“The use of national parks for the advancement of scientific knowledge is … explicit in basic legislation. National Parks, preserved as natural comparatively self-contained ecosystems, have immense and increasing value to civilization as laboratories for serious basic research. Few areas remain in the world today where the process of nature may be studied in a comparatively pure natural situation.” (from Wagner and Kay 1993)

IN ADDITION TO PROVIDING VISITORS with the opportunity to appreciate natural scenery and wildlife, national parks have a long history of scientific research, dating back to the establishment of Yellowstone National Park (Wyoming, Montana, Idaho) in 1872 (Sellars 1997). National parks historically offered unique opportunities for scientists because their ecosystems are largely unmodified relative to the surrounding landscapes. However, national parks are also important to the conservation sciences as we become more aware that they are not “islands” but interact substantially with surrounding environments. The longevity of these invaluable resources will depend heavily on management recommendations and restoration efforts guided in turn by scientific efforts.

Human activities have greatly modified natural ecosystems and threatened biodiversity. One principal mechanism for these threats is the spread of invasive species, characterized by the establishment of species in environments outside of their native range. Their impact is usually measured by the elimination of native species through direct interactions (for example, competition, parasitism, and predation) or indirectly through cascading mechanisms resulting from the loss of keystone species, mutualists, or nutrient availability (Parker et al. 1999; Mack et al. 2000). While national park units are among our most pristine remaining natural resources, they are by no means immune to invasion by nonnative species. In fact, they are increasingly taking a central role as resources for the study of biological invasions.

A change in the type of research conducted within U.S. national parks is reflected in publications of park-based research over three periods (1968–1975, 1985–1987, and 2000–2001). The proportion of journal articles reporting inventories or describing species remained consistent; however, the proportion of articles reporting research that focused on subjects relating to conservation and restoration increased (fig. 1). National parks worldwide have also become increasingly important in research on biological invasions. An online search for “national parks” and “invasion” in the citation database Web of Science® found more than 650 publications, 225 of which were published since 2005.