Sonoma and Mendocino County Pygmy Forest: Ecosystem Definition and Mapping Project
Mendocino pygmy forests are naturally rare, occurring only on very old elevated marine terraces within 1 to 5 miles from the sea. They have been threatened by development, including clearing for airports, pot farms, and housing, for decades. The unusual vegetation on “The Mendocino ecological staircase” is a result of the inhibiting effect of soils subjected to hundreds of thousands of years of weathering in the cool moist north coastal part of the state. This soil “chronosequence” was made famous by UC Berkley professor Hans Jenny’s work in the 1960’s.
In the classic pygmy forest, pygmy cypress (Hesperocyparis pygmaea), Bolander pine (Pinus contorta subsp. bolanderi), and dwarfed individuals of bishop pine (P. muricata), grow in stunted, old stands, sometimes only a few feet tall, within an assemblage of ericaceous shrubs, fruticose lichens, and mosses – all sharing tolerance of nutrient-poor acidic soils. These stands are in stark contrast to the tall, dark forests of redwood, grand fir, and Douglas-fir on deeper soils just off of the ancient terrace soils.
Similar pygmy forest with H. pygmaea, P. muricata, Vaccinium ovatum, and Arctostaphylos nummularia occurs as far south as Salt Point State Park.
For years these pygmy forests were described in a limited range between Fort Bragg south to Albion near the Navarro River in southern Mendocino County. However, similar vegetation, also naturally restricted and threatened by recent development, occurs southward to Salt Point State Park in Sonoma County. These more southerly stands are poorly known and yet contain similarly rare vegetation. Only by collecting data, classifying, and mapping all of these related types of vegetation can we identify how many of these unusual communities there are on these old terraces, know their distribution and abundance, and understand their relationships and conservation value.
Through a multidisciplinary effort lead by California Department of Fish & Wildlife (CDFW) staff, local CNPS members, and concerned land managers, this endangered “pygmy” ecosystem has been targeted for a complete vegetation assessment over the next several months.
The range of pygmy and pygmy-like ecosystems on coastal marine terraces from Ft. Bragg southward into N. Sonoma County with inset (right) of how individual sampling areas are prioritized for the project; based on existing soils mapping, field data, location and age of marine terraces, and other corroborating evidence. The “warmer” the color, the higher likelihood of pygmy-like vegetation present.
Although taller, many bishop pine woodlands on poor soils on marine terraces in Sonoma and adjacent Mendocino counties have some of the same characteristic species as the more stunted pygmy forests. The project will be able to determine if such forests are also rare and limited in distribution (northern part of Salt Point State Park).
To kick-off this sampling and mapping effort led by CDFW regional staff, CDFW headquarters staff of the Vegetation Classification and Mapping Program (VegCAMP), and CNPS will be conducting a vegetation sampling training in Mendocino County’s pygmy forest February 9-13, 2015 with help from Teresa Sholars, Professor Emeritus, College of the Redwoods. Please contact Teresa Sholars (tsholars@mcn.org) or Linda Miller (Linda.Miller@wildlife.ca.gov) if you are interested in helping out on this project.