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Montana De Oro State Park And Vicinity

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Biologically, Montana de Oro State Park is one of the more interesting of the State Parks. Hazard Reef, which begins at Hazard Canyon and continues some 15 kilometers (9 miles) south of the Park boundaries, supports one of the richest assemblages of colonial hydroids, sponges, rock-boring clams, crabs, tunicates, starfish and other marine invertebrates in Central and Southern California. Abalones, Haliotis spp., are particularly abundant. Over 90 species of fish have been recorded here. Some 100 species of algae are present (see Point Buchon and Vicinity). In the intertidal zone there is a unique algal zonation, differing from sites north of Morro Bay and south of Point Sal. In the kelp beds are tremendous numbers of red sea urchins, Strongylocentrotus franciscanus.

On shore, the area includes several Pleistocene marine terraces, underlain by steeply dipping Monterey shales dating to the Miocene. Further inland are low coastal hills dissected by canyons with perennial and intermittent streams. Several plant communities are found here, including northern coastal scrub, grasslands, mixed evergreen, riparian, and coastal strand.

On the higher grounds are mixed evergreens which include stands of Bishop pine, Pinus muricata, and coast live oak, Quercus agrifolia. The Bishop pine type locality is probably in this area. The riparian-community trees include cottonwood, Populus trichocarpa, willows, Salix spp., box elder, Acer negundo, and wax myrtle, Myrica californica.

The upper terraces between Islay and Coon Creeks are a mosaic of the Nassella (Stipa) grassland community with the northern coastal scrub and coastal sage scrub. Purple needlegrass, Nassella pulchra, is the dominant grass. The other communities are typical.

Among the rare plants occurring in the Park are Arctostaphylos pechoensis and Arctostaphylos morroensis as well as Erigeron blochmaniae. These latter two species occur in the northern end of the Park where it abuts the sand spit in Morro Bay State Park and in the non-Park area immediately to the east. This area is of particular importance as the last remaining habitat of the Morro Bay kangaroo rat, Dipodomys heermanni morroensis. The dominant plant here is mock heather, Ericameria ericoides, giving way in the eastern sector to a chaparral community. Unless the kangaroo rat is to become extinct, the unprotected portion of this area must be acquired and managed as a suitable habitat, i.e., clearing of some brush. In this area Prunus fasciculata var. punctata reaches its northernmost limit and the rare Monardella undulata may be found here.

Adjacent to, and possibly within the Park, is a unique reptile population which includes a disjunct population of the rare southern rubber boa, Charina bottae umbratica. (See Coon Creek Area).

Integrity: Despite a eucalyptus grove, much of the area is pristine. Park facility development is minimal, with campsites, roads, trails, etc. Unfortunately, the accessibility of the reef has led to overcollecting and the populations of the various invertebrates are suffering. The kangaroo rat area was used for artillery practice in World War II and was plowed in 1956; however, the vegetation and rats have survived.

Use: Educational, research, observational, light recreational in public area; remainder, private.

Ref: Anderson, Barrett (date unk.) Flora of Montana  de Pro State Park. Unpub. M.S. Thesis, Calif. State Polytechnic University, San Luis Obispo. 

Congdon, J. D. 1971. Population Estimate and Distribution of the Morro Bay Kangaroo Rat. Unpub. Calif. Dept. of Fish and Game, 16 pp.

January 1976.

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Last modified: December 06, 2005