Park officials on Tuesday released a draft environmental study on the effects of an estimated $15 million worth of improvements at Yosemite's popular Mariposa Grove. The proposal includes getting rid of the tram ride, shop and parking lots -- changes designed to restore the habitat for the nearly 500 giant sequoias there.

"Today we know more about how to manage our national parks, and we would not be putting a parking lot within a giant sequoia habitat," park spokesman Scott Gediman said.

Giant sequoias, which grow only in the southern Sierra Nevada, are the largest living things on earth, and their shallow root systems extend several hundred feet sideways.

Park officials hope that by removing the grove's parking lot, they will create a larger habitat for new trees to sprout. Visitors would then be shuttled from a station at the park's south entrance or could hike in on a new two-mile trail.

The tram that carried tourists through an otherwise peaceful grove of giant trees would be discontinued, and a road rerouted so wetlands could be restored.

"The loud trams are not conducive to the visitor experience," Gediman said.

Park officials hope to break ground in June on the 150th anniversary of the date President Abraham Lincoln signed the grant that set aside Yosemite Valley and the Mariposa Grove for preservation, a first for the federal government.

The improvement project would be paid for by the Yosemite Conservancy. The plan is available on the park's website. Comments will be accepted through May 7.