1. Monera - includes bacteria that plays several roles like nitrogen fixation.
2. Protista - produce more oxygen as compared to all land plants put together.
3. Fungi - fungi degrades organic matter and recycle nutrients in the ecosystem.
4. Plantae - plants carry out the process of photosynthesis and maintains the CO2 and O2 level of the atmosphere.
5. Animalia - animals play a key role in stabilizing the food chain of the ecosystem.