Fig. 4
Map of the 220 km2 study area, in the McMurdo Dry Valleys. The area was divided into 554 geographically and geologically distinct ice-free sectors using remote-sensing data, and with geographical and geological variables validated on-the-ground assessments in November 2008. Eventually, 471 sites were sampled in January 2009 and January 2010 to encompass the entire range of geographical and geological heterogeneity in the area. Nematodes were found in 314 sites
