世界植树日的由来可以追溯到20世纪初。1872年，美国的农学家朱利斯·斯特林·莫尔（J. Sterling Morton）提议在内布拉斯加州设立一个专门的植树节，以鼓励人们种植树木，改善环境。该活动逐渐扩展，最终在1977年，联合国大会正式宣布3月12日为“世界植树日”。

这个节日的目的是提高公众对植树和森林保护重要性的认识，促进可持续发展，抵御气候变化，保护生态环境。通过植树活动，人们可以参与到改善空气质量、保持水土、提供栖息地等多方面的生态保护中。

The origin of World Tree Day can be traced back to the early 20th century. In 1872, American horticulturist J. Sterling Morton proposed the establishment of a tree planting day in Nebraska to encourage people to plant trees and improve the environment. This initiative gradually expanded, and in 1977, the United Nations officially designated March 12 as "World Tree Day."

The purpose of this day is to raise public awareness of the importance of tree planting and forest conservation, promote sustainable development, combat climate change, and protect the ecological environment. Through tree planting activities, people can contribute to improving air quality, preventing soil erosion, and providing habitats, among other aspects of ecological protection.