Steve Mowery, age 42, of Lake Charles, La., for his question:

WHAT DOES AN ECOLOGIST STUDY?

Ecology is the branch of biology that deals with the relationships living things have to each other and to their surroundings or environment. An ecologist is the scientist who specializes in studying these relationships.

An ecologist studies the activities and changes in the natural world. He usually studies one area, such as a forest, where plants and animals live together.

The ecologist studying the forest finds that all living things in the area, or their biotic environment as it is called, are related to each other and to the physical environment of earth, water, air and energy.

A biological environment and its physical environment form what ecologists call an ecosystem.

The activities an ecologist studies include the movement of energy, food and other nutrients through an ecosystem. Light energy from the sun is changed to chemical energy in plant cell material. This energy is transferred in the form of food. The energy is changed to a different chemical energy in animal protoplasm after an animal eats the plant.

Finally it is changed again when the animal dies and its body rots.

The ecologist divides the living world into three main levels: population, natural communities of organisms and ecosystems.

A population is a group of the same kind of organism that lives in an area at the same time. Ecologists study a population like other biologists study an individual organism.

A community is a group of animals and plant populations living together in the same environment. Communities are made up of many different kinds    of plants and animals    living together and depending on each other.

When an ecologist studies an ecosystem, he is actually stepping back for a wider view and understanding of the complex organization in nature.

The study of ecology increases man's understanding of the world and all its creatures. This is important because man's survival and well being depend on relationships that exist on a world wide basis. Changes in distant parts of the world    even outer space    affect us and our environment.

One of the many goals ecologists have is to find a way to intelligently manage and control the living and nonliving things in the world.

Many ecologists study air and water pollution and how dirty air and water affect life. They try to see possible problems before they come up, such as crop loses or loses in animal life that building a dam or straightening a river channel may cause.

Ecologists are concerned about the rate at which man is using up such natural resources as coal, oil and gas.

Ecologists use knowledge from many fields, including physics, chemistry and math.