AUTHOR CONTRIBUTIONS
GFF, JP, WT, PT, GAD, DF, RA and MC designed the experiment. SM, GFF, RA, MC, FG, MG, conducted the field work. AG, AB and LG conducted molecular analyses. AG and AB performed the bioinformatic treatment of sequence data. CC, AZ, JP performed edaphic analyses. AG, AC, IC ran statistical analyses. AG, AC and GFF drafted the manuscript. All the authors contributed substantially to the revision process, and accepted the final version.