Historic Resource Study, Crater Lake National Park, Oregon, 1984
V. Geological and Biological Information on Crater Lake Area
F. Other Natural Resources
1. Forests and Plant Life
It should not be presumed from the foregoing discussion that Crater Lake is a sterile expanse, encompassing only barren desert terrain, remnants of rugged volcanic cones, and high, impenetrable lava cliffs and precipices. Actually, a soil of great fertility has been created from the volcanic lava of the Cascades through the processes of time and weathering, permitting a profusion of forests and wildflowers. One approaches Crater Lake National Park through the lowlands outside the boundary where forests of ponderosa and lodgepole pine alternate with junipers, sagebrush, and antelope bitterbrush–an environment characteristic of the Great Basin desert which it adjoins on the east. Passing through this more arid zone onto the lower elevations of Mazama, one finds several varieties of pine (ponderosa, sugar) and fir (white, Douglas), as well as western hemlock, western yew, dogwood, and assorted bushes. The park’s forests are unusual because of the heavy growth of fine virgin trees that have been undisturbed by man except for the removal of diseased members. On the higher slopes of Mount Mazama western white pine and lodgepole are slowly establishing themselves in thick growths. Still higher points introduce mountain hemlocks, red fir, and subalpine fir, but only whitebark pines grow on the high, windblown rim. Over the edge, sparse strips of vegetation descend to the lake in the lee of protecting rock ledges.
At least 570 species of flowering plants and ferns also thrive in the park, ranging from lichen at Palisade Point to the wildflowers of Castle Crest and Munson Meadows to the stunted vegetation of the Pumice Desert and Wizard Island. Water is supplied by springs outside the caldera on the west and southwest slopes, enabling dripping mossy cliffs, bogs, and lush meadows to proliferate. The blooming season here is short, however, from July 1 to mid-September at the latest.