Look around you. If you're in a tall building, look out the window. What do you see? An urban forest. We Minnesotans are justifiably proud of the forests around us. But will our forests survive?

One day in early spring I walked through a small grove of oaks near my home in Eagan. I wanted to see the property before the developer came. But it was already too late; a bulldozer had begun leveling one corner of the property. But on the far corner a ridge crowned with big oaks overlooked a deep swampy ravine.

At the crown of the ridge, I stood listening. Wind sighed and moaned in the treetops. Does any other sound compare to the long slow syllables of the wind talking in the trees? The trees were alive and trembling with the news the wind brought them.

Birds chattered on all sides, sparrows, a cardinal, a dozen or more robins. I stood so long that finally a rabbit hiding near my feet bolted and disappeared among some red pines on the northeast side of the hill. I walked down the ridge, carefully moving the raspberry canes out of my way. It was sunny under the pines. The long, luxuriant grass had not revived from the winter yet, but lay in a brown tangle beneath my feet; small green heads poked out of the tangle, signs of rebirth.

Deer tracks were everywhere on this sunny side of the hill. Here a deer had been killed and partially eaten-probably by a coyote. Out of the corner of my eye I caught the silhouette of a fleeing animal against the blue sky behind the ridge. A mink-not the typical suburban wildlife!

I paused next to a large boulder, multi-hued with lichen. Here is a life process we forget about, I thought. These lichen are turning the stone into soil. I pushed my fingers down into the soil, and felt the life process, the soft factory turning trees and leave to humus. The soil felt warm, rich and alive. Later, I stuck my hand into the soil where the machines had bulldozed the land level. It was cold clay, heavy and wet. The soil factory was defunct.

Why should I be upset when people cut down trees and bulldoze their own land? Certainly the owners have a right to use the land. At the same time, each landowner should take responsibility for the health of the land.

Changes to one piece of land are magnified by similar changes elsewhere. Aldo Leopold demonstrated in his essay, "The Land Ethic," that changes may have far-reaching consequences. The land, he said, "is not just soil. It is a fountain of energy flowing through a circuit of soils, plants, and animals." We are part of that circuit.

According to a recent article in the Pioneer Press, up to 15 percent of all bird species face extinction in this century: "Important ecosystem processes, particularly decomposition, pollination, and seed dispersal, will likely decline as a result." Disrupting the circuit of energy diminishes the world in which we live and hurts us all.

This little piece of land had at most an acre of trees. How much life could it support?

Standing on the ridge, I was surrounded by evidence of life: robins gathering sticks for a nest; signs of mice, rabbits and deer; a beautiful shy rose-colored spider; the offal of earthworms, and the residue in the humus of countless bacteria. These animals that share the planet with me are the genetic pool from which we derive our food; they are the makers of soil and the fixer of nutrients.

The plants around me at that moment, from the smallest lichen and worts and fungi and molds to the raspberries and honeysuckle to the mighty ash and maple, aspen and oak--they give us oxygen and place minerals in the soil; they shelter bees and insects that pollinate half the food we eat; they catch and calm the wind; they cool the planet without electricity. They stand between us and an ecological desert.

We share our backyards with countless other species. We need to build wisely, keeping intact the essential forest we live in.