The
literature on desert cyanobacteria appear to indicate that they mostly colonise
the soil crust or cracks in rock, where they play an important ecological role
in the breakdown of rock into soil. More specifically for example,
cyanobacteria have been found salt rocks in the Yungay region. Cyanobacteria
photosynthesise; therefore, they require access to sunlight. Fungi and lichens
tend to grow in the shade, while cactus roots are underground.