This depends on the type of tree. Most types in Europe have a growing season of between 25 and 40 years. For pine and spruce, this is between 70 and 80 years. For birches, this is between 35 and 40 years. For eucalyptus trees, this is between 12 and 15 years. In comparison: agricultural land produces at least one harvest per year. Agricultural waste becomes available every year.