Subject
- Atmospheric deposition -- Environmental aspects -- United States1
- Atmospheric nitrogen compounds -- Environmental aspects -- Colorado -- Rocky Mountain National Park1
- Atmospheric sulfur compounds -- Environmental aspects -- Appalachian Region, Southern1
- Forest plants -- Effect of acid deposition on -- United States1
- Forest plants -- Effect of air pollution on -- United States1
- Forest plants -- Effect of soil acidity on -- United States1
- Forest soils -- Appalachian Region, Southern1
- Fossil fuels -- Environmental aspects -- United States1
- Nutrient cycles -- United States1
- Plant diversity -- United States -- Environmental aspects1
- Soil acidification -- Appalachian Region, Southern1
- Water acidification -- Appalachian Region, Southern1