“The best time to plant a tree was 20 years ago. The second best time is now.” Anonymous Published Oct. 14, 2008 Trees play a key role in the environment's natural landscape due to their ability to prevent erosion. The Spanish Government says it will plant 45 million trees over the next four years to counter desertification caused by global warming. The massive tree–planting scheme aims to reduce the amount of carbon dioxide (CO2) in the atmosphere, the cause of global warming. It estimates that in the long term, the trees could absorb more than 3.5 million tonnes of CO2 emissions. Soils contain carbon in the form of organic matter. When organic matter is exposed to oxygen in the atmosphere, the carbon in the organic matter combines with the oxygen to produce carbon dioxide, contributing to the greenhouse effect and global warming. Organic matter is being lost from soils for a number of reasons. These include long—term changes in land management practices, changing soil man...