- Slides: 12
Nutrient Cycling • Unlike energy, which flows one -way through an ecosystem, matter is recycled through ecosystems – law of conservation of matter ENERGY MATTER
Nutrient Cycling • Matter (elements, chemical compounds) are recycled through biogeochemical cycles – The Water Cycle – The Carbon Cycle – The Nitrogen Cycle – The Phosphorus Cycle
Main Points: • Carbon (in CO 2 form) cycles between Photosynthesis and Cellular Respiration • CO 2 is in the atmosphere and in the ocean – Photosynthesis: Atmosphere Organisms – Feeding Producer Organisms Consumers – Respiration Organisms Atmosphere • Decomposition of organisms returns carbon to the soil/water/atmosphere • Human activity increases the amount of carbon in the atmosphere, leading to climate change
Main Points: • Major N 2 reservoir is in the atmosphere • Bacteria “fix” nitrogen and convert it into a usable form (from N 2 gas to ammonia (NH 3) – Nitrates & Ammonia in ground • Producers take up nitrogen from the soil • Nitrogen… – Is used in DNA synthesis – Is a part of amino acids (proteins)
Remember… • Biological systems don't use up matter, they transform it! • Entropy: the world slowly becoming more and more disordered….
Nutrient Cycle Limitations • LIMITING NUTRIENT – When ecosystems lack needed nutrients, it restricts growth. – This is often why fertilizer is used!
Over-fertilization • Runoff of nutrients into water sources • More nutrients in water means that producers (algae) grow and reproduce faster • Not enough consumers to eat excess producers. • Leads to an “algal bloom” --- too many algae use up all the oxygen in the water • No oxygen means everything dies eutrophication