Status and Trends of the Nation's Biological Resources - Introduction

that they are alive, and as living organisms they are, if properly maintained, renewable. They sustain Americans by contributing food, water, fuel, medicine, employment, recreation, and, especially, the splendor and wonder that inspire and nurture our spirits. Use of these resources, whether in consumptive ways such as logging, commercial fishing, hunting, and agriculture or in nonconsumptive activities such as hiking, birdwatching, sailing, and catch-and-release fishing, requires effective management that allows for all these uses and more while assuring that the uses are compatible with resource renewal. But effective management of complex life forms and systems demands scientific understanding. Even a seemingly innocent hike in the woods has a range of potential effects, most likely minor, on the living resources in those woods. Simple footprints may lead to developing a path, or may even carry the beginnings of a colonizing species foreign to that place. The pathway, though, may halt nature’s spread of a native plant, open a corridor for a migrant animal, or enable the first nonindigenous seed or insect to spawn a vast invasion unimpeded by natural controls. In such instances, native species could be in a sensitive stage of nesting or pollination, vulnerable to unanticipated disruption by the newcomer. Introduction