Chaparral

 

Red shanks chaparral             Photo by Rick Halsey

Chaparral is California’s most extensive plant community. It is also the state’s most characteristic wilderness, dominating foothills and mountain slopes from the Rouge River Valley in southern Oregon to the San Pedro Martir in Baja California.

Properly defined, chaparral is a semi-arid, shrub dominated association of sclerophyllous (“hard-leaved”), woody plants shaped by summer drought, mild, wet winters, and naturally recurring fires every 30 to 150 years plus. Sclerophyllous leaves are advantageous in a semi-arid climate because they reduce evaporation thorough a variety of traits including waxy coatings, thicker cell layers, and recessed stomata, the pores in leaves permitting evaporation and the exchange of oxygen and carbon dioxide.

    

chamise (greasewood)         Photos by Michael Simpson       ceanothus (wild lilac)

red shanks

Chaparral plants employ four different strategies in response to drought.  They can be classified as avoiders (avoid drought with long roots and hard/thick leaves like laurel sumac), persisters (tolerate drought by physiological adaptations and movements like ceanothus), retreaters (annuals or underground storage organs), or chameleons (evade drought by being semi-summer decidous like black sage).

  

                                  manzanita               Photos by Michael Simpson               toyon     

Because of its density, uniform cover and nonexistent understory of herbaceous plants, the diversity of chaparral animal life is low when compared to a forest ecosystem.  However, the animals that do call the chaparral their home are an interesting assortment of highly territorial survivors including the scrub jay, the sparrow-sized wrentit, western diamondback rattlesnake, big-eared woodrat, and the mountain lion.

  

                                      scrub jay                                                                                                 wrentit         © Scott Streit, 2002

There are three seasons in California chaparral, fall, spring and drought. Fall is subtle, lasting only a few short weeks in June, punctuating spring and drought.  Marked by a brief yellowing of the hillsides as some of the leaves on shrubs like ceanothus and manzanita are discarded, fall prepares the chaparral for long months of desiccation ahead. By mid-July, drought has settled in. Usually in November, moisture arrives and spring begins. The traditional winter months become part of the chaparral’s season of growth.

      

bobcat

  

       Photo by L. Sansone                                Photo by E. Benders-Hyde

brush rabbit                                                grey fox

The distribution of chaparral in southern California is shaped by four main factors:  latitude, coastal mountains, the ocean, and air mass movement. At the equator, warm, moist air rises.  As it cools, rain is squeezed out and dry air cells drop back to earth along bands approximately thirty degrees latitude north and south of the equator.  These areas are where the world’s great deserts appear.  However, in six special places: central Chile; the Cape of South Africa; southwestern and southern Australia; the Mediterranean Basin; and California; a combination of local conditions holds back the desert and creates unique, semi-arid shrubland ecosystems.

In California, coastal mountains block moist, ocean air blowing further inland. Due to the protective mountain barrier, there is just enough rain on the western side to support the chaparral.  Depending on physical factors and past disturbances, regions with 8 to 39 inches of average annual rainfall can support chaparral as the dominant vegetation type.  In areas with rainfall less than 10 inches or especially high evaporation rates, chaparral is typically replaced by a different plant community, the coastal sage scrub.  Above 30 inches, conifer and mixed evergreen forests generally predominate.

A huge, subtropical high-pressure cell over the Pacific Ocean dictates the region’s overall climate.  As this huge air mass moves northward in the summer, it blocks cold, polar storm fronts from reaching California.  In the winter, the air mass backs off and moves toward the equator, allowing storms to break the drought.  Hot, dry summers and mild, wet winters (our spring) characterize California’s weather pattern and define a mediterranean-type climate, creating one of the most pleasant environments on earth.

Chaparral began forming approximately 14 million years ago as summer rains began decreasing. Beginning about ten million years ago fires appeared to dramatically increase. Adaptations to withstand drought and survive fire were selected for and plants requiring more moisture were pushed into canyons and higher elevations.  Two million years ago coastal uplift occurred, creating some of the modern elevational variation we see today.

   

mountain mahogany   Photo by Michael Simpson   

                                                        

gopher snake                                        ©2002 Gena Zolotar

  

                                                                       alligator lizard        ©1976 Dave Hildebrand                                            

Chaparral is filled with groups of unique individuals.  As one becomes familiar with the system, a surprisingly wide variety of distinct communities appear.  One hillside may be covered with a pure stand of chamise, while directly across the canyon, clumps of red-barked manzanita will be mixed with white flowering ceanothus.  The eight basic chaparral types are red shanks, ceanothus, chamise, mixed, manzanita, scrub oak and montane. Although the largest and most pristine stands of chaparral occur in southern California between 500 to 4,500 feet in elevation, smaller patches exist along the coast such as those on Carmel Mountain in San Diego County.  Stands of red shanks chaparral can found at 7,000 feet in the San Jacinto Mountains in Riverside County.  However, if there is one defining characteristic of nearly all chaparral, it is the presence of chamise, the ecosystem’s most pervasive shrub.

Subtle color shifts and changing scents distinguish California’s chaparral seasons in a much more subdued, sensual way than traditional seasonal markers.  Chaparral plants live within a thin band of existence. Living in neither forest nor desert, chaparral organisms do not have the luxury of abundant water nor the ability to store it.  They must be able to quickly exploit moisture when available and survive in between. It is a remarkable evolutionary achievement.

      

                                                           yucca in bloom                   Photos by Michael Simpson

 

Photo Credits:

Benders-Hyde, E. (2000). Photograph of grey fox. Retrieved March 12, 2005 from Blue Plant Biomes at http://www.blueplanetbiomes.org/

California Reptiles and Amphibians. (2005). Photographs of alligator lizards. Retrieved march 12, 2005 from CaliforniaHerps.com

Halsey, R.W. (2005). Photo of red shanks chaparral. Retrieved April 24, 2005 from Southern California Chaparral Field Institute at http://www.californiachaparral.com/pages/1/index.htm

Sansone, L. (2005). Photograph of brush rabbit. Retrieved March 12, 2005 from national Wildlife Federation (ENature) at http://www.enature.com/search/show_search_byShape.asp?curGroupID=5&shapeID=1036

Simpson, M.G. (2005). Photographs of ceanothus, chamise, manzanita, moutain mahogany, scrub oak, toyon, yucca. Retrieved February 23, 2005 from Plants of San Diego County, California, San Diego State University at  http://sci.sdsu.edu/plants/sdpls/indexf/html

Streit, S. (2002). Photograph of wrentit. Retrieved March 8, 2005 from Bird Friends of San Diego Count at http://www.bird-friends.com/

Town of Kiawah Island, SouthCarolina. (2008). Photograph of bobcat. Retrieved March 14, 2008 from http://www.kiawahisland.org/Wildlife/Bobcats.aspx

Zolotar, G. (2002). Photograph of gopher snake. Retrieved March 12, 2005 from Wildlife of Henry W. Coe State Park at http://www.coestatepark.com/wildlife_of_henry_coe_state_park.htm