Above that level the older trees may keep one or more branches that come horizontally out of the main trunk and then turn upward, reaching another one hundred to one hundred fifty feet into the sunlight. Many old giant sequoias are snag-topped in appearance. That is, they have dead wood at the top of their crowns, indicating that they have been taller and then died back somewhat even though they otherwise appear to be healthy and robust. The largest single cause of snag-tops is fire damage. Rate of Growth Coast redwoods may put on six, eight or even more feet of height in a single season whereas the giant sequoia is more likely to grow about two feet in height per year throughout its first fifty to one hundred years.
Growth rings one half inch in thickness are common in young giant sequoias under optimal conditions.
This amounts to an increase of one inch of diameter per year. And rapid growth is likely to continue even when the trunk has become one hundred or more feet in circumference. By then the annual growth rings may have become narrower, but the overall volume of growth may be continuing at the same or an increased rate. As part of their work for the National Park Service, the Hartesveldt research team measured both the size and rate of growth of many giant sequoias. They found that the diameter of the tree had increased about three inches during the forty years years since careful measurements were made in 1931.