This document describes the key components and features of ecosystems, including water, air, solar energy, rocks, soils, and how energy flows through nutrient cycles. The main components are water, air which provides oxygen and carbon dioxide, solar energy from the sun, rocks which weather to provide nutrients, and soils which vary in depth and nutrients. Energy flows through ecosystems as biomass, litter, and soil, with nutrients cycling as plants take them up from the soil, release them when dying and decomposing, and nutrients are lost or gained from weathered rocks.