Sage Habitat
Originally the dominant ecosystem of Southern Coastal California, less than 10% of the coastal sage scrub community now only exists in areas within Los Angeles, San Bernardino, Orange, Riverside and San Diego counties. The rarest subassociation of the Coastal Sage Scrub natural communities is Riversidean Alluvial Sage Scrub (RASS or RAFSS) that is found on inland foothill slopes and canyon washes of the San Gabriel and San Bernardino mountain ranges.
This habitat is designated 'very threatened' by the State of California and is globally imperiled – more endangered than tropical rain forests and forests of the pacific northwest. Among the plants live a variety of animal species, more than 120 are rare threatened and endangered, including the Coastal California gnatcatcher a most precious little songbird.
Within the ecosystem, there are levels of animal and plant life. The bottom level includes decomposers such as fungi, bacteria and worms. They live off decaying material and waste and return organic compounds to the soil--providing nutrients for plants. Herbivores, such as rabbits and squirrels, live off the plants. They, in turn, are eaten by carnivores (meat eaters), such as foxes, hawks, and owls. When these plants and animals die, the decomposers start the cycle again.
This sage scrub environment evolved within the Mediterranean climate. This term refers to climate belts found in both the northern and southern hemispheres on the western coastline of continents, approximately between 30 and 40 degrees latitude. Mediterranean climate belts receive an average of 10 to 20 inches of rainfall a year and experience only occasional frosts. These areas typically have winter rains and dry warm summers with a fairly constant temperature.
The coastal sage scrub and chaparral associated with Mediterranean climates evolved in response to climatic changes beginning about 14 million years ago. In these latitudes, average rainfall decreased from about 80 inches or more per year in the Eocene Epoch to only about 12 inches by the middle of the Miocene Epoch. Coastal sage scrub plants can store moisture and reduce moisture loss during the prolonged hot, dry months between April and October. The plants either conserve water by specialized leaf structures or dormancy. Tough leathery, wax-covered leaves, like those of the lemonade-berry shrub, prevent water from escaping through leaf pores. Minute white hairs keep leaf temperatures down by reflecting sunlight. They also reduce moisture loss by slowing dry winds. Some leaves are so reduced in size that they appear as spines, as on cacti. Other plants simply drop their leaves during summer months. Other species, especially the flowering ones, will dry up and go dormant by middle summer. Although they appear to be inactive during this time, growth is still occurring. Root systems can be extensive, sometimes exceeding 30 feet. The roots anchor the plants, hold soil in place and reduce runoff during winter and spring rains.
The community is both drought and fire-adapted. Fire is a healthy and necessary component of their life cycle. Shrubs respond to recurrent fires in several ways. They sprout again from both crown and roots, and, often at an early age, produce seeds that are both fire resistant and dependent for germination (growth). Fire creates a healthy plant mosaic of different ages and species. As a result, fire increases the diversity of habitats. However, many wildlife species are killed or displaced by fires, those that survive fires may not be able to thrive while burnt habitat is being reestablished.
Southern California has become the epicenter of species extinction. The Habitat Trust is committed to preserving and protecting native communities. If you are presently unable to contribute to THT for habitat acquisition and management, we ask you to help preserve this precious community by not picking, removing, or otherwise disturbing any plant or animal life.