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Increasing forest connectivity is crucial for supporting biodiversity. Fragmentation of forests is the main factor limiting their connectivity. In 2018, the EU’s average forest fragmentation index was 0.21 (on a scale from 0 to 1), but the indicator is, at present, limited to that year. Forest fragmentation shows no changes from 2000 to 2018. The EU Forest Strategy for 2030 and the EU Biodiversity Strategy for 2030, which includes a pledge to plant at least three billion additional trees by 2030, promote forest connectivity. However, the effects of these policies will take time to become visible, making an increase in forest connectivity somewhat unlikely by 2030.

Forests have significant cultural and economic value and are vital in supporting biodiversity and human well-being. Historically, forests have become fragmented due to conversion to cropland and pastures, urbanisation and infrastructure developments .

Maintaining forest connectivity and avoiding forest fragmentation benefit species that thrive in a larger area and enables species dispersal . Forest patches and woody features such as hedges and tree lines can play a key role in bridging gaps between forests, enhancing connectivity and movement of species between suitable habitats.

The EU Forest Strategy for 2030 , the EU Biodiversity Strategy for 2030 and the pledge to plant at least three billion additional trees by 2030 , highlight the importance of expanding tree and forest cover to safeguard biodiversity.

The forest fragmentation indicator measures the degree of forest density. The indicator shows the percentage of forested land not covered by any forest or woody features within a 10 hectare area surrounding a 100m2 forest grid cell . The indicator assesses the forest's structural fragmentation on a grid, meaning it provides a general insight into the environment’s reduced capability to connect local habitats regardless of the type and quality of the forest, rather than to specifically account for the needs of individual species or species groups.

In 2018, the forest fragmentation index for the EU was 0.21. This indicates that on average, 21% of the measured forest area was not covered by forest or other woody features. The indicator is calculated on cells of the grid covered by or adjacent to forest land, i.e. the index shows the level of fragmentation within the 10 hectare area surrounding each 100m2 forest grid cell (see Figure 2). However, any statistically averaged indicator value averages out spatial variability and conceals instances where forests can be disconnected or strongly fragmented. Consequently, regions with large extents of continuous forest cover highly influence the EU average value.

This indicator does not provide a historical trend as data are available only for 2018. However, it uses a similar methodology as the fragmentation indicator reported in Forest Europe , Vogt et al. , Maes et al. , and Vogt and Caudullo . Although these indicators are calculated differently in terms of underlying data and resolution they provide insights into past trends in forest connectivity which remained relatively stable between 2000 and 2018.

Assessing the prospects for improved forest fragmentation by 2030 is challenging and past findings do not show significant changes . The effects of implementing the EU’s forest and biodiversity strategies - such as promoting afforestation, reforestation, and restoring forest ecosystems - will most likely only become visible after 2030 due to the time lag between actions in the field and decreased fragmentation. However, actions to increase forest fragmentation, such as deforestation or removing connecting hedges and tree lines, can have immediate effects.

Forest fragmentation in the EU Member States correlates strongly to the presence of large forest areas (displayed by the class ‘very low fragmentation’). In Member States with smaller and fewer continuous forests, small forest patches or forest strips scattered across the land play an important role in maintaining connectivity (classes ‘high’ and ‘intermediate’ fragmentation).

The indicator assesses fragmentation within a relatively small window of 10 hectares, where large forest patches show low fragmentation (includes not only forest, but also woody features such as treelines). Therefore, most fragmentation estimates at the country level range from 0.14 to 0.30. Based on the country quintiles, an indicator below 0.17 may be considered very low and an indicator above 0.27 may be considered very high fragmentation. The EU average is highly influenced by areas with large continuous forest blocks, mainly in Slovenia, Romania, Finland and Sweden. Few countries show average fragmentation above 0.30.