INTRODUCTION

In 1903, the explorer Robert Scott was one of the first humans ever to see the dry valleys of Antarctica. He called them ‘valley(s) of the dead’ in which ‘we have seen no sign of life, … not even a moss or lichen’. A century later, we know that the soils and rocks are home to many microscopic organisms that Scott could not have seen.

The dry valleys are part of the small percentage of the land surface of the Antarctic continent that is ice-free, amounting to about 4000 km2, and thus have rock and soil surfaces that can be colonized by terrestrial organisms. They are an ancient polar desert, perhaps as much as 2 million years old, located in Victoria Land between about 77 and 79° south (Fig. 1). The valleys are in a precipitation shadow caused by the Transantarctic Mountains, which rise over 4000 m. The Antarctic dry valleys are now recognized as one of the harshest terrestrial environments on Earth, characterized by summer maximum temperatures that rarely exceed 0 °C and only a few tens of millimetres of precipitation, most of which falls as snow and is ablated by strong winds carrying dry air from the polar plateau - potential evaporation far exceeds precipitation (Fig. 1).