The theme of the 2020 International Day of Forests celebration is “Forests and Biodiversity”. Forests are home to 80% of all land-based biodiversity. At the same time, they provide critical ecosystem services that affect the global climate, rainfall patterns, and watersheds. The theme of forests and biodiversity is of particular relevance to the implementation of the SDG 15: Life on Land.

Check UN Forests website for more information.
https://www.un.org/en/observances/forests-and-trees-day