Description:

Students will conduct simple sampling of plant and insect biodiversity at ground level in two contrasting environments of their own choosing. Students need not identify each species found, only recognize different species and be able to compare and contrast species numbers in the two habitats.

The task assesses students' understanding of biodiversity, including an understanding that biodiversity can be quantified in many different ways; the importance of biodiversity in ecosystem stability and resilience; and that biodiversity(as measured by species richness) is different in different habitats due to environmental factors. This task also assesses experimental design.

This task is designed to take students approximately 2 periods in class for discussion, instruction, Internet searches (if used).

Overall Task Content Area:

Life Science

Specific Knowledge Areas:

Effect of various species on ecosystems

  Structure and function in biological systems

Performance Expectations:

• conducting investigations
• using equipment
• gathering, organizing, and representing data
• formulating conclusions from investigational data

National Science Education Standards:

12 A SI 1: Abilities necessary to do scientific inquiry: Grades 9-12

1.3 Use technology and mathematics to improve investigations and communications. A variety of technologies, such as hand tools, measuring instruments, and calculators, should be an integral component of scientific investigations. The use of computers for the collection, analysis, and display of data is also a part of this standard. Mathematics plays an essential role in all aspects of an inquiry. For example, measurement is used for posing questions, formulas are used for developing explanations, and charts and graphs are used for communicating results.

1.4 Formulate and revise scientific explanations and models using logic and evidence. Student inquiries should culminate in formulating an explanation or model. Models should be physical, conceptual, and mathematical. In the process of answering the questions, the students should engage in discussions and arguments that result in the revision of their explanations. These discussions should be based on scientific knowledge, the use of logic, and evidence from their investigation.

12 C LS 4: The interdependence of organisms: Grades 9-12

4.3 Organisms both cooperate and compete in ecosystems. The interrelationships and interdependencies of these organisms may generate ecosystems that are stable for hundreds or thousands of years.

4.5 Human beings live within the world’s ecosystems. Increasingly, humans modify ecosystems as a result of population growth, technology, and consumption. Human destruction of habitats through direct harvesting, pollution, atmospheric changes, and other factors is threatening current global stability, and if not addressed, ecosystems will be irreversibly affected.

(Use the "hot" link on the PALS home page to check the full text of related National Science Education Standards, if desired.)

General Instructions to the Teacher:

This task is designed to take students approximately 2 periods in class for discussion, instruction, Internet searches (if used). .

Students should be ready to work as soon as periods begin. A central supply area, if needed, should be easily accessible. All supplies should be clearly labeled.

Materials for " Suburban Ecosystems":

The student will need:

• graph paper
• computer resources (if available)
• 0.5 meter sampling grids (constructed from wood lath or pvc pipe)

Advance Preparation:

1. As part of the initial introduction to the ecological characteristics of life on Earth (reproduction, energy processing, cycling, homeostasis, diversity), discuss the concept of biodiversity as number and types of species in a given area. In a full or partial class period, allow student teams (2-3 students) to use the Internet and Worldwide Web search engines to find basic information about biodiversity. How it is defined, how it is measured, what areas are the most and least diverse areas on the planet, and what are the advantages and disadvantages of diversity in an ecosystem are all possible questions to use to direct their searches. You may wish to do this as a team search contest, or simply by providing a list of questions to answer. (As of March, 1998, several biodiversity sites contained links to this information, so it should be relatively simple for students to find.)

Once students have found the information, use their answers as a springboard to further discussions about what influences diversity in various ecosystems. Provide students with a set of observations (simulated or actual measurements) that indicate that different terrestrial environments characteristically support different levels of biodiversity.

Sample Data (simulated): This data can be used to spark a discussion of the influence of different environments on Plant communities that appear from a causal observation to be very similar. All data shown below were collected on suburban "lawn" areas, on flat ground, exposed to full sun, moderate foot traffic, and subject to frequent mechanical mowing.

 

Landscape/Location	Plant Species	Animal Species	Total Species
Manila, Philippines	16	12	28
Los Angeles, CA	2	4	6
Seattle, WA	7	9	16
Salem, OR	8	3	11
Sedona, AZ	2	0	2

 

Brainstorm possible reasons why, advantages, disadvantages to high biodiversity, or other issues that arise. Discuss the simplest possible techniques for diversity determinations. These would typically involve .5 to 1-meter square plots--based on appearance only. They need not actually identify species names. Include plants (grass, shrubs, and/or weeds) and animals (usually insects and worms).

As part of the discussion, it would be beneficial to take students to lawn areas around the school and have them practice sampling techniques. Consider producing 0.5 meter square frames out of wood or PVC pipe with string tied across the frame at approx. 10cm intervals to provide a easy sampling grid for students to use.

Allow students to practice with the grids until they appear to be familiar with how they are used and the types of data they can collect.

2. Students will now be asked to examine two different environments around their home, in vacant fields, or in city park areas using the same techniques. They should start with identification of two sites, explanation about why they are different (degree of shade, proximity to house, road, trees, shrubs, degree of cultivation, amount of foot traffic, etc.) and formulation of a hypothesis related to the comparison of the two sites. They will then collect data as carefully as possible, but without very specific instructions about how when to sample, how often to sample, where to sample. They will use the data to produce a written report related to their hypothesis with the following parts:

• Title
• Introduction
• Procedure
• Data
• Analysis and Conclusion

Safety:

• Be careful.
• Teachers and students should always exercise appropriate safety precautions and utilize appropriate laboratory safety procedures and equipment when working on science performance tasks.

Extensions/modifications:

• Students may wish to extend this procedure to examine other areas such as nearby riparian zones (contrasting those in city parks to those in rural or wild-land areas), forests (managed wooded lot vs. wild-land), or wetlands.