Inside leaves, there are many small green disks called chloroplasts and they absorb carbon dioxide (CO2
), a greenhouse gas in the process of photosynthesis. The chloroplasts turn CO2
into oxygen that we can breathe and sugars that are used by the plants to grow, for example forming new leaves and stems. When the seasons change and the leaves turn red, brown or yellow and start to die, they absorb less and less CO2
but they transport sugars out of the leaves into storage in other part of the plant: this process is called "translocation". However, the plants grow back again in the spring. There are even some plants that don't die at all in the winter. Also, plants vary in the timing of when leaves become active and die: this is called "phenology".
In order to grow, plants need energy through photosynthesis. They also need nutrients from the soil and water. The growth produced can be used to produce new leaves, flowers and storage and support parts such as trunks of trees. You can see how leaves all around the world absorb carbon dioxide and release oxygen throughout the different seasons from this video taken by NASA.