By Karen Miner
The Southern California Coast ecoregion includes the coastal plain and hill portions of the counties of Santa Barbara, Ventura, Los Angeles, Orange and San Diego, as well as the Channel Islands. The area is characterized by a Mediterranean-like climate – mild, wet winters and hot, dry summers with brief periods of drought. Habitats in this region include coastal sage scrub, chaparral, grasslands, riparian woodland, beach sand dune, coastal bluff scrub and salt marsh.
Due to the desirable climate and proximity to the Pacific Ocean, humans have been attracted to this region for centuries. Today, several of the largest population centers of California occur here including the Los Angeles Metropolitan Area and Greater San Diego. Roughly 30% of the state’s population resides in this area that comprises less that 5% of California’s land.
This region is renowned for its outstanding biodiversity. At the same time, it is considered one the world’s significant biodiversity hotspots. A biodiversity hotspot is a biogeographic region with a significant number of species that are under threat from human activity. There are more than 300 species in the Southern California Coast ecoregion that are thought to be potentially threatened with extinction. Examples include the California gnatcatcher, least Bell’s vireo, San Diego cactus wren, California least tern, Pacific pocket mouse, light-footed clapper rail, and all the subspecies of island fox.
One of the most important habitats in the South Coast Ecoregion is riparian woodland. This habitat supports nearly two hundred native species including ringtail cat, white-tailed kite, cooper’s hawk, garter snakes, and many kinds of migratory songbirds. Riparian woodlands occur along running water such as rivers and streams – and provide essential habitat critical for these species including nesting and foraging sites, corridors for species movement, and shade (thermal refugia) to cool water for fish and wildlife. They also provide shade for people engaged in fishing, picnicking, trail use, and willows for use in furniture and baskets.
In the absence of past long-range regional planning that balanced ecological values with human needs, riparian woodlands in southern California were severely disturbed by development, agriculture, and livestock ranching. The conflicts between urban development and conservation of species in this region led to the enactment of the Natural Communities Conservation Planning (NCCP) Act of 1991(Fish and Game Code 2800-2835) – which takes an ecosystem approach to the protection of plants, animals, and their habitats while allowing compatible development and economic activity.
San Diego and Orange counties have adopted NCCP processes to develop and implement their regional conservation plans and restore essential ecological processes while accommodating continued economic growth. Interconnected reserve systems are being assembled that will enable the region’s diverse flora and fauna to adapt and persist long into the future, even in the face of a changing climate. The overall effect is the creation of a large, connected reserve system that addresses the regional habitat needs for multiple species.
As part of the California SWAP update, teams of scientists are currently crafting strategies to help reduce the threats and stresses affecting riparian habitat while enhancing its ability to renew itself and provide a variety of structure and food sources that different species need. For example, bewick’s wrens require cavities in mature trees to place their nest and nearby understory growth harboring insects they need to feed themselves and their young. Still very preliminary in its development, the strategy will include education and outreach as one component to help inform individuals and local communities about the value of riparian habitats and promote water conservation. The threat of invasive species to the system and how to avoid their spread will also be highlighted in the strategy, as well as how to allow or mimic natural flooding regimes in some areas in order to rejuvenate the habitat.
With public support, the CDFW’s goal is to maintain the current extent and distribution of riparian habitats in southern California and to look for opportunities to protect and restore currently degraded riparian areas.