AP Environmental Science Unit 5 Essentials

The tragedy of the commons explains why fisheries collapse, why forests get clearcut, and why grazing land gets degraded: when a resource is shared and unregulated, each individual user benefits from taking more while the cost of depletion is spread across everyone. This single framework connects overfishing, deforestation, and groundwater depletion as variations on the same underlying problem.

The Green Revolution, CAFOs, and intensive monoculture all dramatically increase output per unit of land — but each does so by increasing dependence on fossil fuels, water, and synthetic chemical inputs, with consequences for soil health, water quality, and greenhouse gas emissions. Recognizing this tradeoff pattern helps you evaluate any new land-use practice presented on the exam.

Selective cutting instead of clearcutting, drip irrigation instead of flood irrigation, integrated pest management instead of blanket pesticide use, smart growth instead of sprawl — in each case, the more sustainable option produces somewhat less output or requires more planning, in exchange for lower long-term environmental cost. This consistent pattern is a useful lens for analyzing any unfamiliar land-use scenario on the exam.