An all-taxa biodiversity inventory, or ATBI, is an attempt to document and identify all biological species living in some defined area, usually a park, reserve, or research area.
The first use of the term appears to have been in 1993, in connection with an effort initiated by ecologist Daniel Janzen to document the diversity of the Guanacaste National Park in Costa Rica. An ATBI focusing on the Great Smoky Mountains National Park of the southeastern United States is one of the most active and may be one of the most thorough to date.
A number of other, similar, efforts have been initiated for a variety of parks and research field stations.
All ATBIs are inherently incomplete since, a) the biota of even well-studied areas includes many undescribed and often difficult-to-study species, and b) new species are regularly established through immigration and introduction.