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San Mateo Creek Wetlands

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Though somewhat disturbed in the past, the vegetation here has reached a fairly stable level and represents one of the finest mature coastal freshwater marshes in Southern California.  The wetlands support a dense cover of brackish or freshwater marsh vegetation interspersed with willow thickets.  The upland border comprises a stable riparian woodland community; the lower, marshy areas are subject to winter flooding.

Approximately a third (8 hectares, 20 acres) of the wetlands are composed of a cattail-bulrush community, with California bulrush, Scirpus californicus, the dominant in most of the area.  There are also pure stands of Scirpus americanus.  Some 15 hectares (35 acres) are covered by willow thickets consisting of almost pure stands of arroyo willow, Salix lasiolepis.  An undercover is absent in most areas, though at the lower margins the cattails are appearing to invade following clearing.  On the upland margins these thickets grade into shrubby willows or riparian woodland which is dominated by California sycamore, Platanus racemosa.  Fringing the bulrush on the inland border of the marsh is a Jaumea-rush community with Mexican rush, Juncus mexicanus, prominent.  Several algae, Chara sp. and Enteromorpha sp., are found in the open pools. Fifty-eight species of plants have been recorded in the area.

Animal life is abundant.

The marsh, which is formed by the intermittent San Mateo River, is bounded on the northwest by a steep cliff, 15 meters (50 feet) high, on the seaward side by 3-meter (10-foot) dunes, and to the south by gently rising land.  The valley is underlain and bordered by sedimentary rock of Tertiary origin on which rests a thick layer of alluvial material.

Integrity: A railroad crosses the marsh and there has been some road building but little recent activity.  There is some litter.

Use: Research, educational, observational.

Ref: Mudie, Peta J.  1969.  A Survey of the Coastal Wetland Vegetation of North San Diego County.  Mimeo. California Department of Fish and Game, Sacramento.

December 1975  

San Diego
Inventory of California Natural Areas
Revision © 2005 Steven Louis Hartman

 

 

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Last modified: December 06, 2005