Wildflowers Will Bloom in Santa Rosa Preserve

Hard-riding Spanish vaqueros called the deep holes in creek beds tenajas (Spanish for tanks), because the holes, which were full year-round, provided crucial summer water for cows and cowboys. Today the tenajas offer habitat for such amphibians as the Western pond turtle and red-legged frog.

Tenajas and ancient Engelmann oaks on 3,100 acres of rolling grassland are preserved in the Santa Rosa Plateau Preserve, located at the southern end of the Santa Ana Mountains in Riverside County. The plateau is pastoral Southern California at its finest, that is to say the least changed since the days of the caballeros and gracious haciendas. Atop the plateau, time seems to have stood still since 1840.

Off the plateau, it’s very much 1990; huge housing developments are pushing up Clinton Keith Road and will soon leave the plateau an island on the land. And even this island faces Inland Empire-style development. The Riverside County Board of Supervisors recently approved developer Won San Yoo’s proposal to build a huge new residential community called Santa Rosa Springs on the 3,855 acres of the Santa Rosa Plateau that he owns.

For Southern California conservationists, the battle of the Santa Rosa Plateau was a tough one to lose, a bitter end to the 1980s. It wasn’t simply a park or some much-needed breathing room in a fast-developing part of the Southland that was lost in the political process, but an ecological treasure. The Santa Rosa Plateau has been recognized by UNESCO as a biosphere reserve, one of only three such special places in all of California.

Only the part of the plateau owned by the Nature Conservancy is inviolate. The conservancy’s preserve protects one of the last healthy stands of Engelmann oaks, once widespread throughout the Western United States, but now found only between San Diego and Santa Barbara. For reasons researchers can’t quite determine, most stands of Engelmann oaks contain just a few venerable specimens, which are incapable of regeneration. The Engelmann oaks on the Santa Rosa Plateau are quite healthy, however.

The oaks are named for German-born physician/botanist Dr. George Engelmann, who collected specimens in this country during the last century. Engelmann oaks are gnarled fellows, with a kind of checkered trunk and grayish leaves. When you visit the preserve you’ll see that Engelmanns are noticeably different from their more common cousins, the coast live oaks. Coast live oaks are fuller, with smoother bark and leaves that are shiny green. Usually, the coast live oaks grow in lower, wetter locales, while the Engelmanns take higher and drier ground.

For those with an interest in Southern California ecology, now is an interesting time to visit the preserve. About 700 acres of the preserve recently received some “natural housekeeping” by way of a controlled burn. The fire, which did not harm the oaks, burned off accumulated brush and will encourage the growth of native grasses and wildflowers.

A visit to the preserve now, in its blackened state, followed by a visit in spring, when wildflowers will blanket the slopes, would provide a dramatic ecology lesson.

Directions to trailhead: From Los Angeles, take Interstate 15 in Riverside County, go several miles past Lake Elsinore and exit right on Clinton Keith Road. (From San Diego, stay on Interstate 15, go past the junction with Interstate 215 and exit left after a few miles on Clinton Keith Road.) Follow Clinton Keith Road west for about 5 miles. Just as the road makes a sharp 90-degree right turn and becomes Tenaja Road, you’ll spot a turnout and the main gate of the Santa Rosa Plateau Preserve on the left. Park in a safe manner off the road.

The preserve is open every day, dawn to dusk. Guided tours, given the first Saturday of every month, begin at 9:30 a.m. at the main gate. For more information, call (714) 677-6951.

The hike: At the main gate, scan the bulletin boards, pick up a preserve map (stay within shaded area on map), then join the Trans Preserve Trail. The trail heads south across grassy slopes, dips into an oak-filled draw, then contours around Poppy Hill. To the east you’ll see Ranch Road, your return route to the trailhead, and to the west, on private land, some cows may be grazing.

If you use your imagination, you can step back a century and a half in time, when the Santa Rosa Plateau was part of the 47,000-acre Mexican land grant Rancho Santa Rosa, given to cattle rancher Juan Moreno by Gov. Pio Pico. The land was held by various ranching companies until 1984, when the Nature Conservancy acquired it from the Kaiser Corp. and established the preserve.

Follow Trans Preserve Trail and signs to Mesa de Colorado. Atop the mesa, you’ll find (if it ever rains again) a few vernal pools, some of the last in Southern California. (Vernal pools are depressions in the rock that collect water during the rainy season.) The mesa is capped with basalt, making it an ideal collector of rainwater. After winter and spring rains, the pools are visited by ducks, geese and other waterfowl. Wildflowers--particularly goldfields--are much in evidence when the water recedes.

After visiting the pools, descend to the main dirt road (Ranch Road) and head east toward a windmill. You’ll soon come upon an old adobe and some ranch buildings, now used as preserve headquarters.

If you want to tour a little more of the preserve, continue east past preserve headquarters on Ranch Road, which becomes a footpath. On a clear day, you might be able to get a glimpse of Oceanside and the wide blue Pacific, about 20 miles away. Pick up signed Adobe Loop Trail, which meanders among old oaks, passes an olive grove and loops back to headquarters.

Follow Ranch Road back to the trailhead.