Giant sequoias live in a total of only 67 groves on the western Sierra Nevada range where water and sun is plentiful. A sequoia tree requires 600 to 800 gallons of water per day. It wasn’t until 1890 after a tremendous amount of clearcutting had already taken place that Sequoia National Park was established to preserve these natural icons.
Ironically, the lumber was cut for commercial purposes, yet the brittle, dry nature of giant sequoia wood did not make it suitable for building houses or furniture. Sometimes when a sequoia fell the timber cracked. All that logged wood could only be sold as toothpicks, shingles and grape stakes.
It is upsetting to see huge stumps 20+ feet in diameter in a forest that once supported 2,000-year-old sequoias. In fact, there is a trail you can take called Stump Trail not far from the visitor center that features huge stumps surrounding a meadow. It gives you perspective on what was sacrificed.
Park managers are now seeking the right balance in these groves to ensure sequoia survival. In the past, it was believed that more trees would thrive if there were no fire; however, the approach meant natural fires were suppressed, which inadvertently allowed fast-growing, shade-tolerant trees, such as the white fir, to dominate the forests and compete with sequoias. Fire suppression also meant that there was no ash that sequoia seeds require to germinate.
The National Park Service, in collaboration with other agencies, is compensating for past management practices. Prescribed burns are carried out in different groves each year to reduce fuel that natural fire would have taken out. Groves are re-burned, if budget permits, after about 10 years. This method allows fires to burn less hot, which usually also means less high. One can see burn scars several stories high in sequoias on the Congress trail and other places in the park.
A mature sequoia is resistant to fire. Like certain other tree species, it has tannins in the bark and sapwood, but to a greater degree. Like pine trees, its lower branches fall off reducing the ability of ground fires to rise up the tree. The bark can grow two feet thick, a major form of protection. But full maturity takes at least 500-1,000 years.
Is the climate crisis affecting giant sequoias? Yes. One of the fire rangers explained that a brand new study is showing that some giant sequoias have died of bark beetle infestations. This phenomenon occurs when drought weakens a tree, and bark beetles, of which there are many species, enter it to feed and reproduce. They emanate a pheromone that tells other beetles this is their tree, which makes the other beetles spread out to other trees, potentially damaging an entire forest. It is hitting certain coniferous forests quite intensely not only in California, but other states as well. Some researchers call it a plague.
Of course, drought reduces water availability. Without water, the sequoia can’t grow properly. Finally, pollution also harms sequoias. It rises from Fresno and surrounding cities and affects the air quality that sequoias breathe.
Nonetheless, I’m optimistic—park managers now take into consideration a complex range of factors when making plans and decisions that affect the fate of the giant sequoia. Hopefully that will be adequate to protect them and encourage them to thrive.