Roberta Averna Valente

Zoneamento agroecológico para a região de Ribeirão Preto utilizando um sistema de informações geográficas

Objetivando contribuir com a metodologia de identificacao de potencialidades de uso das terras, este trabalho apresenta uma proposta de zoneamento agroecologico da quadricula de Ribeirao Preto, SP, localizada entre as coordenadas de 21o00S a 21o30S e 47o30W a 48o00W, com base em caracteristicas de solo, relevo e clima, utilizando-se de um Sistema de Informacoes Geograficas. Para caracterizar o regime termico-hidrico da area utilizou-se os dados de temperatura do ar e de chuva, de 22 localidades, referentes ao periodo de 1967 a 1996. De acordo com os criterios adotados, quanto a capacidade de uso das terras, o zoneamento identificou seis unidades de utilizacao da area: agricultura (I); agricultura (II); agricultura (III); pecuaria; agrossilvicultura e preservacao. As principais conclusoes referentes a area de estudo foram: o regime termico-hidrico e praticamente homogeneo, a vocacao dominante e para agricultura (I) representando aproximadamente 191.118 hectares, correspondentes a 66,3% da area e cerca de 82,5% das terras possuem vocacao para agropecuaria e 10,4% devem ser preservadas ou utilizadas seguindo tecnicas conservacionistas.

Avaliação multicriterial no mapeamento de risco de incêndios florestais, em ambiente sig, na bacia do Rio Corumbataí, SP

n Fire is one of the agents most used in the suppression of forest areas in the State of Sao Paulo, Brazil, and, when out of control, it can be responsible for the destruction of extensive ecosystems. In the case of the CorumbataI river basin, SP, fire is one of the main causes of forest fragmentation and degradation. The purpose of this study was to map forest fire hazard for the CorumbataI river basin, using multi-criteria evaluation (Ordered Weighted Average method) using a Geographic Information System. Factors considered important to the study were: slope; aspect; rainfall; proximity to roads; proximity to urban areas; proximity to water; forest fragment neighborhood; and wind exposure. The combination of these factors resulted in a regional fire hazard map for the river basin. The analysis of the area just surrounding the forest remnants (30m) made it possible to determine the fire hazard in each individual fragment. Such map was reclassified into three hazard levels: low, medium, and high. According to this map, approximately 20% of the native forest fragments are classified as high-hazard class; 55% as medium-hazard class; and 25% as low-hazard class. In the current situation of land use/land cover and management, the forest remnants of the CorumbataI River basin are seriously threatened by fire.

Precipitação efetiva em diferentes formações florestais na floresta nacional de ipanema

RESUMO – O presente trabalho foi conduzido na Floresta Nacional de Ipanema, unidade de conservacao de uso sustentavel localizada no municipio de Ipero-SP, com o objetivo de quantificar e comparar as fracoes de precipitacao efetiva e interceptacao da chuva em tres povoamentos florestais distintos, sendo eles: Eucalyptus cloeziana, Pinus caribea var. hondurensis e Floresta Estacional Semidecidual. Para tanto, realizou-se o monitoramento das variaveis precipitacao interna, escoamento pelo tronco, interceptacao e precipitacao em aberto em cada formacao florestal, ao longo do periodo de novembro de 2009 a maio de 2010. O estudo revelou a precipitacao efetiva de 86,2%, 85,0% e 77,2%; interceptacao de 13,8%, 15,0% e 22,8% em relacao a precipitacao em aberto em Eucalyptus cloeziana, Pinus caribea var. hondurensis e Floresta Estacional Semidecidual, respectivamente. A influencia dos povoamentos na distribuicao da chuva apresentou diferenca significativa somente para o processo de interceptacao entre Floresta Estacional Semidecidual e os demais.

