E. L. Bolfe

Análise do uso da terra na microbacia do Arroio do Meio - Santa Maria - RS, por Sistema de Informações Geográficas e imagem de satélite

Geographic Information System (GIS) and satellite image were tested to analyze the current land use and automatic localization of areas where conflicts between present land use and land capability occurence, in Arroio do Meio watershed. Geoprocessing techniques map algebra, consultation database and image reclassification were used. The watershed object of this study was chosen because it is considered by many authors, the best unit for social and economic planning and development of population of rural areas. In the studied microbasin: 555ha was covered by forests (24% of the total area). Cultivated crops occupy 1.314ha, 56% of the microbasin. Glassland covers 184ha (8% of the total area). The flooded areas represent 11% of the area of the microbasin, with 265ha. The use of 31ha could not be detected with accuracy due to shadowing. In areas with steepness above 47%, 32ha were detected without forest cover, totalizing 1,4% of the area of the microbasin. With slopes above 30%, 71ha (3%), are used for agriculture. Areas with Phaeozems and leptosols (Ciriaco-Charrua mapping units) with slopes above 30% and without forest coverage performe 14ha (0,6%). Areas with conflict use reached only 5% of the total area, indicating that in most of the microbasin, the land is being used in agreement with its capability.

Correlação de variáveis espectrais e estoque de carbono da biomassa aérea de sistemas agroflorestais

O objetivo deste trabalho foi avaliar a correlacao entre variaveis espectrais e o estoque de carbono da biomassa aerea de sistemas agroflorestais da regiao de Tome‑Acu, PA. Foram testados 24 indices de vegetacao de tres grupos (razao simples, diferenca normalizada e complexos), gerados a partir de imagens do sensor TM/Landsat‑5, adquiridas em 2008. As variaveis obtidas foram correlacionadas, por meio de regressao linear simples, ao estoque de carbono de quatro classes de sistemas agroflorestais, de diferentes idades e composicoes floristicas. As correlacoes obtidas entre as variaveis espectrais e o estoque de carbono foram significativas em 47% dos indices testados e variaram de acordo com as diferencas de biomassa nos sistemas analisados. As melhores correlacoes foram obtidas pelos indices de vegetacao de razao simples e de diferenca normalizada, em sistemas agroflorestais jovens, e pelos indices de vegetacao complexos, em sistemas agroflorestais mais antigos.

Digital classification assessment of forest stands in satellite images using accuracy indices

The use of forest raw products has increased significantly in the last decades. The search for high productivity has led to the introduction of exotic species, mainly Eucalyptus sp. and Pinus sp. This work evaluated the precision of classification obtained from surveying forest implemented and natural stands in the region of the map area of Cachoeira do Sul - RS, using geoprocessing techniques, remote sensing, GIS (geographic information system) and GPS (global positioning system). It was verified that the area is occupied by natural vegetation (35.54%), Pinus sp. (1.89%) and Eucalyptus sp. (0.77%), with the following values precision in the supervised digital classification: Global precision (85.23%), Kappa (84.90%) and Tau (77.74%). It was concluded that the three accuracy indexes can be used, although Kappa and Tau were more consistent.

Análise florística e estrutural de sistemas silviagrícolas em Tomé-Açu, Pará

O objetivo deste trabalho foi analisar a composicao floristica e estrutural de sistemas silviagricolas em Tome-Acu, Para. Os dados dendrometricos foram obtidos por inventario em 40 parcelas amostrais, com tres unidades cada uma, no total de 120 unidades de 10x10 m. Foi inventariada a media de 1.424,3 individuos por hectare, pertencentes a 27 familias e a 54 especies. Tendo-se considerado a variabilidade dos estagios vegetativos, os diferentes sistemas silviagricolas (SAF) foram divididos em quatro classes hierarquicas: SAF 1, SAF 2, SAF 3, e SAF 4, para estabelecer um sistema de classificacao passivel de ser utilizado em outras avaliacoes de campo e em classificacoes digitais por meio do sensoriamento remoto. Especies observadas em outros sistemas da regiao amazonica tambem foram relevantes para este estudo, especialmente Theobroma cacao, T. grandiflorum e Euterpe oleracea que, juntas, apresentaram medias de frequencia relativa de 51%, densidade relativa de 69,2%, dominância relativa de 50,1% e indice de valor de importância de 56,8%. Os dados medios de diversidade floristica, abundância, area basal e valor de importância indicam os sistemas silviagricolas da regiao de Tome-Acu como sistemas de producao com potencial economico e ambiental, se adotado manejo adequado e racional.

