Teacher's Guide

Episode 5: "SEAS OF GRASS" (25 minutes)

Overview

Among the most endangered ecosystems today are the world's grasslands.  Threats menacing them include overgrazing, soil erosion, urbanization, and replacement of natural vegetation with agricultural fields and tree plantations.  When native grasslands disappear, so do the unique plants and animals that depend on them.  Also at risk, are unique human cultures and lifestyles specially adapted to them: Mongolian nomads, Argentine Gauchos, and American cowboys all have developed distinctive ways of thriving in the challenging conditions of the world's grasslands, whether we call them prairies, pampas, veldts, or steppes.  The preservation of both our cultural and our natural heritages, therefore, depend upon how successfully we can preserve the natural grasslands that support both.

Learning Objectives

Students will be able to:

1. Identify some of the threats confronting natural grasslands worldwide.

2. Describe some of the distinctive cultures and lifestyles that have developed as adaptations to grassland conditions.

3. Describe measures that people are taking to preserve grassland ecosystems and the cultures that depend on them.

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Pre-Viewing Activities

1. Introduce the following key terms to the students:

   Pampas — the vast plains of southern South America, chiefly in Argentina, but also in Uruguay, southern Brazil, and southeastern Paraguay

   Veldt — the extensive grasslands of South Africa

   Prairie — grasslands, especially in the interior of North America

   Steppe — the plains of interior Eurasia

   Savannah — a grassland with scattered trees, typical of East Africa

   erosion — the carrying away of soil by wind, ice, water and animals

   carrying (grazing) capacity — the amount of animals that can be supported by a piece of land or body of water

   sedimentation — the deposition of eroding soil onto land or into water

   2. To familiarize students with the areas in the program segments, use a wall map, desk map or an atlas and have students locate
   

   • Shanghai

   • Inner Mongolia

   • Kenya

   • Lake Baringo

   • Buenos Aires

   • New Mexico

After the students have found each of these locations, begin a discussion to discover what they already know about these regions.  Have the discussion center on environmental problems that are familiar to the students.

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Post-Viewing Discussion

Inner Mongolia

1. What weather conditions create the grasslands in Inner Mongolia?  (Answer: Hot and dry summers, long, cold winters.  These typically create grasslands worldwide.)
   
2. Why do the people who live on the Mongolian grasslands roam around instead of living in one place?  (Answer: They move in search of grass to feed their animals.)
   
3. How do they live when roaming on the grasslands?  (Answer: They live in mobile tents and carry everything they need with them.)
   
4. What is motivating people to overgraze the grasslands?  (Answer: China is undergoing an economic boom, and increasing numbers of people want to buy meat and milk.  The herders want to take advantage of the demand for their animals, so they want to raise as many as possible.)
   
5. What pressures are threatening the traditional Mongolian nomadic culture?  (Answer: Environmental deterioration, notably soil erosion, is making it difficult to make a living.  Increasing educational and employment opportunities in cities and town lure young people away from the traditional nomadic way of life.)

Kenya

1. Why is the erosion occurring?  (Answer: Overgrazing the land destroys the vegetation that holds the soil in place.)
   
2. What is causing the overgrazing?  (Answer: Significant human population growth around the lakes, leading to increased numbers of animals.  Fewer people living a nomadic lifestyle, more people living year-round in villages.  This forces livestock to focus their grazing on small areas close to villages, rather than spreading out over a wider area.)
   
3. What are some people doing about soil erosion?  (Answer: They are planting native grasses and other plants which will hold the soil in place and provide fodder for stock.)

South Africa

1. What are some ways in which the natural grasslands of South Africa (the Veldt) are ecologically important?  (Answer: Habitat for over 800 species of wildflowers, 360 species of birds, and many wild mammals.  Grasslands also absorb rainwater and release it gradually to streams, rivers, and lakes.  This greatly reduces the risk of extreme cycles of floods and droughts.)
   
2. What are some ways in which people use the grasslands?  (Answer: The grasslands provide natural medicines and grazing for livestock.)
   
3. What is the unemployment rate in rural South Africa?  (Answer: Over 60%.)
   
4. What happens to many of the trees?  (Answer: They are sent to Japan, Australia and the United States to make paper and pulp.)

