Shedding Light on Plant Respiration Olivia Trase Joe

Shedding Light on Plant Respiration Olivia Trase & Joe Redmond oversight by Paul Gauthier

Background Photosynthesis LIGHT 6 CO 2 + 6 H 2 O → 6 O 2 + C 6 H 12 O 6 Respiration 6 O 2 + C 6 H 12 O 6→ 6 CO 2 + 6 H 2 O ENERGY

Motivation Climate Models - parameters PAR, Ci, RH, Anet, TLeaf, Tair, gs Metabolism of Arctic plants (Gauthier et al 2010) Gauthier et al. (2010) proposed necessary Day-Night cycle for N-fixation. Measuring respiration in the light rather than dark respiration Broad leaves in Abisko, unlike Alaska Homogenous forest for C-flux measurements

Potential Implications Library of parameters (Γ*, Rd, etc. ) increased accuracy Hypothesis: Inhibition will increase as the season progresses from 24 -hours of sunlight into periods of darkness.

Methods: LICOR Instrument

Light Response Curves Inhibition = 1 -(Rd/RN)

Our data and Kok Effect As seen from this graph, our data shows only a very slight Kok effect that is very low Rn Rd

CO 2 Response Curves This graph is an example of three CO 2 response curves measured at different light intensities. From the highest light intensity, we can calculate Vcmax using the Michaelis Menten Equation.

Results Reference: Medlyn et al 2002

Inhibition Correlates Negatively with Temperature But we didn’t have enough data to cut through the noise.

Summary Hypothesis not verified: Rlight did not change over season Potential relationship between temperature and Inhibition Implications for Climate Change models

Things we Learned How to manage issues in the field How to create a scientifically accurate and reproducible experiment How to further our science education outside of Princeton Big picture of climate science

Thanks for listening!