Yes, it's true.
Yesterday was a minor Jewish holiday, Tu B'Shevat. Also known as the New Year for Trees.
The Bible contains many directives for an agrarian society. When to plant, when to reap, when to allow a field to lie fallow.
The age of a fruit tree is calculated on Tu B'Shevat. It is forbidden to eat the fruit of a tree that is 3 years old or younger. Fruit from a 4 year old tree was to be brought to the Temple in Jerusalem or given to the poor.
Later, the Kabbalists in the city of Sfat came up with a ritual, based on the Passover Seder, involving four cups of wine and four different types of fruit. A Tu B'Shevat Seder wasn't widely practiced, except by scholars and mystics, until modern times.
But the idea of planting a tree in Israel ...that began with the early Zionists who wanted to renew the land. Organizations such as the Jewish National Fund collected charitable funds, which were then used to plant trees, create forests, etc.
In modern Israel Tu B'Shevat is all about ecology, like Earth Day.
I guess I come by my environmentalism honestly. It's part of my heritage.