1. Influence of greater Nitrogen Deposition in Missoula, MT Anne Trainor Exercise 3 October 2, 2007

2. Introduction Substantial increase of nitrogen deposition since the industrial boom large impacts on forested ecosystems. Objective: Examine how a significant increase in nitrogen could influence annual and seasonal nutrient cycling dynamics within an evergreen forest.

3. Study System Missoula, MT Meteorological Data: 1950-1993 1 m Loamy Soil 30% sandy, 50% silt, 20% clay Evergreen Needleleaf system Used all defaults

4. Modeling Biome-BGC (version 4.1.2) Carbon levels constant at default value (294.842 ppm) Consisted of 3 runs for 88 years A) Spin up: Default pre-industrial nitrogen level (0.0001 kgm 2 yr 1 ) B) Typical Nitrogen: Based off previous Spinup ran simulation with default pre-industrial nitrogen level (0.0001 kgm 2 yr 1 ) C) Increased Nitrogen: Based off original Spinup ran simulation with Nitrogen increased to 0.005 kgm 2 yr 1

5. Methods Selected a consecutive dry and wet year to compare extremes 1980 and 1981 1973 and 1974

6. Relevant Variables Modeled Variables AnnualDaily Maximum LAILAI NPP GPPSoil carbon fluxes (SoilC 1-4) EvapotranspirationLitter stores (LitterC 1-4) Leaf water potential