Of the 131,983 acres/53,41.6 hectares comprising Redwood National and State Parks in Northern California, 32,982 acres/13,347.3 hectares are old-growth forest. While many trees and plants thrive within an old-growth forest, at this mosaic of parks, it really is all about the coastal redwoods.
So, are coastal redwood trees related to giant sequoia trees? Yes, as members of the cypress family (Cupressaceae), these trees are closely related to each other. The sequoia is not as tall, but its trunk is much wider (some are 40 feet/12 meters in diameter) and they are longer-lived (some are greater than 3,000 years in age). Coastal redwoods can grow over 300 feet/91.4 meters tall and range in age from 500-2,000 years old.
It takes a specific climate to produce a coastal redwood tree: the maritime climate along the Pacific Coast, from central California to southern Oregon, provides plenty of rain annually (60-140 inches/152.5-355.6 cm), summer fog to reduce evapotranspiration (water transferred from the land to the atmosphere); temperate climate, average temperatures between 45-61oF/7-16oC; rich soil in river bottom flats; few natural enemies; burl sprouts which promote growth after injury by fire or toppling; wind protection by other redwoods.
Looking way up to the top of coastal redwood trees, Redwood National and State Parks / Rebecca Latson
How is it these trees have survived the vagaries of time, weather, and other outside factors for thousands of years? Bark thickness and chemistry have played a part in keeping fires, insects, and diseases at bay. Have you ever touched a redwood trunk? The fibrous bark feels spongy, doesn’t it? This bark can be as thick as 12 inches/30.5 cm, providing insulation and fire protection. Lack of flammable pitch or resin also protects against fire, while bitter, chemical compounds known as tannins make them unappetizing to insects and fungi.
Ever heard of a “goose pen?” While wandering the trails within Redwood National and State Parks, you may sometimes encounter a redwood with a triangular hollow opening, some large enough for you to actually enter. Even with their fire-resistant bark, redwood trees can still burn. When this happens, a hollow cavity may form at the base of the tree where the fire has burned deep into the redwood’s heartwood. Settlers used these triangular hollows as pens to hold their geese, hence the name “goose pen.”
Some "goose pen" hollows are large enough for one or more people to stand in, Redwood National and State Parks / Rebecca Latson
Several layers make up a coastal redwood tree, each with a specific role in that tree’s protection and growth.
Layers of a coastal redwood tree, Redwood National and State Parks / Rebecca Latson
According to savetheredwoods.org:
Bark – the outer layer of the tree, the bark, protects the tree from damage and disease. Coast redwood and giant sequoia bark is rich in a chemical called tannic acid, which insects and fungus avoid. The thick bark also protects the inner wood from fires.
Phloem – just below the bark is the phloem layer. The phloem carries the food, mostly sugar, from the leaves to the rest of the tree. That is where you find sap (water with sugars and nutrients).
Cambium – moving inward, the cambium is just below the phloem layer. This very thin layer is where new wood is made. When the cambium gets damaged, the tree’s growth stops or slows down.
Sapwood – this layer is also called the xylem. The sapwood is between the cambium and heartwood. It carries water from the roots to the rest of the tree. Old sapwood turns into heartwood over time.
Heartwood – the darker wood at the center of the tree is the heartwood. It keeps the tree tall and strong, giving support. The heartwood also stores water.
Roots – The roots take in water and nutrients from the soil. They grow long distances from the tree trunk but rarely grow deep. They have a special partnership with a fungus, which grows on the roots and helps the tree absorb nutrients.
Coastal redwood trees possess a shallow root system which makes them susceptible to windthrow, Redwood National and State Parks / Rebecca Latson
Speaking of roots, redwood trees have a shallow root system (10-13 inches/25.4-33 cm vertically) but which extend quite some length horizontally away from the tree (60-80 ft/18.3-24.4 m), intertwining with other redwood roots or stability. Also, redwood trees have no taproot (a straight root growing vertically downward to form the center from which other roots grow).
How do these tall trees, some of which grow over 300 feet/91 meters in height, get water from the ground to the tip top of the trunk and all its branches?
According to park staff:
At such towering heights, you might wonder how redwoods deliver water from their roots to the top branches. By an astonishing feat of physics, water evaporating from the tiny pores in leaves (stomata) creates enough suction through the tree’s water pipelines (xylem) to make the lift. But there is more to the story. Redwoods also absorb water from fog at all levels of the canopy through their stomata. In the dry summer, fog accounts for nearly 40 percent of their water uptake. This “stripping” of fog onto redwood leaves also benefits the entire redwood ecosystem, as excess water drops onto the forest floor.
How do redwood trees reproduce?
According to park staff:
Redwoods are monoecious (monos = single, oikos = house), meaning that male and female parts grow on the same tree. Inconspicuous, yellowish male cones (~0.2 in/5.08 mm) release pollen in late winter and early spring. The 1-inch-long (2.54 cm) woody female cones drop seeds in the late fall, but most do not germinate. Redwoods reproduce primarily asexually. The twisted and lumpy burls [hard conglomerates of many dormant buds created when either an original single bud fails to develop into a branch, instead growing, dividing, and redividing until a lump has formed] typically growing at the base of the tree can sprout new growth if the tree is damaged. This new growth nourishes the tree’s vast root system and can eventually develop its own root system. If you’ve ever stepped inside a perfect circle of redwood trees, sometimes called a fairy ring, you are experiencing the new generation of sprouts from the base of an old, fallen redwood or its stump.
Burls at the base of a redwood tree, Redwood National and State Parks / Rebecca Latson
