Using different satellite imagery and classification techniques to assess the contribution of trees outside forests in the municipality of Maringá, Brazil

Forest cover of the Maringá municipality, located in northern Parana State, was mapped in this study. Mapping was carried out by using high-resolution HRC sensor imagery and medium resolution CCD sensor imagery from the CBERS satellite. Images were georeferenced and forest vegetation patches (TOFs - trees outside forests) were classified using two methods of digital classification: reflectance-based or the digital number of each pixel, and object-oriented. The areas of each polygon were calculated, which allowed each polygon to be segregated into size classes. Thematic maps were built from the resulting polygon size classes and summary statistics generated from each size class for each area. It was found that most forest fragments in Maringá were smaller than 500 m². There was also a difference of 58.44% in the amount of vegetation between the high-resolution imagery and medium resolution imagery due to the distinct spatial resolution of the sensors. It was concluded that high-resolution geotechnology is essential to provide reliable information on urban greens and forest cover under highly human-perturbed landscapes.

Biotic factors and occurrence of Lutzomyia longipalpis in endemic area of visceral leishmaniasis, Mato Grosso do Sul, Brazil

The relationships between environmental exposure to risk agents and health conditions have been studied with the aid of remote sensing imagery, a tool particularly useful in the study of vegetation cover. This study aims to evaluate the influence of environmental variables on the spatial distribution of the abundance of Lutzomyia longipalpis and the reported canine and human visceral leishmaniasis (VL) cases at an urban area of Campo Grande, state of Mato Grosso do Sul. The sandfly captures were performed in 13 residences that were selected by raffle considering four residences or collection station for buffer. These buffers were generated from the central house with about 50, 100 and 200 m from it in an endemic area of VL. The abundance of sandflies and human and canine cases were georreferenced using the GIS software PCI Geomatica. The normalized difference vegetation index (NDVI) and percentage of land covered by vegetation were the environmental variables extracted from a remote sensing IKONOS-2 image. The average NDVI was considered as the complexity of habitat and the standard deviation as the heterogeneity of habitat. One thousand three hundred sixty-seven specimens were collected during the catch. We found a significant positive linear correlation between the abundance of sandflies and the percentage of vegetation cover and average NDVI. However, there was no significant association between habitat heterogeneity and the abundance of these flies.

Comparação de dados dos satélites Ikonos-II e Landsat/ETM+ no estudo de áreas cafeeiras

O objetivo deste trabalho foi avaliar o impacto do aumento da resolução espacial e radiométrica da imagem pancromática do Ikonos-II na identificação de plantios de café (Coffea arabica), em comparação com as imagens do Landsat/ETM+. A área de estudo está localizada no Município de Pedregulho, SP, onde foram selecionados 50 talhões com plantios de café, e foram levantados dados referentes à altura, idade, espaçamento e variedade de cada talhão. As imagens permitiram a identificação de talhões com características diferentes em campo, tendo-se destacado a imagem do Ikonos-II, que apresentou melhor desempenho. Para os talhões com características iguais em campo, as imagens analisadas não se mostraram eficientes, independentemente do satélite utilizado. As correções atmosféricas e radiométricas, na imagem do Ikonos-II, não proporcionaram ganho efetivo nas análises realizadas. A maioria dos talhões identificados na imagem do Ikonos-II pode ser localizada na imagem do Landsat/ETM+ (68%). A correlação significativa entre a banda 4 do Landsat/ETM+ e o canal pancromático do Ikonos-II indica uma forma de ligação entre as imagens dos dois satélites.

