Tuesday, July 7, 2020
Giant Sequoia - Sequoiadendron giganteum
The "Giant Sequoia" - Sequoiadendron giganteum - is most well known for it's sheer size. They are the largest single living thing on the planet, growing on average from 164-297 feet tall in ideal conditions. They are also among the oldest with some being recorded (based on ring measurements) at over 3500 years old. They grow in a very small native area on the western slopes of the Sierra Nevada Mountains in California. Generally the Giant Sequoias grow in groves or natural stands, currently there are only 68 known groves that exist. Groves range in size from 6-20,000 trees each. Giant Sequoias have been successfully grown outside of their native range in The Pacific Northwest, Southern United States, Western & Southern Europe, British Columbia, Southeast Australia and New Zealand. There are some specimen trees planted in parks and private lands around the world that reach great heights (191 feet is record outside of the US near Ribeauvillé, France), but none nearly as grand as the Giants growing in the Sierra Nevada Mountains.
Image Citation (General): Brian Lockhart, USDA Forest Service, Bugwood.org
The sheer size of this type of tree, has lead to extensive research regarding ability to maintain and supply water within such a large living structure. Osmotic pressure can only force water a few meters then the tree's xylem must take over, still it is not possible for these capillaries to transport water hundreds of feet in the air even accounting for the sub-pressure caused by the leaves water evaporation. Sequoias have the ability to supplement their water intake from the ground or soil by using moisture in the air, generally this comes in the form of fog which frequently blankets the native growth range .
Image Citation (Cone and Foliage): Tom DeGomez, University of Arizona, Bugwood.org
Over time, the Giant Sequoias have developed a resistance to fire damage. The first way is because their extremely thick bark is almost impenetrable to fire damage. Secondly the heat from fire causes the cones to dry and then open, disbursing seeds which will go onto become new seedlings repopulating what may have been lost below. Fire damage also wipes out any small ground cover that may have competed for sunlight and nutrients the new seedlings require to thrive. On their own without help from fires the Giant Sequoias seed have trouble germinating as shade loving species tend to choke the new seeds out.
The leaves are evergreen, awl shaped 0.12-0.24 inches in length and arranged spirally on each shoot. The bark is very furrowed, thick and fibrous. The seed cones are 1.5-2.8 inches long and mature in 18-20 months, though they usually remain closed and green for upwards of twenty years. Cones are made up of 30-50 spirally arranged scales, each scale containing several seeds. Each individual cone can produce approximately 230 seeds each. Seedlings grow from seeds but do not begin to produce cones until at least their 12th year. Once mature the tree does not produce shoots on their stumps as the Coast Redwood does, they do however sprout from boles after fire damage.
The most well known Giant Sequoias in the United States are:
1. General Sherman (located in the Giant Forest, 274.9 feet tall)
2. General Grant (located in General Grant Grove, 268.1 feet tall)
3. President (located in the Giant Forest, 240.9 feet tall)
4. Lincoln (located in the Giant Forest, 255.8 feet tall)
5. Stagg (located in Alder Creek Grove, 243 feet tall)
6. Boole (located in Converse Basin, 268 feet tall)
7. Genesis (located in the Mountain Home Grove, 253 feet tall)
8. Franklin (located in the Giant Forest, 223.8 feet tall)
9. King Arthur (located in Garfield Grove, 270.3 feet tall)
10. Monroe (located in the Giant Forest, 247.8 feet tall)
The Giant Forest is home to over half of the worlds Giant Sequoia Trees. Located in Sequoia National Park, The Giant Forest should be included as a top "to do" on any tree lovers list. You can visit there website directly at: http/www.visitsequoia.com/giant-sequoia-trees.aspx