Pygmy forest

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Pygmy Forest at Salt Point State Park

A pygmy forest is a forest which, for pedological and geological reasons, contains only miniature trees. Pygmy forests may occur over various world locations with notable occurrences at the Ross of Mull on the Isle of Mull in Scotland,[1] as example locations.

A variant of the pygmy forest is sometimes called elfin forest in parts of Southern California, Mexico, and Central America.[citation needed]

Ecological staircase[edit]

Trail signs at Salt Point alert hikers they are entering a Pygmy forested region

In the case of coastal Pygmy forests in northern California and Oregon, the formation began with a series of marine terraces and should be viewed as part of that formation. 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 solidified and slid under the one before it, raising the terraces. Pioneer plant communities colonized and took over the young terrace. The succession of plant communities that repeated on each terrace eventually formed a very specific podzol known as the Blacklock series,[2] 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. Plant communities on this terrace have reacted to limited root mobility and acidic soil by evolving stunted forms. Remnants of ecological staircases doubtless exist, however most have been destroyed for development or logging.

Examples of high-terrace podzol pygmy forests include:

Soil chemistry and effect on plant growth[edit]

Analyses of pygmy forest soils show low levels of macro— and micro—nutrients, and high levels of exchangeable aluminum, 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.

Alkaline soils[edit]

Stunted tree growth can also occur in some cases of highly alkaline soils such as the Stora Alvaret or Great Alvar formation on the island of Öland in Sweden. In that area there are certain extents of pygmy tree growth and also areas devoid of trees entirely with many associations of rare species, due to the unique soil chemistry.[citation needed]

Other examples of California pygmy forests[edit]

  1. 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.[6]
  2. 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 Cypress (Cupressus 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. [7] [8]
  3. Dwarf Cupressus Preserve — a second West Cuesta Ridge grove of the pygmy cypress forest (Cupressus sargentii), managed by the Land Conservancy of San Luis Obispo County.[9]
  4. Henry Cowell Redwoods State Park — select pygmy forest locales in the Santa Cruz Mountains, near Santa Cruz, in Santa Cruz County.
  5. Mount Tamalpais dwarf forest — a forest of small Cupressus pigmaea trees. The mountain’s serpentine soil stunts the growth of these trees, causing them to mature when only a few feet tall. On Old Stage Road, 0.5 miles northeast of the Bootjack Picnic Area. [10]
  6. San Geronimo Ridge — just south of Whites Hill in Marin County.
  7. Hood Mountain — near Santa Rosa in Sonoma County. A pygmy cypress forest dominated by Sargent's Cypress (Cupressus sargentii) and Arctostaphylos species can be found on the northwest slopes.

See also[edit]