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Ecology of Crater Lake National Park

Crater Lake sits inside a mountain caldera, a fact that isolates the ecosystem here from other bodies of water.

View of Crater Lake
View of Crater Lake 


Crater Lake National Park, Oregon’s only national park, is located on the crest of the Cascade Mountains and holds the remnants of what was once a tall stratovolcano known as Mt. Mazama. This area has one of the highest annual volumes of snow (over 500 inches) in the continental United States and is snow-covered during about nine months each year. By the time spring begins, 10 to 15 feet of snow are generally still on the ground. The three warmest and driest months of the year in the park are July, August, and September, which have temperatures between 40°F to 80°F. No streams flow into or out of Crater Lake, the deepest lake in the United States.




Fish are not native to Crater Lake. In fact, only two species have survived since the introduction of the six species that were originally placed in the lake between the years 1888 to 1941. Rainbow Trout and Kokanee Salmon, the only two surviving species, are allowed to be fished out of the lake with artificial bait due to being non-native. It is important that artificial bait is used in order to prevent the introduction of another non-native species.

Brook Trout
Brook Trout/NPS 

Brook Trout are native to eastern North America and have also have been introduced to the western United States through the stocking of rivers and streams for sport fishing. There has been a large decline in the native Bull Trout population because of their new resource competitors (Brook Trout) and because of hybridization between the Brook Trout and Bull Trout produces sterile offspring. Because of their quick decline, Bull Trout were listed as threatened under the federal Endangered Species Act in 1999.

Newt and Crayfish

Before 1915, no crayfish species existed in Crater Lake. As soon as the signal crayfish was introduced to the lake, the native and endemic Mazama newt began to be displaced. It was observed that the Mazama newts were found in areas where the crayfish were absent, but rarely occupied areas where crayfish were found. This is now about eighty percent of the lakeshore. These two animals have similar diets, so this displacement occurs primarily due to competition of limited food sources. Crayfish prey on newts as well, despite being on similar positions in the food web. It is predicted that if the population of crayfish continues to expand, the Mazama newt may become extinct.

Map of Crater Lake
Map of Crater Lake
Foodweb of Crater Lake
Food web of Crater Lake
Amphibians of Crater Lake
Amphibians of Crater Lake
Birds of Crater Lake
Birds of Crater Lake
Mammals of Crater Lake
Mammals of Crater Lake 


The plants in Crater Lake National Park vary by elevation and the amount of precipitation each area receives and includes a wide range of trees, wildflowers, grasses, and grass-like plants known as sedges. Crater Lake National Park has its own invasive vegetation management program, which manages the spread of exotic invasive species such as: dyer’s woad, Canada thistle, bull thistle, spotted knapweed, and St. John’s wort.


Most of Crater Lake National Park’s forests contain old growth conifers. The trees provide shade, secure volcanic-based soils, and give nutrients back to the soil. The tree canopy creates a stabilized habitat for the grasses, shrubs, herbs, fungi, bacteria, and invertebrates that can be found beneath it.

Conifer Trees:

Fir trees: White, Subalpine, Red, Douglas

Pine trees: Whitebark, Western White, Sugar, Ponderosa, LodgepoleOther conifers: Mounain and Western Hemlock, Incense Cedar

Deciduous Trees:

Quaking Aspen, Black Cottonwood

Invasive Plants of Crater Lake
Invasive Plants of Crater Lake 


Dry, subalpine meadows are located at high elevations near the caldera rim along peaks and cinder cones. Grass and sedge-dominated meadows are located near Crater Peak, Sun Notch and Rim Village, and wet meadows are present at lower elevations and near streams.

Pumice Desert
Pumice Desert/NPS 


From the end of snow season until the beginning of the next snowfall, red to orange and blue to purple wildflowers are nearly everywhere. These wildflowers grow in a variety of unique habitats, which is why they are the most diverse group of plants in Crater Lake National Park.

Wildflowers of Crater Lake
Wildflowers of Crater Lake 

Other Wildflowers:

Elephant’s Head Pedicularis, Pussypaws, Prince’s Pine, Applegate’s Paintbrush, Alpine Chaenactis, Alpine Shooting Star, Steer’s Head, Washington Lily, Cluster Lily, Wax Current, Red Elderberry, Alpine Laurel, Howell’s Monkshood, Peregrine Fleabane, Blue Eyed Mary, Mahala Mat, Blue Stickseed, Dagger Pod, Hookedspur Violet, Idaho Blue Eyed Grass, California Jacob’s Ladder, Spreading Phlox, Royal Penstemon, Rydberg’s Penstemon, Davidson’s Penstemon, Prostrate Lupine, Anderson’s Lupine, White Pollen Skyrocket, Silvery Raillardella, Stream Violet, Streambank Birdsfoot Trefoil, Mountain Agoseris, Dwarf Hulsea, Sierra Eriogonum, Oregon Sunshine, Cascade Desert Parsley, Orange Peel Fungus, Bolander’s Tarweed, Crater Lake Current, Goosefoot Violet, Vanilla Leaf, Cow Parsnip, Fleeceflower, Woodland Strawberry, Palm Leaf Ballhead Gilia, Tobacco Brush, Western Springbeauty, Dwarf Mountain Fleabane, Slender-Tubed Iris, Patridgefoot, Long-Spurred Bog Orchid, Pearly Everlasting, Western Bistort, Starry False Solomon’s Seal, Mountain Catchfly, Ranger’s Buttons, Small White Violet, Hotrock Beardtongue