Between the Ten Mile and Navarro Rivers the Pygmy Forest occurs in a number of localities. For the 25 sites listed for Mendocino County (Pygmy Forest A thru U, Russel Redwood Forest) the more generalized information is given in this and the following (Pygmy Forest A1) description. Areas Pygmy Forest Ecological Staircase, Pygmy Forest Ecological Staircase - Eastern Extension, Table Mountain and Van Damme State Park are treated separately.
The Pygmy Forest ecosystem is one of the most remarkable in the entire temperate zone and is as close to a terminal steady-state ecosystem as will be found. The vegetation is unique, and the extremely old soil is the most strongly developed podsol known. A podsol is a soil formed by a combination of time and rainfall that creates a high rate of leaching. Water soluble chemicals and clay particles in suspension move down through the surface zone, leaving a nutrient-deficient, bleached, gray soil.
In the Pygmy Forest belt there are three main soil types, Noyo, Blacklock and Aborigine. Of the three, the Noyo, which occurs on remnant dunes, is only partially podsolized. The dune minerals have weathered to clay, the bases (Ca+, K+, Mg+, Na+) have been depleted by percolation and the mineral acidity greatly increased. The deeper subsoil exhibits a rusty, mottled clay.
The Blacklock and the less common Aborigine soils are fully podsolized. The Aborigine soil is highly acidic and derives from clayey beach material. Some 30 centimeters (12 inches) below the surface there is a rust-stained clay pan with up to 60+% clay that effectively restricts root penetration. Most of the Pygmy Forest, though, is on Blacklock soil, a coarse, sandy beach deposit, whitish, now essentially a non-weatherable quartz flour, underlain at 45 and more centimeters (18 inches) by a concrete-like, iron-cemented hardpan. It has a pH of 2.8 - 3.9, almost the same as vinegar.
While the dunes have good drainage, the level areas where the Blacklock and Aborigine soils occur have poor drainage that creates wet, even flooding conditions. These soils have evolved over a period of up to 500,000 years. During this period the land along this section of the coast has risen at an average rate of 2 - 3 centimeters (1 inch) per century.
There are five terraces, each representing an age increment of approximately 100,000 years. The terraces were carved by wave action when the sea level was rising relative to the land, as it is now. Nearly flat surfaces, sloping gently upward to the east, were cut in the hard Franciscan formation graywacke which underlies the region. When the sea level declined, the terrace emerged covered with beach deposits, sand, rocks and clays, up to 10 meters (30 feet) thick. Locally wind-lain sand formed dunes. Though podsols may occur on the second terrace, they are best developed on the third, fourth and fifth.
Pygmy Forest A is the only remnant of a well-developed pygmy forest on the second terrace. It is on Blacklock soil.
Integrity: A road borders the area and there are exotics in the disturbed portion. A house lies on the edge of the forest.
Inventory of California Natural Areas
Revision © 2009 Steven Louis Hartman