Mapeamento dos fragmentos de vegetação florestal nativa da bacia hidrográfica do rio Alegre, Espírito Santo, a partir de imagens do satélite IKONOS II

O estudo teve como objetivos elaborar o mapa de uso da terra e diagnosticar, em nível de paisagem, os fragmentos de vegetação florestal nativa por meio da classificação visual da imagem do satélite IKONOS II. A pesquisa foi desenvolvida na bacia hidrográfica do rio Alegre, situada no extremo sul do Estado do Espírito Santo, Brasil. Foram mapeadas 12 classes de uso da terra, destacando-se 475 fragmentos florestais. As classes cafezal (2.086,2 ha), pastagem (14.130,1 ha) e fragmento florestal (2.978,9 ha) ocuparam 92,16% (19.195,2 ha) da área total da bacia, que é de 20.819,8 ha. A maioria dos fragmentos florestais possui formas fortemente alongadas e área média de 6,3 ha. Também se constatou que a maior parte está sujeita a um elevado nível de perturbação, com 452 e 166 fragmentos florestais vizinhos às classes pastagem e cafezal, respectivamente.

Using aster multispectral imagery for mapping woody invasive species in pico da vara natural reserve (Azores Islands, Portugal)

This paper aims to assess the effectiveness of ASTER imagery to support the mapping of Pittosporum undulatum, an invasive woody species, in Pico da Vara Natural Reserve (S. Miguel Island, Archipelago of the Azores, Portugal). This assessment was done by applying K-Nearest Neighbor (KNN), Support Vector Machine (SVM) and Maximum Likelihood (MLC) pixel-based supervised classifications to 4 different geographic and remote sensing datasets constituted by the Visible, Near-Infrared (VNIR) and Short Wave Infrared (SWIR) of the ASTER sensor and by digital cartography associated to orography (altitude and "distance to water streams") of which the spatial distribution of Pittosporum undulatum directly depends. Overall, most performed classifications showed a strong agreement and high accuracy. At targeted species level, the two higher classification accuracies were obtained when applying MLC and KNN to the VNIR bands coupled with auxiliary geographic information use. Results improved significantly by including ecology and occurrence information of species (altitude and distance to water streams) in the classification scheme. These results show that the use of ASTER sensor VNIR spectral bands, when coupled to relevant ancillary GIS data, can constitute an effective and low cost approach for the evaluation and continuous assessment of Pittosporum undulatum woodland propagation and distribution within Protected Areas of the Azores Islands.

Aplicação da geotecnologia no estudo de cadastro técnico rural e no mapeamento de áreas de preservação permanente e reservas legais

Este trabalho teve como objetivo principal mapear as classes de cobertura e o uso da terra, bem como as áreas de preservação permanente (APPs) e de reservas legais de imóveis rurais. A área de estudo compreendeu parte dos municípios de Canaã, Araponga e Ervália, Estado de Minas Gerais. Foi utilizada uma imagem ortorretificada de alta resolução do sensor Ikonos II com 1 m de resolução espacial. A partir da interpretação visual da imagem, foram criadas sete classes temáticas, a saber: cobertura florestal, pasto sujo, pasto limpo, cafezal, edificações, área agrícola e reflorestamento. As APPs foram obtidas a partir de um modelo digital de elevação hidrologicamente consistente. Os resultados mostraram a predominância das classes de cafezal com 24,5% e de cobertura florestal com 28,8%, perfazendo mais de 50% da área de estudo. As áreas delimitadas como de preservação permanente totalizaram 55,1%.

Similar understorey structure in spite of edaphic and floristic dissimilarity in Amazonian forests

Forest structure determines light availability for understorey plants. The structure of lowland Amazonian forests is known to vary over long edaphic gradients, but whether more subtle edaphic variation also affects forest structure has not beenresolved. In western Amazonia, the majority of non-flooded forests grow on soils derived either from relatively fertile sediments of the Pebas Formation or from poorer sediments of the Nauta Formation. The objective of this study was to compare structure and light availability in the understorey of forests growing on these two geological formations. We measured canopy openness and tree stem densities in three size classes in northeastern Peru in a total of 275 study points in old-growth terra firme forests representing the two geological formations. We also documented variation in floristic composition (ferns, lycophytes and the palm Iriartea deltoidea) and used Landsat TM satellite image information to model the forest structural and floristic features over a larger area. The floristic compositions of forests on the two formations were clearly different, and this could also be modelled with the satellite imagery. In contrast, the field observations of forest structure gave only a weak indication that forests on the Nauta Formation might be denser than those on the Pebas Formation. The modelling of forest structural features with satellite imagery did not support this result. Our results indicate that the structure of forest understorey varies much less than floristic composition does over the studied edaphic difference.

