Tuolumne Meadows - Natural History

Natural History

The meadow vegetation is supported by shallow groundwater. The water comes from 1,000 mm (39 inches) of precipitation annually, predominately in the form of snow. Water arises from snowmelt and hill-slope aquifers, and flows through the Tuolumne River, Budd Creek, Delaney Creek, and Unicorn Creek. In spring as soon as the snow melts, it is not uncommon to see large areas of the meadows flooded and practically transformed into a lake.

The mountains of the Sierra near the meadows have some permanent snowfields: in the summer they are mostly free of snow. Although brief, the late spring and summer wildflower bloom in Tuolumne Meadows is host to a wide variety of California wildflowers, including the relatively rare Purple Webber, a type of lupin.

Plant species composition changes across the meadows with different landforms, landscape positions, and summer water-table depths. Areas with seasonal flooding and deep-standing water support the inflated sedge and Sierra willow. The main herbaceous wet-meadow species include alpine aster, nearly-black sedge, King’s ricegrass, western bistort, Breweri’s reed grass, and dwarf bilberry. Thread-leaved sedge, pussy-toes, Sierra lodgepole pine, and Ross sedge are found in drier uplands within or on the edge of the meadow.