• A system is sustainable if it can continue
indefinitely
– Without depleting material or energy resources
• Sustainable yields in forestry and fisheries
– Harvest resources but stay within the capacity of the
population to grow and replace itself
– Also applies to fresh water, soils, pollution absorption
• Sustainable ecosystems are natural systems that:
– Thrive over time by recycling nutrients
– Maintain a diversity of species
– Use the Sun as a source of energy