Images © by James L. Reveal, Norton-Brown Herbarium, University of Maryland, unless otherwise credited.

Steep chaparral slopes in the San Gabriel Mountains, California

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X. General features of scrubland biomes

• A. Introduction.
  B. Origin.
  C. Environment.
  D. Biota.
  E. Population structure.
  F. Productivity.

XI. Chaparral

• A. Location: Coastal southern California and northern Baja California, Mexico. Widely scattered elsewhere in the world: southern Europe and northern Africa, Cape Region of southern Africa.
  B. Features:
  • 1. Dominated by microphyllous (small), sclerophyllous (e.g. leathery), xerophytic (dry) evergreen shrubs and a mixture of low conifers and hardwood trees.
    2. Climate: Cool and wet in winter; hot and dry otherwise.
    • a. Precipitation as rain in late Nov to early Apr, 14-29 in (35-75 cm); falls as rain or rarely as snow.
      b. Seasonally warm in winter, hot in summer, frost infrequent, can exceed 110° F.

    3. Slope and exposure critical; moist north-facing, dry south-facing; slopes usually steep.
    4. Hot winds and fire frequently occur in late fall at end of dry season.
    5. Generally poor soils, shallow and rocky.
    6. Fire climax community.

  C. Vegetation:

  • 1. Dominant shrubs are chamise (Adenostoma fasciculatum), California buckwheat (Eriogonum fasciculatum), various species of manzanita (Arctostaphylos), and (at higher elevations) species of ceanothus (Ceanothus).
    2. Dominant trees are oaks (see right) (Quercus) and pines (Pinus).
    3. Madrone (Arbutus menziesii) and bay (Umbellularia californica) are also characteristic. Our Lord's candle (Yucca whipplei) is a frequently seen member.
    4. Many endemic species of wildflowers; flowers most common from March to June.
    5. Many species have volatile oils in the leaves meaning that they burn rapidly.
    6. Many species specially adapted to repeated burning (e.g., root crowns ("lignotuber") from which new shrubs can grow; cones of pines ("cone serotiny") that require high heat to open).
    • a. Chamise
      b. Manzanita
      c. Pine

  D. Animals:

  • 1. Diversity of birds, especially ground birds, deer and small mammals.
    2. Many narrowly endemic.

  E. History:

  • 1. Chaparral a more southern biome, moved to its present position during Pliocene and Pleistocene times, becoming less expansive.
    2. Formed as a result of drying trend over last 10 my.
    3. Frequent fires have done much to maintain biome.

  F. Exploitation:

  • 1. Intensively grazed has resulted in some extinction.
    2. Fire suppression is resulting in larger and hotter fires that kill plants otherwise adapted to fire.
    3. Population growth coupled with urban expansion is fragmenting the vegetation.

Scars of a recent burn in the chaparral of California

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Last revised: 17 Oct 1997 - Reveal