The video on the previous page introduced the idea of matter cycling through an ecosystem. Several key elements essential for life cycle through ecosystems. 

Important cycles in ecosystems:

• Oxygen cycle
• Carbon cycle
• Nitrogen cycle
• Phosphorus cycle
• Hydrologic cycle (water)
• Hydrologic & Carbon Cycles (Crash Course)
• Global Carbon Cycle (Crash Course)
• Nitrogen & Phosphorus cycles (Crash Course)

Or the Bozeman Science video, Biogeochemical Cycles sums them all up in one video.