Prologue: The Flight of Apollo 13 -- Ch. 1. The Life-Support Environment -- Ch. 2. Levels of Organization -- Ch. 3. The Ecosystem -- Ch. 4. Energetics -- Ch. 5. Material Cycles and Physical Conditions of Existence -- Ch. 6. Population and Community Ecology -- Ch. 7. Development and Evolution -- Ch. 8. Major Ecosystem Types of the World -- Epilogue: The Transition from Youth to Maturity