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May 22, 2024
Giant Sequoias are Dying
Giant sequoia, Sequoiadendron giganteum, is an endangered species which grows only on the western slopes of the Sierra Nevada in Central California. It has a narrow habitat range - for a distance north and south of about 250 miles at elevation of 4,000 to 8,000 feet. The matured giant sequoia is about 300 feet high with 40 feet diameter. The matured trees area about 3,200 years old. It is a slow glowing tree. It is a slow growing tree. The diameter of a 100-year old tree is about the size of quarter!
There is a similar species called coast redwood, Sequoia sempervirens, which grows narrow band along the Pacific Coast from central California to southern Oregon. The matured coast redwood is taller, skinner, and younger (2,000 years old) than giant sequoia. This species is also an endangered species.
For such a large tree, cones of giant sequoia are small. Seed cones are about 1.5 - 3.5 inches. Seed cones can mature and open in 2 years but can remain on the trees for 20 years until fires dry out, open and release their seeds.
Ref: https://hcihunkasequoia.weebly.com/sequoia-trees.html
Western cedar bark beetle
Steven Valley, Oregon Department of Agriculture, Bugwood.org
Bark is about 23 to 31 inches thick, fibrous, ridged and furrowed. It is very dry and looks like coconut husk. The thick and fibrous bark can protect trees from fires.
This tree needs forest fires to sustain growth. Because we (human) put out forest fires in recent years, there are no young giant sequoia trees. When forest fires are managed, it does not create a high nutrient ash layer on the ground for seed germination and does not increase sunlight by killing some of the competing pines and fires. Another fact is that giant sequoia had been attacked by western cedar bark beetle, Phloeosinus punctatus. The Monarchs (3000+ years old matured trees) are dying because of the beetle. It is a native bark beetle which is about 1/8 inch (3mm) long (size of rice grain). I could not believe how this small bark beetle could burrow through the thick bark. WCBB can fly and attacks upper canopy where the bark is relatively thin. Scientists believe that combination of historic drought in 2012-2016, low severity fires, and fire injury may have weakened trees.
If you are interested in learning more about giant sequoia and their life cycle, here are some good reading materials.
Giant Sequoias Face New Threats
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