Urban tree cover

Tree cover serves as​ a​ proxy for crucial ecosystem services that can directly benefit  human health and well-being by reducing heat stress, improving air quality and supporting mental well-being. 

Short method description  

Three indicators describing urban tree cover dynamics between 2000 and 2020 were derived: (1) net tree cover in 2020 (stable tree cover plus gains, as a percentage of city area), (2) tree cover gain and loss (each expressed as a percentage of city area), and (3) relative net tree cover change compared with the 2000 baseline. Cities with at least 30% net tree cover were classified as meeting a critical tree cover threshold. City-level indicators were then aggregated to country and subregional levels by calculating the mean and standard deviation, with each city given equal weight regardless of its size or urban area.

​​Main findings ​​​ 

​​​​​ ​​​​Between 2000 and 2020, urban tree cover across 851 European cities exhibited a concerning trend: tree loss consistently outpaced gains (on average -1.13% vs +0.55%)​​. Despite well-established evidence linking a minimum 30% canopy cover to enhance climate resilience and health equity, only 116 cities (13.6% of the sample) met or exceeded this benchmark by 2020.​​​

Caveats  

Areas classified as "short vegetation gain from trees" following disturbance were not considered an absolute loss of tree cover in this analysis, following the European legislation, however this might have led to overestimation of results. Indicators are based on unweighted city-level averages, reflecting average urban trends rather than area-weighted changes, and are therefore not influenced by differences in city size or baseline tree cover. Results are also sensitive to the definition of urban boundaries based on Local Administrative Units (LAUs).