The Mishnah (Rosh HaShanah 1,1) cites four dates as "New Years":

• The first of Nissan is the "new year" for dating the reigns of kings of Israel and for setting the cycle of the calendar of festivals;
• The first of Elul is the "new year" for tithing cattle;
• The first of Tishrei is the "new year" for calculating sabbatical and jubilee years as well as the agricultural year;
• And the first of Shevat is the "new year" for trees.

The designation "New Year of the Trees" was not merely a poetic phrase, but had profound bearing on Jewish law. In order to observe certain mitzvot, it was necessary to know how old a tree was.

In Temple days, tithes and heave offerings (terumah) had to be set aside from all new fruit and crop produce. Fruit gathered from last year's produce could not be used for tithes and terumah on fruit gathered this year.

But how could one be certain of the age of a tree? It was not possible, so Tu B'Shevat became the birthday of all trees. The age of a tree was significant from another halachic aspect -- the laws of Orlah forbids eating from fruit trees during the first three years after they have been planted. The fruit of the fourth year was to be consecrated (Leviticus 19:23-25). The custom of waiting until a male child turns three years old before cutting his hair traces it origins back to this law.

I read a heart-breaking article recently about the destruction of ancient olive trees by Israeli settlers who were victims of ambush from Arab gunmen hiding out in the tree orchards. Apparently the only solution was to cut down the trees, which had served as the sole source of income to generations of Arab olive tree farmers. The value of Pikuah Nefesh, the saving of a life, of course takes precedence over the life of the tree, but it saddened me, nonetheless, knowing that it would take decades for new trees to take the place of the old ones.

We are blessed with many types of trees here in Southern California. Driving around the city one can spot maple, weeping willow, palm, oak, and countless other varieties. Yet my favorite tree remains the Torah, often referred to by our tradition as a Tree of Life.