Despite two centuries of research, systematists have described only about 1.4 million species. The ecology, or role of these species in ecosystems, has been studied for less than one percent. We know more about large, economically important plants and animals than we do about fungi and bacteria, despite their important ecological roles. Only about 200,000 species of fungi have been described of the estimated 1-1.5 million species. In contrast, virtually all of the 9,000 species of birds and 4,500 species of mammals have been described.
Recent research suggests that fungal biodiversity is much higher than previously thought.
145 different species of microfungi have been found in very small samples of fresh and decayed leaves from the forest floor of tropical rainforests. About 29,000 microfungi have been estimated to occur in the United States. The number of macrofungi in the United States has been estimated to range from 5,000 to 10,000 species. Despite their importance, none of the 711 federally listed endangered and threatened species under the jurisdiction of the U.S. Fish and Wildlife Service are fungi. Earth's biodiversity is rapidly decreasing in response to pollution and habitat destruction as forests are logged, prairies converted to subdivisions, and wet lands drained for development.