This indicator shows forest area in absolute terms and as a percentage of total land area of Slovenia. The presented data covers the period 1875–2013.

In the Forest Act (Official Gazette of the Republic of Slovenia, No. 30/93 and amendments), a forest is defined as land containing forest trees in the form of a stand or other woodland fulfilling any of the functions of a forest. According to this act, any areas reverting to natural vegetation that have been classified as a forest in the spatial part of the Forest Management Plan are considered to be forests.

According to FAO, a forest is a piece of land bigger than 0.5 ha with more than 10 per cent of tree crown cover (or equivalent stocking level). The trees should be able to reach a minimum height of 5 m at maturity in situ. Young natural stands, plantations established for forestry purposes and areas normally forming part of the forest area that are temporarily unstocked as a result of human intervention or natural causes are also included. This definition also includes forest nurseries and seed orchards that constitute an integral part of the forest, forest roads, firebreaks, etc.

Forest area is one of the most basic and most easily measurable indicators for forests, which is why we already have extensive data reaching back to 1875, when forests represented only 36% of the Slovenian territory. Since then (for more than 130 years), the forest area has been increasing constantly. The trend of change, however, is not uniform throughout Slovenia. Forest area is increasing where forests are already a predominant landscape feature, while in agricultural and, particularly, suburban areas, forests are now being exposed to great pressures, leading to further shrinking of the already meagre forest remnants in those areas (Resolution on National Forest Programme, Official Gazette of the Republic of Slovenia, No. 111/07).

According to a report by the Slovenia Forest Service, in 2013, forests covered 1,186,044 hectares. Today, forests cover 58% of Slovenia's territory. The distribution of and changes in forest area is also monitored by the Ministry of agriculture, forestry and food within the monitoring of the use of agricultural land. The Slovenia Forest Service participates by checking the mapped forest edge. According to these data, forest area in 2010 amounted to 1,213,944 hectares, which was slightly below 60% of the territory of Slovenia.

According to the FAO Global Forest Resources Assessment, Slovenia has a large percentage of forests in comparison with the rest of Europe; however, the absolute percentage is much lower. The total surface area of forests in Europe (the EU-27) in 2005 was 177,015,800 hectares, which was 42% of the entire EU-27 territory. In the period 2000–2005, the surface area of forests increased by 764,800 hectares, or 1.6%.

Similar trends have been noted in past decades on the European scale. A large share of afforestation was carried out immediately after World War II, and this trend has settled over the last decades. Areas appropriate for afforestation are shrinking and the cost of such activities is increasing. The share of managed forests has been increasing at an even slower rate as a result of the growing share of protected areas in the total surface area.