Relationships Among Stressors, Forests, and Aquatic Systems *As Number and Severity of Stressors Increase, The Impacts to Forests and Associated Aquatic Systems Increase STRESSORS -Air Pollutants -Altered Fire Regimes -Changes in Land Use-- Urbanization -Exotic Species (Insects and Plants) AQUATIC SYSTEMS -Chemistry -Sedimentation -Species Diversity -High and Low Flows FOREST SYSTEMS Growth Reproduction Mortality Species Diversity Tree Condition

Nitrogen Deposition Primary Effects on Forest Ecosystems Tree Growth Stimulus Change ing Understory Species Diversity Changes in Lichen Diversity Nitrogen Saturation Acidification Of Soil Loss of Nutrient Cations Mobilization of Toxic Cations Stream Degradation -Increased Cations Decreased Water Quality Decreased Aquatic Life Forest Degradation -Reduced Growth -Deteriorated Crowns -Increased Tree Mortality -Increased Sensitivity to Stressors Nitrogen Fertilization

Relationships between Cations in Streams and Forest Health Indicators Nutrient Cations in Streams Crown Condition Tree Growth, Mortality, & Regeneration Understory Species

Neversink Watershed Calcium in Soil and Foliage of Yellow Birch and Sugar Maple, and levels of Putresine in Foliage

Phase 4 Plots --probability estimate for entire watershed Phase 5 Plots --deliberately co-located with process studies

P4 Tree Data (25%) Neversink Watershed

Phase 4 Plots Neversink Watershed cm Mineral Soils Percent Total CarbonpH (water)Percent Total NitrogenECEC pH or % Cmolc/ kg

Hypothetical Relationships among P4 + P5 Indicators and Steam Condition

Since Thresholds for Water Quality, for Human Consumption and Aquatic Life, have been Established, they can be used to Determine Thresholds for P4 and P5 Indicators. By use of GIS and Analytical Models, the Indicator Values observed on P2 and P3 Plots can be Analyzed using Ecologically-Meaningful Thresholds