Biological Diversity: The Key to Human Existence

 From “Conserving Biological Diversity in Our National Forests”-1986

Why should we care about the loss of trees, bugs or swamps? The basic answer is that human life cannot exist without the other kinds of life on Earth. We are dependent on plants and animals for our very existence. Life on this planet is our greatest natural resource, and on which we depend for food, medicines, clothes, energy, building materials, clean air, clean water, psychological well-being and countless other benefits.

The Products of Life

Wild plants, animals and microorganisms have provided essential products since humans first walked the Earth. Both industrialized and less developed nations still depend on living things to sustain them. As supplies of nonrenewable geological resources decrease, and as we gain greater ability to design organisms with new combinations of characteristics through genetic engineering, biological diversity will likely provide a growing share of the products that sustain humankind.

Food comes from agricultural fields, grasslands, forests, rivers and oceans. Virtually, everything we eat has biological origins. Domestication of a few species in our diets, such as wheat and rice, began 10,000 years ago, but intensive use of many species is much newer. Many more wild organisms or those grown only in a small area could become more important foods in the near future.

Breeders of modern crops and livestock use wild relatives of domesticated crops and animals, and primitive varieties grown by traditional peoples. Genes from these varieties improve productivity, tolerance to extremes of weather, and resistance to pests and diseases. Of course, without genetic diversity--the raw material of biotech­nological innovation--such improvements will be impossible.

Biological diversity helps food production in other ways. For one, bees and other insects pollinate billions of dollars worth of crops each year. Without them, we could not afford to pollinate some of our most important crops. We would have no grapes, apples, peaches, cherries, strawberries, almonds, peanuts, soybeans, peas, tomatoes, peppers, broccoli, lettuce, cu­cumbers, squashes or a whole host of other foods.

An increasingly important use of biological diversity in food production is in controlling crop pests. Some synthetic chemical pesticides, including insecticides, nematicides and herbicides, can pollute groundwater, kill wild­life and contaminate people. Agro-ecologists are finding that pesticide use can be cut sharply by using integrated pest management practices that employ animals, fungi and microorganisms as biological pest controls. Unfortunately, just as we are learning how useful these organisms can be, people are destroying their habitats and driving them to extinction.

Ecosystem Services

Biological diversity is essential for another reason: interacting communities of ants, animals and microorganisms provide us with indispensable services. These ecosystem services are free, although we can manipulate some of them to improve their usefulness. Without them, the Earth would be a very different place.

For example, the water in the biosphere--the thin film of land, air and water that supports all life on Earth--is effectively a single pool, including the oceans, ice caps, groundwater, lakes, rivers, the atmosphere, and life. As this water cycles through living things, they change its chemistry. The wastes added by innumerable bacteria, plants, fishes and people would long ago have rendered the water undrinkable except for the fact that one organism's waste is another's vital nutrient. Decomposers such as bacteria, fungi and pro­tozoans clean water contaminated with human wastes, dead plants and ani­mals by breaking them down into nutrients and incorporating them into their own bodies.

Forests and other ecosystems also maintain the chemical composition of the atmosphere. Before the evolution of plants, our atmosphere lacked free oxygen and consisted largely of ammonia, cyanide, hydrocarbons and carbon monoxide.  Early plants changed the atmosphere to one that can support animals, including humans, by producing the oxygen we need to breathe. Ecosystems also remove natural and human-made wastes from the air, al­though human activities are now overwhelming the ability of ecosystems to maintain the composition of the atmosphere.

Living things help to prevent both erosion and flooding by binding the soil surface and encouraging rain to sink into the soil where it raises the water table and is released to streams and springs slowly, rather than running off quickly. In general, crops and orchards are less effective than forest ecosystems in preventing erosion.  Natural communities of species minimize temperature fluctuations, slow winds, and create the soil upon which all civilizations are built.

Trees and soils have a major role in determining the world's climates by taking carbon from the air. Although carbon dioxide makes up only a tiny fraction of the atmosphere, it is very important to the heat balance of the Earth. The burning of fossil fuels, the cutting of forests, and the clearing of land oxidizes carbon in vegetation and soils, increasing atmospheric carbon dioxide. Because carbon dioxide is increasing, the atmosphere will almost certainly grow warmer in coming decades. Shifting temperature and rainfall patterns are likely to have serious consequences for world food production, and biological diversity in the natural ecosystems that remain.

Living things maintain the habitability of the Earth. Without the services performed by diverse, intact communities of plants, animals and microorgan­isms, we would be starving, baking, gasping for breath and drowning in our wastes.

Why Conserve Biological Diversity in our Forests?

Why should Americans be concerned about maintaining biological diversity on our public lands?  There are several basic answers. Trees, fishes and insects have adapted for millions of years to the unique combination of climates, soils and other organisms in our country. It is unrealistic to believe that we can allow the extinction of our native species and find others to replace them. Until this century, the American chestnut was one of the most abundant and valuable trees of our eastern deciduous forests. When an introduced disease virtually wiped it out, people planted the disease-resistant Chinese chestnut in hope of replacing our native species. The attempt failed.

In other cases, introduced organisms--brown and black rats, European starlings, walking catfish, gypsy moths, kudzu vine, and water hyacinths—have fared too well in our country, becoming serious problems. It is easier and less expensive to conserve what we already have than to find an acceptable replacement or cure once we have altered the environment.  

The United States has long been a world leader in conservation. Our Endangered Species Act is a model for conservation of biological diversity around the world. We were the first nation to designate a National Park and among the first to recognize that forests have importance beyond the number of board feet they produce. Nations everywhere look to us for leadership in conservation. If America, the world's richest country, with all its scientific expertise and managerial know-how, does not conserve the biological diver­sity in its forests, then why should developing countries? We just might find that the most important reason to conserve our wildlife and wildlands is the example we set for people worldwide.