elizabeth waring thesis defense
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Flooding tolerance of native and nonnative grasses: variation in photosynthesis, transpiration, respiration and carbon isotope discrimination. Elizabeth Waring Thesis Defense. Wetlands and Invasion. - PowerPoint PPT PresentationTRANSCRIPT
Flooding tolerance of native and nonnative grasses: variation in photosynthesis, transpiration, respiration and carbon isotope
discrimination
Elizabeth WaringThesis Defense
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
Flooding
• Importance to wetlands• Effects of flooding on vegetation
• Drought mode
Cheyenne Bottoms Oct. 2007
http://geospectra.net/cheyenne/bottoms
• Previous flooding studies focused on biomass accumulation as indicator of tolerance to disturbance
• Examine physiological changes in species due to flooding
Why study physiology in invasive species?
Physiological processes are the link between environment and performance
GrowthReproduct
ion
Metabolic
Adaptations
Disturbances
Flooding
Performance
Physiological
Processes
Environment
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
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
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
Spartina pectinata
• “prairie cordgrass”• Native to Kansas
• C4 photosynthetic species
• Wetland indicator: FACW
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
Flooding setup
CollectionDepthsTreatments
• 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
“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. AllenLund University
(Raven et al. 2005)
Pmax
Quantum Efficiency
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
Spartina pectinata, prairie cordgrass (native)
After 7 days close ratesAfter 28 days clear preference to deep floodingInteraction of time X trt significantly higher (p=0.044)
Phragmites australis, common reed (nonnative)
Always favors flooded conditionsNo significant differences
Phalaris arundinacea, reed canarygrass (nonnative)
After 7 day no preferenceAfter 28 days clear difference between deep flooding and other treatments--- 3 deep flooded plants diedSignificantly different over time (p=0.029)
Sorghum halepense, johnsongrass (nonnative)
After 7 days does well After 28 days all deep flooded and 3 medium flooded plants diedA significantly decreased over time (p<0.001)
Spartina 7 days
Sorghum 7 daysPhalaris 7 days
Phragmites 7 days
Spartina 28 days
Sorghum 28 daysPhalaris 28 days
Phragmites 28 days
P=0.001 RM ANOVA, interaction of time X spp
• p=0.027 in interaction of time X spp
• Tukey’s HSD post-hoc used
• Spartina > Phalaris & Phragmites > Sorghum
• No significant differences between times or interactions
• Low observed power
A Pmax
Spartina ↑ ↑Phragmites ↑ ↑Phalaris ↑↓ ↑↓Sorghum ↓ ↓
Oxygen evolution
Maximum JO2
Gross qe
O2
evo
luti
on
O2
• 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
• RM ANOVA p=0.014 over time
• p=0.001 in interaction of time X spp
• Tukey’s HSD: Phragmites >
Phalaris & Spartina > Sorghum
A Pmax
Spartina ↑ ↑Phragmites ↑ ↑Phalaris ↑↓ ↑↓Sorghum ↓ ↓
JO2 gross qe
↑ ↑↑ ↑↓ ↓↓ ↓
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
• 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
A Pmax JO2 gross qe
Spartina ↑ ↑ ↑ ↑Phragmites ↑ ↑ ↑ ↑Phalaris ↑↓ ↑↓ ↓ ↓Sorghum ↓ ↓ ↓ ↓
Fv/Fm
↑↑↓↓
• Ratio of 13C/12C in leaf can give information on photosynthesis
• Reported on a “per mil” basis (parts per thousand, ‰)
• Differs based on photosynthetic typeFrom Stable Isotope Ecology, Fry 2008
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
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
• Two-way ANOVA used• p<0.001 between trt• Tukey’s HSD: Deep> Med & Low > Dry
A Pmax JO2 gross qe Fv/Fm
Spartina ↑ ↑ ↑ ↑ ↑Phragmites ↑ ↑ ↑ ↑ ↑Phalaris ↑↓ ↑↓ ↓ ↓ ↓Sorghum ↓ ↓ ↓ ↓ ↓
13C
↓↓↑−
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.
Pyruvatedecarboxylase
Pyruvate
CO2
AcetaldehydeNADH
NAD+
Ethanol
ALCOHOL DEHYDROGENASE
Different types of adaptations shownp<0.001 between species and p=0.032 in the interaction of species and treatment
A Pmax JO2 gross qe Fv/Fm 13C
Spartina ↑ ↑ ↑ ↑ ↑ ↓Phragmites ↑ ↑ ↑ ↑ ↑ ↓Phalaris ↑↓ ↑↓ ↓ ↓ ↓ ↑Sorghum ↓ ↓ ↓ ↓ ↓ −
ADH
↑−↑↑↓
www.uvm.edu
www.wi.dnr.gov
Future research
• Bigger sample sizes• Low observed power
• Conduct field studies
• If field and greenhouse results overlap than can be applied to management plans
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
Isotopes
From Stable Isotope Ecology, Brian Fry, 2008