Abstract16.1 Introduction16.2 Air Pollution, Climate, and Their Interactions: Present Status and Projections for the Future16.3 Present Knowledge on Impacts of Air Pollution, CC, Biotic Stressors and Management on Growth and Health of Forests16.4 Possible Future Changes in U.S. Forests Caused by Climate Change and Air Pollution16.5 Projected Hydrological, Nutritional, and Growth Changes in Mixed Conifer Forests of the SBM (Southern California) Due to CC, N Deposition, and O316.6 Projecting Hydrological, Nutritional and Growth Responses of Forested Watersheds at the Hubbard Brook Experimental Forest, Reflective of the American Northeast16.7 Conclusions16.8 Research and Management NeedsAcknowledgementsReferences