Geography 316: Biogeography
In progress
12/16/2002
Geography 316: Biogeography In progress
12/16/2002
The Biogeography of Tanoak (Lithocarpus densiflorus)
Tanoak
Tree
Charles Webber © California
by Melanie Gadwah, student in Geography
316
Thank you for visiting our site. This web pages was written by a student in Geography 316:
Biogeography and edited by the instructor, Barbara Holzman, PhD. All photos and maps
are posted with specific copyright permission for the express use of education on these
web pages. The students have tried to be as accurate as possible with the information
provided and sources and references are cited at the end of each page.
Species Name: Lithocarpus densiflorus
Kingdom: Plantae
Division: Magnoliophyta
Class: Magnoliopsida
Order: Fagales
Family: Fagaceae
Genus: Lithocarpus
Blume
Species: Lithocarpus denisflorus var. densiflorus
Lithocarpus densiflorus var. echinoides (shrub form)
Description of Species:
Lithocarpus densiflorus, commonly known as tanoak, is a bushy leafed evergreen, and is considered a tree or a shrub. It is medium sized raniging from 50-90ft. with the tallest trees reaching around 150ft. high, and as a shrub, it is less than 10ft high (USDA, 2001).They may live to be 300 to 400 years old, but the average life span is 180 years. It has thick, sclerophyllous (hard, leathery, waxy, and water resistant), dark green leaves that are serrated on the edges. Although Lithocarpus densiflorus is not a true oak, its acorns resemble that of the oak tree, and are considered a relative. Also, because its flowers resemble that of a Chestnut, it is actually believed to be a cross between an oak and a chestnut (USDA, 2001). The flowers are yellowish white and the acorn is 2-3cm long and shaped like an egg. The acorns are yellowish brown however the tanoak acorn's cap is hairy, rather than scaly like true oak acorns.
"The form of tanoak varies greatly. In
closed stands, particularly in dense coniferous forests, tanoaks develop one central axis,
narrow crowns, ascending branches, and long trunks that are clear for 30 to 80 ft.
In this form, tanoak is one Tanoak
Acorns. Charles Webber© of the most
stately broadleaved trees in the West. In open stands, however, especially in
association with
California
Academy of Science Pacific Madrone
and California black oak, tanoaks are free branching; the crowns are broad, the
limbs horizontal and large,
and the trunks short and thick. The main trunk divides into several large branches
and forms a rounded crown"(forestworld.com).
Tanoak Shrub. © Br.
Alfred Brousseau, Saint Mary's College
Natural History:
The tanoak is a hardwood and is rarely found without conifer association. It generally grows with redwoods, Doulglas-fir, Pacific madrone, many of the oaks; live oak, black oak, and interior live oak to name a few. Other species associated with the tanoak are; the sword fern, grasses such as; bromes and fescues, Shrubs; California hazel, poison oak, and Cascade holly grape. In the mixed evergreen forest Lithocarpus densiflorus is the most abundant angiosperm.
The tanoak is monoecious, having both male and female flowers on the same branch with the male flowers on the upper part and the female flowers at the bottom. Acorns are produced by the tiny flowers, which are wind pollinated in spring. They usually bloom in the summertime, June, July, or August. Tanoaks can produce acorns as early as five years old; however they generally don't produce consistently until 30-40 years of age (forestworld.com). Once frequent production begins, lots of seeds are produced every year, but the germination process is very slow and the acorns are usually consumed by various species.
Despite the acorns hard seed coat, at least 38 species of animals eat them. Principal consumers include 4 bird species, 11 rodent species, deer, bears, and raccoons. Goats, hogs, and cattle also prevent seedling reproduction by devouring acorns and nibbling on seedlings. Other biotic factors such as insects are a threat to acorns because insects like the filbert weevil and the filbert worm lay their larva inside the acorns. One study found insect larvae infesting 51 percent of the acorns. Abiotic factors that limit its survival are; frost, drought, and fire.
