not combined in smaller-scale investigations of aquatic ecosystems. A few research sites also have a capability for large-scale or multiple experimental manipulations. Finally, several research centers have shown how basic science and management perspectives can be combined.
A wide variety of research centers have made important contributions to the basic understanding of aquatic ecosystems. Examples, discussed below, are Hubbard Brook Experimental Forest, Experimental Lakes Area, University of Wisconsin–Madison, Woods Hole Marine Biological Laboratory, Lake Washington, Coweeta Experimental Forest, and H. J. Andrews Experimental Forest.
The Hubbard Brook Experimental Forest (HBEF) is a striking example of the contributions that can be made by a research center. The HBEF was established by the U.S. Forest Service in 1955 to investigate the management of watersheds in New England. The research program at the forest, developed largely through the efforts of G. E. Likens and F. H. Bormann, has made substantial contributions to the general understanding of both aquatic and terrestrial ecosystems (e.g., Likens et al., 1977; Bormann and Likens, 1979; Likens, 1985a). Work has focused on processes occurring in the forests and streams in the area and on Mirror Lake near the base of HBEF. Fundamental techniques for assessing ecosystem nutrient cycling were developed by combining the perspectives of hydrologists and biogeochemists (Likens et al., 1977). Insights gained into nutrient cycling at HBEF through whole-watershed clear-cutting experiments and other harvesting programs illustrate the usefulness of ecosystem-scale manipulations (Likens et al., 1977). Detection of the acid deposition phenomenon in North America through precipitation records collected over an extended period has demonstrated the importance of long-term monitoring (Likens et al., 1972, 1984). Research has helped to delineate the role of streams in processing nutrients and organic matter (Fisher and Likens, 1973; Meyer and Likens, 1979). Documented responses to varied timber harvesting techniques at Hubbard Brook have also illustrated the ways in which research with a fundamentally basic science perspective can shed important light on the impact of land-use practices (e.g., Bormann and Likens, 1985; Likens, 1985b). More recently, the Hubbard Brook Experimental Forest has been incorporated as a site within the National Science Foundation's Long-Term Ecological Research (LTER) program, facilitating the continued evaluation of aquatic and terrestrial ecosystem processes at the site (Franklin et al., 1990).