Glacier Bay National Park and Preserve provides an outstanding natural environment. Within the park's environs are found five major land ecosystems: wet tundra (muskeg), coastal western hemlock/Sitka spruce forest, alpine tundra, glaciers and icefields and early post-glacial meadows and thickets.
Three major marine ecosystems have been identified in and around the park and preserve: continental shelf, wave-beaten coasts and fjord estuaries.
The plants and animals of Glacier Bay are mainly those of the temperate North Pacific coast between northern California and south central Alaska rather than the biota of interior Alaska. Glacial movements past and present complicate the distribution of species. As glaciers retreat, a new barren land emerges. Highly adaptable plant forms begin to colonize this sterile environment. Seeds and spores are transported by birds and carried by wind to the exposed land surfaces. Lichens, algae and mosses produce a fertile blanket on which succeeding plants can grow. Horsetail, fireweed, dryas and willow shrubs are the early pioneers. Alder, an important nitrogen fixing plant, followed by cottonwood, is usually the first tree to develop. These set the stage for the later and climactic plant species to play their role in the plant succession drama.
Spruce, hemlock, blueberry, devil's club and skunk cabbage develop rapidly in a mature forest ecosystem. The final act is found in the climax muskeg-bog, yellow cedar and sphagnum community. In time, the cycle resumes as plant material decomposes, forming a rich and fertile base. There are approximately 420 species of plants found in the park.
While birds and marine life are mobile enough to recolonize quickly, mammals have a more difficult problem. Some mammal species have not reached Glacier Bay since the last major ice age drew to a close. If ice covered nearly all lowland areas between Seward Peninsula, Alaska and Puget Sound, Washington, within the last 12,000 years, then it is understandable why the distribution of animals is not yet complete. However, this has not prevented most species from colonizing Glacier Bay. In recent times, the coyote, moose and wolf have found suitable habitat in the park. The mountain goat and brown bear, both highly mobile creatures, have roamed the region for thousands of years. As a result, these species have had less difficulty finding habitat. Many smaller mammals such as the vole, wolverine, marmot and porcupine are found in the park as well.
Marine mammals include the humpback whale, killer whale, harbor porpoise, harbor seal, Steller sea lion, and sea otter. There are currently about 40 different species of mammals in Glacier Bay National Park and Preserve.
An endangered species is any plant or animal in danger of extinction throughout all or a significant portion of its range. A threatened species is one that is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range. The Federal Endangered Species Act of 1973 has as its goal to restore all federally listed endangered and threatened species to the point where they are again viable, self-sustaining members of their ecological communities.
Those species, which are endangered or threatened in Glacier Bay, include the humpback whale (threatened: Mexico wintering population), the Steller sea lion (threatened), and the spectacled eider (threatened). Some wildlife, such as the marbled murrelet, endangered outside of Alaska, and the bald eagle, threatened outside of Alaska, are found in strong numbers in Glacier Bay National Park. The Park Service is dedicated to protecting and restoring habitat for all wildlife including restoring species to healthy populations.