Many trees flourish in the presence of fire, however to the tanoak fire is a predator. Before the twenty first century, fires generally occured frequently in 5-50 year intervals, however in the present, infrequent fire conditions, tanoaks are able to rejuvenated and become a dominant species in this kind of stand (Hunter 1997). They usually occur as single trees, in clumps or groves, or areas up to 100 acres(McDonald 1996) and is very rarely found as a pure stand.
In the journal by John C. Hunter, Fourteen years of change in two old-growth Pseudotusga-Lithocarpus forests in northern
Evolution:
It is estimated that Lithocarpus
contains 300 species (Jones 1986). With the exception of the tanoak, which is found in the
Pacific southwestern part of North America, this genus is restricted to Southeast Asia,
Indonesia, and southern Japan. Since
there are similar characteristics to other genus, mainly Castanopsis and Quercus(oaks), the placement of
certain species has created some controversy. The
tanoak is not a true oak, however its striking resemblance to the oak family gives it, its
name. The leaf form of Lithocarpus is generally entire or only partly
toothed, but Lithocarpus densiflorus is the only
species with strongly serrated edges.
Fossil records indicate that hardwoods existed in the Miocene epoch of 12-26 million years ago. This species is well adapted and has survived glaciation, volcanism, upthrusting, and subsidence. The tanoak has adapted both morphologically and physiologically. “Morphological features include special structures and coatings on leaves and stems to inhibit moisture loss, smooth upper stem bark to facilitate the transport of water to the base of the tree via stem flow, extensive deep-thrusting root system, capability of forming a burl at an early age, and the capacity to produce both enormous amounts of seed and large numbers of rapidly growing root crown sprouts. Physiological processes involve photosynthesis, transpiration and respiration which govern plant metabolism, energy intake, water losses and eventually dominance potential” (McDonald 1996).
The journal Evolution of The Fagaceae: The Implications of Foliar Features, by Jay H. Jones, focuses on leaf fossils to find out where and when the family Fagaceae first existed, however there has been a lot of confusion about the accuracy of the findings. Although it has been suggested that fossil records of the family Fagaceae date back to the Cretaceous, Pre-Tertiary periods, poor data may indicate otherwise.
Distribution:
Tanoaks are not widely distributed at all. They flourish in the
moist, foggy climates of the West Coast of the
Map of Distribution:
Distribution map of the Tanoak tree.
Other interesting issues:
Uses: The wood of tanoak os used for many things besides firewood. It has been used for flooring, railcar decking, paneling, yeneer, plywood, gunstocks, pallets, crossties, baseball bats, and pulpwood. Another way it was used was by stripping the bark from the trees for tannin extraction. Past history tells us the acorns were a main staple for the Native American Indians(forestworld.com).
Sudden Oak Death
A recent discovery that has been the now leading cause of tanoak deaths is due to sudden oak death, caused by Phytophthora ramorum. Phytophthora ramorum is a fungus-like organism (Phytophthora
species are water molds), that was first discover in Marin county in tanoaks in 1995. Sudden oak death has been confirmed to be the cause of oak mortality in ten counties in the state of California; Alameda, Mendocino, Marin, Monterey, Napa, San Mateo, Santa Clara, Santa Cruz, Solano and Sonoma.Observed symptoms of SOD in Tanoaks
1) Tree has dark green foliage, no trunk symptoms.
2) Foliage turns from dark green to yellow-green, to light brown. Seeping may or may not be detected. This sequence is particularly characteristic of juvenile trees.
3) Seeping appears on the lower trunk. This may be
represented by small, light to dark stains or by droplets of hardened reddish-brown to
black exudate. On those trees with few seeps, these tend to be located near the ground
(lower than 20 cm), or may be on the upper surface of exposed roots.
4) Seeping may become extensive, covering more of
the trunk, typically within 2 m above the
5) Bark and ambrosia beetles tunnel into bark,
often entering through natural fissures. Beetles are found on larger diameter trees.
