Coastal-sage-scrub

The coastal-sage-scrub (CSS) plant community is unique to Mediterranean climates, the kind we have here in western Riverside County. We have hot, dry summers and mild, wet winters. Commonly, CSS shrubs are half-woody, aromatic, and 1-6 feet tall. Many have soft gray-green leaves and shallow root systems. Most CSS shrubs are adapted to prolonged summer-fall drought: they drop or curl their leaves and become dormant to survive dry conditions.

Characteristic plant species of CSS include California Sagebrush, California buckwheat, brittlebush, black sage, and white sage. The shrubs of Riverside area CSS (Riversidian sage-scrub) are often spaced out, providing an open canopy that allows interspersed growth of grasses, forbs, and succulents.

Nearly one hundred plant and animal species associated with CSS are classified as rare, sensitive, threatened, or endangered including the Stephens Kangaroo Rat, , the California Gnatcatcher (a bird), the Cactus Wren (a bird), the Orange-throated Whiptail (a lizard), and the San Diego Horned Lizard.

Coastal-sage-scrub used to be the predominant vegetation type below 1000 feet elevation. The amount that has been lost in Riverside County is estimated to be close to 90%. Of the remaining habitat, more than half is considered degraded as a result of grazing, frequent fires, weed invasion, military activity, and off-road vehicle use.

Periodic fire is important to the regeneration of many CSS species and can help to maintain high levels of biodiversity. Fire at intervals of more than 20 years is necessary, but more frequent fire results in decreased shrub regeneration, increased invasion by non-native grasses, and a decrease in biodiversity. In addition, air pollution may contribute to the degradation of CSS by depositing abnormally high levels of nitrogen on the soil, which promotes the rapid growth of non-native grasses and other weed species.