Benefits people derive from ecosystem. Ecosystem services are typically grouped in four broad categories: provisioning, such as the production of food and water; regulating, such as the control of climate and disease; supporting, such as nutrient cycles and crop pollination; and cultural, such as spiritual and recreational benefits. (Source: Wikipedia)
Elastic (goods and services)
Elastic goods and services generally have plenty of substitutes. Inelastic goods have fewer substitutes and price change doesn't affect quantity demanded as much. Some inelastic goods include gas, electricity, water, drinks, clothing, tobacco, food, and oil.