Activity 2A

43 Species of Ants up a Tree

Learner Objectives

After completing this activity, learners should be able to:

• List, describe, and study environmental problems related to tropical deforestation.
  
  
• Gather information to answer a scientific question through direct observations, including collecting and recording data, displaying data in an appropriate format, looking for patterns in observable data, relating findings to new situations or large group findings, answering a question or presenting a point of view using data, and identifying areas for further investigation.
  
  

Preparation

This activity requires research by teams. If they chose to do the biological diversity study (Activity Sheet 2A.1), help students select their study areas. Find two areas that are close to one another that represent altered and intact habitats. You may be able to use a school forest and parking lot, for example. Other ideas include:

Activity Sheet 2A.2 offers optional projects. You may wish to review them and help the group think of other projects.

Make copies of activity sheets as needed. Give some thought about reporting formats for data. Would you like students to write a report? Present data using graphs and models? Use overheads and charts? Use a news-report format?

Doing the Activity

Part I: Overview. In this activity, students answer a scientific question about the environmental impacts of deforestation on tropical rainforests.

Summarize for students, or give them opportunities to volunteer, some of the environmental impacts of tropical forest clearing, including:

Loss of Biological Diversity. Many of the areas in the tropics that are deforested remain without forest plants and animals for long periods of time. Yet biological diversity is the true wealth of the rainforest. Biologist Dr. E.O. Wilson reported 43 different species of ants on one tree found in a rainforest.

Erosion. Lands cleared of forests lose their ability to slow runoff. Rain washes over the land, uncaptured by vegetation. As a result, more and more soil is moved with the precipitation, resulting in mudslides and the loss of the top, and most fertile, layer of soil.

Loss of Soil Productivity. The red and yellow soils of many tropical forests are nutrient poor, having been washed by rains for centuries. Fallen leaves, twigs, and other organic matter provide needed nutrients to living things. When canopies and forests are removed, the nutrient source is eliminated. Burned areas are covered with ash, which fertilizes the soil for a few quick years. Soon, though, nitrogen and potassium, among other nutrients, are used up or washed away.

Water Quality. The Amazon and Congo rivers are part of large, forested watersheds. These rivers are the lifeblood of their areas, transporting residents and supporting a wealth of wildlife. When hillsides or other areas within the watershed are deforested, silt and soil run into the rivers, harming the clearness of the water and the animals within. This changes the number and abundance of aquatic organisms. People may not be able to catch as many fish or harvest other food from an impaired river.

Global Climate Change and Warming. Like other living things, trees are carbon based. They store carbon in their trunks, branches, and roots. Once cut and burned, trees release the carbon back into the atmosphere. This release of carbon contributes to the potential for global warming.

Part II: Researching an Environmental Impact. Help students work in teams of two or three to research different areas of environmental impacts on lands in their own backyards and communities. All research will follow the same format, where students:

1. Frame the research question that they wish to explore or answer.
   
   
2. Design the experiment that will help them answer the question.
   
   
3. Collect and record the data.
   
   
4. Display the data so they can be read and used.
   
   
5. Look for patterns in the data.
   
   
6. Relate their findings to other situations or to the larger group's findings.
   
   
7. Answer a question or present a point of view using their data.
   
   
8. Identify areas for further investigation.
   
   

Activity Sheet 2A.1 gives complete information to students about studying biological diversity. Hand these sheets out to students choosing this option. Review the information with teams. You may need to explain concepts about biological diversity. One concept that sometimes causes confusion is the idea of structure in a habitat. Habitats that have lots of nooks and crannies creatures can use to meet their needs are generally more biologically diverse than less structure-rich habitats. For example, a forest with lots of fallen logs, snags (standing dead trees), leaning trees, and layers of plants has ample structure for many different living things. A well-managed plantation of trees may lack these elements and may be less biologically diverse. Make sure students understand this important concept.

Optionally, use Activity Sheet 2A.2 for students who wish to investigate other environmental impacts of deforestation. Teams will have to devise their own research questions and design their own study. You or the teams can decide which topic will be researched.

Also decide how the information will be reported to the larger group. Should teams make overheads to present data? Should they write a report? Design posters with graphs and charts of data? Explain reporting methods to students.

Part III: Reporting to the Larger Group. Give each team an opportunity to present their findings to the larger group. Questions to ask include:

• Were you able to answer your research question? Why or why not?
  
  
• Did the data collection go smoothly? What unexpected things happened?
  
  
• Did the intact or altered area have more biological diversity? Did this result surprise you? Why or why not?
  
  
• How did the structure of the area affect the number of living things present?
  
  
• Do you think intact or cleared rain-forest areas have more biological diversity? Why?
  
  
• What would be the effect of clearing all the tropical rainforest area in the world?
  
  
• Do you think biological diversity is important to the world? Why or why not?
  
  

Evaluating Results

Use the chart below to assess each student's progress. Circle the rating that best reflects his or her efforts.

Extension

Another potential effect of tropical deforestation is global warming and climate change. Trees store carbon in their trunks, branches, and roots. But once cut and burned, trees release the carbon back into the atmosphere. This release of carbon dioxide acts to trap heat in the earth's atmosphere, contributing to the warming of the earth. As the earth warms, the climates of different areas change-some become warmer, some receive more rain, and so on.

Students with Internet access can evaluate their total carbon dioxide emissions each year. Each gallon of gasoline we burn, each pound of garbage we throw away, and each Btu of energy we use for home heating and other purposes results in carbon dioxide emissions. Have students visit the American Forests web site to calculate their carbon debt and find out how many trees they would need to plant to absorb the carbon dioxide: