Coniferous trees, in cold and temperate climates, generate a blockage mechanism of soil pedogenesis. Their lignin, once into the soil, evolves in producing a great amount of polyphenolic inhibitors. This type of lignin is also found in many tropical tree species but high soil temperatures break the inhibitor effect to some extent. In cold and temperate climates, ramial wood from coniferous species must be avoided or restricted to 20% of the overall content. Coniferous trees are characterized by an asymetrical lignin (guaiacyl).