Kim Stinebring, age 11, of Hennessey, Okla., for her question:

WHAT EXACTLY IS ECOLOGY?

This word was invented when certain sensible folk woke up to the fact that they belong to the planet earth. It was coined from a couple of older words meaning house and study. Basically, it's the study of how groups of plants and animals share life in a natural environment, somewhat as people share life in an orderly household.

Nowadays we hear a lot of scary reports of how people are destroying the earth's ecology. It is easy enough to understand how thoughtless pollution contaminates our air, water supplies, soils and even the oceans. We need a wider understanding to see why this changes the global ecology  for the worse.

Outdoors the global scenery changes from mountains to flat plains, from moist rivers to dry deserts, from tropical to polar zones. All these landscapes are bounded by the salty seas. And every scene provides a suitable home for a certain group of plants and animals to share life in a special environment. This is ecology.

It works in balanced harmony because each local species can make a living in its natural environment. What's more, in so doing it also helps all the neighboring plants and animals to make a living. The various animals produce carbon dioxide and organic wastes for the plants, which provide oxygen and basic food.

One of the most important threads in the interwoven ecology is the food chain. For example, the deer who dwell in woodsy areas eat greenery and add wastes to enrich the soil. As they multiply, they could consume all their local food supplies, creating famine and starvation.

    However, the laws of nature are stern and may seem cruel. Pumas or other large predators share the local ecology and help to keep down exploding deer population. The puma population is limited by the numbers of meat producing deer.  Meantime, bobcats and other smallish predators keep the ratty rodent population within bounds. This is but one of many systems that keep a local ecology in balanced harmony.

Basically, everything depends on planetary features such as climate and air, soil and water. When a marsh is drained, frogs, fishes and water birds lose their homes. Even a small change can upset the delicate ecological balance. For example, when hordes of humans attack the bull rushes, the secret nests are left without shade and numerous birds lose their winter supplies of seeds.