Forests in Slovenia are relatively well preserved, in particular with regard to the variety of natural composition of tree species and the structure (vertical as well as horizontal) of stands. The percentage of natural forests in Slovenia exceeds 50%, while only about one tenth of the forests are heavily altered forests, anthropogenic spruce forests and completely altered forests.
This indicator shows the degree to which current forest composition differs from the natural one. It is calculated by comparing the percentages of actual growing stock of individual tree species in a forest community with natural tree composition. Forest communities represented in a given forest sub-compartment are taken into account.
Based on the percentage of non-native tree species on the site, four categories are distinguished:
According to FAO, forests are divided according to their naturalness as follows:
The two methodologies are not directly comparable, and it should be noted that plantations do not count as forests in Slovenia.
Slovenia Forest Service, 2014.
The sustainable development of forest as an ecosystem within the meaning of its biodiversity and all of its ecological, economic and social functions.
Preservation and restoration of natural composition of forest communities, including forest areas left entirely to natural development.
How was the indicator measured?
The basic method of calculating the indicator has been defined in previous chapters. Updates of the Forest Management Unit Plans take place over a ten-year cycle. When updating a specific plan, the naturalness of the tree composition is calculated for each forest sub-compartment by means of the Euclidean distance method, based on the actual ratio of tree species and the site which helps us define the natural tree composition.
Because of the gradual renewal of forest management plans, the data on the naturalness of forests in Slovenia for each year are on average 5 years old (e.g. for 2006, the plans valid from 1997 to 2006 are used).
Data for Slovenia:
• name of the original database: data from the Forest Management Unit Plans;
• institution acting as the administrator of the database: Slovenia Forest Service;
• description of the data source: data were calculated based on the actual growing stock according to tree species acquired from permanent sample plots and the expected values of growing stock for individual sites. Manner of renewal: every 10 years for each forest management unit (233 in Slovenia).
• data are shown for the period 2001 – 2013.
Data for Europe:
• name of the original database: Global Forest Assessment 2005, Global Forest Assessment 2000;
• institution acting as the administrator of the database: UN FAO, Department of Forestry;
• description of the data source: Data and analyses in the report were calculated based on reports from individual countries.
o Slovenia Forest Service, Central Database of Forest Management Unit Plans, 2008
o Bončina, A., Robič, D., 1998. Ocenjevanje spremenjenosti vrstne sestave rastlinskih skupnosti [Estimation of the species composition alteration in plant communities]. – Journal of Forestry and Wood Science vol. 57, pp. 113 –130.
o Slovenian National Forest Development Programme, Official Gazette of the Republic of Slovenia, no. 14/1996 of 8-3-1996.
o Rules on the forest management and silviculture plans, Official Gazette of the Republic of Slovenia, no. 5/1998 of 23-1-1998, pp. 256 – 282.
o Rules amending the Rules on forest management and silviculture plans, Official Gazette of the Republic of Slovenia, no. 70/2006 of 6-7-2006, pp. 7293-7298.
o National Environmental Action Plan (NEAP), Official Gazette of the Republic of Slovenia, no.. 83-3953/1999, p. 12765.
o Global Forest Resources Assessment 2005, UN FAO, Department of Forestry, 2006.
o Global Forest Resources Assessment 2000, UN FAO, Department of Forestry, 2001.