Ecological site group description

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

These deflation basins are more stable, low-lying areas intermixed within the dunes that have a consistent water table at or near the soil surface most, if not all year long, and are dominated by water obligate and facultative wetland species. They will be found in depressional areas and have little to no slope or aspect influence.

LRU A is primarily influenced by hydrological processes and contains beaches, dunes, rivers, and marine terraces below 400 feet elevation. Wet forests, lakes, estuarine marshes, and tea-colored (tannic) streams are characteristic features of this LRU. Marshes and wetlands have been widely altered and/or drained with many converted to agriculture and urban developments.

Climate

The average annual precipitation in this MLRA is 23 to 98 inches (585 to 2,490 millimeters), increasing with elevation inland. Most of the rainfall occurs as low-intensity, Pacific frontal storms. Precipitation is evenly distributed throughout fall, winter, and spring, but summers are dry. Snowfall is rare along the coast, but snow accumulates at the higher elevations directly inland. Fog is a significant variable that defines this MLRA from other similar MLRAs. Summer fog frequency values of greater than 35% are strongly correlated to the extent of coast redwood distribution, which is a primary indicator species in this MLRA. Nightime fog is approximately twice as common as daytime fog and seasonally, it reaches its peak frequency in early August, with the greatest occurrence of fog from June through September (Johnstone and Dawson 2010). The average annual temperature is 49 to 59 degrees F (10 to 15 degrees C). The freeze-free period averages 300 days and ranges from 230 to 365 days, decreasing inland as elevation increases.

Soil features

The soils for this ESG are generally Typic, isomesic Psammaquents and a representative soil would be Clambeach. They are very poorly drained, have very high runoff, and frequent ponding, with a water table strongly connected to the ocean levels and adjacent streams that outlet into the ocean.

Vegetation dynamics

Beach dunes represent the more rapidly changing to older, more stabilized areas directly adjacent to the beaches. These deflation basins are more stable, low-lying areas intermixed within the dunes that have a consistent water table at or near the soil surface most, if not all year long, and are dominated by water obligate and facultative wetland species. This ecological site concept is unique to this LRU however it needs more data collected in order to properly refine the soil-site characteristics and better describe the dynamics of the site.

Abiotic Factors/Primary Disturbances

Poor drainage, onshore winds, nutrient limitations, and some limited sand burial are the most important disturbances that naturally drive the dynamics of this ecological site concept. The species that dominate this ecological site are adapted to poorly drained soil conditions, using various rooting strategies, leaf morphologies that can withstand anaerobic conditions, brackish water conditions, wind desiccation, and root and shoot strategies to ameliorate the low-fertility soil conditions.

Major Land Resource Area

MLRA 004B
Coastal Redwood Belt

Stage

Provisional

Contributors

Kendra Moseley