Global efforts to avoid anthropogenic conversion of natural habitat rely heavily on the establishment of protected areas. Studies that evaluate the effectiveness of these areas with a focus on preserving the natural habitat define effectiveness as a measure of the influence of protected areas on total avoided conversion. Changes in the estimated effectiveness are related to local and regional differences, evaluation methods, restriction categories that include the protected areas, and other characteristics. The overall objective of this study was to evaluate the effectiveness of protected areas to prevent the advance of the conversion of natural areas in the core region of the Brazil’s Cerrado Biome, taking into account the influence of the restriction degree, governmental sphere, time since the establishment of the protected area units, and the size of the area on the performance of protected areas. The evaluation was conducted using matching methods and took into account the following two fundamental issues: control of statistical biases caused by the influence of covariates on the likelihood of anthropogenic conversion and the non-randomness of the allocation of protected areas throughout the territory (spatial correlation effect) and the control of statistical bias caused by the influence of auto-correlation and leakage effect. Using a sample design that is not based on ways to control these biases may result in outcomes that underestimate or overestimate the effectiveness of those units. The matching method accounted for a bias reduction in 94–99% of the estimation of the average effect of protected areas on anthropogenic conversion and allowed us to obtain results with a reduced influence of the auto-correlation and leakage effects. Most protected areas had a positive influence on the maintenance of natural habitats, although wide variation in this effectiveness was dependent on the type, restriction, governmental sphere, size and age group of the unit.
The soils that lay below humid ecosystems are characterized as being significant holders of carbon. Because of the great susceptibility of this type of environment to anthropic changes, expressive quantities of carbon stored in the soil can be released into the atmosphere. In the Cerrado biome (Brazil), only a few types of vegetation have had carbon storage levels in their soil estimated. The main purpose of this study was to obtain basic quantitative parameters for carbon storage and to identify the general aspects of soil in regions where there exists Humid Grasslands (Campo Limpo Úmido), a kind of humid area phytophysiognomy found in the Cerrado. We selected 6 regions of the Federal District with this kind of vegetation formation, characterized by low anthropic impact and located either in the interior or in the proximity of specially protected areas. In each one of the sampled regions, we marked a transect with 4 equidistant points and collected material at 7 different levels of depth: 0-5, 5-10, 10-20, 20-30, 30-40, 40-50 and 50-60 cm. We obtained 168 samples, with 84 related to Humid Grassland areas in gleysols and 84 samples related to areas in plinthosols-types of soil dominant in this environment. We determined the texture, bulk density and concentration of nitrogen and carbon at each depth. The average concentration of carbon for Humid Grassland areas was 55.19 g•kg −1 , with an average of 61.65 g•kg −1 for Gleysols and 48.73 g•kg −1 for Plinthosols. The soil samples displayed distinct textural differences between gleysols and plinthosols. There were no significant differences in soil density (0.75 kg•dm −3 for Gleysols and 0.72 kg•dm −3 for Plinthosols). The average concentration of nitrogen was 20.66 g•kg −1 , with 23.98 g•kg −1 for Gleysols and 17.34 g•kg −1 for Plinthosols. The average carbon storage for Humid Grassland areas, down to 60 cm deep, was 244.17 mg C ha −1 and the total estimated stock for these areas in the Federal District was 206.71 Gg•C. In general, the samples obtained in gleysols showed a carbon content and nitrogen level superior to those in plinthosols, although a greater sampling effort is needed to confirm the differences observed. The density values A. M. S. França et al. 778 of stored carbon in the soil beneath Humid Grassland areas proved to be superior to those values observed for other types of vegetation typical for the Cerrado environment.
Agradeço à Universidade de Brasília, instituição pela qual tenho especial carinho e à qual devo a maior parte da minha instrução formal, também sendo agradecido pelo fundamental papel que desempenha na sociedade. Agradeço ao Instituto de Geociências pela acolhida nesta empreita.Agradeço a todos os professores, servidores e colegas da Pós-Graduação em Geociência Aplicadas pela oportunidade de desenvolvimento nessa interessante área do conhecimento, com caráter multidisciplinar e com importantes aplicações para diversas finalidades, inclusive para a conservação da biodiversidade e do meio ambiente, tópico especialmente explorado nesta dissertação.Agradeço especialmente ao Professor Ricardo Brites, pelo apoio sempre presente, mesmo em momentos menos favoráveis, pelo trabalho sempre visando a qualidade e sempre disponível a novas ideias, qualidades fundamentais a um excelente pesquisador, e, não menos importante, pela ótima relação que pudemos construir.Agradeço a todas as pessoas que participaram deste momento da minha vida. Aos colegas de trabalho por, sempre que possível, facilitarem a minha participação neste curso. A meus amigos, pelos momentos de descontração tão indispensáveis.Agradeço com amor a minha família e a minha companheira. Agradeço à vida.
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