In this subtitle the following words have the meanings indicated. “District board” means any district forestry board created under this subtitle. “Landowners” means any person owning woodlands, located in the State. “Natural resources” means forests, fish and game, water and waterpower, soils, minerals, and all other similar sources of wealth. “Woodlands or forest lands” means any land of an area of 3 acres or more held by the same owner and primarily devoted to the growth of forest products.