Advanced Placement Environmental Science examining environmental systems and human impact.
Ecosystems are vibrant communities where living things (plants, animals, microbes) interact with each other and with their physical environment. These systems include both biotic (living) and abiotic (non-living) components like soil, water, and sunlight.
Energy enters ecosystems primarily through sunlight, which plants use for photosynthesis. This energy moves through food webs from producers (plants) to consumers (herbivores, carnivores) and decomposers. At each step, some energy is lost as heat, meaning not all energy gets passed on.
Only about 10% of the energy at one trophic level is transferred to the next level. This is why food chains usually have just a few links!
Understanding energy flow helps us see why protecting producers and maintaining biodiversity are vital for ecosystem health.
\[E_{n+1} = 0.1 \times E_n\]
A grassland ecosystem where grass (producer) is eaten by rabbits (primary consumers), which are then preyed upon by foxes (secondary consumers).
Energy from sunlight is converted by algae in a pond and transferred to snails that eat the algae.
Ecosystems rely on energy flow from the sun through producers and consumers, with energy lost at each step.