U.S. forests continue to add to their stores of carbon, but at a decreasing rate, while the rate at which carbon is stored in wood products and paper in landfills is increasing. Industry-managed forests have higher tree growth rates than do other lands. Stream nitrate concentrations in the few forested watersheds that are monitored are generally far below drinking water standards, and much lower than in urban or agricultural areas. More extensive data will be available in the future. There are no comprehensive national data on forest soil properties.
Monitoring is difficult because intensive sampling is needed to account for natural variability.
High levels of ozone can change forests by reducing the growth of ozone-sensitive plants. Pilot surveys found symptoms of ozone injury in New England, the Great Lakes region, and the western Mid-Atlantic region. No consistent national information is available, but such data will be available in the future. The area of forest burned by wildfires is much lower today than it was in the 1920s and 1930s. In recent years, the area of forest affected by wildfires in National Forests, which are mostly in the West, has been increasing.