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We Jews appreciate the trees, don't we?

We plant trees in Israel in honor, in memory, and for those beautiful certificates like the one I still treasure from my friend Jason when I was accepted into Hebrew University's year-abroad program.

More significant, we sing "Eitz Chaim He" — It is a Tree of Life — every time we return the Torah to the ark. We even study and meditate upon the Tree of Life, depicted by the 17th century kabbalists to represent various attributes of the Divine.

The answer, however, is not so clear when we look at many of our daily activities and realize their effect on our trees.

When we travel by car, rather than by foot, bicycle or mass transit, we send noxious emissions into the air that kill trees (and people). We do the same when we heat our homes with conventional power rather than the new green power that is now available in California. And we are ensuring the liquidation of virgin forests when we create mountains of paper at work — unless it's 100 percent post-consumer content or non-wood fiber.

If we are to appreciate the tree as metaphor, then we must also appreciate the real trees of our world.

Our sages understood that trees were essential to human life. "If not for the trees, human life could not exist" (Midrash Sifre to Deuteronomy 20:19).

Yet our trees are dying, and not just in Redwood Country. Entire species of trees are dying throughout our country: on the ridges of the Appalachian chain, in the sugar bush of Vermont, in the mixed forests of the mid-South border states, in the thick forests of central Michigan and on the mountainsides of Colorado and California.

Charles Little, author of "The Dying of the Trees," tells how this phenomenon has come about from 150 years of industrial expansion and pollution.

Not only trees are dying. The World Resources Institute estimates that one half of all the world's species will be driven to extinction by the end of this century. Another ominous threat from this massive deforestation is global warming. Some scientists have even measured a depletion of life-giving oxygen in the atmosphere.

Genesis 2:7 tells us that "God formed Adam of adamah." We're of the same stuff. When we desecrate adamah, the earth, we endanger Adam, the human.

Paul Hawkin, in his book "The Ecology of Commerce," tells of the despair of one epidemiologist who, after convening a conference to examine the effects of chlorinated compounds on embryonic development, went into a quiet mourning for six months. The implications of that conference were astonishing. The immune system of every unborn child in the world may soon be irrevocably affected by the persistent toxins in our food, air and water.

How do we explain to our children that we knew they would be born with compromised immune systems, but we did nothing? From this perspective, the ceremonial planting of a tree or the celebration of a seder on Tu B'Shevat is about as effective as building Noah's ark with toothpicks.

So what do we do? The blessing of faith is knowing that miracles can happen, but they need our coaxing.

Nothing in our tradition is more sacred than the preservation of life. What then is the meaning of Tu B'Shevat? Like Passover, its message is not confined to the seder, but rather is repeated throughout our liturgy and calendar. This way we keep in our hearts the memory of what HaShem did for us when planting the seeds of life everywhere upon the earth.

Please include the trees and the earth in your prayers, meditations, and rituals throughout the year, and look at the many way you can make a difference in your daily life. Please contribute to environmental tikkun olam by also joining our efforts at the Bay Area Coalition on the Environment and Jewish Life.

This is the meaning of Tu B'Shevat., which starts tonight. This is the way we honor the Tree of Life.