The common spruce (Picea abies) provides quality wood in spruce forests planted for forestry. The standard distance between two trees is 8.2 feet (2.50 meters). As they grow, the spruces prune naturally under the pressure of their density - which minimizes the number of nodes in the future timber - and clearings optimize their individual growth. It takes sixty years to obtain mature logs (trunks stripped of their branches). In the mountains, the high forests are more irregular with stands made up of subjects of different ages.