Transcript Exploring the Ichetucknee River System: A Stoichiometric

Stoichiometric Investigation of the Relationship
between Ecosystem Metabolism
and the Plant Community
Rachel L. Douglass
November 12, 2010
Ecological Stoichiometry
• Investigates the balance of multiple chemical substances
involved in ecological interactions and processes
•
•
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Carbon-C
Nitrogen-N
Phosphorus-P
• Used to increase mechanistic understanding of:
• Trophic interactions
• Population dynamics
Research Objectives
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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
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.
Hypotheses

 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.
Hypotheses


 H3:
Changes in species abundance and distribution
lead to changing ecosystem metabolic stoichiometry
and alter nutrient cycling efficiency within the
system.
Field Methods
Year 1
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In-situ nutrient sensors
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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
Anticipated Results and Contributions
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Quantification of the relationship between ecosystem
metabolism and the plant community
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Information on patterns including
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Changing abundance and distribution of plant species
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Nutrient cycling efficiency changes
Model of ecosystem metabolic changes
Comments,
Suggestions, and
Questions?