Exploring the association between Trypanosoma cruzi infection in rural communities and environmental changes in the southern Gran Chaco

The association between land use and land cover changes between 1979-2004 in a 2.26-million-hectare area south of the Gran Chaco region and Trypanosoma cruzi infection in rural communities was analysed. The extent of cultural land, open and closed forests and shrubland up to 3,000 m around rural communities in the north, northwest and west of the province of Córdoba was estimated using Landsat satellite imagery. The T. cruzi prevalence was estimated with a cross-sectional serological survey conducted in the rural communities. The land cover showed the same patterns in the 1979, 1999 and 2004 satellite imagery in both the northwest and west regions, with shrinking regions of cultured land and expanding closed forests away from the community. The closed forests and agricultural land coverage in the north region showed the same trend as in the northwest and west regions in 1979 but not in 1999 or 2004. In the latter two years, the coverage remote from the communities was either constant or changed in opposite ways from that of the northwest and west regions. The changes in closed forests and cultured vegetation alone did not have a significant, direct relationship with the occurrence of rural communities with at least one person infected by T. cruzi. This study suggests that the overall decrease in the prevalence of T. cruzi is a consequence of a combined effect of vector control activities and changes in land use and land cover.

Spatial distribution of triatomines in domiciles of an urban area of the Brazilian Southeast Region

Reports of triatomine infestation in urban areas have increased. We analysed the spatial distribution of infestation by triatomines in the urban area of Diamantina, in the state of Minas Gerais, Brazil. Triatomines were obtained by community-based entomological surveillance. Spatial patterns of infestation were analysed by Ripley’s K function and Kernel density estimator. Normalised difference vegetation index (NDVI) and land cover derived from satellite imagery were compared between infested and uninfested areas. A total of 140 adults of four species were captured (100 Triatoma vitticeps, 25Panstrongylus geniculatus, 8 Panstrongylus megistus, and 7 Triatoma arthurneivai specimens). In total, 87.9% were captured within domiciles. Infection by trypanosomes was observed in 19.6% of 107 examined insects. The spatial distributions ofT. vitticeps, P. geniculatus, T. arthurneivai, and trypanosome-positive triatomines were clustered, occurring mainly in peripheral areas. NDVI values were statistically higher in areas infested by T. vitticeps and P. geniculatus. Buildings infested by these species were located closer to open fields, whereas infestations of P. megistus andT. arthurneivai were closer to bare soil. Human occupation and modification of natural areas may be involved in triatomine invasion, exposing the population to these vectors.

Comparison between artificial neural networks and maximum likelihood classification in digital soil mapping

Soil surveys are the main source of spatial information on soils and have a range of different applications, mainly in agriculture. The continuity of this activity has however been severely compromised, mainly due to a lack of governmental funding. The purpose of this study was to evaluate the feasibility of two different classifiers (artificial neural networks and a maximum likelihood algorithm) in the prediction of soil classes in the northwest of the state of Rio de Janeiro. Terrain attributes such as elevation, slope, aspect, plan curvature and compound topographic index (CTI) and indices of clay minerals, iron oxide and Normalized Difference Vegetation Index (NDVI), derived from Landsat 7 ETM+ sensor imagery, were used as discriminating variables. The two classifiers were trained and validated for each soil class using 300 and 150 samples respectively, representing the characteristics of these classes in terms of the discriminating variables. According to the statistical tests, the accuracy of the classifier based on artificial neural networks (ANNs) was greater than of the classic Maximum Likelihood Classifier (MLC). Comparing the results with 126 points of reference showed that the resulting ANN map (73.81 %) was superior to the MLC map (57.94 %). The main errors when using the two classifiers were caused by: a) the geological heterogeneity of the area coupled with problems related to the geological map; b) the depth of lithic contact and/or rock exposure, and c) problems with the environmental correlation model used due to the polygenetic nature of the soils. This study confirms that the use of terrain attributes together with remote sensing data by an ANN approach can be a tool to facilitate soil mapping in Brazil, primarily due to the availability of low-cost remote sensing data and the ease by which terrain attributes can be obtained.

