The tallest giant sequoia at
the Mariposa grove in the
Yosemite National Park is
87 meters. RANVIR SHAH
on these remarkable giants
with their specialized
IT is an early February morning. The dawn is yet to break. We are heading for Yosemite and the car picks up speed and the automobile is like a projectile on the lonely freeway. Leaving San Francisco behind us, we come to the wine-growing areas, whizz past hundreds of silent windmills standing mute testimony to much of the Quixotic in us and allowing us to dream the impossible. Just at the break of dawn, we reach the Mariposa grove of the giant sequoia trees in the southern part of the Yosemite National Park. The Spanish named this region Mariposa for the many butterflies in the foothills. In 1864, Abraham Lincoln paused during the Civil War to set aside the Mariposa Grove and Yosemite Valley as a protected state reserve “for the pleasuring of the people.” The Yosemite National Park was established in 1890 and this grove was incorporated into the park in 1906. Huge trees lunge out from the earth, as if trying to bring down the corners of the is 87 meters, while the largest known basal diameter of a giant sequoia is about 12 meters.
These trees are still alive, and the story of their growth is simply explained at various stages along the trail, allowing the visitor to understand nature’s myriad complexities. The crown of a mature giant sequoia may bear thousands of green cones at any one time. Each cone contains about 200 tiny flat seeds resembling a rolled oak flake. Late winter storms bring strong winds that carry the pollen from the lower branches of one tree to the upper branches of others, continuing the genetic mixing necessary for healthy reproduction. To germinate, the seeds need direct sunlight, adequate moisture and bare mineral soil. Over the years, with the suppression of fires, other trees quickly spread over the forest floor, reducing sunlight, competing for the moisture and blanketing the mineral soil with their debris. It became impossible for the sequoia seeds to get started. However, a dependency on natural lightning — caused fires, was discovered for reproduction of the sequoias in the early 1960s.
By then, nearly a 100 years of unburned forest litter and young evergreens had accumulated, producing a natural fuel load. Had lightning ignited a fire under these unnatural circumstances, an intense fire would have occurred killing even the largest trees. To promote the sequoia reproduction, the park staff started a series of prescribed burns, deliberately set and closely monitored by rangers. During spring and fall, this would burn away the leaf litter leaving a thin layer of nutrient rich ash over the mineral soil. At the same time, the heat from such a fire would dry the cones causing a shower of seeds to fall after the fire on to a perfectly prepared seed bed. As the snow melts after the winter, the spring brings sunlight, moisture and the fresh seeds come alive to create a sequoia nursery. On August 7, 1990, lightning from intense thunderstorms ignited approximately 40 separate fires all over the park. Some of the fires became the most significant ecological events on record in Yosemite’s 100-year history. Without. fire, plant succession is stagnated and biological.