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Merced Grove Giant Sequoia Restoration Fence Installation

Yosemite National Park » Merced Grove Giant Sequoia Restoration Fence Installation » Document List

The imminent closure of the Mariposa Grove is expected to significantly raise the level of visitation to Merced and Tuolumne Groves. The cumulative impact of larger numbers of visitors in the Merced Grove may lead to accelerated damage to tree root systems, wear of bark on lower tree trunks and unacceptable levels of visual and environmental deterioration in the core of the grove.

This project will install approximately 170 feet of new zig-zag style fencing as a protection measure, while maintaining as unconstrained a visitor experience as possible. The locations for proposed fencing installation are two clusters of sequoias adjacent to the Merced Grove trail that receive considerable impact. Visitors are approaching the base of large sequoia trees at the following two sites:

1) A cluster of large adult sequoias at the entrance to the grove. Fencing will follow the trajectory of the trail and cut off direct access to the trees. This section of fencing will be approximately 100 feet long. The fencing site is gently sloped away from the trees.

2) Two of the largest sequoias in the grove, which are located directly across the trail from the Merced Grove Cabin. Current use has resulted in considerable impact to the base of these two large sequoias, including some 'eco-graffiti' in a fire scar on one of the trees. This site is flat and will consist of 70 feet of new fencing.

The proposed type of fencing for this project is the 'parallel zig-zag' style that is consistent with style and dimensions of existing fencing in both the Mariposa Grove and Tuolumne Grove. This style of fencing minimizes impacts to giant sequoia roots and archaeological sites and does not require post holes to be dug as anchors. It is also the least costly to remove if found to no longer be needed in the future. Because of the fence's zig-zag design, it is largely self-supporting, but is designed to be anchored with ½ inch gauge rebar at a depth of 12 inches for added stability. Rebar is installed at the end of each 10 foot cedar rail. The proposed total fencing length is approximately 170 feet, which will require 19 rebar reinforcement rods to be installed. The zig-zag fencing is approximately 4 feet wide and 3 feet tall.