Brazil observes September 21 as Arbor Day (Dia da Árvore), dedicated to raising awareness about the importance of trees and forest conservation. The observance is linked to Decree No. 55,795, issued in 1965, which instituted the National Tree Week (Semana da Árvore) to be celebrated annually from 21 to 26 September. Arbor Day is marked by educational activities, tree-planting initiatives, and environmental campaigns across the country.
