Éder de Souza Martins

Fertility and acidity status of latossolos (oxisols) under pasture in the Brazilian Cerrado

The Cerrado region, with over 50 million hectares of cultivated pasture, provides 55% of Brazilian beef production. Previous investigations have shown that about 70-80% of this pasture is affected by some kind of degradation, leading to low productivity. However, until now, few surveys have been carried out on a regional scale. The aim of the present work is both to assess the fertility and acidity levels of Cerrado soils under pasture and compare the variability of the soils characteristics on a regional scale. Two soil depths were sampled in different places within the studied area: (1) a surface horizon (0.0-0.2 m) in order to evaluate its fertility and acidity status for pasture, and (2) a subsurface horizon (0.6-0.8 m), used for classification. Most of soils had levels of nutrients below the reference values for adequate pasture development. Whatever the texture, about 90% of soils had low or very low availability of phosphorus. Only 7 to 14% of soils had low pH, high exchangeable aluminum, and aluminum saturation above the critical acidity level. Except for nitrogen, no significant difference was found between Latossolos Vermelhos and Latossolos Vermelho-Amarelos.

Tratamento de ruídos e caracterização de fisionomias do Cerrado utilizando séries temporais do sensor MODIS

Cerrado is formed by a mosaic of grassland, shrubland and woodland physiognomies with a typical phenological cycle. Thus, MODIS data provide daily measurements which allows to monitor the seasonal phenology of the vegetation. The objective of this work was to characterize savanna formations, forest formations and cerrado areas converted by anthropic actions, by using temporal series of MODIS NDVI and EVI after noise reduction. The adopted methodology should be divided into the following steps: (a) elaboration of the temporal cube with NDVI and EVI, in which the z profile corresponds to temporal signature, (b) noise elimination, (c) detection of temporal signature. The Minimum Noise Fraction Transformation (MNF) method was applied to reduce noise in temporal signature. The results showed that the NDVI values were higher than the EVI; and there was a relationship with the seasons of the year. The forest formations presented the highest values of NDVI and EVI, showing the lowest variations among the seasons. The converted areas of Cerrado presented the lowest values in both indices, and their values decreased in the beginning of the dry season, probably because it was the harvesting season. The study concluded that the NDVI and EVI temporal series are useful in differentiation among vegetation types.

Aplicação do método de identificação espectral para imagens do sensor ASTER em ambiente de cerrado

The spectral classifiers allow a good estimate for the mapping of the materials from the similarity between the reference curve and the image. Initially the spectral classifiers had been developed for hyperspectral images analysis. However, some works demonstrate good results for the application of these techniques in multispectral images. The present work aims to evaluate the spectral classifier Spectral Identification Method (SIM) in ASTER image. The Spectral Identification Method (SIM) is proposed to establish a new similarity index and three estimates according to the significance levels (5%, 10% and 15%) of the materials. This method is based on two statistical procedures: ANOVA and Spectral Correlation Mapper (SCM) coefficient. This information can be used to evaluate the degree of correlation among the materials in analysis. The advantage of this method is to validate according to levels of significance of the most probable areas of the sought material. The method was applied to ASTER image at the Military Instruction Field located Formosa (GO) close to Federal District. The images were acquired with atmosphere correction. The pixels size from the SWIR image were duplicated in order to join the VNIR and SWIR images. Endmembers were detected in three steps: a) spectral reduction by the Minimum Noise Fraction (MNF) transformation, b) spatial reduction by the Pixel Purity Index (PPI) and c) manual identification of the endmembers using the N-dimensional visualizer. The classification was made from the endmembers of nonphotosynthetic vegetation (NPV), photosynthetic vegetation (PV) and soil. These procedures allowed to identify the main scenarios in the study area.

