Current issue: 54(3)
The forest sites have typically been classified by two principles, either as stand quality classes or as locality (site) classes. This article describes the principles of Finnish forest site types (forest quality classes) which are based on classification of localities according to their forest plant associations. All the stands that belong to the same forest site type are characterized by a distinct, more or less identical plant species composition. The forest site types are independent of the tree species. The forest site types in a larger area are relatively numerous, but can be grouped according to their normal form. The Finnish forests are separated to dry moss forest class, the moist moss-forest forest class and grass-herb forest class. The different forest site types belonging to the classes are described in detail. Growth of the trees is different for the different forest site types, but varies little within a same site type. The forest site types suit therefore well for the purposes of forest mensuration and for yield tables. The forest site types reflect also the properties of the soil.