Giant sequoias, the planet’s largest trees and among the oldest living things on Earth—many of the largest are over 3,000 years old—depend on fire to help them reproduce. Learn how a destructive force is necessary for new life in this clip from Nature on PBS. Some background from

In the early 1960s, Dr. Richard Hartesveldt explored the connection between fire and sequoia regeneration. His small-scale prescribed fires followed nearly a century of fire suppression, and resulted in the germination of sequoia seeds and the recruitment of sequoia seedlings – something that had not occurred in the absence of fire.

Since those first experiments, researchers have further shown the benefits to sequoias from fire. Dendrochronology has determined that low intensity surface fires swept through the big trees approximately every 5 to 15 years. Sequoias rely on fire to release most seeds from their cones, to expose bare mineral soil in which seedlings can take root, to recycle nutrients into the soil, and to open holes in the forest canopy through which sunlight can reach young seedlings.

Sequoias also need fire to reduce competition from species such as white fir (Abies concolor) and Incense cedar (Calocedrus decurrens), which are shade-tolerant and able to recruit seedlings in heavy litter and duff. Fire suppression has resulted in heavy accumulation of forest litter and the encroachment of thick stands of white fir and incense cedar, both of which compete with sequoias for water and nutrients. A natural fire cycle thins these competing species, and provides suitable conditions for sequoia growth.

Related reading: Differences between giant sequoia and redwood and the science of Fire Ecology.

Next: How do firefighters combat and control wildfires? Plus, more time lapse plants and more giant sequoias and redwoods, including how scientists climb & measure redwood giants.

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