Energy balance with Landsat images in irrigated central pivots with corn crop in the São Paulo State, Brazil

The energy balance (EB) components were quantified in a commercial farm with corn crop, irrigated by central pivots, in the Northwestern side of São Paulo state, Southeast Brazil. The SAFER (Simple Algorithm For Evapotranspiration Retrieving) was applied to retrieve the latent heat flux (λE), considering six pivots, covering irrigated areas from 74 to 108 ha. With λE quantified and considering soil heat flux (G) as a fraction of net radiation (Rn), the sensible heat flux (H) was acquired as a residual in the energy balance equation. Seven Landsat satellite images, covering all corn crop stages from 23 April 2010 to 29 August 2010, allowed relating the energy balance components according to the accumulated degree-days (DDac) from the planting to harvest dates. The average Rn values ranging from 5.2 to 7.2 MJ m-2 day-1, represented 30 to 45% of global solar radiation (RG). Considering the variation of the energy balance components along the corn crop growing seasons, the average ranges for λE, H and G were respectively 0.0 to 6.4 MJ m-2 day-1, -1.5 to 6.7 MJ m-2 day-1 and 0.1 to 0.6 MJ m-2 day-1. The fraction of the available energy (Rn - G) used as λE was from 0.0 to 1.3 indicated a good irrigation management, insuring that the water deficit could not be the reason of any yield reduction. Although Rn did not reflected well the crop stages, its partition strongly depended on these stages. λE higher than Rn and the negative H/Rn, happening sometimes along the corn growing seasons, occurred after the vegetative growth and before the harvest times, indicated heat advection from the surrounding areas to the irrigation pivots, which represented an additional energy source for the evaporative process. The models applied here with only the visible and infrared bands of the Landsat sensor are very useful for the energy balance analyses, considering the size of the corn crop irrigation pivots in Southeast Brazil, when subsidizing a rational irrigation water application in corn crop.

Coupling MODIS images and agrometeorological data for agricultural water productivity analyses in the Mato Grosso State, Brazil

Mato Grosso state, Central West Brazil, has been highlighted by the grain production, mainly soybean and corn, as first (November-March) and second (April-August) harvest crops, respectively. For water productivity (WP) analyses, MODIS products together with a net of weather stations were used. Evapotranspiration (ET) and biomass production (BIO) were acquired during the year 2012 and WP was considered as the ratio of BIO to ET. The SAFER (Simple Algorithm For Evapotranspiration Retrieving) for ET and the Monteiths radiation model for BIO were applied together, considering a mask which separated the crops from other surface types. In relation to the first harvest crop ET, BIO and WP values above of those for other surface types, happened only from November to January with incremental values reaching to 1.2 mm day-1; 67 kg ha-1 day-1; and 0.7 kg m-3, respectively; and between March and May for the second harvest crops, with incremental values attaining 0.5 mm day-1; 27 kg ha-1 day-1; and 0.3 kg m-3, respectively. In both cases, during the growing seasons, the highest WP parameters in cropped areas corresponded, in general, to the blooming to grain filling transition. Considering corn crop, which nowadays is increasing in terms of cultivated areas in the Brazilian Central West region, and crop water productivity (CWP) the ratio of yield to the amount of water consumed, the main growing regions North, Southeast and Northeast were analyzed. Southeast presented the highest annual pixel averages for ET, BIO and CWP (1.7 mm day-1, 78 kg ha-1 day-1 and 2.2 kg m-3, respectively); while for Northeast they were the lowest ones (1.2 mm day-1, 52 kg ha-1 dia-1 and 1.9 kg m-3). Throughout a soil moisture indicator, the ratio of precipitation (P) to ET, it was indeed noted that rainfall was enough for a good grain yield, with P/ET lower than 1.00 only outside the crop growing seasons. The combination of MODIS images and weather stations proved to be useful for monitoring vegetation and water parameters, which can contribute to the sustainability of the agro-ecosystems exploration in Mato Grosso state, avoiding water scarcity in the near future.

Examining effective use of data sources and modeling algorithms for improving biomass estimation in a moist tropical forest of the Brazilian Amazon

ABSTRACT Previous research has explored the potential to integrate lidar and optical data in aboveground biomass (AGB) estimation, but how different data sources, vegetation types, and modeling algorithms influence AGB estimation is poorly understood. This research conducts a comparative analysis of different data sources and modeling approaches in improving AGB estimation. RapidEye-based spectral responses and textures, lidar-derived metrics, and their combination were used to develop AGB estimation models. The results indicated that (1) overall, RapidEye data are not suitable for AGB estimation, but when AGB falls within 50–150 Mg/ha, support vector regression based on stratification of vegetation types provided good AGB estimation; (2) Lidar data provided stable and better estimations than RapidEye data; and stratification of vegetation types cannot improve estimation; (3) The combination of lidar and RapidEye data cannot provide better performance than lidar data alone; (4) AGB ranges affect the selection of the best AGB models, and a combination of different estimation results from the best model for each AGB range can improve AGB estimation; (5) This research implies that an optimal procedure for AGB estimation for a specific study exists, depending on the careful selection of data sources, modeling algorithms, forest types, and AGB ranges.

Geoprocessamento e sensoriamento remoto aplicados à análise de recursos florestais

This study presents a methodology for survey and analysis of the forestal resources of natural and implanted populating located in the topographic leaf SH.22Y-A, Cachoeira do Sul, RS, (Brazil) by using geoprocessing and remote sensing technics. For this purpose, the Geographic Information Systems, associated to satellite images, processed by digital classification and mathematics’ functions were used. In so doing data gathering and quantification of different thematic bases of the studied area. Variables and thematic bases eere accomplished the satellite images, assessed in the field and topographic maps and the geospacials crossings obtaining the land use, implanted species, taken area, besides the localization of the forest concerning slope, edaphic, hydrographic and road availability. Thus, these information obtained by comparing these variables, made it possible to analyze the forestal cover of the study area, supplying subsidy to the forestal resources management and the environmental preservation.

Análise comparativa de classificadores digitais em imagens do Landsat-8 aplicados ao mapeamento temático

The objective of this work was to evaluate the performance of SVM and K‑NN digital classifiers for the object‑based classification on Landsat‑8 images, applied to mapping of land use and land cover of Alta Bacia do Rio Piracicaba‑Jaguari, in the state of Minas Gerais, Brazil. The pre‑processing step consisted of using radiometric conversion and atmospheric correction. Then the multispectral bands (30 m) were merged with the panchromatic band (15 m). Based on RGP compositions and field inspection, 15 land‑use and land‑cover classes were defined. For edge segmentation, the bounds were set to 10 and 60 for segmentation configuring and merging in the ENVI software. Classification was done using SVM and K‑NN. Both classifiers showed high values for the Kappa index (k): 0.92 for SVM and 0.86 for K‑NN, significantly different from each other at 95% probability. A major improvement was observed for SVM by the correct classification of different forest types. The object‑based classification is largely applied on high‑resolution spatial images; however, the results of the present work show the robustness of the method also for medium‑resolution spatial images.

Agroforestry in Tomé-Açu: An Alternative to Pasture in the Amazon

This chapter focuses on historical perspectives of land use in Tome-Acu using remote sensing as a tool to assess land use/land cover and ecosystem goods and services such as carbon sequestration. The results show that agroforestry systems in Tome-Acu play an important role at the property and landscape scales, trends that should be monitored as they appear to offer an alternative to conversion of forest to pasture. The Amazon-wide dominant trajectory toward conversion to pasture, based on reduced labor needs, if compared to intensive agroforestry systems, requires much more land to yield the same returns to a household at current management levels. If one considers the potential of agroforestry as a source of carbon sequestration, the returns are even higher and may contribute to the mitigation of greenhouse effects.