that balancing the call to protect resources and the call to provide citizens with opportunities to enjoy the parks is a constant challenge.
The 1916 act's mandate has been invaluable in setting a basic course for the NPS, but it is insufficient to guide the agency in a world of accelerating change. Informed resource management is impossible without science in its broadest sense—that is, the acquisition, analysis, and dissemination of knowledge about natural processes and about the human influences on them.
Protecting the resources of the national parks1 requires scientific knowledge, and an increasingly sophisticated application of that knowledge. The problems faced by the parks today are too many and too complex to solve without the help of science. Threats to indigenous species caused by exotic species, threats to park resources caused by air pollution or overcrowding, and threats to long-term ecosystem viability caused by the myriad stresses of the twentieth century all jeopardize this unique and invaluable system. Although an adequate science program alone cannot ensure the integrity of the national parks, it can enable faster identification of problems, greater understanding of causes and effects, and better insights about the prevention, mitigation, and management of problems. Science supports resource management so NPS staff can manage park resources wisely, and it supports interpretive programs for the public. Science today is an investment in the future of the parks.
With the 20/20 vision of hindsight, any examination of the national park system can uncover many cases in which a lack of understanding of park resources has led to problems—degradation of resource quality, increased conflicts between visitors and resources, or the escalation of minor issues into major problems. Visitor facilities were developed in habitat critical to endangered species before the con-