Final answer:
Carbon in plants is released into the soil during decomposition, becoming part of the carbon cycle and can also be released as carbon dioxide. Some of the carbon may become part of the soil's stable compounds or turn into fossil fuels over a very long period.
Step-by-step explanation:
When plants die, the carbon they contain is not lost; rather, it enters the soil through the process of decomposition. Decomposers, such as bacteria and fungi, break down dead plant material, which releases organic carbon into the soil. This organic carbon can be utilized by other plants, making it part of the carbon cycle.
Some of the carbon may also be released back into the atmosphere as carbon dioxide during the decomposition process. However, not all carbon is immediately available as some can become part of more stable soil compounds or be leached into water reservoirs. Over time, parts of this carbon can be stored in sediments and may eventually become fossil fuels, which are a non-renewable resource.