Over the past decade there has been considerable interest in the effects of atmospheric deposition on forest ecosystems. This volume summarizes the results of the Integrated Forest Study (IFS), one of the most comprehensive research programs conducted. It involved intensive measurements of deposition and nutrient cycling at seventeen diverse forested sites in the United States, Canada, and Norway. The IFS is unique as an applied research project in its complete, ecosystem-level evaluation of nutrient budgets, including significant inputs, outputs, and internal fluxes. It is also noteworthy as a more basic investigation of ecosystem nutrient cycling because of its incorporation of state-of-the-art methods, such as quantifying dry and cloud water deposition. Most significantly, the IFS data was used to test several general hypotheses regarding atmospheric deposition and its effects. The data sets also allow for far-reaching conclusions because all sites were monitored over the same period using comparable instruments and standardized protocols.

The Oak Ridge National Laboratory's Environmental Sciences Division initiated the Walker Branch Watershed Project on the Oak Ridge Reservation in east Tennessee in 1967, with the support of the U. S. Department of Energy's Office of Health and Environmental Research (DOE/OHER), to quantify land-water interactions in a forested landscape. It was designed to focus on three principal objectives: (1) to develop baseline data on unpolluted ecosystems, (2) to contribute to our knowledge of cycling and loss of chemical elements in natural ecosystems, and (3) to provide the understanding necessary for the construction of mathe matical simulation models for predicting the effects of man's activities on forested landscapes. In 1969, the International Biological Program's Eastern Deciduous Forest Biome Project was initiated, and Walker Branch Watershed was chosen as one of several sites for intensive research on nutrient cycling and biological productivity. This work was supported by the National Science Foundation (NSF). Over the next 4 years, intensive process-level research on primary productivity, decomposition, and belowground biological processes was coupled with ongoing DOE-supported work on the characterization of basic geology and hydrological cycles on the watershed. In 1974, the NSF's RANN Program (Research Applied to National Needs) began work on trace element cycling on Walker Branch Wa tershed because of the extensive data base being developed under both DOE and NSF support."