What is the main source of carbon in an ecosystem?

The main source of carbon dioxide in an ecosystem is the carbon dioxide gas present in the atmosphere. This carbon dioxide is used by the  plants and animals in different ways.

The plants use this carbon dioxide to perform the process of photosynthesis.This is carried out by the help of green pigment called chlorophyll that absorbs light from the sun, water from soil and carbon dioxide from atmosphere.

The carbon in animals comes when they eat these plants.

well first you need the sample of the temperature and gas level. i couldnt write a hypothesis unless i had some data. i think temperature changes will effect volumes of gas because gas changed into a solid or liquid at specific temperatures.