Multi-temporal analysis of radiometric changes in satellite images of forest edges to infer selective-logging areas in the Amazon forest

Abstract

Radiometric changes observed in multi-temporal optical satellite images have an important role in efforts to characterize selective-logging areas. The aim of this study was to analyze the multi-temporal behavior of spectral-mixture responses in satellite images in simulated selective-logging areas in the Amazon forest, considering red/near-infrared spectral relationships. Forest edges were used to infer the selective-logging infrastructure using differently oriented edges in the transition between forest and deforested areas in satellite images. TM/Landsat-5 images acquired at three dates with different solar-illumination geometries were used in this analysis. The method assumed that the radiometric responses between forest with selective-logging effects and forest edges in contact with recent clear-cuts are related. The spatial frequency attributes of red/near infrared bands for edge areas were analyzed. Analysis of dispersion diagrams showed two groups of pixels that represent selective-logging areas. The attributes for size and radiometric distance representing these two groups were related to solar-elevation angle. The results suggest that detection of timber exploitation areas is limited because of the complexity of the selective-logging radiometric response. Thus, the accuracy of detecting selective logging can be influenced by the solar-elevation angle at the time of image acquisition. We conclude that images with lower solar-elevation angles are less reliable for delineation of selecting logging. KEYWORDS: timber exploitation, deforestation, remote sensing, forest monitoring.Análise multitemporal das mudanças radiométricas em imagens de satélite de bordas de floresta para inferir áreas de corte seletivo na floresta Amazônica RESUMO Mudanças radiométricas observadas em imagens multitemporais de satélites ópticos têm importante papel na caracterização de áreas afetadas pelo corte seletivo. O objetivo desse estudo foi analisar o comportamento multitemporal da resposta da mistura espectral em imagens de satélite de áreas simuladas por corte seletivo de madeira na floresta amazônica, considerando as relações espectrais do vermelho/infravermelho próximo. Para a análise dos dados foram utilizadas as margens da floresta para inferir a infraestrutura de exploração florestal em diferentes orientações a partir da transição entre áreas de floresta e desmatamento em imagens de satélite. Imagens do sensor TM/Landsat-5 adquiridas em três datas distintas com diferentes geometrias de iluminação solar foram utilizadas na análise. O método utilizado presume que as respostas radiométricas entre a floresta com efeitos do corte seletivo e as margens da floresta em contato com áreas recém-desmatadas estão relacionadas. Os atributos da frequência espacial das bandas espectrais do vermelho/infravermelho próximo foram analisados. A análise dos diagramas de dispersão mostraram dois grupos de pixels que representam áreas de corte seletivo. Os atributos de tamanho e distância radiométrica representando esses dois grupos fora...

Natural recovery of skid trails: a review

“…This is especially the case in assessments of secondary and tertiary skid trails, where the area between the machinery wheels or tracks may be only slightly compacted and recovered quickly. Moreover, there are many options available to inventory and classify skid trail use intensity with rapidly developing remote sensing technologies such as high-resolution satellite imagery, Unmanned Aerial Vehicles (UAVs) and airborne Light Detection And Ranging (LIDAR) (Pierzchała et al 2014;Graça et al 2015;Melendy et al 2018;Robichaud et al 2020). So, the question remains if skid trails naturally recover.…”