Detection of karst depression by aster image in the Bambui Group, Brazil

Karst is a characteristic geological feature of areas comprised of limestone. Due to the solubility of these rocks in water, exhibit an extreme heterogeneity of hydraulic conductivities. The characterizing features of karst aquifers are the open conduits, which provide low resistance pathways for ground water flow. Overall cave orientation is largely controlled by hydraulic gradient, joint patterns and other tectonic features, such as faulting and folding. The karst depressions may form on the surface by subsurface actions (dissolution and collapse). Thus, the depressions often show regularity of pattern or alignments, frequently in association with structurally guided cave systems below. The present work aims at to detect depressions zone, as dolines and uvalas in the limestone of the Bambui Group (Central Brazil) using ASTER and ASTERDEM images. A photogeological study, carried out on aster image allowed us to elaborate geomorphological map of dolines. Some guidance to detect dolines can be associated with fracture permeability dominated by nearly vertical joints and joint swarm is provided by fracture trace mapping from remote sensing. Commonly, dolines can be identified on the image and DEM as topographic depressions, which very often contain water or moist vegetation. The methodology allowed determining a doline distribution pattern what is important to environmental planning.

Acidity control in Latosols under long-term pastures in the Cerrado region, Brazil

High acidity and aluminium saturation are among the main limiting factors for crop production in tropical soils. The aim of this work was to measure the acidity of Latosols under pastures in the Brazilian Cerrado and to assess the influence of clay mineralogy as a controlling parameter of soil acidity. Topsoils (n=73, 0-0.2m depth) of Latosols developed on different parent materials were sampled in two sub-regions of the Cerrado region. The main chemical characteristics weredetermined by standardprocedures,andkaolinite andgibbsite contentswere determinedby dissolution with sulfuric acid and thermogravimetric analyses. The exchangeable concentrations of calcium (Ca), magnesium (Mg), and potassium (K) varied considerably among soil samples, with ranges of 0-13.9cmolckg -1 (meanstandard deviation 1.77 � 1.91cmolckg -1 ) for Ca; 0.2-3.2cmolckg -1 (1.13 � 0.68cmolckg -1 ) for Mg; and 0-1.0cmolckg -1 (0.24 � 0.24cmolckg -1 ) for K. The mean concentration of exchangeable aluminium (Al) was 0.55 � 0.61cmolckg -1 (range 0-2.3cmolckg -1 ). The content of kaolinite (282 � 96gkg -1 ) was higher than of gibbsite (106 � 77gkg -1 ). The amount of exchangeable Al and Al saturation rate varied according to the mineralogy of the clay fraction of the soils. The contentofexchangeableAl 3+ remainedlowwhengibbsitewasthepredominantmineral,whereasitincreasedwithkaolinite content. The ratio kaolinite/(kaolinite+gibbsite) could be used as a useful indicator of the sensitivity of soils affected by acidity and Al toxicity. Additional keywords: Brazilian Cerrado soils, gibbsite, kaolinite, protonation, soil acidification.

Mapeamento da vegetação na floresta atlântica usando o classificador de árvore de decisão para integrar dados de sensoriamento remoto e modelo digital de terreno

The management and ecological monitoring of national parks and other protected areas requires a detailed description of the vegetation distribution patterns. This paper aims to produce a vegetation map for the Serra dos Orgaos National Park (PARNASO). This conservation unit is localized in Atlantic Forest within a topographic variation from sea level to 2,263 meters. The vegetation classification based on the ASTER satellite data, high-resolution aerial photographs and Digital Elevation Model (DEM). The DEM indicates vegetation structures in landscape with high spatial variability because it correlates with environmental factors, such as microclimate, moisture, soil and geomorphological processes. Decision tree classifier was used to extract information of DEM and remote sensing data. Seven classes were identified: Agropecuaria (1.29% of total Park area), Campos de Altitude (24.27%), Floresta Ombrofila Densa Alto-Montana (37.47%), Floresta Ombrofila Densa Montana (21.54%), Floresta Ombrofila Densa Sub-Montana (5.22%), Floresta Secundaria (4.13%), and no vegetation area (6.08%). The three highest physiognomies were associated with altitude higher than 1,000 m and represented 55.5% of the total area. The construction of decision trees combining the DEM and remote sensing information can improve the result on the forest tropical distribution.

