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Sensitivity Analysis of Nitrogen Uptake Efficiency in Simulated Arctic Tundra Vegetation

Presenters Name: 
Daniel Collins
Co Presenters Name: 
Primary Research Mentor: 
Howard Epstein
Secondary Research Mentor: 
12:30 - 1:45
Time of Presentation: 
2019 - 12:30pm to 1:45pm
Newcomb Hall Ballroom
Presentation Type: 
Presentations Academic Category: 
Grant Program Recipient: 
USOAR Program

Roots comprise over half of the biomass of plants in arctic tundra ecosystems; despite this, the representation of roots in ecosystem models is typically lacking, in part due to the difficulty in observing roots and their behavior in nature, in contrast to the better realized representation of the above-ground portion of plants. The goal of this study is examine how root representation in tundra vegetation models affects the simulation of competition for soil nitrogen. For this study, we use a tundra vegetation dynamics model, ArcVeg, developed with the intention of modeling the growth of various plant types in arctic/subarctic climates. Within the model, we varied the root nutrient uptake efficiency of three different plant functional groups (deciduous shrubs, evergreen shrubs, and sedges) to determine how this affected the biomass of all simulated plant types. We found that a 57% increase in Low Arctic (LA) deciduous shrub N-uptake efficiency, led to a 45% increase in LA deciduous shrub biomass and a 65% decline in LA evergreen shrub biomass. A 57% decline in LA deciduous shrub N-uptake efficiency led to a 99% decline in LA deciduous shrub biomass and a 72% increase in LA evergreen shrub biomass. We conclude that the plant community composition is highly sensitive to variability in root nitrogen uptake. This line of inquiry could lead to a better understanding of competition dynamics in arctic tundra ecosystems and specifically the role that roots play.