The health status of forests in Slovenia has been relatively stable in recent years, but with a slight negative trend. In 2014 and 2015 we observed an increased defoliation, due to ice storm and wind throws, followed by a stable defoliation status in both - conifers and deciduous trees. In 2020, for the first time, the average defoliation of conifers was lower than the average defoliation of deciduous trees.

In general, the average defoliation in Slovenian forests is 28% (2020) - still higher than the average of the European Union, where in 2019 it was 23%. The trend of increasing defoliation is also observed at the European level.

The most damaged tree species are black pine, sweet chestnut, black locust, oaks (especially Q.robur), common beech, hornbeam and Norway spruce. According to recent findings, annual differences in estimates are mainly a combination of the unforeseen weather conditions between years and other biotic and abiotic causes.