Fire and the Giant Sequoia

Giant Sequoia
Majestic Giant Sequoia

Growing in a lush grove, giant sequoia trees can stand up to 325 feet tall and live as long as 3,000 years. Their imposing size makes Sequoiadendron giganteum seem remote and invincible, but these trees that only grow on the western slope of the Sierra Nevada need the unpredictable heat of fire to reproduce.

Fire helps giant sequoias in many ways. Small, green cones full of seeds awaiting germination grow near the crown of the trees, yet without fire or insects to crack open the cone, the seeds remain trapped inside. Green cones can live with viable seeds inside them for up to twenty years. Fire dries out the cones, enabling them to crack open and deposit their seeds on the forest floor.

Female cone
Female cone

Giant sequoias have many trees and shrubs growing around their bases. A mixture of debris from these smaller plants coats the forest floor, creating a barrier that prevents falling seeds from reaching the rich soil. Shade from the smaller plants also makes the ground level too cool for tiny seeds to survive. Fire eradicates these problems. Brush and smaller trees are destroyed, leaving sunny patches and a clear forest floor, perfect for germinating seeds.

Fire loosens the soil, allowing seeds to fall into the mineral-rich earth and gather moisture that was previously drawn by larger plants. Tiny sequoia seeds then have a fighting chance to grow to the size of their huge cousins. As the forest debris, or duff, builds up again, the seedling is protected from the cold and seed-eating creatures.
Only a small percentage of seeds ever germinates and grows to adulthood. Too much sun, not enough moisture, or an unexpected fire can kill young, barely rooted seedlings. Even trees that are two or three years old can die when nature is not in perfect balance. However, fire remains one important part of the life cycle of the giant sequoia and a normal part of life in the forest.

Charred sequoia

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