Carbon enters the biotic part of the ecosystem primarily through the process of photosynthesis. During this process, green plants, algae, and some bacteria use carbon dioxide (CO2) from the atmosphere and water (H2O) to produce glucose (C6H12O6) and oxygen (O2). The equation for this process can be summarized as:
6 CO2 + 6 H2O → C6H12O6 + 6 O2
This means that carbon is continually recycled in the ecosystem. When animals consume plants, they take in the carbon that was fixed in the plant tissues, which then becomes part of their own biological processes. When these organisms respire, decompose, or die, the carbon is returned to the soil and atmosphere, thus continuing the cycle. Overall, this movement of carbon from the atmosphere into living organisms and back again is vital for maintaining the balance of carbon in our environment.