Edward P. Riehl, age 11, of Littleton, Mass., for his question:

How long do trees live?

The sturdy trees arrived late in the long history of the plant world. The first of them rooted in the soft soil of the Earth many millions of years ago, and if there had been no accidents, some of them might have managed to survive until the present time.

Each type of animal has a life span, And after a certain number of years we can expect him to die. During his life span he grows from a small infant to an adult. He then steps growing and in time reaches a stage of old age. The trees have a very different way of growing up and growing old. There are thousands of different trees around the world, and every true tree begins life as a f1ower on a bough of its parent. Some tree flowers, however, are so small and shy that we never notice them.

An infant seedling tree sets its roots in the soil and points its stem to the sky. It begins to grow, and every year it adds new wood and new roots, new bark and foliage to its size. In time, the flowering dogwood trees may reach up to 80 feet. The stately douglas fir may reach 120 feet.: the spreading oak may lift its top branches 120 feet above the ground.

You would think that these trees become adults and stop growing, but this is not so. A tree never stops growing as long as it lives. In later years it grows more slowly, and after it reaches a certain size it does not appear to get much bigger, but every year it lives it adds SOME new wood, new roots and shoots. Although the heart of its trunk has crumbled away, a hollow tree continues to grow.

A tree does not die from old age, and if conditions were perfect there would be no limit to how long it might live. Some live for centuries, and some live for thousands of years, but conditions are not perfect and sooner or later every tree meets with a fatal accident. If it grows to be top heavy, it may be fe11ed by a blizzard. It may be ki11ed by diseases or termites or by insects. It may be burned in a forest fire, perish from drought or from lack of food in the soil. It may be fel1ed by men, by beavers or by animals that nibble its bark. If these and other accidents never occurred, a tree could live for ages and not perish from old age.

The giant sequoias of California resist fire and insects, and some have lived 3,000 years, but accidents caused by men could destroy them. When loggers cut down surrounding forests the soil is weakened by rains. The roots of the big trees are exposed, and the weakened giants may topple in the wind. But barring such accidents they could live 3,000 years longer.