Biology 105 2000 Lab 3
Feb. 8-9-10

Plant Biodiversity of Southern California
 
 
Plants and biodiversity Assignment Habitats Plant links Bio 105 home

This lab will focus on some of the unique plant species of Southern California.  We will learn common names of the species, their habitats, and some adaptations to these habitats.

Importance of plants to understanding biodiversity

Many people don't even notice individual wild plants, but rather view them as just part of the landscape.  Here are some reasons for appreciating plants and their contribution to biodiversity:
 

  1. Plants comprise 17.84% of the total described number of species.
  2. Plants provide important ecosystem services, such as the delivery of oxygen into the atmosphere and the absorption of carbon dioxide from it.
  3. Plants are an important part of the Earth's nutrient cycles.
  4. Plants slow the impact of rain on the earth, preventing erosion.
  5. Plants provide the base of both natural and agricultural food chains.
  6. Plants form the original source or even the current basis of many pharmaceutical preparations, e.g. salicin extracted from willow trees was the original aspirin, taxol from Pacific yew is a cancer-fighting drug, psuedephedrine in cold medicine originally came from a Chinese plant.
  7. Southern California has the highest plant biodiversity of any place in the Western U.S.
  8. Features of plants can give you information about the habitat in which they grow.

 
 
 

Dichotomous keys:  tools for identification

 Botanists (and other biologists) make use of a tool called a dichotomous key (also called a key) to identify species.  A key presents the user with a series of choices that describe features of the species to be identified.  Choosing one alternative will instruct the user to proceed to another set of choices, and this procedure is continued until only one alternative is left, which should give the correct species identification. Pairs of letters and/or numbers indicate the choices available.

To learn how to use a key, observe the various keys on display.

Try to make yourself a key using a selection of lab tools or hardware provided.
 

Assignment
Develop a key to the plants on display.  Your key is due next week in lab.

Representative Plants of Local Habitats

Habitats are usually named for the plants that inhabit them.  Below you will find a description of four local habitats and a list of some plants that grow there.  These plants are on display in lab.
 
 
Coastal Sage Scrub Chaparral Southern Oak Woodland Riparian woodland

Coastal Sage Scrub
 

 < 1000 ft. elevation, below frost line; coastally and inland throughout cismontane region.
Does best under influence of maritime climate, where fog is common.
Rainfall usually 10 inches/yr. or less.
Vegetation usually about knee-high, not difficult to walk through.
Many plants are drought-deciduous: lose leaves and become dormant in dry season, but respond quickly to winter rains by leafing out and flowering.
Shallow-rooted.

Three categories of plants are common:
1) drought-deciduous, small leaves, odoriferous (e.g. sages)
2) succulents (e.g. cactus)
3) evergreen with large leaves (e.g. laurel sumac, lemonadeberry)

Pronounced slope-aspect difference in species present (we'll see this in the field next week).

 California sagebrush
California buckwheat
White sage
Black sage
Monkeyflower

Chaparral

between 1000-6000 ft. elevation, frost tolerant.
Rainfall 10-15 inches/yr.
Vegetation up to 10 ft. tall, difficult to walk through.
Plants are spiny:
Leaves small, and leathery with hairs or a waxy covering: this reduces water loss.
Some species have spiny leaves: this may promote heat loss.
Plants are evergreen so they are able to photosynthesize all year.
A fire-adapted community: we=ll talk about these features in class.
Pronounced slope differences.
Deep-rooted.

California lilac
Laurel sumac
Golden currant
Manzanita
Toyon

Southern oak woodland

An oak woodland dominated by one of several large trees; here, the dominant species is Coast Live Oak (live because it is evergreen; some oaks are winter-deciduous).  Oaks have enormous root systems that enable them to tap into water supplies deep in soil.   They are not affected drastically by summer drought, and their thick bark protects them from fire.  This species occurs in moist sites with deep soil, particularly in canyon bottoms and north-facing slopes, sometimes as islands of trees surrounded by grassland, coastal sage scrub, or chaparral.

Another abundant plant in this habitat is poison oak.  Learn it and avoid it!!!

Riparian woodland

Species that need a large amount of water and grow along streams and rivers in canyons.  Since there is usually a lot of cold air drainage from mountains, they live in a cool, moist climate, that is quite different from the surrounding slopes and flat areas.  This community has a high species diversity, both because it is very productive (high NPP) and because it is a zone of overlap between water and land so shares characteristics of each.

Most of these species are winter-deciduous, wind-pollinated, and wind-dispersed.

White Alder
Willow
Western sycamore
Mulefat