The River of the Mother of God: and other Essays by Aldo Leopold

A Biotic View of Land [1939]

A Biotic View of Land [1939] This is one of Leopold's landmark papers, delivered as a plenary address to a joint meeting of the Society of American Foresters and the Ecological Society of America on June 21, 1939, in Milwaukee, Wisconsin. It was subsequently published in the Journal ofForestry. From the most recent contemporaneous ecological theory it abstracts an emerging new portrait of nature-the biotic or ecosystemic concept. Like "The Conservation Ethic," the essay represents a milepost on Leopold's intellectual pilgrimage, and substantial portions of it were incorporated in Sand County Almanac's "The Land Ethic." In pioneering times wild plants and animals were tolerated, ignored, or fought, the attitude depending on the utility of the species. Conservation introduced the idea that the more useful wild species could be managed as crops, but the less useful ones were ignored and the predaceous ones fought, just as in pioneering days. Conservation lowered the threshold of toleration for wildlife, but utility was still the criterion of policy, and utility attached to species rather than to any collective total of wild things. Species were known to compete with each other and to cooperate with each other, but the cooperations and competitions were regarded as separate and distinct; utility as susceptible of quantitative evaluation by research. For proofof this we need look no further than the bony framework of any campus or capitol: department of economic entomology, division of economic mammalogy, chief of food habits research, professor of economic ornithology. These agencies were set up to tell us whether the red-tailed hawk, the gray gopher, the lady beetle, and the meadowlark are useful, harmless, or injurious to man. Ecology is a new fusion point for all the natural sciences. It has been built up partly by ecologists, but partly also by the collective efforts of the men charged with the economic evaluation of species. The emergence of ecology has placed the economic biologist in a peculiar dilemma: with one hand he points out the accumulated findings of his search for utility, or lack 266 A Biotic View of Land 267 of utility, in this or that species; with the other he lifts the veil from a biota so complex, so conditioned by interwoven cooperations and competitions, that no man can say where utility begins or ends. No species can be "rated" without the tongue in the cheek; the old categories of"useful" and "harmful" have validity only as conditioned by time, place, and circumstance. The only sure conclusion is that the biota as a whole is useful, and biota includes not only plants and animals, but soils and waters as well. In short, economic biology assumed that the biotic function and economic utility of a species was partly known and the rest could shortly be found out. That assumption no longer holds good; the process offinding out added new questions 'faster than new answers. The function of species is largely inscrutable, and may remain so. When the human mind deals with any concept too large to be easily visualized, it substitutes some familiar object which seems to have similar properties. The "balance of nature" is a mental image for land and life which grew up before and during the transition to ecological thought. It is commonly employed in describing the biota to laymen, but ecologists among each other accept it only with reservations, and its acceptance by laymen seems to depend more on convenience than on conviction. Thus "nature lovers" accept it, but sportsmen and farmers are skeptical ("the balance was upset long ago; the only way to restore it is to give the country back to the Indians"). There is more than a suspicion that the dispute over predation determines these attitudes, rather than vice versa. To the lay mind, balance of nature probably conveys an actual image of the familiar weighing scale. There may even be danger that the layman imputes to the biota properties which exist only on the grocer's counter. To the ecological mind, balance ofnature has merits and also defects. Its merits are that it conceives of a collective total, that it imputes some utility to all species, and that it implies oscillations when balance is disturbed. Its defects are that there is only one point at which balance occurs, and that balance is normally static. If we must use a mental image for land instead of thinking about it directly, why not employ the image commonly used in ecology, namely the biotic pyramid...