Ecosystems

An ecosystem is a community of living organisms (plants, animals, microbes) that interact with each other and with their physical environment (air, water, soil, climate). (What do you find in each of the following spheres on earth) It is both biotic (living) and abiotic (non-living) parts working together as a system. (see: Biotic or Abiotic)

• Biotic factors: producers (plants, algae), consumers (animals), decomposers (fungi, bacteria).
• Abiotic factors: sunlight, temperature, water, minerals, atmosphere.
• Related: Biotic or Abiotic

• Energy flows: usually from the sun → producers → consumers → decomposers. (see: Lesson 2: Energy in Ecosystems, Energy Loss Between Trophic levels)
• Matter cycles: nutrients are reused (e.g., carbon, nitrogen, water).
• Balance: if one part changes (like loss of a predator), it affects the whole system.

• Tiny: a rotting log, a pond.
• Large: a rainforest, a desert.
• Global: the biosphere (Earth’s system of all ecosystems).

An ecosystem is not just a place—it’s the interactions that make it function. Think of it as a network: each part depends on others for survival and stability.

• In a forest ecosystem:
  • Trees provide food + shelter.
  • Deer eat plants.
  • Wolves hunt deer.
  • Fungi decompose dead material → nutrients return to soil.
  • Climate + rainfall affect all of this.