Photosynthesis is the most important and significant chemical reaction in nature on which all life on Earth depends. It is the only known reaction in which organic matter is created from purely inorganic matter.
The products of photosynthesis are sugar and starch. The proteins and fats produced from them serve as food for animals and humans and are vital for all organisms.
Photosynthesis converts the Suns energy into chemical energy and stores it in organic compounds (sugar and starch). For this process trees need CO2, light as a source of energy, chlorophyll as the absorber of light energy, and water.
For more information on photosynthesis and carbon offset, go to link (Wikipedia on Photosynthesis).
The trees planted within the framework of the Evers-ReForest projects together make up a mixed deciduous forest. It consists of several different species of broadleaf trees which each guarantee a specific carbon offset.