Natural Resources
Conservation Service

ecological site group F004BM100CA

Windy coastal stabilized dunelands and mountain slopes

Accessed: 09/17/2026

Home / esg CATALOG / MLRA 004B / ecological site group F004BM100CA

Ecological site group description

Key Characteristics

West of the San Andreas fault line on the Pacific Plate – LRU M
Coastal, wind-affected slopes

Provisional. A provisional ecological site description has undergone quality control and quality assurance review. It contains a working state and transition model and enough information to identify the ecological site.

Physiography

Hills with slopes range from 9-75% and elevations are from 20-1000 ft.

Climate

The average annual precipitation is 25-35 inches with annual average temperatures between 53-57 degrees F, and frost-free days from 300-365 days.

The Point Reyes/Farallon Islands LRU M includes the Point Reyes Peninsula, Bodega Head and the sand spit at the north end of Bodega Bay, and the offshore Farallon Islands. The maritime climate is temperate and humid, and fog often occurs. Heavy coastal winds are an influential factor in vegetation expression in this LRU that occur primarily in the summer months, explaining the large extent of coastal prairies and coastal scrub species along much of the coastline. Where trees are present along or near the coastline and within the reach of these heavy winds, the tree canopies form unidirectional windswept crowns.

Soil features

The soils for this ESG are moderately deep, strongly sloping to very steep, well drained soils underlain by sandstone and quartz-diorite. The representative soils are Kehoe soils with a very dark grayish brown loam surface and the Sheridan Variant soils that are brown coarse sandy loams over weathered quartz diorite.

Vegetation dynamics

This provisional ESG attempts to describe the bishop pine forests of this small LRU. Fragments of bishop pine forests exist along the coast of California where the climate, soil and fire regime are just right for their growth, and in LRU M, they exist primarily all along the northern end of Inverness Ridge. This concept lacks soil mapping and is therefore supported solely through literature and available information from Point Reyes National Seashore. This provisional ecological site concept covers a narrow range of bishop pine dynamics, however since there is no soils information for most of this LRU, future work will need to be done to better understand the soil and site characteristics that drive the vegetation expression for this provisional ecological site concept.

Abiotic Factors

Pinus muricata (Bishop pine) forests are unique to granitic quartz-diorite soils. Although bishop pine can grow on a variety of soils, within MLRA 4B the soils are primarily old, shallow, acidic and poorly drained. Bishop pines prefer the cool, maritime climate that provides fog drip and sufficient summer moisture to mollify evapotranspiration rates in the summers, and low elevation slopes that are within 7-8 miles of the ocean.

Primary Disturbances

Fire plays a prominent role in the life history and reproductive patterns of bishop pine. Bishop pine is a serotinous, closed cone species, meaning some or all of its cones are locked shut until high heat loosens the resin coating the cones, unlocking seed chambers and allowing seed to be dispersed in large quantities following fire. Stands are characteristically single-aged and originate after fires when the serotinous cones are opened (Cope, 1993). There is some research that suggests that bishop pine cones will also open during very hot days and disperse seeds. Depending on the fire intensity, some bishop pine can survive the fires, creating a more complex age-class distribution, however in most cases, fires will open wide areas by removing most all of the bishop pine and the seeds will germinate shortly after and grow rather rapidly post-fire. Although shrubs often fill in first after the fires in most bishop pine forests, the bishop pine does not seem to be affected and overtops the shrubs over time.

Citations

Cope, Amy B. 1993. Pinus muricata. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.usda.gov/database/feis/plants/tree/pinmur/all.html [2025, March 6].

Major Land Resource Area

MLRA 004B
Coastal Redwood Belt

Stage

Provisional

Contributors

Kendra Moseley

Download full description

Add ecological site groups and Major Land Resource Areas to your briefcase by clicking on the briefcase () icon wherever it occurs. Drag and drop items to reorder. Cookies are used to store briefcase items between browsing sessions. Because of this, the number of items that can be added to your briefcase is limited, and briefcase items added on one device and browser cannot be accessed from another device or browser. Users who do not wish to place cookies on their devices should not use the briefcase tool. Briefcase cookies serve no other purpose than described here and are deleted whenever browsing history is cleared.

Ecological site groups

Major Land Resource Areas

State and transition model

More interactive model formats are also available. View Interactive Models
Click on state and transition labels to scroll to the respective text

Ecosystem states

1. Reference State

State 1 submodel, plant communities

1.1. Reference Community Phase

1.2.

State 1
Reference State

The dynamics described below are general to the level that the site concept has been developed for provisional ecological site concept identification and further investigation purposes only. It is meant to give a general overview of the ecological dynamics of the system and should not be viewed as a model for a specific ecological site level management. It is supported by the current available literature that was reviewed for a general understanding of the system and basic understanding of the abiotic and biotic drivers. Further investigations and soil-site data collection and analysis should be conducted before specific land management can be applied at the ecological site specific scale. This STM only serves to explain the general ecology and dynamics. No alternative states were found during the literature review, however that does not mean they do not exist and more time should be spent determining whether or not this model captures all the dynamics of this system, especially once more is known about the soil-site characteristics of this LRU and ecological site concept. Reference State (State 1) – This reference state includes the generally single-aged stands of bishop pine with an understory comprised of shrubs, and the post-fire community that is dominated by rapidly resprouting shrubs and bishop pine seedlings. Dense pine patches alternate with dense stands of blue blossom and the rare Marin manzanita. Over time, young forests self-thin, giving way to mature forests mixed with hardwoods, and swordfern.

Community 1.1
Reference Community Phase

This community phase represents the more stable and resistant and resilient community phase dominated by bishop pine. Bishop pine are well adapted to the high, frequent summer winds and salty air near the coast line and are highly competitive and capable of capitalizing on the available resources of the cool, maritime climate in this LRU. Bishop pine do not share their upper canopy with any other conifers in this ecological site and are multiple age classes, unlike many other bishop pine sites in MLRA 4B. This community phase is characterized by a multiple age-class stand of bishop pines, however the age classes are still grouped in pulse-like events (whole stands all one class). Some of these age classes do not correspond with any known fires, and therefore support the idea that bishop pine in this ecological site do not require fire to regenerate like most serotinous coned species do. The understory is a mix of Umbellaria californica (California bay laurel), Arbutus menzeisii (Pacific madrone), Quercus agrifolia (coast live oak), Notholithocarpus densiflorus (tanoak), Ceanothus thrysiflorus (blue blossom), Arctostaphylos virgate (Marin manzanita), Vaccinium ovatum (California huckleberry), Gaultheria shallon (salal), and Polystichum munitum (swordfern).

Community 1.2

This community phase represents the thick shrub dominated community that resprouts after fire. It is often dominated by blue blossom, however bishop pine seedlings, manzanita, and salal are also present. In some cases, Erechtites minima (fireweed) may dominate after fire, and can slow the bishop pine regeneration.

Pathway 1.1a
Community 1.1 to 1.2

This pathway occurs after a fire that is sufficient enough to remove most of the bishop pine and hardwoods and open the canopy and soil resources to the sprouting shrubs and new bishop pine seedlings. Herbaceous species may capitalize on this drought-caused mortality.

Pathway 1.2a
Community 1.2 to 1.1

This pathway occurs over time (as short as 10 years depending on fire severity and seed source) as the bishop pine seedlings re-establish dominance in the canopy and begin to self-thin and shade out many of the shrubs in the understory.

Print Options

Sections

General information
Ecological dynamics
Citations

Font

Arial
Times New Roman

Other

Two-column format
Include images

Search

Natural ResourcesConservation Service