Method for Large-scale Mapping of Forest Gap Fraction and Logging in Amazonia
Amanda
Naslund
Cooper, Carnegie Institute of Washington, acoop@stanford.edu
(Presenting)
Gregory
Paul
Asner, Carnegie Institute of Washington, gpa@stanford.edu
Kathleen
Heidebrecht, Carnegie Institute of Washington, kheide@globalecology.stanford.edu
Amanda
Susan
Warner, Carnegie Institute of Washington, amanda@globalecology.stanford.edu
José
Natalino Macedo
Silva, EMBRAPA, natalino@cpatu.embrapa.br
Mercedes
Maria Cunha
Bustamante, (6) Universidade de Brasilia, mercedes@unb.br
Over recent years the use of satellite imagery has been an invaluable tool in monitoring land cover change in Amazonia. Using Landsat ETM+ data, automated mapping of photosynthetic vegetation fraction and canopy gap fractions for the Brazilian states of Acre, Northern Mato Grosso, Rondonia, Para and Amazonas was performed. An initial mosaic of orthorectified data, available from Earthsat, was used as the base ETM+ coverage. Each scene was only available for one year, ranging in acquisition date from 1999 to 2001. The raw ETM+ images were converted to reflectance using an atmospheric correction code. Masks were created and applied for clouds, water and cloud shadows. Masked reflectance data were then processed through a spectral unmixing model, Carnegie’s AutoMCU which determines photosynthetic vegetation (PV), non-photosynthetic vegetation (NPV), bare soil, and shade fractions. The raw MCU output was then corrected to remove the effects of the shade fraction. Image rescaling was needed to standardize PV, NPV and soil results between images, as there were discrepancies between images due to atmospheric artifacts and differing dates of image acquisition. Lastly, for 1999 to 2002, state-level mosaics of high resolution imagery have been produced. These maps highlight the diversity of forest structural conditions and land use throughout much of Amazônia and represents an advance in mapping of large ecosystems.
Submetido por Amanda Naslund Cooper em 25-MAR-2004
Tema Científico do LBA: LC (Mudanças dos Usos da Terra e da Vegetação)