Comparison between detailed digital and conventional soil maps of an area with complex geology

Since different pedologists will draw different soil maps of a same area, it is important to compare the differences between mapping by specialists and mapping techniques, as for example currently intensively discussed Digital Soil Mapping. Four detailed soil maps (scale 1:10.000) of a 182-ha sugarcane farm in the county of Rafard, São Paulo State, Brazil, were compared. The area has a large variation of soil formation factors. The maps were drawn independently by four soil scientists and compared with a fifth map obtained by a digital soil mapping technique. All pedologists were given the same set of information. As many field expeditions and soil pits as required by each surveyor were provided to define the mapping units (MUs). For the Digital Soil Map (DSM), spectral data were extracted from Landsat 5 Thematic Mapper (TM) imagery as well as six terrain attributes from the topographic map of the area. These data were summarized by principal component analysis to generate the map designs of groups through Fuzzy K-means clustering. Field observations were made to identify the soils in the MUs and classify them according to the Brazilian Soil Classification System (BSCS). To compare the conventional and digital (DSM) soil maps, they were crossed pairwise to generate confusion matrices that were mapped. The categorical analysis at each classification level of the BSCS showed that the agreement between the maps decreased towards the lower levels of classification and the great influence of the surveyor on both the mapping and definition of MUs in the soil map. The average correspondence between the conventional and DSM maps was similar. Therefore, the method used to obtain the DSM yielded similar results to those obtained by the conventional technique, while providing additional information about the landscape of each soil, useful for applications in future surveys of similar areas.

Multispectral remote sensing for site-specific nitrogen fertilizer management

The objective of this work was to evaluate the use of multispectral remote sensing for site-specific nitrogen fertilizer management. Satellite imagery from the advanced spaceborne thermal emission and reflection radiometer (Aster) was acquired in a 23 ha corn-planted area in Iran. For the collection of field samples, a total of 53 pixels were selected by systematic randomized sampling. The total nitrogen content in corn leaf tissues in these pixels was evaluated. To predict corn canopy nitrogen content, different vegetation indices, such as normalized difference vegetation index (NDVI), soil-adjusted vegetation index (Savi), optimized soil-adjusted vegetation index (Osavi), modified chlorophyll absorption ratio index 2 (MCARI2), and modified triangle vegetation index 2 (MTVI2), were investigated. The supervised classification technique using the spectral angle mapper classifier (SAM) was performed to generate a nitrogen fertilization map. The MTVI2 presented the highest correlation (R²=0.87) and is a good predictor of corn canopy nitrogen content in the V13 stage, at 60 days after cultivating. Aster imagery can be used to predict nitrogen status in corn canopy. Classification results indicate three levels of required nitrogen per pixel: low (0-2.5 kg), medium (2.5-3 kg), and high (3-3.3 kg).

