Download Redwood Forest - Fort Hays State University

Coastal
Forests
Redwood National
and State Parks
California
Department of Biological Sciences, Fort Hays State University
Instructor: Mark Eberle
Course Homepage
Our last stop along the Pacific Coast is the redwood forest in northern California. Coast
Redwood (Sequoia sempervirens) is confined to a section of the lowland coastal forest in
northern California and a small area of adjacent southern Oregon. The redwood forest is the
southern end of the temperate coastal rain forest that extends northward into Alaska. Northern
California receives less total precipitation than the Washington and Oregon coasts to the
north, but it compensates for that deficiency with regular summer fogs, which are an
important component to the regional hydrologic cycle. About 34% of the annual water input
in redwood forests of northern California comes from fog drip from the trees, compared to
only about 17% in areas where trees are absent (Dawson, 1998). Thus, Coast Redwoods are
important in making this water available within the ecosystem, not just for themselves, but
also for other plants. During the foggy summers, about 19% of the water in Coast Redwoods
and about 66% of the water in understory plants is derived from fog drip onto the soil.
Morning Fog at Gold Bluffs Beach, Prairie Creek Redwood SP, California
Photograph by Curtis Wolf, July 2005
The redwood forest also includes Sitka Spruce (Picea sitchensis) and other species that we
saw at sites visited prior to this on the coasts of Oregon and Washington. However, in the
often foggy river valleys, Coast Redwoods dominate the forest community, with a lush
understory of Sword Ferns (Polystichum munitum) and Redwood Sorrel (Oxalis oregana)
(also known as Oregon Oxalis; surrounding the frog in the photograph on the right at the
bottom of the last page). A spectacular display of ferns covers the walls of Fern Canyon,
which opens toward the Pacific Ocean. Natural meadows, such as the one at the entrance to
our campground at Prairie Creek Redwoods State Park, offer excellent opportunities to see
Elk (Cervus canadensis), especially in the morning or evening.
Fern Canyon, Prairie Creek Redwood SP, California
(with Mark Eberle and Aaron Austin)
Photograph by Curtis Wolf, July 2005
Coast Redwoods are adapted to floods and fires. One adaptation is the presence of
dormant buds near the base of the tree. If a flood deposits silt around the base of its trunk, a
redwood will grow new roots from these buds to keep its roots close to the surface. In
addition, redwoods that are burned or cut can sprout new stems from these buds, forming a
“fairy ring” of new trunks (next page, right photograph). Masses of these buds sometimes
bulge from the side of the tree to form a burl. The thick bark and virtually nonflammable pitch
also help Coast Redwoods resist fire damage. However, some fires are severe enough to kill
trees, and large floods can topple redwoods growing in river valleys, but the bare seedbed
cleared by the fire or deposited by the flood is ideal for the establishment of Coast Redwood
seedlings (information from summary by Johnston, 1994:15‒19).
Forest Trail and Redwood “Fairy Ring”, Redwood NP/SP, California
Photographs by Alaina Elliott, August 1997, and Mark Eberle, July 2002
One important aspect of forest ecology we are unable to explore occurs in the canopies of
tall trees of old-growth forests. The summary presented here is derived from studies of this
ecosystem by Stephen Sillett and others, and he provides some excellent images and
descriptions of the canopy ecosystem on his website (accessed 24 November 2009). Just as
we have seen new trunks established as fairy rings near the ground, damage in the trunks near
the tops of trees can result in the growth of “reiterated trunks,” which can also be damaged
and give rise to their own reiterated trunks. Damaged branches also can give rise to reiterated
trunks, after which they are referred to as “limbs” that develop buttresses on their lower
surface to help support their weight. The result of this potential regrowth is that the number of
reiterated trunks on a single tree can be in the hundreds, providing incredible structural
diversity in the canopies.
The crotches of reiterated trunks and the large platforms on the surface of limbs provide
habitat for lichens and epiphytic vascular plants, such as ferns, shrubs, and even trees. This
increase the structural diversity of the Coast Redwood canopy provides habitat for a variety of
animals, including the Wandering Salamander (Aneides vagrans). About 10‒20% of Coast
Redwood leaves are shed annually, and some collect in the crotches or on limbs, where they
decompose and contribute to the initial canopy soil. Canopy soils in the redwood canopy are
most frequently associated with Leather-leaf Fern (Polypodium scouleri), which can form
deep mats composed primarily of dead fern rhizomes. One fern mat had an estimated 336 kg
(740 pounds) of dry mass, and held 500 L of water (dry summer season) to 1,500 L (wet
winter season). Fern mats formed in the crotch of reiterated trunks typically hold more
moisture than those on limbs.
Red-legged Frogs, Del Norte Coast Redwoods SP and
Prairie Creek Redwoods SP, California
Photographs by Jenn Nylund, August 1997, and William Cook, August 2000
Literature Cited
Dawson, T. E. 1998. Fog in the California redwood forest: ecosystem inputs and use by plants.
Oecologia 11:476‒485.
Johnston, V. R. 1994. California Forests and Woodlands: A Natural History. University of California
Press, Berkeley.
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