Ecosystems · EcoLab

Grass, flowers, rabbits, bees, birds and foxes on a small island, plus the decomposers in its soil, form an ecosystem you can change by hand. Remove a species and watch populations shift in a chain reaction through the food web; adjust decomposer strength and lift a block of soil to see litter, humus and the nutrient cycle; then open the energy ledger and energy pyramid to follow energy from one trophic level to the next. The energy panel switches between high-school and middle-school views.

Subject: Biology · Level: Middle school, High school · Topics: Population change, Food webs, Matter cycling and decomposers, Energy flow

Chapters

Ecological balance and self-regulation

Take the foxes off the island. Will the rabbits keep multiplying? Guess first, then fast-forward to see. In this qualitative model the rabbits surge to more than double, graze the grass down to about a tenth, fall to under half, and from then on fluctuate below their old level.

Follow the guide, who stops at key moments to introduce negative feedback regulation, population fluctuation, carrying capacity, resistance stability and recovery stability, and to show that self-regulation has limits. Then try the task cards yourself: what must you remove to wipe out the rabbits? Remove the birds, and who is hit hardest? A short quiz wraps up the lesson.

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