When I studied population biology in junior college we conducted our field work in a large expanse of land along the alluvial fan that drained the San Gabriel Mountains to the Inland Empire valley below. Our specific field site was a 750+ acre area containing coastal sage scrub and coastal sage chaparral plant communities that were intersected by riparian corridors of alder, willow and occasionally sycamore trees.
Coastal sage scrub is a type of ecoregion that is located along the southern and central coast of California. It is important because is an endangered ecosystem that contains many unique species that occur nowhere else in the world (endemic), a number of which are endangered species. Coastal sage scrub is imperiled because it is also located on highly valued coastal real estate and threatened by human development.
Coastal sage scrub occurs from sea level to 1500 feet in elevation, along the coastal and inland valley foothills where coastal fog moderates the climate. Habitat contains sparse, low-growing soft, aromatic shrubs that range from dull-green to gray-green in color. In hot, dry summer months, shrubs often lose their leaves and become dormant as an adaptation to drought tolerance. They become green and vibrant again when winter rains arrive.
Some characteristics species in coastal sage scrub communities include:
- The California gnatcatcher
- Quino checkerspot butterfly
- Stephen’s kangaroo rat (article for kangaroo rat)
- Rosy boa
- California legless lizard
Federally recognized threatened and endangered species include the California gnatcatcher (Polioptila californica), the San Diego banded gecko (Coleonyx variegatus abbottii ), the cactus wren (Campylorhyncus brunneicapillus), Merriam kangaroo rat (Dipodomys merriami), flannel-mouthed sucker (Catostomus latipinnis), western patch-nosed snake (Salvadora hexalepis), and cheese-weed moth lacewing (Chrysoperla spp.). Thirteen plant species of the coastal sage scrub are also recognized as threatened or endangered. (1)
A few years later the area began rapidly developing and our field area was threatened by a series of housing developments. Through the efforts of many people who fought to see the area protected to stem the decline of chaparral and coastal sage communities, a 762 acre section was set aside as a reserve. The area lies between the developed portions to the south and the national forest to the north and is protected on the southern end by a very wide power transportation corridor that serves as a buffer between the two land uses.
After several years of being away from this site, I recently revisited it yesterday afternoon and was surprised to see signs pointing the way to the preserve as I drove to the parking area. I was further surprised to see a dozen cars in the parking area at 3 pm on a Tuesday. When I last visited the site, it was protected, but still the completely undeveloped area that few people ever ventured into.
I quickly saw that the preserve has since been enhanced with formal trails, interpretive signs, and a few scattered picnic sites. It was now a popular place for hiking due to its cultural and recreational significance. Many people were taking a new trail that lead to a side canyon that contained a waterfall and shade beneath the alder trees. Others hiked around the lower portion of the preserve stopping at gazebos and interpretive signs.
While it was strange to see so many people in a place I used to walk around without seeing a soul, I was thrilled to see that the plant communities I fondly remembered were still there and appeared to be thriving. Walking through the scrub and chaparral I was transported back in time to my first population biology class, awestruck by the sight and smell of white sage and asking myself the same questions about the distributions of the plants I encountered along my hike.
Walking along one of the trails I saw massive shifts in the vegetation communities along a 1-mile length. Vegetation changed from stands that were dominated by white sage, to stands co-dominated by chemise and buckwheat containing little white sage. Walk a little further and the vegetation became co-dominated by black sage and sagebrush. Along this stretch I could not detect a difference in soil texture or aspect. So the sudden shifts of vegetation may the result of secondary successional processes where fire and floods disturb the vegetation and a different plant community begins growing in the areas that were disturbed. The overall pattern looked like waves of different vegetation along the hillside that was fascinating and worthy of more examination. Some of those communities are shown in the photos below.
Intersecting what I used to think was scorching hot chaparral (I’ve since lived in Arizona, so I have a new definition of hot) are wonderfully different riparian habitats containing cool, lush, shade tolerant species and – water. Water is a powerful force in these regions, winter rains and spring meltwater can move large amounts of water down the mountain through these canyons. Occasional fires remove vegetation and later rains bring floods that break trees and push large granite boulders downstream too. These processes cause regular disturbances in the canyons and adjacent lands, and the vegetation is always in some state of recovery. The dense canopy of alder trees in the canyon bottoms is evidence of that those areas were previously disturbed, new trees grew to replace those that were killed, but self-thinning has not yet completed restructuring the tree stand.
The Southern California coastal sage scrub and chaparral communities are a wonderful place to explore with very interesting ecology that is worthy of protection and study. I’m happy that the North Etiwanda Preserve exists and look forward to continued visits.
For more information about the North Etiwanda Preserve see: http://sbcnep.org/
Photos of common coastal sage scrub and chaparral plants (from the nearby Cal State San Bernardino campus) can be seen at: http://biology.csusb.edu/PlantGuideFolder/
Finally, more information about coastal sage scrub and chaparral can be found at: http://www.eoearth.org/article/California_coastal_sage_and_chaparral
Happy exploring !