Stretching from the arctic of Alaska to the Florida Keys, and the coast of Maine to Hawai`i’s volcanic islands, the United States supports an extraordinary diversity of life. Encompassing more than 3.5 million square miles of land and with 12,000 miles of coastline, the nation spans 120 degrees of longitude—nearly a third of the globe. This expanse includes an exceptional variety of terrains, from the Badwater Basin in Death Valley at 282 feet below sea level to the peak of Denali at 20,320 feet above.
The resulting range of climates has given rise to a wide array of ecosystems, from tundra and subarctic taiga to deserts, prairie, boreal forest, deciduous forests, temperate rain forests, and even tropical rain forests. Military installations are widely represented among these varied ecosystems. This ecological tapestry sustains an equally remarkable array of species. Although the total number of species inhabiting America’s lands and waters is far from fully known, an estimated 200,000 U.S. species have been formally described and named by science (Stein et al. 2000). Additional species continue to come to light as new areas are explored, and new and increasingly powerful scientific techniques for documenting diversity are developed. While many of these discoveries are among poorly known groups of organisms, such as insects and fungi, even among relatively well-known groups such as flowering plants up to thirty new North American species are described every year.
The U.S. military has played an important role in helping to discover and understand the nation’s biological wealth. When Captain Meriwether Lewis of the First Infantry and Lieutenant William Clark set out in 1803 to cross the continent with their Corps of Discovery, they were under orders from President Thomas Jefferson to record everything they could about the countryside, including “the soils and face of the country, its growth and vegetation productions…the animals of the country…the remains and any which may be deemed rare or extinct.” Many of western North America’s most characteristic, and charismatic, wildlife species were first scientifically documented by the Corps of Discovery, including grizzly bear, pronghorn, and mule deer.
Lewis and Clark’s journey was followed by other military expeditions exploring different routes across the continent, many of which included accomplished naturalists. The expeditions fueled the dramatic expansion in scientific knowledge about our flora and fauna that took place in the mid-1800s. A multitude of western plant and animal species have enshrined in their names the contributions of military men, such as Major John C. Frémont (Fremontodendron californicum, the California flannelbush), Major Howard Stansbury (Uta stansburiana, the western side-blotch lizard), and Captain John W. Gunnison (Cynomys gunnisoni, Gunnison prairie dog).
As exploration of the North American continent brought the nation into better focus, it became clear that the lands and waters harbored a spectacular assemblage of plants and animals. And while most people think of tropical rainforests as the region on earth teeming with the greatest diversity of life, for certain groups of organisms the United States is the global leader. For example, more salamander species are found in the United States than any other country on Earth, with the greatest concentrations of diversity in the Southeast. The United States is the global center of diversity for several other freshwater groups, including freshwater mussels and crayfishes. Among plants, the United States is second only to China in its variety of gymnosperms, a group that includes conifers like pines, firs, and spruces.
Hawai`i’s inclusion in the United States, first as a territory in 1898 and later as a state in 1959, added tremendously to the richness of the nation’s biological fabric. This set of mid-oceanic volcanic islands has never been connected to the mainland, and all life forms naturally occurring in the archipelago either arrived from elsewhere or evolved in place from earlier arrivals. The combination of isolation from other land masses, multiple islands within the archipelago, and the island’s dramatic contrasts in terrain and climate—from tropical beaches to icy volcanic peaks—has led to perhaps the most distinctive and unique flora and fauna in the world. A species that is restricted to a specific area is referred to as endemic to that area, and Hawai`i has some of the highest levels of endemism in the world. More than two-fifths (43%) of Hawai`i’s vertebrate animals are endemic, as are 87% of its vascular plants, and 97% of its insects (Stein et al. 2000). Not only are these species found just in Hawai`i, but many are extremely localized, a factor greatly contributing to the high levels of endangerment found in the Hawaiian flora and fauna, including on DoD installations.
Next Page: How is America’s Biodiversity Faring?
Author
Bruce Stein, Ph.D., Chief Scientist and Associate Vice President
National Wildlife Federation
State of the Nation: The Condition of Biodiversity Across the United States Sections
State of the Nation: The Condition of Biodiversity Across the United States
How is America’s Biodiversity Faring?
Endangered Species Act Listings
NatureServe Conservation Status Assessments
Species of Greatest Conservation Need