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Elizabeth Waring Thesis Defense

Flooding tolerance of native and nonnative grasses: variation in photosynthesis, transpiration, respiration and carbon isotope discrimination. Elizabeth Waring Thesis Defense. Wetlands and Invasion.

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Elizabeth Waring Thesis Defense

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  1. Flooding tolerance of native and nonnative grasses: variation in photosynthesis, transpiration, respiration and carbon isotope discrimination Elizabeth Waring Thesis Defense

  2. Wetlands and Invasion • Nonnative plants are those that are introduced in an area due to intentional or accidental methods (Pysek et al. 2004) • Nonnative to invasive • Wetlands are particularly likely to be invaded • Sinks in hydrological systems • Seeds and plant parts are easily dispersed by water or flotation

  3. Flooding • Importance to wetlands • Effects of flooding on vegetation • Drought mode Cheyenne Bottoms Oct. 2007 http://geospectra.net/cheyenne/bottoms

  4. Previous flooding studies focused on biomass accumulation as indicator of tolerance to disturbance • Examine physiological changes in species due to flooding

  5. Why study physiology in invasive species? Physiological processes are the link between environment and performance Growth Reproduction Disturbances Flooding Metabolic Adaptations Physiological Processes Performance Environment

  6. Phragmites australis • “common reed” • Few native populations in North America • Hybrid of native and Eurasian population • C3 photosynthetic species • Wetland indicator: FACW • Model wetland invasive species www.uvm.edu

  7. Phalairis arundinacea • “reed canarygrass” • Few native populations in North America • Mostly hybrid of native European and Asian populations • C3 photosynthetic species • Wetland indicator: FAC Invasive.org

  8. Sorghum halepense • “johnsongrass” • Native to Mediterranean Europe and Africa • Invasive to croplands • C4 photosynthetic species • Wetland indicator: FACU • Has been seen invading flooded ditches www.wi.dnr.gov

  9. Spartina pectinata • “prairie cordgrass” • Native to Kansas • C4 photosynthetic species • Wetland indicator: FACW

  10. Questions • Do Phragmites, Phalaris, and Sorghum have greater photosynthetic capabilities in flooded conditions compared to Spartina? • Determine if nonnative species demonstrate adaptations to tolerate flooding better than native species? • increased ADH activities

  11. Flooding setup • Collection • Depths • Treatments

  12. Flooding Measurements • After 7 days • Measurements with LI-6400 • After 28 days • Measurements with LI-6400 • Harvest roots for ADH assay tests • Leaves collected for carbon isotope analysis

  13. “I once had a zoologist friend who worked on limpets. His opinion was ‘Photosynthesis is fine – just as long as plants don’t stop doing it.’ If you really do not care about how life on Earth converts sunlight to sustain the biosphere, then you have no natural curiosity. And, probably, no soul.” -John F. Allen Lund University

  14. (Raven et al. 2005)

  15. Pmax Quantum Efficiency

  16. Carbon fixation • Repeated measures analysis of variance (RM ANOVA) were used on data collected at 1500 PPFD for photosynthesis (A) • Within species were analyzed to test for differences between treatments • RM ANOVA also used to analysis Pmax and net qe

  17. Spartina pectinata, prairie cordgrass (native) • After 7 days close rates • After 28 days clear preference to deep flooding • Interaction of time X trt significantly higher (p=0.044)

  18. Phragmites australis, common reed (nonnative) • Always favors flooded conditions • No significant differences

  19. Phalaris arundinacea, reed canarygrass (nonnative) • After 7 day no preference • After 28 days clear difference between deep flooding and other treatments--- 3 deep flooded plants died • Significantly different over time (p=0.029)

  20. Sorghum halepense, johnsongrass (nonnative) • After 7 days does well • After 28 days all deep flooded and 3 medium flooded plants died • A significantly decreased over time (p<0.001)

  21. Phragmites 7 days Spartina 7 days Phalaris 7 days Sorghum 7 days

  22. Spartina 28 days Phragmites 28 days P=0.001 RM ANOVA, interaction of time X spp Phalaris 28 days Sorghum 28 days

  23. p=0.027 in interaction of time X spp Tukey’s HSD post-hoc used Spartina > Phalaris & Phragmites > Sorghum

  24. No significant differences between times or interactions Low observed power

  25. Oxygen evolution Maximum JO2 O2 Gross qe O2 evolution

  26. RM ANOVA p>0.05 over time and interactions • JO2 indicates damage to PSII • No significance differences indicates impact in photosynthesis is not in PSII

  27. RM ANOVA p=0.014 over time • p=0.001 in interaction of time X spp • Tukey’s HSD: Phragmites > Phalaris & Spartina > Sorghum

  28. Fluorescence • 3 pathways • Photochemistry, heat, light • Fluorescence is measure of light re-emitted by plant • Fv/Fm is the dark adjusted efficiency of excitation capture by PSII • Maximum of 0.83 • Measure of health of PSII

  29. RM ANOVA p<0.001 over time and interaction of time X spp. p=0.005 interact of time X trt • Tukey’s HSD : Spp: Phragmites > Phalaris & Spartina >Sorghum Trt: Medium > Low & Deep > Dry

  30. Ratio of 13C/12C in leaf can give information on photosynthesis • Reported on a “per mil” basis (parts per thousand, ‰) • Differs based on photosynthetic type From Stable Isotope Ecology, Fry 2008

  31. C3 plants • Phragmites and Phalaris • 1st step in C3 photosynthesis involves conversion of CO2 to 3-carbon acid • Enzyme involved (Rubisco) has higher affinity to 12C • If stomata are closed, expect increase in ‘heavy’ carbon

  32. C4 plants • Spartina and Sorghum • 1st step in C4 photosynthesis involves conversion of HCO3 to 4-carbon acid • Enzyme involved (PEPCase) has higher affinity to 13C • If stomata are closed, expect increase in ‘light’ carbon

  33. Two-way ANOVA used • p<0.001 between trt • Tukey’s HSD: Deep> Med & Low > Dry

  34. ADH assays • Alcohol dehydrogenase (ADH) catalyzes ethanol production in fermentation. • The more ADH produced the better the plant respires anaerobically. • Can be an indicator of adaptation to environment. Pyruvate Pyruvate decarboxylase CO2 Acetaldehyde NADH ALCOHOL DEHYDROGENASE NAD+ Ethanol

  35. This research is cool

  36. Different types of adaptations shown • p<0.001 between species and p=0.032 in the interaction of species and treatment

  37. www.wi.dnr.gov www.uvm.edu

  38. Future research • Bigger sample sizes • Low observed power • Conduct field studies • If field and greenhouse results overlap than can be applied to management plans

  39. Acknowledgments • Dept. of Biological Sciences • Li-Cor LEEF grant • Kansas Academy of Science • Thesis Committee • Dr. Channell for statistical assistance • Dr. Ray Lee for isotope assistance • Ms. Susan Eaton for greenhouse assistance • Elita Baldridge, Jessica Casey, Ashley Inslee, and Georgina Jacquez

  40. Isotopes d From Stable Isotope Ecology, Brian Fry, 2008

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