When products from sustainably managed forests replace products from nonrenewable resources, this may reduce carbon emissions, particularly in the case of energy intensive materials such as steel or concrete. Substitution of nonrenewable energy sources by renewable energies reduces carbon emissions. However, for both products and energy, the carbon benefit of substitution varies widely according to the pathway chosen, and must be analysed in detail using Life Cycle Assessment (LCA). The time profile of carbon emissions, with a large emission at harvest, compensated by gradual sequestration over the rotation is also an issue.