An ecosystem includes all of the living things (plants, animals and organisms) in a given area, interacting with each other, and also with their non-living environments (weather, earth, sun, soil, climate, atmosphere).
In an ecosystem, each organism has its own role to play.
Consider a small puddle at the back of your home. In it, you may find all sorts of living things, from microorganisms, to insects and plants. These may depend on non-living things like water, sunlight, temperature, atmospheric pressure and even nutrients in the water for life.
This very complex, wonderful interaction of living things and their environment, has been the foundations of energy flow and recycle of carbon and nitrogen.
Anytime a ‘stranger’ (living thing(s) or an external factor such as rise in temperature) is introduced to an ecosystem, it can be very bad for that ecosystem. This is because the new organism (or factor) can upset the natural balance of the interaction and maybe harm or destroy the ecosystem.
Unfortunately ecosystems have been disrupted, and even destroyed by natural disasters such as fires, floods, storms and volcanic eruptions. Human activities have also contributed to the disturbance of many ecosystems and biomes.
(Information adapted from Interactive Learning Resource – eschooltoday.com )