Recycling of All Chemical Elements Required by Living Organisms in Ecosystems
- Life on Earth depends on the continuous recycling of essential chemical elements.
- These elements such as carbon, hydrogen, oxygen, nitrogen, and phosphorus are required to build the macromolecules that make up living organisms.
- Carbon, hydrogen, and oxygen form carbohydrates, lipids, and proteins, which are the foundation of life.
- Nitrogen and phosphorus are critical for proteins, nucleic acids, and other molecules.
- Approximately 15 other elements—used in trace amounts—are also essential, including potassium, sodium, and calcium.
- Without recycling, these finite resources would quickly be exhausted, disrupting the balance of ecosystems.
The Role of Decomposers in Nutrient Cycling
- Decomposers such as bacteria and fungi are the backbone of nutrient cycling.
- These organisms:
- Break down organic matter, such as dead organisms, releasing nutrients back into the environment.
- Convert complex compounds (e.g., proteins) into inorganic forms (e.g., ammonia in the nitrogen cycle).
- Ensure nutrients like nitrogen and phosphorus are available for reuse by plants.
Fungi breaking down fallen leaves return nitrogen to the soil, making it accessible to nearby plants.
Key Nutrient Cycles
1. The Carbon Cycle
- Photosynthesis: Plants absorb carbon dioxide from the air, storing it as glucose.
- Respiration: Animals and plants release carbon dioxide back into the atmosphere.
- Decomposition: Dead organisms and waste products release carbon dioxide via decomposers.
- Don’t confuse the carbon cycle with the energy flow.
- While energy is lost as heat, carbon is continuously recycled.
