1. Module 3 Intro

1.6. Lab

Lesson 1

Module 3—Ecosystems and Their Diversity

Read


Interactions between organisms influence how a community is structured. Some possible interactions found in a community are

  • competition between individuals of the same species (intraspecific competition)
    Example: two elk fighting

    This photograph shows two male elk locking antlers.
    Courtesy of U.S. Dept of the Interior, Bureau of Land Management

  • competition between individuals of different species (interspecific competition)
    Example: different species of African animals competing for water

    A photograph shows gazelles and zebras at a watering hole.
    © 2007 Jupiterimages Corporation
  • predator and prey relationships
    Example: wolves hunting elk

    An aerial photograph shows a pack of wolves circling a lone elk.
    Courtesy of U.S. National Park Service

  • populations interacting with abiotic factors
    Example: trout in water vs. bison on land


    An underwater photograph shows a lake trout.A photograph shows bison grazing in a pasture.
    Fish: © Ilya D. Gridnev/shutterstock
    Buffalo: © Image courtesy of Syncrude Canada Inc.

All of these interactions are dynamic—they are constantly changing. An area that was once suitable for trees can be made unsuitable by fire, rockslides, or a variety of other disturbances. The new habitat created by these disturbances may be less suitable for trees but will be more suitable to other species, such as moss and lichens. Over time, the moss and lichens can change the habitat so that it once again becomes suitable for shrubs and grasses to grow.

 

The following graph shows how the types of species change as time passes. The graph describes a habitat recently exposed by a melting glacier.

 

This is a stacked bar graph depicting Change in Abundance of Species Over Time. Number of Species is on the y-axis from 0–50, Time Elapsed (in years) is on the x-axis from 0–1500. The legend for this graph is purple = low shrubs and herbs, green = mosses and lichens, orange = small shrubs, yellow = trees. In the first two bars (10 and 23 years), purple is dominant, with a bit of green. The number of species remains below 20. In the next two bars (33 and 44 years), orange is added to the top. The number of species remains below 20. The next bar jumps ahead 50 years and there is now a bit of yellow added to the bar. The species count raises to 40, with the greatest increase happening in the green. The next bar jumps ahead another 100 years. There is still yellow at the top of the bar. The orange and purple sections have decreased and the species count is just above 30. In the final two bars (500 and 1500 years), yellow remains at the top and increases slightly. The purple section shows an increase, which increases the overall species number to between 40 and 50.

 

Self-Check

 

SC 2. Why does it take over 100 years for trees to appear in this habitat?

 

SC 3. Before you continue, think of some abiotic conditions that could influence the size of leaves on a plant.

 

Check your work.
Self-Check Answer

 

SC 2. It takes a long time for the nutrients in the soil to build up so that they could supply enough nutrients to the extensive root system of a tree.

 

SC 3.

  • amount of moisture
  • amount of nutrients in soil
  • amount of available sunlight