It's time for the annual Christmas question: Chop down a living tree or support petrochemicals?

After a few years of swinging toward artificial trees (practical, reusable, so natural looking they almost shed needles), the environmental pendulum seems to be reversing. That's partly because the National Christmas Tree Assn. is making a vigorous promotional push.

The virtues?

The nation's 1 million acres of Christmas tree farms produce enough oxygen for 18 million people daily. For every real tree harvested, three seedlings are planted. Christmas tree farms stabilize soil, protect water supplies and create scenic green belts, often in substandard soil.

Furthermore, real Christmas trees (endorsed by 46% of tree-trimming households last year) are an all-American recyclable resource. Artificial trees, mostly manufactured elsewhere, are plastic and metal, which never degrade in a landfill.

Fortified with this information, if you \o7 still\f7 feel guilty about cutting down a tree, you can replace it by planting another. One of the many groups that makes it easy is Los Angeles-based TreePeople. For a contribution of $15, they will plant a tree in someone's name and send them a personalized holiday card.

Information: (818) 753-TREE.