Nonbiologists may be excused for questioning whether microbial diversity is really under threat. At a superficial level, micro-organisms seem to be tolerant of almost any set of conditions thrown at them. Also, they appear to have reproductive capacities able to generate populations of truly astronomic numbers in very little time. However, that is a superficial understanding and any belief that microbial species are not threatened is simply wrong.

James T. Staley of the University of Washington gave his answer to the challenge ‘Microbiologists are not concerned with endangered species, are we?’ in a commentary published in 1997 (Staley, 1997). His simple answer to this question is ‘Yes, some microbial species are threatened’, but the argument Staley develops is interesting and has some valuable points for mycologists to ponder. Even though the commentary was written largely from the bacteriologist's point of view, Staley mentions lichens and fungi so it is clear that he does include even the mushrooms and toadstools within his definition of micro-organisms. This is useful for us as we attempt in this brief introductory chapter to highlight and provide cross-references to the wide variety of aspects of fungal conservation that are included in this book. We are not alone in the belief that such topics are important!

Indeed, Staley puts the level of importance very high. Micro-organisms produced the original biosphere of Earth.