Fig. 2

Worldwide arid environments studied. Dots depict 325 sampled sites from the 66 reports included in this systematic review, plotted using their GPS coordinates and ggmap tool from ggplot2 package in the R software [21]. Country colour denotes the number of main affiliations from each author in the articles included. Each arid environment sampled is depicted by a different colour, this map was built using the online tool Mapchart. Abbreviations: WA, Western Antarctica; AP, Argentinian Patagonia; AD, Atacama Desert; ChiD, Chihuahuan Desert; US, South Western United States; ND, Namibia Desert; PeA, Princess Elisabeth Station Antarctica; ChD, Chad Desert; MD, Moroccan Desert; AlgD, Algerian Desert; TD, Tunisian Desert; NED, North Egyptian Desert; NeD, Negev Desert; Jdn, Jordan arid soils; QD, Qatari Desert; IrD, Iran Desert; ID, Indian Desert; KshD, Kazakhstan Desert; NCD, North China Deserts; SAD, South Australia Desert; ADV, Antarctic Dry Valleys; Nrw, Norway