Mule deer and black bear are frequently seen in this area. Coyote, porcupine, badger, and bobcat are rather common but also elusive, so there is less of a chance to spot them. Fisher, pine marten, red fox, and wolverine roam the Wilderness, too, but they are really rare and park officials encourage visitors to report sightings which will help to learn more about their abundance. Desolation’s rodents are represented by yellow-bellied marmot, golden-mantled ground squirrel, Douglas squirrel, and pika.
As for the area’s birds, they include the Steller's Jay, Clark's nutcracker, mountain chickadee, blue grouse, mountain, bluebird, American dipper, golden eagle, and others. Rainbow, brook, brown, and golden trout species make homes in the local lakes and streams.
The Desolation Wilderness contains a wide range of ecosystems associated with the range of elevations and soil types. The area's red fir and lodgepole forests are mainly made up of Jeffrey pine, mountain hemlock, western juniper, and western white pine. The wooded areas are mostly clustered within elevations between 7,400 feet and 9,000 feet and become patchy as you climb higher. Another group of plants found in the Wilderness is montane chaparral that includes pinemat manzanita, huckleberry oak, and mountain pride penstemon. The ground surface is mainly composed of bedrock granite and fertile soils are limited to the wet meadows scattered throughout the Wilderness, as well as the lands surrounding lakes and streams. Aspen and willow trees are common there and numerous wildflowers, sedges, and grasses blanket these areas.