in northern California Elfin forests of
California are the primary example of coastal temperate dwarf forests. They are expansive, and cover most of the mountains in the southern half of
California, extending into
Mexico,
Nevada, and
Arizona. Other expanses of elfin forest are found throughout the state, in the northern and central regions. In
northern California,
Salt Point State Park is home to an elfin forest with Mendocino cypress (
Cupressus pygmaea), which is endemic to the Mendocino area. On the
Central Coast of California, on the southeastern shore of
Morro Bay,
Los Osos contains the El Moro
Elfin Forest Natural Area. The area is approximately . It derives the "elfin forest" title from the short
California live oaks, which range in height from , compared to the typical . This region also contains the federally endangered Morro shoulderband snail (
Helminthoglypta walkeriana). At a higher
elevation, on
Cuesta Ridge, the
Land Conservancy of San Luis Obispo County manages the
San Luis Obispo Elfin Forest of dwarf cypresses. Factors such as soil moisture, solar radiation, and rockiness of soil influence
species composition along an elevation gradient, resulting in certain shrub species, such as
Adenostoma fasciculatum and
Arctostaphylos glauca, being present in elfin forest habitats. Fire occurs at low-moderate frequency with high severity. Many plants have adapted to this by having serotinous seeds that open to germinate only under high heat.
Invertebrates include
burrowing scorpions (
Opistophthalmus spp.), and various species of scorpions,
spiders and
ticks.
Seasonal variations The Californian climate usually exhibits wet winters and dry summers. Plants found in elfin forests grow during winter months, and become dormant during the summer due to drought stress. Plant communities also rely on taking in moisture from the air by intercepting fog to supplement the low, seasonal rainfall.
Formation Formation of coastal elfin forests in northern California and Oregon, began with a series of
marine terraces. A combination of uplift and changes in ocean level formed a system of terraces, resulting in an “ecological staircase”, with each terrace approximately 100,000 years older than the one below it and supporting a distinct association of soils, microbes, plants, and animals. A dune being pushed farther away from the coast by fluctuating sea levels slides over the one before it and solidifies, raising the terraces. Pioneer plant communities colonize the young terrace. The succession of plant communities that repeats on each terrace eventually forms a very specific
podzol known as the Blacklock series, which offers an inhospitable environment for species and greatly stunts further growth on the terrace. Part of this soil profile includes an underlying clay or iron hardpan. Each terrace is relatively level and many are footed by paleo-dunes. Drainage is poor at best on these stairs and plants sit in a bath of their own
tannins and acids for much of the wet season. Due to limited root mobility and acidic soil, plant communities on these terraces grow into stunted forms. Remnants of ecological staircases doubtless exist, however most have been destroyed for development or logging. Analyses of pygmy forest soils show low levels of
macro- and
micronutrients, and high levels of exchangeable
aluminium, which limits the ability of plants to grow. Low pH conditions support formation of an
iron hardpan, preventing the trees from setting deep
roots and preventing internal drainage of soil water. As a result, the pine trees in the area are rarely more than three or four feet high, in a sort of natural
bonsai effect. Many of the tree trunks, though only an inch thick, contain 80 or more
growth rings. Only yards away, but with younger soils, the same species of tree grows many dozens of feet high.
Examples Examples of high-terrace podzol pygmy forests include: • Mendocino pygmy forest in
Mendocino County, California, for example, is an
oligotrophic community caused by
podzolized (nutrient-poor, highly acidic) soils. The forest flora is dominated by dwarfed
bishop pine, bolander pine (a variety of
shore pine), and
Cupressus pygmaea. Bishop pine occurs in both dwarfed and full size form, the latter being trees whose roots have broken through the hardpan layer into the more fertile soil beneath. This forest is found in several discontinuous areas, with significant portions on the following public lands: •
Jug Handle State Natural Reserve, where it is the feature of the highest portion of the Ecological Staircase Trail. Adjacent, to the east, is the Pygmy Forest
National Natural Landmark. within
Jackson Demonstration State Forest. •
Russian Gulch State Park. •
Jackson Demonstration State Forest includes a large pygmy forest area east of the towns of
Mendocino and
Casper. • The Hans Jenny Pygmy Forest Reserve, co-managed by the
University of California Natural Reserve System and
The Nature Conservancy. • Within the
Van Damme State Park is the
Charlotte M. Hoak Pygmy Forest, located along the northern border of the park. A second pygmy forest location on the southern border has a self-guided nature trail built entirely on an elevated walkway forming a short loop through the site. •
Salt Point State Park in
Sonoma County, California has a much smaller pygmy forest and a fifth terrace prairie ranging from 900 to 1000 feet and formerly supporting elk populations. Like the Mendocino forest, the dominant trees are also bishop pine, bolander pine, and
C. pigmaea. Most of Salt Point is on the northernmost portion of the
Salinian Block and the terrace staircase drops suddenly into the
gulch that lies over the
San Andreas Fault. • SFB Morse Botanical Reserve in the
Del Monte Forest of the
Monterey Peninsula is centered on the small Huckleberry Hill pygmy forest of bishop pine and
C. goveniana, in the middle of a more extensive forest of
Monterey pine. Bishop pine, which tolerates extreme podzol conditions better than Monterey pine, is found in the most heavily podzolized areas, with a zone of bishop pine/Monterey pine hybrids dominating the less heavily podzolized area. Other examples of California pygmy forests include: •
Elfin Forest Natural Area - El Moro Elfin Forest — 90 acre State Nature Reserve of 'pygmy oaks' (coast live oak,
Quercus agrifolia). Located on the southeastern shore of
Morro Bay, in
Los Osos of coastal
San Luis Obispo County. A raised wooden boardwalk loops through and around the forest, with viewing platforms. • Cuesta Ridge Elfin Forest — in the Cuesta Ridge Botanical Special Interest Area, on western Cuesta Ridge of the
Santa Lucia Range, in San Luis Obispo County. A pygmy Sargent's cypress (
Hesperocyparis sargentii) forest, where
serpentine soil stunts growth. Protected within the 1,334 acre Cuesta Ridge Botanical Special Interest Area, in the Santa Lucia Ranger District of the
Los Padres National Forest. • Dwarf Cupressus Preserve — a second West Cuesta Ridge grove of the pygmy
cypress forest (
C. sargentii), managed by the
Land Conservancy of San Luis Obispo County. •
Henry Cowell Redwoods State Park — select pygmy forest locales in the
Santa Cruz Mountains in Santa Cruz County. •
Mount Tamalpais dwarf forest — a forest of small
C. pigmaea trees. The mountain's serpentine soil stunts the growth of these trees, causing them to grow only a few feet tall. On Old Stage Road, 0.5 miles northeast of the Bootjack Picnic Area. • San Geronimo Ridge — just south of Whites Hill in
Marin County. •
Hood Mountain — near
Santa Rosa in
Sonoma County. A pygmy cypress forest dominated by
C. sargentii and
Arctostaphylos species can be found on the northwest slopes. ==Other types==