Boring dust may be abundant, particularly in crevices, spider
6) Fruiting bodies of Hypoxylon thouarsianum may
be found on the main stem. These structures may appear to a height of 5 m or
greater.
7) Foliage may become bleached and yellowed. Branch
tips may wilt and turn brown, as if treated with herbicide. In latter stages,
leaves turn pale yellow-green, then brown. New shoots may appear at the
base. These typically wilt before they reach
8) Brown leaves may be retained on dead trees for 6 months or more. Basal shoots may be produced for at least several years after the main stem is dead (McPherson, 2000).
"Careful research is still needed to address many questions about how the fungus infects trees, the length of time between infection and symptom development, how and where the fungus survives in the environment, how it is transported between trees, and how long the fungus has been present in California. It must be emphasized that the required studies may take some time to complete, partly because the Phytophthora is a species new to science, and partly because many of the processes being studied may be slow"(Swiecki, 2000).
The California Oak Mortality Task Force
“Created in August 2000, the California Oak Mortality Task Force (COMTF) is a non-profit organization, under the California Forest Pest Council, that brings together public agencies, other non-profit organizations and private interests to address the issue of elevated levels of oak mortality. The Task Force will implement a comprehensive and unified approach for research, management, education and public policy”(The California Oak Mortality Task Force, 2002).
Bibliography
1) Harrington, TB;
Tappeiner, JC II. Growth Response of young Douglas Fir and Tanoak 11 years after various
levels of hardwood removal and understory
suppression in
2) Hunter, JC. Fourteen
years of change in two old-growth Pseudotsuga-Lithocarpus forests in
3) Lithocarpus densiflorus
(Hook &Arn..) Rehd. Tanoak, Life History-Sapling and pole
4) McDonald
PM, Tappeiner JC II. 1987. Silviculture, ecology, and management of
McDonald is a research forester at the USDA Forest Services Pacific Southwest
5) USDA, NRCS. 2001. The PLANTS Database,
Version 3.1 (http://plants.usda.gov).
6)
7) Jones, Jay H., Phylogeny of the Hamamelidae Evolution of the Fagaceae: The
Implications of Foliar Features, Annals of the Missouri Botanical Garden, Vol.
73, No. 2. (1986), pp.
228-275. Stable URL:
8) Axelrod, Daniel I., Biogeographical Relationships between temperate Eastern Asia nd Temperate Eastern North America: The Twenty-Ninth Annual Systematics Symposium[Part 2], Biogeography of Oaks in the Arcto-Tertiary Province, Annals of the Missouri Botanical Garden, Vol. 70, No. 4. (1983), pp. 629-657.
9) Kuchler, A.W.,The Broadleaf Deciduous Forests of the Pacific Northwest Annals of
the Association of American Geographers, Vol. 36, No. 2. (Jun., 1946),
pp. 122-147. Stable
URL:
11) R. H. Waring, J. F. Franklin, Evergreen Coniferous Forests of the
Pacific Northwest,Science, New Series, Vol. 204, No. 4400. (Jun. 29, 1979), pp.
1380-1386. Stable URL:
12) Swiecki, Tedmund J. Ph.D., Plant Pathologist and Principal Phytosphere
Research, Observations and Comments on Oak and Tanoak Dieback and Mortality in
13) Gottschalk, Kurt W., Morin, Randall S., Liebhold,
Andrew M., Potential Susceptibility of Eastern Forests to Sudden Oak Death,
Phytophthora ramorum, USDA
14) Sudden Oak Death: What is sudden oak death? Copyright © 2001, Province of
15) McPherson, Brice A,
Wood, David L., Storer, Andrew J., Svihra, Pavel, Rizzo, David M.,
Kelly,N. Maggi, and Standiford,Richard B., Oak Mortality
Syndrome: Sudden Death of Oaks and Tanoaks, Tree notes, California Department of Forestry
and Fire Protection, August 2000
16) The California Oak Mortality Task Force, November 2000 http://www.suddenoakdeath.org/
send comments to bholzman@sfsu.edu
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