Global roadless areas: Hidden roads.

Abstract

![Figure][1] Clusters of lights that appear isolated suggest the presence of roads that can't be seen. PHOTO: NASA EARTH OBSERVATORY IMAGE BY ROBERT SIMMON, USING SUOMI NPP VIIRS DATA PROVIDED COURTESY OF CHRIS ELVIDGE (NOAA NATIONAL GEOPHYSICAL DATA CENTER) In their Report “A global map of roadless areas and their conservation status” (16 December 2016, p. [1423][2]), P. L. Ibisch et al. cataloged roads across the world. However, they overlooked roads that have not been mapped into global databases. In parts of tropical Asia, which are depicted as “roadless” by Ibisch et al. , abundant data indicates the presence of roads. The National Oceanic and Atmospheric Administration's (NOAA's) lights at night ([ 1 ][3]) data set reveals numerous cities and towns visible at night, but apparently disconnected from the mapped road network, particularly in Myanmar and Southern China. Furthermore, the OpenStreetMap 2013 data set (used in Ibisch et al. 's analysis) is incomplete relative to the 2016 data set ([ 2 ][4]), and many regions shown as “roadless” by Ibisch et al. (such as West Africa and much of Asia) now have dense road networks mapped by OpenStreetMap. Deforestation is also known to primarily occur in close vicinity to roads. The Global Forest Watch ([ 3 ][5]) deforestation database makes it possible to locate many deforestation areas that are linear in shape, revealing the presence of roads. This is particularly true in Borneo. Similar underrepresentation of roads is visible in other tropical regions with high rates of forest lost (such as East Madagascar). Thus, Ibisch et al. 's analysis falls short for developing regions and for those with high deforestation rates. 1. [↵][6]NOAA, National Centers for Environmental Information, Version 4 DMSP-OLS Nighttime Lights Time Series ([https://ngdc.noaa.gov/eog/dmsp/downloadV4composites.html][7]). 2. [↵][8]OpenStreetMap 2016 data set ([https://extract.bbbike.org/][9]). 3. [↵][10]Global Forest Watch ([data.globalforestwatch.org/][11]). [1]: pending:yes [2]: /lookup/doi/10.1126/science.aaf7166 [3]: #ref-1 [4]: #ref-2 [5]: #ref-3 [6]: #xref-ref-1-1 View reference 1 in text [7]: http://ngdc.noaa.gov/eog/dmsp/downloadV4composites.html [8]: #xref-ref-2-1 View reference 2 in text [9]: http://extract.bbbike.org/ [10]: #xref-ref-3-1 View reference 3 in text [11]: http://data.globalforestwatch.org/