim, a 43-year-old man, was bitten just above his right heel and presented a clinical condition compatible with mild Bothrops poisoning: local edema with hemorrhage at the bite site and pain, although without coagulopathy.

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The forest has a crucial ecological role and the continuous forest loss can cause colossal effects on the environment. As Armenia is one of the low forest covered countries in the world, this problem is more critical. Continuous forest disturbances mainly caused by illegal logging started from the early 1990s had a huge damage on the forest ecosystem by decreasing the forest productivity and making more areas vulnerable to erosion. Another aspect of the Armenian forest is the lack of continuous monitoring and absence of accurate estimation of the level of cuts in some years. In order to have insight about the forest and the disturbances in the long period of time we used Landsat TM/ETM + images. Google Earth Engine JavaScript API was used, which is an online tool enabling the access and analysis of a great amount of satellite imagery. To overcome the data availability problem caused by the gap in the Landsat series in 1988- 1998, extensive cloud cover in the study area and the missing scan lines, we used pixel based compositing for the temporal window of leaf on vegetation (June-late September). Subsequently, pixel based linear regression analyses were performed. Vegetation indices derived from the 10 biannual composites for the years 1984-2014 were used for trend analysis. In order to derive the disturbances only in forests, forest cover layer was aggregated and the original composites were masked. It has been found, that around 23% of forests were disturbed during the study period.

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INTRODUCTION: Malaria is a serious problem in the Brazilian Amazon region, and the detection of possible risk factors could be of great interest for public health authorities. The objective of this article was to investigate the association between environmental variables and the yearly registers of malaria in the Amazon region using Bayesian spatiotemporal methods. METHODS: We used Poisson spatiotemporal regression models to analyze the Brazilian Amazon forest malaria count for the period from 1999 to 2008. In this study, we included some covariates that could be important in the yearly prediction of malaria, such as deforestation rate. We obtained the inferences using a Bayesian approach and Markov Chain Monte Carlo (MCMC) methods to simulate samples for the joint posterior distribution of interest. The discrimination of different models was also discussed. RESULTS: The model proposed here suggests that deforestation rate, the number of inhabitants per km², and the human development index (HDI) are important in the prediction of malaria cases. CONCLUSIONS: It is possible to conclude that human development, population growth, deforestation, and their associated ecological alterations are conducive to increasing malaria risk. We conclude that the use of Poisson regression models that capture the spatial and temporal effects under the Bayesian paradigm is a good strategy for modeling malaria counts.

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An infinite-horizon discrete time model with multiple size-class structures using a transition matrix is built to assess optimal harvesting schedules in the context of Non-Industrial Private Forest (NIPF) owners. Three model specifications accounting for forest income, financial return on an asset and amenity valuations are considered. Numerical simulations suggest uneven-aged forest management where a rational forest owner adapts her or his forest policy by influencing the regeneration of trees or adjusting consumption dynamics depending on subjective time preference and market return rate dynamics on the financial asset. Moreover she or he does not value significantly non-market benefits captured by amenity valuations relatively to forest income.

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Introduction We analyzed the vertical and monthly distributions of culicid species in the gallery forest of Brasília National Park, with an emphasis on the potential vectors of yellow fever (YF). Methods Between September 2010 and August 2011, mosquitoes were captured on the ground and in the canopy of the forest for five consecutive days per month, from nine to 15 hours. The mosquitoes were examined to verify natural infection with flaviviruses by isolation in Aedes albopictus Skuse, 1864 cells followed by indirect immunofluorescence. Results We identified 2,677 culicids distributed in 29 species. Most of the mosquitoes were captured at ground level (69%) during the rainy season (86%). The most abundant species were Sabethes (Sabethes) albiprivus Theobald, 1903; Limatus durhamii Theobald, 1901; Haemagogus (Conopostegus) leucocelaenus Dyar & Shannon, 1924; Haemagogus (Haemagogus) janthinomys Dyar, 1921; Aedes (Ochlerotatus) scapularis Rondani, 1848; Psorophora (Janthinosoma) ferox Von Humboldt, 1819; and Aedes (Ochlerotatus) serratus Theobald, 1901. Limatus durhamii, Limatus durhamii, Psorophora ferox, Aedes scapularis and Aedes serratus showed significant differences (p<0.05) in their habitat use. Limatus durhamii was found more often in the canopy, unlike the other species. During the rainy season, the most abundant species were Sa. albiprivus, Haemagogus leucocelaenus and Limatus durhamii. During the dry season, the potential YF vectors exhibited a very low frequency and abundance, except Aedes scapularis and Aedes serratus. No flavivirus was detected in the 2,677 examined mosquitoes. Conclusions We recommend continued and systematic entomological monitoring in areas vulnerable to the transmission of YF in the Federal District of Brazil.

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Introduction Panstrongylus megistus is commonly found in wild environments of the State of Rio Grande do Sul, Brazil. The aim of this study was to characterize the network of refuges used by triatomine in a forest fragment of Porto Alegre and to identify Trypanosoma cruzi infection, associated hosts and the epidemiological importance of both hosts and triatomines. Methods Techniques including the spool-and-line method and active searching (transects) were used to identify natural foci. Results The food source for each triatomine was determined using the precipitin test, and the infection of marsupials was determined by xenodiagnosis. A total of 33 adults (domestic environment) and 27 nymphs (wild environment) of P. megistus were found in addition to 43 Didelphis albiventris specimens. The infection rates of triatomine adults, triatomine nymphs and opossums with T. cruzi I were 64%, 73% and 69%, respectively. Birds, rodents and opossums were the main resources used by triatomine. Conclusions This work presents the first characterization of a natural focus of P. megistus in Rio Grande do Sul. The natural characteristics of this focus and its implication in the transmission of T. cruzi are discussed.

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AbstractINTRODUCTION: This study evaluated the effects of cattle removal on the Culicidae mosquito community structure in a tropical dry forest in Brazil.METHODS: Culicidae were collected during dry and wet seasons in cattle presence and absence between August 2008 and October 2010 and assessed using multivariate statistical models.RESULTS: Cattle removal did not significantly alter Culicidae species richness and abundance. However, alterations were noted in Culicidae community composition.CONCLUSIONS: This is the first study to evaluate the impact of cattle removal on Culicidae community structure in Brazil and demonstrates the importance of assessing ecological parameters such as community species composition.

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The calls of 18 species of Amazonian forest frogs were recorded in 3 localities: the Tapajos National Park near Itaituba, the Reserva Ducke near Manaus, and the INPA-WWF reserves near Manaus. Structural and time parameters and sonographs of these calls including previously undescribed vocalization by 10 species are presented. Unlike open habitat species, several forest frong species characteriscally demonstrated one on more of the following temporal parameters: very low call rates, sporadic intervals, infrequent nights of calling and synchronized chorusing. It is hypothesized that predation has influenced the evolution of vocal behaviour in Amazonian forest frogs.