AVALIAÇÃO MULTICRITERIAL NO MAPEAMENTO DA SUSCETIBILIDADEDE DESLIZAMENTOS DE TERRA

The mapping of landslides susceptibility requires the aggregation of landscape characteristics that act differently in the process of landslides and may represents specificities of a region. In this context, the general objective of this study was to evaluate the Ordered Weighted Averaging (OWA) method in the mapping of landslide susceptibility. The method presupposes the integration of different characteristics of the landscape (factors), associating weights to them (named Importance Weights - IW). IW express the importance of these factors to the study. In the study, we used the factors: geological substrate, soil type, slope, land-use and land-cover, and precipitation. In the definition of factors and their weights, the Participatory Technique was used. In order to evaluate the OWA, two susceptibility maps were generated, calculating the decision making risk (R), and compensation level among factors (C). For the first one, only the IW and the total compensation among factors were considered (C = 100%) and for the other one, a second group of weights (the Order Weights (OW), that represents the influence of factors). Using the OW we obtain C = 72%. In the first map the medium level of susceptibility was predominant, by excessive influence of the slope factor (the most influent factor; with the highest IW). In the second map, by influence of OW, there was the aggregation of factors according to the importance predefined for them and the best distribution, in relation to the first one, of area between susceptibility levels. We conclude that OWA is adequate to mapping the landslide susceptibility and that the coherence between IW and OW is responsible to determine the robustness to the method.

Throughfall in different forest stands of Iperó, São Paulo

In forestry, throughfall (Pi) is that fraction of rainfall that runs directly through the tree canopy and reaches the ground. It is characterized as the main source of water supply in a watershed. This study aimed to analyze the dynamics of throughfall in three types of forest stands, namely Eucalyptus cloeziana, Pinus sp. and seasonal semideciduous forest (FES), all located in Ipanema National Forest, in the municipality of Ipero-SP. In each stand, a 300 m² plot was established in which ten rain gauges were installed for monitoring throughfall, and three rain gauges were installed in an open area adjacent to the stand for measuring gross precipitation (P). At the end of 25 observations, it was observed that, relative to P values, Pi values were 76.2% in semideciduous forest (FES), 85.1% in E.cloeziana forest and 84.0% in Pinus sp forest. In addition, comparing these stands, a larger leaf canopy coverage and consequently greater capability for water retention was noted in the semideciduous forest. However, no statistical differences were observed (P<0.05) between the stands of interest regarding throughfall.

Multicriteria Evaluation for Protected Area Definition Aiming at Water Quality Improvement

This study aimed to define potential areas for forest conservation to improve water quality, using Multicriteria Evaluation (MCE); and to verify differences between results from a multidisciplinary group of experts. We worked with the Pirapora River Watershed, Piedade/SP. The participatory method was used to identify the criteria and their relative importance. Priority maps representing expert opinion were elaborated, as well as a map with average weight values. We compared the differences between the criteria weight values and the maps of priority areas. The maps proposed distinct spatialization of priority areas, supporting the understanding of criteria that influence the decision-making process. The highest priority level was associated with areas near to springs, forest patches, and with the highest slope values. We concluded that the MCE is an efficient method to identify priority areas; however, the selection of an expert group is an essential step to generate representative analyses.

MULTICRITERIA DECISION ANALYSIS FOR PRIORITIZING AREAS FOR FOREST RESTORATION

Urbanization process transforms original landscapes into an anthropic mosaic, causing impacts on hydrologic cycles and on landscape structure and functions. Aiming at the maintenance of the water resources and biodiversity, in an urbanized watershed, the objective of this study was the definition of priority areas for forest restoration. We used a Multicriteria Evaluation (MCE) method, following the steps: criteria definition, identification of the criteria importance, and criteria aggregation through Weighted Linear Combination (WLC). According to the experts, consulted in the context of the Participatory Technique, only two criteria represented the studied landscape: proximity to drainage network and proximity to forest patches. The first criterion was considered twice more important than the second, and through the pairwise comparison matrix, it was obtained respectively the criterion weights of 0.83 and 0.17. The priority map was obtained through the criteria aggregation, using WLC, that considered the criterion weights. The result was a priority map, indicating 5.06% of the study area with very-high priority for forest restoration; 5.22% with high priority; 5.76% with medium priority; 5,42% with low and; 78.53% with very-low priority. We can say that the framework predefined for the study proposed a scenario for priority areas that allowed driving the actions in order to obtain a landscape restoration, beginning through a forest corridor in the riparian zone. Thus, we concluded that the definition of priority areas for forest restoration is possible in an urbanized landscape, using the traditional WLC Multicriteria method.