Ecosystems | Activity 2.4

Use 2.4 Pools in Other Ecosystems PPT to compare the Meadow Simulation to different ecosystems.

• Remind students that the Meadow Simulation was a simulation of one specific ecosystem: a meadow. Show students the biomass pyramid on Slide 3 and discuss how it represents the patterns observed in the simulation.

Use slide 3 to introduce four different types of ecosystems. Have students consider two ecosystems at a time—prairie vs. desert and cornfield vs. forest—during Slides 4-11. Students should write down a prediction on a piece of paper. Ask: Which ecosystem will have the most organic carbon? They could also predict which pool they think will be the largest.

Accommodation: Have students share their predictions to the class for the question “Which ecosystem will have the most organic carbon?” As students share their predictions, write down these predictions on a sheet of paper or the board.

Use Slide 12 of the PPT to prompt students to write down as many observations as they can about the differences between the four ecosystems.

• The main thing they should notice is that the relative sizes of ecosystem pools is the same across ecosystems: the largest pool is the soil organic carbon, followed by producers, then herbivores, then carnivores.
• They may also notice that soil organic carbon is the largest pool in the prairie, but the forest has the most organic carbon in producers. You may use this opportunity to talk about how pool sizes are different because of the history of the site (lots of grasses growing and dying increase the soil organic carbon pool) and the size of the organisms that live there (trees versus corn).
• They should also notice that the total organic carbon differs across ecosystems.
• Use Slide 13 to revisit the main pattern from the meadow simulation: the biomass pyramid.
• Use Slide 14 to introduce carrying capacity. Carrying capacity is the amount of total organic carbon in an ecosystem. Students will be exploring carrying capacity more in Lesson 4. Ecologists answer the last question (about why different ecosystems have different carrying capacities) by identifying limiting factors, including:
  • Water (the primary limiting factor for deserts)
  • Temperature (the primary limiting factor in Arctic and alpine ecosystems)
  • Nutrient availability (the primary limiting factor in rain forests)

This is a good time elicit students’ ideas and questions about what limits carrying capacity of different ecosystems. You do not need to teach about limiting factors at this point.

Accommodation: For the information on the final slide, as a class create biomass pyramids or other bar graphs to show the size of the pools as visuals. Have students describe the organic matter pools in the four ecosystems (desert, forest, corn field, and prairie) including the herbivores, producers, and carnivores that live in each ecosystem.

If you decided to use the Big Idea Probe: Wolves and Deer, have students complete it and share their ideas for a second time. See Assessing Big Idea Probe: Wolves and Deer for suggestions about how to use the Big Idea Probe.