By Tom Oberbauer, Chapter President, CNPS-San Diego
The foothills and valleys in San Diego County would have exhibited even greater differences in vegetation from those of modern times. In addition to El Cajon, the major valleys, including Escondido and Ramona, would have supported low growing shrubs but also grassland due to increased precipitation and fine soils and the large numbers of herbivorous mammals.
Except for the big animals, the environment including the vegetation here would have modeled that of the inner mountain foothill slopes of the Monterey/Santa Cruz areas. Winter snow levels would have been repeatedly at 2,000 to 2,500 feet rather than the 3,500 feet that it is now. The foothill mountains, like Otay Mountain, Big Black Mountain, Mount Woodson, Viejas, Poser, Potrero and Tecate Peaks, were regularly snow- capped forested peaks following winter storms.
The vegetation on the foothill mountains would have been pines with Pinus coulteri (Coulter pine), more Hesperocyparis forbesii (Tecate cypress), Hesperocyparis stephensonii (Cuyamaca cypress) Pseudotsuaga macrocarpa (Big-coned Douglas fir) mixed with Quercus chrysolepis (Canyon live oak), and Quercus kelloggii (California black oak). Average precipitation on Otay Mountain would have been close to 40 inches. Acer macrophyllum (Big leaf maple) andArbutus menziesii (Madrone) were also part of the forest vegetation community, the big leaves providing large yellow patches on the hillsides in the fall. However, Madrones were dark and grew with large shiny leaves and red bark. In the favorable locations with a bit more shade and rainfall, these trees would have also been mixed with Pinus lambertiana (Sugar pine), Pinus ponderosa (Ponderosa pine), Abies concolor (White fir), and Calocedrus decurrens (Incense cedar). This was the same type of forest that currently occurs near the top of the Cuyamaca Mountains and Palomar Mountain. In the hilly areas, Saber tooth cats, Jaguars, and Short-faced and Grizzly bears were common, preying on the Elk, Mule deer, and Bighorn sheep. Mastodons and sloths were individual food processors pulling down low hanging tree branches and shrubs in the forested areas, feeding machines that were actively engaged in eating through much of the day. Shrub oxen browsed on the chaparral and sage scrub vegetation, feeding and chewing for hours at a time, moving in small clusters and tilting their heavy horned heads at unexpected sounds. A Scimitar cat watched them from a shadowy vantage point.