Trees give us oxygen through photosynthesis by absorbing water through their roots, which is carried to their leaves and needles. At the same time trees absorb carbon dioxide from the air. The trees use sunlight as fuel to transform water and carbon dioxide into oxygen and sugar. The trees use the sugars to grow bigger, storing carbon in the process as wood, and release the oxygen back into the atmosphere for us to breathe. This is why sustainable forestry is good for us all, it produces a continuous cycle of growing, harvesting and replanting our forests.