Creative Thinking Assignment: Why Tree give a Fresh air?

A tree needs carbon dioxide and water for photosynthesis.
Photosynthesis is the process in which light energy absorbed by chlorophyll is transformed into chemical energy. The chemical energy is used to synthesise carbohydrates from water and carbon dioxide. Water and carbon dioxide are the raw materials for photosynthesis. Oxygen is released during the process.
The limiting factors in photosynthesis are light intensity, concentration of carbon dioxide and temperature.
After photosynthesis, glucose and oxygen are produced. Fresh air which is oxygen for living organisms to respire. Tree do have a reason to give fresh air. It is a process of respiration which gases exchange. Gases such as oxygen and carbon dioxide exchange through diffusion.
Diffusion is the net movement of particles from a region of higher concentration to a lower region of concentration. The gases exchange in the spongy mesophyll. It has numerous large intercellular air spaces among the cells. It allows rapid diffusion of carbon dioxide and oxygen into and out of mesophyll cells. In daylight when photosynthesis occurs, the carbon dioxide in the leaf is rapidly used up. The carbon dioxide concentration in the leaf becomes lower than that in the atmospheric air, so a diffusion gradient exists. Therefore, carbon dioxide diffuses from the surrounding air through the stomata into the air spaces in the leaf. The surfaces of the mesophyll cells are always covered by a thin film of water so that carbon dioxide can dissolve in it. The dissolved cartoon dioxide then diffuses into the cells.
Trees and plants are producers. They are the lowest in the pyramid of numbers at each trophic level as they are the main source of food. There will not be a food web without producers.