gered species before the concept of endangered species was appreciated. Exotic fish species were introduced to improve recreational fisheries without thought to the implications for native species and the predators that feed on them. Fire suppression led to unanticipated changes in the distinctive character of forests. A common thread in these examples is that almost invariably, the establishment and early management of the parks was done with inadequate scientific knowledge of these ecological systems. Today, our information base is substantially greater, but so too are the threats the park system must face.
Illustrations of the importance of scientific understanding in the management of the parks can be found in every NPS unit. When parks were first established, there was often a lack of understanding of the resources they contained. Problems arose when park boundaries failed to encompass complete ecosystems or enough land to support critical ecological processes (e.g., Everglades National Park), or because visitor facilities were built in inappropriate places (e.g., Sequoia-Kings Canyon, Yosemite, and Yellowstone National Parks), or because of inappropriate management actions (e.g., predator removals, control of native species perceived as pests, control of natural fire, disruption of natural hydrologic regimes, and introduction of exotic fish) (Soulá and Wilcox, 1990; Holland et al., 1991). In the early years of park management, many resources were damaged or lost simply because managers were unaware of their existence or did not know how to manage them (Allen et al., 1981).
These examples illustrate that research is needed for several purposes ranging from simply identifying resources to deciding on appropriate short-and long-term management strategies. In summary, research is important in the national parks for three broad purposes:
To determine what resources are present in order to protect them, manage them, and detect changes in them.
To understand the natural dynamics and processes of populations, ecosystems, and other park resources.
To assess the effects of specific threats and to devise and evaluate management responses.