Reconstructing historical forest cover change in the Lower Amazon floodplains using the LandTrendr algorithm

Autor(es)

Fragal, Everton Hafemann ^[1] ; Freire Silva, Thiago Sanna ^[2] ; de Moraes Novo, Evlyn Marcia Leao ^[1]

Afiliação do(s) autor(es)

^[1] Inst Nacl Pesquisas Espaciais, Div Sensoriamento Remoto, BR-12227010 Sao Jose Dos Campos, SP - Brazil

^[2] UNESP Univ Estadual Paulista, Inst Geociencias & Ciencias Exatas, BR-13506900 Rio Claro, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Acta Amazonica; v. 46, n. 1, p. 13-24, JAN-MAR 2015.
• Citações Web of Science: 9

Resumo

ABSTRACTThe Amazon várzeas are an important component of the Amazon biome, but anthropic and climatic impacts have been leading to forest loss and interruption of essential ecosystem functions and services. The objectives of this study were to evaluate the capability of the Landsat-based Detection of Trends in Disturbance and Recovery (LandTrendr) algorithm to characterize changes in várzeaforest cover in the Lower Amazon, and to analyze the potential of spectral and temporal attributes to classify forest loss as either natural or anthropogenic. We used a time series of 37 Landsat TM and ETM+ images acquired between 1984 and 2009. We used the LandTrendr algorithm to detect forest cover change and the attributes of "start year", "magnitude", and "duration" of the changes, as well as "NDVI at the end of series". Detection was restricted to areas identified as having forest cover at the start and/or end of the time series. We used the Support Vector Machine (SVM) algorithm to classify the extracted attributes, differentiating between anthropogenic and natural forest loss. Detection reliability was consistently high for change events along the Amazon River channel, but variable for changes within the floodplain. Spectral-temporal trajectories faithfully represented the nature of changes in floodplain forest cover, corroborating field observations. We estimated anthropogenic forest losses to be larger (1.071 ha) than natural losses (884 ha), with a global classification accuracy of 94%. We conclude that the LandTrendr algorithm is a reliable tool for studies of forest dynamics throughout the floodplain. (AU)

• Processo FAPESP: 10/11269-2 - Modelagem da dinâmica espacial de comunidades de macrófitas na várzea amazônica.
• Beneficiário: Thiago Sanna Freire Silva
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 11/23594-8 - Sensoriamento remoto aplicado à modelagem de impactos antropogênicos sobre propriedades ecológicas de ambientes alagáveis e aquáticos da planície do Solimões/Amazonas
• Beneficiário: Evlyn Márcia Leão de Moraes Novo
• Modalidade de apoio: Auxílio à Pesquisa - Regular