What Makes Ecosystems Open Systems?
- Ecosystems are open systems, meaning they exchange energy and matter with their surroundings.
- This exchange drives the processes that sustain life and maintain the functionality of ecosystems.
- The continuous movement of energy and matter through ecosystems is essential for the biodiversity, growth, and reproduction of organisms.
Energy Flow in Ecosystems
- Energy enters ecosystems primarily from the Sun.
- Producers (autotrophs) capture solar energy and convert it into chemical energy through photosynthesis.
- This energy is stored as biomass, which moves through trophic levels as organisms feed on one another.
- The transfer of energy follows the pathway:
Sun → Producers → Primary consumers → Secondary consumers → Tertiary consumers → Decomposers - At each transfer, a portion of energy is lost as heat through metabolic processes such as respiration.
- Because of these losses, energy flow is unidirectional.i
- It cannot be recycled like matter.
- In a food chain, when a herbivore eats a plant, only about 10% of the plant's energy is passed on to the herbivore.
- The rest is lost as heat through respiration.
Matter Cycling in Ecosystems
- While energy moves in one direction, matter cycles continuously through biotic (living) and abiotic (non-living) components.
- Nutrients such as carbon, nitrogen, phosphorus, and water move through the biosphere via biogeochemical cycles.
- Producers absorb inorganic nutrients, consumers obtain them through feeding, and decomposers recycle nutrients back to the environment.
- This closed-loop process maintains nutrient balance and prevents depletion.
- Energy flows, matter cycles.
- Energy leaves as heat, while nutrients are reused.
Interrelationship Between Energy and Matter
- Energy drives the processes that allow matter to be cycled (e.g., photosynthesis converts solar energy into chemical energy stored in matter).
- The cycling of matter supports the growth and reproduction of organisms, which in turn supports energy transfer across trophic levels.
The First Law of Thermodynamics in Ecosystems
What is the First Law of Thermodynamics?
Definition
First Law of Thermodynamics
The First Law of Thermodynamics states that energy cannot be created or destroyed. It only changes from one form to another, maintaining a constant total amount.
- The First Law of Thermodynamics, also known as the Law of Conservation of Energy, states that energy cannot be created or destroyed, only transformed from one form to another.
- Within ecosystems, energy enters as sunlight, is converted to chemical energy, and is eventually released as heat.
- The total quantity of energy remains constant, even though its form and availability change.
