Influence of greater Nitrogen Deposition in

Missoula, MT

Anne TrainorExercise 3

October 2, 2007

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.

Study System

Missoula, MT Meteorological Data: 1950-1993 1 m Loamy Soil

30% sandy, 50% silt, 20% clay Evergreen Needleleaf system

Used all defaults

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 kgm2yr1)

B) Typical Nitrogen: Based off previous Spinup ran simulation with default pre-industrial nitrogen level (0.0001 kgm2yr1)

C) Increased Nitrogen: Based off original Spinup ran simulation with Nitrogen increased to 0.005 kgm2yr1

Methods

Selected a consecutive dry and wet year to compare extremes

1980 and 1981

1973 and 1974

Relevant Variables ModeledVariables

Annual Daily

Maximum LAI LAI

NPP NPP

GPP Soil carbon fluxes (SoilC 1-4)

Evapotranspiration

Litter stores (LitterC 1-4)

Leaf water potential