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Yosemite National Park Officials Planning To Restore Mariposa Grove of Giant Sequoias


Better drainage, reduced infrastructure, and better protection of giant sequoias are the end goals of a plan by Yosemite National Park officials to restore the Mariposa Grove in the southern end of the park.

The Mariposa Grove is the largest of the three giant sequoia (Sequoiadendron giganteum) groves in Yosemite and was part of the original Yosemite Grant signed by President Abraham Lincoln in 1864 (the rest of the grant included Yosemite Valley). The giant sequoias can measure up to 35 feet in diameter and up to 300 feet tall. There are approximately 500 mature sequoia trees in the grove.  

The proposed plan aims to restore the Giant Sequoia habitat in the Mariposa Grove. This would be accomplished through a range of actions including:

  • Restoring the natural hydrology within the grove
  • Removing unnecessary infrastructure 
  • Realigning roads and trails in sensitive sequoia habitat
  • Relocating the existing visitor parking 
  • Reducing visitor trampling of soils and vegetation around the giant sequoias

The project also seeks to improve the visitor experience within the Mariposa Grove by assessing visitor facilities and transportation.

Through October 15 the park is accepting public comment on an environmental impact plan examining how best the Mariposa Grove can be restored. A public open house is set for Wednesday, September 28, from 1 p.m. to 4 p.m. in Yosemite Valley at the Visitor Center Auditorium. Park staff will be available to discuss the project, answer questions, and accept comments.

Online comments can be submitted through the Planning, Environment, and Public Comment website at


This summer my family visited the Mariposa Grove at Yosemite and what a phenomenol sight! Anything that can be done to preserve these giant masterpieces is worth it!

Over 50 years ago, Dr. Richard Hartesveldt of San Jose State University studied the human
impacts upon giant sequoias in the Mariposa Grove and discovered among other results that
sequoia tree rings widened following historic fires.  This result led later to his pioneering the
fire ecology of giant sequoias at Sequoia-Kings Canyon NP with Drs. Tom Harvey, Howard Shelhammer,
and Ron Stecker, the first to study insects among the high canopies via an elevator device attached
to one tree in the Redwood Canyon Grove.  Of importance here is to remember Hartesveldt's studies
and their teams' role pioneering an ecological understanding of giant sequoia groves.  His studies
were met with some degree of resistance from the NPS pseudo-scientists employed out of the
San Francisco Regional Office.  One of these characters who later pioneered pseudo-science at
the new Redwoods NP was in disagreement when Hartesveldt discovered dead and dying giant
sequoias in Yosemite as a result of NPS construction changing the watertable levels surrounding one
wet-mesic meadow.  NPS maintenance crews also severed roots of the General Sherman when digging
trenches for the restroom facilities below the General Sherman giant sequoia in SEKI.  All of these tragic
incidents tells us today that the NPS needs a serious watchdog since many of its staff are not as
knowledgable as they may think.  So, Beware the NPS restoring habitats within the Mariposa Grove.

I hiked all through this grove in early June and was impressed by how healthy the trees are. Prescribed fire has resulted in many sequoia seedlings. In the 1960's you could drive through the grove. Now you either walk or ride a tram. A six mile hike will take you through the upper and lower part of the grove.

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