Argentina

1. Why is the pampas perfect for raising cattle?  (The weather is constant — mild and moist.) 
   
2. What is the chief threat to the pampas?  (Answer: Conversion to croplands.  This wipes out native vegetation, puts more insecticides and fertilizers into the environment, and reduces water storage in spongy grassland soils.)

New Mexico

1. What are people trying to do with the Gray Ranch?  (Answer: Maintain an environment that will prove healthy for wildlife, livestock, and a traditional way of life far into the future.)
   
2. What are some measures being implemented to bring this about?  (Answer: Maintaining native vegetation, restricting the numbers of livestock that roam the ranch so that they do not overgraze, using fire to remove alien plant species and to encourage new and nutritious plant growth, employing traditional ways of managing the ranch.)

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Special Projects

1. To help your students learn where the major biomes of the world are found, divide the students into work groups and assign to each a biome (tundra/alpine; coniferous forest; deciduous forest; tropical rain forest; grassland/Savannah; desert) to research.  Each group should prepare a map showing where in the world each biome is found and present some animals typical of each.  Results may be presented on a poster or an oral presentation, or each group can combine efforts to prepare a large world map for the classroom wall or the hallway, decorated with pictures of wildlife cut out from magazines or downloaded from the internet.

2. To compare the life found in fields, pastures, or grasslands in your neighborhood with other local ecosystems such as forests, have your students carry out a mini-transect study.  The students will tie a string five meters long to two sticks and stake them into the ground in each habitat being compared.  Then they will carefully survey the plants and animals they find.  A range of field guides are available to your students to help them identify what they find.

3. To see the effects of soil erosion, take your students on a neighborhood stroll to compare the soil in both eroded and intact sites.  Have your students consider the following:

   • Differences in soil color, texture, and moisture.
     
   • Plant life in each site.
     
   • Reasons why erosion occurred in one site and not the other.
     
   • Which soil evidently contains a higher percentage of decomposed plant material.
     
   • Which soil evidently contains more worms and other soil fauna.
     
   • Which habitat is healthier.
     
4. Have a discussion with your students about human carrying capacity.  Ask them how humans can raise their carrying capacity, (e.g. irrigation, plant breeding, fertilization) and how humans can decrease it (e.g. desertification, soil erosion).  What will happen if human populations continue to increase and human carrying capacity decreases?  Do your students know of examples around the world that look like this?
   
5. As an extension, ask your students to consider vanished civilizations, such as ancient Mesopotamian city-states, classic Mayan, and the Anasazi of the American Southwest.  Many scientists now believe that environmental degradation, notably deforestation and soil degradation, contributed to their demise.  What archaeological evidence would your students expect to find if significant environmental degradation did, indeed, occur?
   
   • Ask a farmer to visit your class and discuss how he or she works to conserve soil.  Have their crop yields been increasing, decreasing, or remaining the same, and why?  Or, ask an agricultural extension agent to speak with your students.  What soil conservation problems occur in your neighborhood, and what can people do to solve them?  What can your students do?
     
   • With the help of an agricultural extension agent, have your students prepare a soil conservation demonstration plot on school property.  If your school is in the Midwestern United States, have your students prepare a plot of native prairie plants.  Agricultural extension agents, the local land grant college, or local environmental or nature study organizations may be able to help.  You may be able to have your school property warrant registration as an official wildlife habitat.  Contact the National Wildlife Federation (see listing below) for information about its Backyard Wildlife Habitat program.
     
   • To compare the water retention capacity of eroded and healthy soil, collect a sample of each.  Then take two one-liter clear plastic bottles and cut off the bottom.  Insert each bottle into a clear glass jar and fill each about two-thirds full with one of the soil samples.  Now, take a container of water and gently pour into each bottle.  Have the students compare the quantity and clarity of the water that comes out the other end.
     
   • Have your students compose travel brochures describing the various grasslands worldwide and the cultures (e.g. Mongolian nomads, Gauchos, African pastoralists, American cowboys) found there.  The brochures should accurately present what the discriminating eco-tourist can find and do in these places.  Your students can use images cut from magazines or downloaded from the Internet.