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@Article{CarreirasPereCampShim:2006:AsExAg,
               author = "Carreiras, Jo{\~a}o M. B. and Pereira, Jos{\'e} M. C. and 
                         Campagnolo, Manuel L. and Shimabukuro, Yosio Edemir",
          affiliation = "Department of Forestry, Instituto Superior de Agronomia, Tapada da 
                         Ajuda, 1349-017 Lisboa, Portugal and Department of Forestry, 
                         Instituto Superior de Agronomia, Tapada da Ajuda, 1349-017 Lisboa, 
                         Portugal and Department of Mathematics, Instituto Superior de 
                         Agronomia, Tapada da Ajuda, 1349-017 Lisboa, Portugal and 
                         {Instituto Nacional de Pesquisas Espaciais (INPE)}",
                title = "Assessing the extent of agriculture/pasture and secondary 
                         succession forest in the Brazilian Legal Amazon using SPOT 
                         VEGETATION data",
              journal = "Remote Sensing of Environment",
                 year = "2006",
               volume = "101",
               number = "3",
                pages = "283--298",
                month = "Apr.",
             keywords = "VEGETA{\C{C}}{\~A}O, Brazilian Legal Amazon (BLA), agriculture, 
                         pasture, secondary succession forest, SPOT-4, vegetation, 
                         supervised classification land-cover change, biosphere-atmosphere 
                         experiment, NOAA AVHRR data, tropical forest, accuracy assessment, 
                         eastern amazonia, satellite data, prior probabilities, abandoned 
                         pastures.",
             abstract = "There has been growing concern about land use/land cover change in 
                         tropical regions, as there is evidence of its influence on the 
                         observed increase in atmospheric carbon dioxide concentration and 
                         consequent climatic changes. Mapping of deforestation by the 
                         Brazil's National Space Research Institute (INPE) in areas of 
                         primary tropical forest using satellite data indicates a value of 
                         587,727 km(2) up to the year 2000. Although most of the efforts 
                         have been concentrated in mapping primary tropical forest 
                         deforestation, there is also evidence of large-scale deforestation 
                         in the cerrado savanna, the second most important biome in the 
                         region. The main purpose of this work was to assess the extent of 
                         agriculture/pasture and secondary succession forest in the 
                         Brazilian Legal Amazon (BLA) in 2000, using a set of multitemporal 
                         images from the 1-km SPOT-4 VEGETATION (VGT) sensor. Additionally, 
                         we discriminated primary tropical forest, cerrado savanna, and 
                         natural/artificial waterbodies. Four classification algorithms 
                         were tested: quadratic discriminant analysis (QDA), simple 
                         classification trees (SCT), probability-bagging classification 
                         trees (PBCT), and k-nearest neighbors (K-NN). The agriculture/ 
                         pasture class is a surrogate for those areas cleared of its 
                         original vegetation cover in the past, acting as a source of 
                         carbon. On the contrary, the secondary succession forest class 
                         behaves as a sink of carbon. We used a time series of 12 monthly 
                         composite images of the year 2000, derived from the SPOT-4 VGT 
                         sensor. A set of 19 Landsat scenes was used to select training and 
                         testing data. A 10-fold cross validation procedure rated PBCT as 
                         the best classification algorithm, with an overall sample accuracy 
                         of 0.92. High omission and commission errors occurred in the 
                         secondary succession forest class, due to confusion with 
                         agriculture/pasture and primary tropical forest classes. However, 
                         the PBCT algorithm generated the lower misclassification error in 
                         this class. Besides, this algorithm yields information about class 
                         membership probability, with similar to 80% of the pixels with 
                         class membership probability greater or equal than 0.8. The 
                         estimated total area of agriculture/pasture and secondary 
                         succession forest in 2000 in the BLA was 966 x 103 and 140 x 103 
                         king, respectively. Comparison with an existing land cover map 
                         indicates that agriculture/pasture occurred primarily in areas 
                         previously occupied by primary tropical forest (46%) and cerrado 
                         savanna (33%), and also in transition forest (19%), and other 
                         vegetation types (2%). This further confines the existing evidence 
                         of extensive cerrado savanna conversion. This study also concludes 
                         that SPOT-4 VGT data are adequate for discriminating several major 
                         land cover types in tropical regions. Agriculture/pasture was 
                         mapped with errors of about 5%. Very high classification errors 
                         were associated with secondary succession forest, suggesting that 
                         a different methodology/sensor has to be used to address this 
                         difficult land cover class (namely with the inclusion of ancillary 
                         data). For the other classes, we consider that accurate maps can 
                         be derived from SPOT-4 VGT data with errors lower than 20% for the 
                         cerrado savanna, and errors lower than 10% for the other land 
                         cover classes. These estimates may be useful to evaluate impacts 
                         of land use/land cover change on the carbon and water cycles, 
                         biotic diversity, and soil degradation. (c) 2006 Elsevier Inc. All 
                         rights reserved.",
           copyholder = "SID/SCD",
                  doi = "10.1016/j.rse.2005.12.017",
                  url = "http://dx.doi.org/10.1016/j.rse.2005.12.017",
                 issn = "0034-4257",
             language = "en",
           targetfile = "carreiras - assessing.pdf",
        urlaccessdate = "27 jan. 2021"
}


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