Villanueva Sierra is the town that held the first Arbor Day in the world. The initiative was launched in 1805 by the local priest.
While Napoleon was ravaging Europe with his ambition in this village in the Sierra de Gata lived a priest, don Ramón Vacas Roxo, which, according to the chronicles, "convinced of the importance of trees for health, hygiene, decoration, nature, environment and customs, decides to plant trees and give a festive air. The festival began on Carnival Tuesday with the ringing of two bells of the church, and the Middle and the Big. After the Mass, and even coated with church ornaments, don Ramón, accompanied by clergies, teachers and a large number of neighbours, planted the first tree, a poplar, in the place known as Valley of the Ejido. Tree plantations continued by Arroyada and Fuente de la Mora. Afterwards, there was a feast, and did not miss the dance. The party and plantations lasted three days. He drafted a manifesto in defence of the trees that was sent to surrounding towns to spread the love and respect for nature, and also he advised to make tree plantations in their localities.
— Miguel Herrero Uceda, Arbor Day
Arbor Day is celebrated every Carnival Tuesday and is an important day in the local festival calendar.