Urban forestry tries to connect the concept of forest ecosystem with the idea of nature preservation as well as with social needs of urban society, often living close to such a natural environment, thus being a part of it. The ability to connect the human need for the natural environment with life support system of persistent forest ecosystem should become an important contributing factor of urban forestry for well-being of urban society. In the range of 1 km walking distance around the city of Ljubljana and within urban areas of the city, forests comprise more than one quarter of the area. The most prevalent in the area are patches of forest fragments, estimated to have a shallow depth of the inner environment. The concept of urban forests in the Ljubljana Green System as a backbone of a green network has been confirmed especially by the two largest forest patches of Golovec and Rožnik, indented as a part of forest matrix up to the city centre. Based on the analysis of the continuum of these forests, it was possible to assume that in the past, more than three quarters of forest grounds were meant for no other land use. In the other quarter of the city and its Green System, forests were more significantly reduced in the past, given the fact that we can estimate its continuum only for one half of today's area. On a detailed level, it is recommended for the urban forests to contain a significant percentage of trees and other species that would naturally appear on the sites of the area. Whereas on a landscape level, it is not enough to address only such species, but also temporal stability of forest patches, corridors or even forest matrix in urban areas and its urban-rural gradient into suburban areas.