Analysis of channel morphology of Sao Francisco River using remote sensing data

The objective of this paper is to describe qualitatively channel morphology from the reflectance pattern of high sediment concentrations. The spectral behaviour of the aquatic environment is not only a function of water depth, but also the concentration and spatial distribution of suspended sediments, inorganic and organic, among others. We used Landsat 7/ETM+ (Enhanced Thematic Mapper Plus) images for mapping river channel morphology in São Francisco river in Brazil. The methodology was based on: (a) the elaboration of the digital elevation model (DEM) of bathymetric data, (b) the development of an algorithm based on bands ratio index of Landsat7/ETM+ digital image, and (c) the comparison between bathymetry and developed index. Our approach was to develop an index for the emission feature in red band (ETM+ 3 band) considering its height. A difference behaviour in relation to the index and the depth for both symmetric and asymmetric channels was observed. Thus, the river morphology was established, in an indirect way, by considering the spatial distribution of the sedimentary plumes.

Chapada dos Veadeiros: The Highest Landscapes in the Brazilian Central Plateau

The Chapada dos Veadeiros National Park is a nature conservation protected area, which was included in the World Heritage List by UNESCO in December 2001 because of the geomorphological and ecological sites that characterize the Brazilian Central Plateau and the Cerrado Biome. The forms of the Veadeiros plateau have been developed mainly on gently folded rocks from the Neoproterozoic Arai and Paranoa groups. The elevation of the plateau is about 1,200 m above mean sea level and is characterized by smooth topography. The edges of the Veadeiros Plateau are controlled by fault zones showing precipitous escarpments. The highest step is located in the western part of the plateau where many waterfalls occur along the rivers descending from the plateau surface. Thus, the park is well known for its natural landscape of great beauty, particularly due to the waterfalls, vertical escarpments, canyons, and bedrock rivers. Such a wonderful scene results from differential landscape dissection controlled by a variety of Neoproterozoic rocks crossed by faults and fractures, mostly subvertical. In this chapter, we present geological and geomorphological aspects that have influenced region, considering four environments: (a) Veadeiros Plateau; (b) Preto River in the region controlled by faults; (c) Escarpment; and (d) Moon Valley.

Análise fatorial multivariada aplicada a caracterização de áreas de ocorrência de babaçu (Attalea speciosa Mart. ex Spreng) na bacia do Rio Cocal

O presente artigo possui como objetivo avaliar a distribuicao espacial do babacu na bacia do rio Cocal, estado de Tocantins. Os dados foram obtidos em levantamento de campo considerando 80 parcelas, considerando os diferentes ambientes presentes na area de estudo. O estudo considerou 16 variaveis referentes as caracteristicas do babacu (quantidade de individuos, quantidade de cachos, altura maxima do fuste e altura media do fuste) e do meio ambiente (altitude, declividade, area de contribuicao, indice topografico, relevo, distância do rio, distância das casas, distância da estrada, declividade do relevo no campo, solo, uso do solo e vegetacao). A analise dos dados foi realizada utilizando tecnicas de sistema de informacoes geograficas e analise multivariada. O emprego da analise fatorial multipla permitiu classificar as variaveis ambientais de maior significância para a ocorrencia do babacu e da quantidade de cachos. O principal fator que controla a distribuicao do babacu e o manejo adotado pelos fazendeiros.

IDENTIFICAÇÃO DAS ÁREAS VULNERÁVEIS À EROSÃO A PARTIR DO EMPREGO DA EUPS – EQUAÇÃO UNIVERSAL DE PERDAS DE SOLOS NO MUNICÍPIO DE RIACHÃO DAS NEVES – BA.

Due to agricultural expansion in the last decades, there was a considerable reduction of the Brazilian Biomes. The Bioma Cerrado, specifically, has lost 42% of its original vegetation for agricultural activities (SANO et al.,2002) , resulting in irreparable environmental damage depending on the degree of environmental degradation. Therefore the present study is to apply the EUPS - Equation Universal Soil Loss (Wischmeier & Smith, 1978) to qualitatively identify areas susceptible to erosion laminar in the city of Riachao das Neves- BA. The municipality is part of the agricultural hub of the west of Bahia in recent decades witnessed the advancement of agriculture in the region while the reduction of vegetation in places that should be preserved, especially along watercourses, thus accelerating the erosion process. Keywords: USLE, Topographic Factor, Use and Occupation of the Land.