Giant Sequoia Groves
The Mariposa Grove, 35 miles south of Yosemite Valley, is the largest of three Sequoia groves in Yosemite.
The Tuolumne and Merced Groves are near Crane Flat.
Despite human pressures, these towering trees, largest of all living things, have endured for thousands of years.
Only in recent years, however, have we begun to understand the Giant Sequoia environment.
During the last 100 years protection has sometimes been inadequate and sometimes excessive.
For example, in the late 1800s tunnels were cut through two trees in the Mariposa Grove.
Conversely, good intentions created another problem, protection from fire has resulted in adverse effects.
Sequoias are wonderfully adapted to fire. The wood and bark are fire-resistant. Black scars on a number of large trees that are still prospering indicate they have survived many scorching fires. Sequoia reproduction also depends on fire. The tiny seeds require minimal soil for germination, and seedlings need sunlight. Historically, frequent natural fires opened the forest, thinned out competing plant species, and left rich mineral soil behind. But years of fire suppression have allowed debris, such as fallen branches, to accumulate, stifling reproduction and allowing shade-tolerant trees to encroach. Prescribed fires, intended to simulate natural fires and improve the health of the forest, are now set by the National Park Service.
As you look at these trees, keep in mind that they have been here since the beginning of history in the western world. The Mariposa Grove's Grizzly Giant is 2,700 years old and is thought to be the oldest of all Sequoias. Private vehicles are not permitted beyond the parking area in the Mariposa Grove. You may ride the trams through the Grove from May until October. Trails are available year-round for hiking or cross-country skiing.
Giant sequoias are a fire adapted species. Their bark is fire resistant and fire helps open the sequoia cone and scatter the tiny seeds. Fire also clears forest debris from the mineral soil and provides a nutrient rich seed bed as well as clearing competing species.
Where to go and when?
Massive, ancient giant sequoias live in three groves in Yosemite National Park.
The most easily accessible of these (spring through fall) is the Mariposa Grove near the park's South Entrance, off of the Wawona Road (Highway 41). Two smaller--and less visited--groves are the Tuolumne and Merced Groves near Crane Flat.
The Mariposa Grove Road is closed to cars approximately November to April, depending on conditions. You can hike up the two-mile road (500 feet of elevation gain) when it is closed.
No roads enter the Tuolumne or Merced Groves; two to three miles of hiking (about 500 feet of elevation gain) is required before you will see giant sequoias.