Northern California Coastal Forests

• Category: Forest Biomes.
• Geographic Location: North America.
• Summary: The coastal redwood forests of northern California form a unique and cherished forest ecosystem that has been the focus of extensive conservation efforts to protect and preserve some of the largest trees on the planet.

The coastal redwood forest is the dominant ecosystem in coastal northern California. Commonly called redwood (Sequoia sempervirens), the tree belongs to the redwood family Sequoioideae, a relative of the giant sequoia (Sequoiadendron giganteum), found inland in California on the western slopes of the Sierra Nevada mountain range and the dawn redwood (Metasequoia glyptostroboides), which is native to China. Coast redwoods are the tallest trees on Earth and the second-longest-lived. They can grow to more than 350 feet (107 meters) tall and live more than two thousand years.

Redwoods are second only to giant sequoias in terms of their individual biomass volume, and the northern redwood forests are among the most productive on the planet, with productivity rates that rival those of tropical forests. These forests grow within a limited range in northern California, have several unique structural characteristics, and have been the focus of conservation efforts for more than one hundred years.

Though coast redwoods and their close relatives were distributed across much of the mid-latitude Northern Hemisphere during the Cretaceous and early Tertiary Periods (144 million to more than 30 million years ago), they now are native only in a north-south stretch of approximately 466 miles (750 kilometers) from the southwestern tip of Oregon to Monterey County, California. They occur only within a narrow fog belt that stretches east-west from near the ocean up to 40 miles (65 kilometers) inland. In fact, the presence of fog during the otherwise dry summer is a defining characteristic of coast redwood forests.

Not only does the fog reduce water loss by the trees during dry seasons, but the redwoods can obtain water, and sometimes nutrients, from the fog as its molecules are stripped from the air by the redwood needles (leaves) and drip to the ground. The reduction in water loss and additional water supply are important because the overall climate of northern California is Mediterranean. Almost all the rainfall occurs during the cool, wet winter, and there is little to no rain during the warmer, dry summer.

Vegetation

Redwood forests typically are found in alluvial areas near streams, and on hills and slopes with sandstone bedrock; they do not grow well in soils with very high iron or magnesium concentrations (ultramafic, or igneous-type soils). Toward the drier, southern end of their range, they do not grow well on exposed hilltops, which are dominated instead by chaparral or mixed evergreen forests consisting of Douglas fir, tanoak, bay laurel, and Pacific madrone. These other trees occasionally occur together with redwoods and as small mixed evergreen stands within redwood forests throughout the range. Nor do redwoods grow immediately next to the coast; the spray of sea salt inhibits their growth. Beach, coastal grasslands, and coastal chaparral ecosystems dominate the land areas close to the ocean, or they can contain western hemlock, coast live oak, Sitka spruce, and other tree species instead of redwood.

The tops of the tall, large redwood trees to the north are a canopy ecosystem unto themselves. Canopy soil that forms from decomposing litter in the nooks between large branching trunks can be more than 1 foot (0.3 meter) deep, allowing ferns and trees such as Sitka spruce and western hemlock to grow high up in the tree canopy.

Animals

The dominant redwood forest stands within this biome, harboring a diverse range of animals, including the black bear, Roosevelt elk, and bobcat among the larger mammals, and the gray fox, big brown bat (Eptesicus fuscus), and Douglas squirrel or chickaree (Tamiasciurus douglasii) among the smaller species.

Along and within tidal pools are found such characteristic species as the purple shore crab (Hemigrapsus nudus), California mussel (Mytilus californianus), and the giant green anemone (Anthopleura xanthogrammica). Shoreline birds range from killdeer (Charadrius vociferus) to sanderling (Calidris alba) and willet (Catoptrophorus semipalmatus).

Birds within the forest proper include varied thrush (Ixoreus naevius), Steller's jay (Cyanocitta stelleri), chestnut-backed chickadee (Parus rufescens), and winter wren (Troglodytes hiemalis). Chief among avian predators here is the bald eagle (Haliaeetus leucocephalus).

More than three hundred fungal species have been found in coast redwood forests, supporting many animals that prowl the well-shaded zones around the redwood trunks; another often-seen denizen of the forest floor is the banana slug (Ariolimax columbianus). The canopy above is home to diminutive species such as the California slender salamander (Dicamptodon tenebrous) and the Pacific tree frog (Pseudacris regilla).

While the forests are vastly protected, some of the animals found within it are listed as threatened or endangered by the Endangered Species Act. For example, the Northern Spotted Owl (Strix occidentalis caurina) is listed as threatened, while some argue for a reclassificiation to endangered. Also threatened is the Western Snowy Plover (A. nivosus), a small shorebird infamous for its camouflage.

Logging and Preservation

Old-growth coast redwood forests have unique structural characteristics that provide habitat for endangered species such as the northern spotted owl (Strix occidentalis caurina) and marbled murrelet (Brachyramphus marmoratus), as well as salmon spawning in their streams. The redwoods are highly cherished for their cultural and natural value, in part because they occur naturally within a very limited range of the world. For these reasons—and their rapid decline due to logging in the early twentieth century—redwood forests have been the focus of intensive conservation efforts.

At the turn of the twentieth century, there were more than two million acres (809,400 hectares) of old-growth redwood forest. Much of this was cut down for timber, and less than 5 percent of the old-growth redwood forest present before European settlement remains today. Of the remaining old-growth forest, about 80 percent is protected in a park or preserve or by a land preservation agreement. The majority of the rest of present-day redwood forests are secondary forests that are operated by logging companies for timber production or have regrown after logging.

While logging threats have diminished, concerns remain around global warming and an increase in wildfires in the area. However, according to experts, redwoods grow quickly and are adaptable. They also have bark that contains acid that retards flame. Of more concern are the species that are dependent upon them, such as the northern spotted owl. These species need careful monitoring and conservation, if necessary.

Bibliography

Biggar, Hugh. "How Are California's Redwood Forests Weathering Fires and Climate Change?" Landscape News, 17 Aug. 2021, news.globallandscapesforum.org/46322/what-can-redwood-forests-teach-us-about-other-biodiversity-hotspots/. Accessed 28 Oct. 2024.

Bourne, Joel. "Redwoods: The Super Trees." National Geographic, vol. 215, no. 10, 2009, pp. 28-59.

Evarts, J., and M. Popper, editors. Coast Redwood: A Natural and Cultural History. Cachuma Press, 2001.

Noss, R. F., editor. The Redwood Forest: History, Ecology, and Conservation of the Coastal California Redwoods. Island Press, 2000.

Sloss, Lauren. "The Quiet Strength of an Old-Growth Forest." The New York Times, 15 June 2021, www.nytimes.com/2021/06/15/travel/california-redwoods-oldgrowth.html. Accessed 28 Oct. 2024.

Stokstad, Erik. "Ancient Redwoods Recover From Fire By Sprouting 1000-Year-Old Buds." Science, 1 Dec. 2023, www.science.org/content/article/ancient-redwoods-recover-fire-sprouting-1000-year-old-buds. Accessed 28 Oct. 2024.