Energy Transfer through Ecosystems
Energy Transfer through Ecosystems
Overall Concept
- Energy flows through an ecosystem in one direction.
- The energy originates from the sun and is taken in through photosynthesis.
- Photosynthesis is the process in which green plants and some other organisms use sunlight to synthesize foods with the aid of chlorophyll pigments.
- The energy is then passed on through various trophic levels (different levels of a food chain).
- Each organism in an ecosystem fits into multiple food chains and is part of a complex food web.
- Energy is lost in each transfer between trophic levels. This can be due to respiration, movement, egestion, or death and decay (non-consumption).
Photosynthesis and Primary Producers
- Green plants (also known as autotrophs or primary producers) capture the sun’s energy and convert it into chemical energy in the form of glucose.
- This process is called photosynthesis and involves converting carbon dioxide (CO2) and water (H2O) into glucose (C6H12O6) and oxygen (O2).
- 6CO2 + 6H2O + light energy –> C6H12O6 + 6O2
Herbivores and Primary Consumers
- Organisms that consume plants are called herbivores or primary consumers.
- They obtain energy by eating plants and converting the plant matter into a form they can use.
- These organisms include rabbits, cows, and sheep.
Secondary and Tertiary Consumers
- Carnivores (secondary and tertiary consumers) obtain energy by consuming primary consumers.
- This includes organisms such as wolves, lions, and eagles.
- They convert the consumed matter into a form they can use.
- Omnivores, organisms that eat both plants and animals, can be primary, secondary, or tertiary consumers.
Energy Loss in Trophic Levels
- As energy moves up the food chain, much of it is lost at each level.
- Approximately 90% of energy is lost with each transfer, only about 10% of energy is passed to the next trophic level.
- Much of the lost energy is used for metabolic processes in the organisms, such as growth, reproduction, and movement.
- Other means of energy loss include faeces, urine, and heat loss due to cellular respiration.
Efficiency of Energy Transfer
- The efficiency of energy transfer between trophic levels can be calculated using the following equation: Energy transfer efficiency = (Energy available after the transfer / Energy available before the transfer) * 100%.
- The calculation shows that, on average, only about 10% of the energy is transferred from one trophic level to the next level.
The 10% Rule and Pyramid of Energy
- Due to the limited energy transfer, the structure of an ecosystem is often presented as a pyramid.
- This is known as a pyramid of energy where each level represents the amount of energy present at each trophic level.
- The size of each level depends on the energy available to it, supporting the “10% Rule”. It is represented broader at the base (plant level) and becomes narrower towards the top (higher consumers).
Decomposers and Detritus Feeders
- Detritus feeders and decomposers play a crucial role in the ecosystem. They obtain energy by breaking down dead organic material.
- Decomposers, such as fungi and bacteria, break down complex organic compounds into simpler substances.
- Detritus feeders, such as earthworms and woodlice, consume dead plant and animal material, which they return to the soil as nutrients.
Importance of Ecosystem Energy Flow
- The flow of energy within an ecosystem is essential for the survival and functioning of that system.
- It determines the abundance and diversity of organisms in an ecosystem.
- Understanding this energy flow is key to managing natural resources, conserving biodiversity, and addressing issues such as climate change.