1. Stoichiometric Investigation of the Relationship between Ecosystem Metabolism and the Plant Community
Rachel L. Douglass
November 12, 2010

2. Ecological Stoichiometry
Investigates the balance of multiple chemical substances involved in ecological interactions and processes
Carbon-C
Nitrogen-N
Phosphorus-P
Used to increase mechanistic understanding of:
Trophic interactions
Population dynamics

3. Research Objectives
1) To characterize overall ecosystem metabolism and individual species stoichiometry at varying timescales
2)To examine consequences of species stoichiometry, abundance, and distribution on overall ecosystem metabolism
3) To measure across time, seasons, flooding episodes and locations to quantify relationship between plant tissue stoichiometry and stoichiometry of ecosystem metabolism

4. Hypotheses
H1: Individual taxa possess unique C:N:P stoichiometric signatures; yet these signatures exhibit daily, seasonal and episodic variation.
Plants within the mixing zone at the 2500 site of the Santa Fe River exhibit temporal changes to their stoichiometry on episodic time intervals related to the stage of the river.

5. Hypotheses
H1: Individual taxa possess unique C:N:P stoichiometric signatures; yet these signatures exhibit daily, seasonal and episodic variation.
H2: There will be a direct quantifiable relationship between ecosystem metabolism stoichiometry and the stoichiometry of the primary producers within the system with the ability to partition overall ecosystem metabolism by producer groups.

6. Hypotheses
H1: Individual taxa possess unique C:N:P stoichiometric signatures; yet these signatures exhibit daily, seasonal and episodic variation.
H2: There will be a direct quantifiable relationship between ecosystem metabolism stoichiometry and the stoichiometry of the primary producers within the system with the ability to partition overall ecosystem metabolism by producer groups.
H3: Changes in species abundance and distribution lead to changing ecosystem metabolic stoichiometry and alter nutrient cycling efficiency within the system.

7. Field Methods Year 1 In-situ nutrient sensors
Monitor DO, NO3- and SRP concentrations
Field collection of vascular plant and algal species
Collection on a seasonal basis
Used to analyze specimens for C:N and C:P ratios
Year 2 (in addition to all Year 1 activities)
Mesocosm experiments
Collection before, during and after flooding episodes

8. Anticipated Results and Contributions
Quantification of the relationship between ecosystem metabolism and the plant community
Information on patterns including
Changing abundance and distribution of plant species
Nutrient cycling efficiency changes
Model of ecosystem metabolic changes

9. Comments, Suggestions, and Questions?