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 prools.
Table of Contents
1. Introduction.- 2. Background on Research Sites and Methods.- Site Descriptions.- Prools.- 3. Water Balances.- Site Characterizations.- Model Description and Parameterization.- Simulation Results and Discussion.- Summary.- 4. Patterns of Tropospheric Ozone in Forested Landscapes of the Integrated Forest Study.- Methodology.- Patterns of Ozone in the Integrated Forest Study.- Physiological and Ecological Role of Ozone.- Summary.- 5. Sulfur Chemistry, Deposition, and Cycling in Forests.- Overview.- Atmospheric Deposition and Canopy Interactions of Sulfur.- Sulfur Distribution and Cycling in Forest Ecosystems.- Retention or Loss of Sulfur for IFS Sites and Evaluation of Relative Importance of Processes.- Analysis of Selected Sulfur Cycles in Polluted versus Unpolluted Environments.- Summary and Conclusions.- 6. Nitrogen Chemistry, Deposition, and Cycling in Forests.- Overview.- Atmospheric Deposition and Canopy Interactions of Nitrogen.- Experimental Laboratory Measurements of Reactive N Gas Deposition to Forest Landscape Surfaces: Biological and Environmental Controls.- Nitrogen Distribution and Cycling.- Retention or Loss of N in IFS Sites and Evaluation of Relative Importance of Processes.- Analysis of N Cycles in Polluted versus Unpolluted Environments.- Conclusions.- 7. Relationships among N, P, and S in Temperate Forest Ecosystems.- Data Analysis.- Relationships in Living Vegetation.- Canopy Processes.- Changes During Organic Matter Decomposition.- Organic Relationships in Mineral Soils.- Inorganic Interactions in Mineral Soils.- Case Study: Effect of Short-Term N Accumulation.- Ecosystem Inputs and Outputs.- Summary and Conclusions.- 8. Base Cations.- Atmospheric Deposition and Throughfall Fluxes of Base Cations.- Canopy Interactions of Ca2+, Mg2+, and K+.- Base Cation Distribution and Cycling.- Summary and Conclusions.- 9. Cation Exchange and A1 Mobilization in Soils.- Cation Exchange Reactions in Acid Forested Soils: Effects of Atmospheric Pollutant Deposition.- Evidence of Historical Influences of Acidic Deposition on Wood and Soil Chemistry.- 10. Mineralogy and Mineral Weathering.- Site Characteristics.- Mineral Weathering at the IFS Sites.- Observations from the Rhizosphere.- Summary.- 11. Processing of Acidic Deposition.- Atmospheric Deposition of Acids.- Canopy Interactions.- Summary of Acid Deposition and Canopy Interactions.- H+ Budgets.- 12. Recovery from Acidification.- IFS Case Study.- Acidification.- Recovery from Acidification.- Summary and Conclusions.- 13. Regional Evaluations of Acid Deposition Effects on Forests.- Eastern Spruce-Fir.- Eastern Hardwoods.- Southern Pines.- European Forests.- 14. Synthesis and Modeling of the Results of the Integrated Forest Study.- and Acknowledgments.- Summary and Synthesis of the Integrated Forest Study.- The Nutrient Cycling Model (NuCM): Overview and Application.- Appendix: Nutrient Flux and Content Data from the Integrated Forest Study Sites.