Humans harvest food and materials from living systems. This lesson covers agriculture, fisheries and forestry, and how each can be made sustainable.
You will calculate a crop yield and a maximum sustainable yield. Answer the questions and collect ⭐.
Agriculture converts land and inputs into food. Intensive systems use high inputs (fertiliser, machinery, agrochemicals) for high yield per unit area; extensive systems use lower inputs over larger areas.
Yield is output per unit area, e.g. tonnes per hectare.
Yields can be raised with fertilisers, pesticides, selective breeding and GM crops, but these carry trade-offs: fertiliser run-off causes eutrophication, pesticides can harm non-target species, and monocultures reduce biodiversity.
Overfishing removes fish faster than they can reproduce, collapsing stocks. The maximum sustainable yield (MSY) is the largest catch that can be taken repeatedly without depleting the stock.
Controls include quotas, minimum net mesh sizes (letting young fish escape) and closed seasons or areas.
Deforestation for timber or farmland reduces biodiversity, releases stored carbon and increases erosion. Sustainable forestry keeps the resource intact through selective logging, replanting and afforestation, harvesting no faster than the forest regrows.
Sort each method into the correct area.
Match each term to its meaning.
Agriculture: Intensive vs extensive; yield = output ÷ area; trade-offs of inputs
Fisheries: Overfishing; MSY; quotas, mesh size, closed seasons
Forestry: Deforestation vs selective logging, replanting, afforestation
Sustainability: Harvest no faster than the resource regenerates
The theme throughout is harvesting within nature’s capacity to renew. Press Finish.
You've worked through Biological Resources. 🎉
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Next: test yourself in the Evaluate stage, then lock it in with Verify.