Uso de imagens orbitais como base de dados para projetos de reforma agrária

Análises técnica e econômica foram realizadas em imagens dos sensores IKONOS, TM/Landsat 5, ETM+/Landsat 7 e CCD/CBERS, objetivando a verificação da viabilidade destas como base de dados em projetos de reforma agrária. Essas análises efetuadas e a situação de mercado indicaram que a imagem IKONOS apresenta excelente desempenho técnico, mas o custo de aquisição inviabiliza sua utilização como base de dados para a reforma agrária. A imagem do Landsat 7, com baixo custo de aquisição, apresentou grande viabilidade técnica para fins de reforma agrária. No entanto, a perda do contato com a plataforma Landsat 7 inviabilizou a compra de novas imagens do sensor ETM+. A imagem CCD/CBERS apresentou a segunda maior similaridade com a verdade de campo e o menor índice Kappa para a classificação. Apesar do baixo índice de exatidão para a classificação, as análises de custo, o lançamento do CBERS-2 e a possibilidade de correção dos problemas de radiometria podem tornar as imagens da plataforma CBERS-2 concorrentes de peso no mercado e, ainda, preencher a lacuna deixada pela perda do Landsat 7. A imagem do Landsat 5 apresentou o mais baixo desempenho técnico nas análises efetuadas. Entretanto, seu potencial como base de dados é amplamente reconhecido pelo INCRA, que ainda utiliza tais imagens. O declínio da vida útil do Landsat-5 atribui mais importância ao lançamento do CBERS-2.

Identificação de conflito de uso da terra em áreas de preservação permanente no entorno do parque nacional do Caparaó, Estado de Minas Gerais

Este estudo teve como objetivos elaborar um mapa de uso da terra com base nas imagens do satélite IKONOS II, delimitar de maneira automática as áreas de preservação permanente e identificar a ocorrência de conflitos de usos, tendo como referência legal o Código florestal e a Resolução n.º 303 do CONAMA. A pesquisa foi desenvolvida na entorno do Parque Nacional do Caparaó, pertencente aos municípios de Alto Jequitibá, Alto Caparaó, Caparaó e Espera Feliz, todos situados no estado de Minas Gerais. Utilizando os recursos disponíveis no geoprocessamento, foi possível mapear 8 classes de uso da terra e delimitar as áreas de preservação permanente situadas em áreas com altitudes superior a 1.800 metros (8,42 ha), no terço superior dos morros (18,67 ha); encostas com declividade superior a 45 graus (92,96 ha); nascentes e suas respectivas áreas de contribuição (1.989,44 ha); margens dos cursos d´água com largura inferior a 10 metros (3.957,19 ha); e no terço superior das sub-bacias (6.031,54 ha), perfazendo um total de 12.098,22 ha (48,06%) da área total da bacia. A área de uso indevido correspondeu a 8.922,91 ha (73,75%), sendo as classes cafezal (5.183,43 ha) e pastagem (3.650,74 ha) as principais ocorrências nessas áreas. Apenas 2.160,69 ha (18,40%) das áreas de preservação permanente estão protegidas por vegetação nativa.

Mapeamento de áreas de preservação permanentes e identificação dos conflitos legais de uso da terra na bacia hidrográfica do ribeirão São Bartolomeu - MG

Este trabalho teve como objetivo delimitar, de maneira automática, as áreas de preservação permanentes e identificar as ocorrências de conflitos legais de uso da terra na bacia do ribeirão São Bartolomeu, situada no município de Viçosa, Minas Gerais. Aplicando-se a técnica clássica de fotointerpretação visual em tela a uma ortoimagem do satélite Ikonos II, foi possível mapear 9 classes de uso e cobertura da terra. O mapeamento automático das áreas de preservação permanentes, com base no Código Florestal brasileiro e respectivas Resoluções do CONAMA, resultou na identificação de 1.530,67 ha de áreas protegidas, distribuídas nas seguintes categorias: ao longo dos divisores d'água (1.037,32 ha), encostas com declividades superiores a 45 graus (5,51 ha), nascentes e suas respectivas áreas de contribuição (436,06 ha), zonas ripárias (325,96 ha) e no topo de morros (27,96 ha). Essas áreas especialmente protegidas correspondem a 54,15 % da área total da bacia estudada, que é de 2.826,83 ha. Identificaram-se 905,14 ha (59,70 %) de APPs ilegalmente utilizadas em empreendimentos agropecuários, sendo as classes de pastagem com 40,06% (613,12 ha) e de cafezal com 7,12 % (109,02 ha) as principais ocorrências.