Yosemite’s two northern giant sequoia groves, Merced and Tuolumne, are home to hundreds of towering trees and provide vital habitat for an array of species. Fire is essential to the sequoias’ long-term health: The trees rely on fire to release seeds from their cones, to make the soil seedling-friendly, and to create space in the forest canopy so sunlight can reach the floor. 

The 2013 Rim Fire provided a rare window of opportunity to learn how fire affects seedlings in the Tuolumne and Merced groves. In 2015, your support helped park scientists undertake a second year of research focused on understanding fire’s impact on the groves and identifying conditions that young sequoias need to thrive. Study results can be used to identify potential sequoia “nurseries” within the groves, where special protections can be put in place to ensure the seedlings survive, and to inform decisions about fire management.

With help from a college intern, the team surveyed and analyzed 157 plots across the two groves, studying factors that influence seedling growth, such as temperature, light, humidity and soil moisture. They also conducted a visitor use study to help shape efforts to protect the sequoias, restored numerous social trails, surveyed for rare and invasive plants, and mapped wetland areas.

Your support allowed scientists to conduct research that will help protect Yosemite’s sequoias and ensure future generations can gaze at them in wonder.

Completed in partnership with Yosemite National Park.

Alison Colwell


Project Notes

In 2013, we were startled to discover that there are few young trees and no seedlings in either Merced or Tuolumne Grove, likely a result of insufficient fire. Serendipitously, as a consequence of actions taken during the Rim Fire, these two groves (the Merced Grove prevented from burning; the Tuolumne Grove back-burned as a protection measure) have become an inadvertent controlled study testing the recommendation for increased clearing and understory burning.