Dataverse

Data

e28d6be3042c325390dc8e6e897feac0

2016-11-16

39.1 MB

7Z Archive

We digitized the extent of primary logging roads by visually analyzing our 268 LANDSAT images acquired over 1972–2010. Wide logging roads were readily detectable in the LANDSAT imagery. We were capable to detect logging roads under most areas of persistent haze, by zooming in closely and applying a local contrast enhancement, and by digitizing logging roads underneath haze by mouse-click. The expansion of the road network overtime was observed for c.1973, 1990, 2000, and 2010. Imagery acquired a year or two before and after these nominal years served to reduce cloud contamination. We also inspected imagery from ca. 1995 and 2005 to better detect disused logging roads less visible due to rapid forest regrowth. Similarly to our approach for mapping industrial plantations LANDSAT 5&7 (TM and ETM+) images were viewed as band 4-5-3 (or 5-4-3) false color composites enhanced to optimize road detection. Likewise, LANDSAT MSS images were viewed as band 4-3-2 (or 3-4-2). We used ancillary public-road maps from the Indonesian Ministry of Public Works and the Sabah-based NGO HUTAN for Sarawak and Sabah to help distinguish unpaved public roads from logging roads. We further divided ‘Forest’ into ‘Intact’ and ‘Logged’ using our published dataset of logging roads and a buffer distance method (see information describing how logging roads have been mapped). Briefly, we consider that the forest has never been logged if our database of images never detected the presence of large (> 10m wide) logging roads in the forest. Degradation by logging usually becomes undetectable within a few years, due to fast forest re-growth. From a satellite perspective, the spectral colors of logged forests resemble those of intact forests, which explains why recently published state-of-the-art deforestation analyses categorized logged forests as forest.

2016-11-16