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Environmental Change and Pollination Ecology in a common legume, Trifolium repens

Environmental Change and Pollination Ecology in a common legume, Trifolium repens. Nicole E. Miller & Tiffany M. Knight Washington University in St. Louis. Environmental Change. Anthropogenic activities changing our environment Tropospheric Ozone is increasing, particular in urban areas

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Environmental Change and Pollination Ecology in a common legume, Trifolium repens

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  1. Environmental Change and Pollination Ecology in a common legume, Trifolium repens Nicole E. Miller & Tiffany M. Knight Washington University in St. Louis

  2. Environmental Change • Anthropogenic activities changing our environment • Tropospheric Ozone is increasing, particular in urban areas • Agricultural fertilizers are also enhancing biologically available P and K • Salt from road runoff is entering ecosystems • Climate factors changing as secondary impact of environmental change

  3. Environmental Change • Atmospheric CO2 Concentrations • Expected to double over next 100 years (IPCC 2001) • Fossil fuel combustion • Coal • Gasoline • Burning of vegetation and trash

  4. Environmental Change • Human beings fix more nitrogen (N) than any other source (Vitousek et.al. 1997; IPCC2001) • Agricultural inputs • legumes • Synthetic fertilizers • Fossil fuel combustion (NOx) Intergovernmental Panel on Climate Change 2001

  5. CO2 N Environmental Change Environmental Change factor

  6. CO2 N Reward C:N Flower longevity Environmental change and Floral Traits Environmental Change factor Floral traits Floral Output

  7. CO2 N Reward C:N Flower longevity Environmental change and Floral Traits Environmental Change factor Floral traits Floral Output + + Wagner et. al. 2001, Jablonski et al. 2002, Garbutt and Bazzaz 1984 Wagner et. al. 2001, Erhardt and Rusterholz 1998

  8. CO2 N Reward C:N Flower longevity Environmental change and Floral Traits Environmental Change factor Floral traits Floral Output + + ?(+) ?(-) Henning et. al. 1996, Drake et. al. 1997, Mevi-Schütz et. al. 2003, King et. al. 2004Paterson et. al. 1997

  9. CO2 N CO2 N Reward C:N Flower longevity Environmental change and Floral Traits Environmental Change factor Environmental Change factor Floral traits Floral traits Floral Output + + + ?(+) ?(-) + + Osborne et. al. 1997Scagel 2004 (mycorrhizal inoculation)

  10. Seed number CO2 N Seed quality Environmental change and reproductive success Environmental Change factor Floral traits Reproductive success

  11. Seed number CO2 N Seed quality Environmental change and reproductive success Environmental Change factor Floral traits Reproductive success

  12. Seed number CO2 N Seed quality Environmental change and reproductive success Environmental Change factor Floral traits Reproductive success + + Wagner 2001, Jablonski et. al. 2002; Thürig et. al. 2003; Quadari and Reid 2005 Tromp et. al. 1994

  13. Seed number CO2 N Seed quality Environmental change and reproductive success Environmental Change factor Floral traits Reproductive success + + 0 0 Germination rate, Huxman et. al. 1998, Wagner et. al. 2001, Thürig et. al. 2003Germination rate, Nimje 1993, Wagner et. al. 2001

  14. Seed number λ Seed quality Reproductive success and population growth Environmental Change factor Floral traits Reproductive success Population growth

  15. Seed number λ Seed quality Reproductive success and population growth Environmental Change factor Floral traits Reproductive success Population growth ?

  16. Seed number λ Seed quality Reproductive success and population growth Environmental Change factor Floral traits Reproductive success Population growth ? + Shimizu et. al. 1998

  17. Seed number CO2 N Reward C:N λ Seed quality Flower longevity Grand Scheme Environmental Change factor Floral traits Reproductive success Population growth Floral Output + + + ? + ?(+) ?(-) ? + + 0 0

  18. Seed number CO2 N Reward C:N λ Seed quality Flower longevity Grand Scheme Environmental Change factor Floral traits Reproductive success Population growth Floral Output

  19. Seed number Visitation rate CO2 N Reward C:N λ Seed quality Visitationduration Flower longevity Grand Scheme Environmental Change factor Floral traits Pollination success Reproductive success Population growth Floral Output

  20. Importance of Pollination • 90% flowering plants depend on pollinators for some degree of fertilization (Buchman and Nabhan 1996) • Have direct impact on plant demography and growth rate via reproductive success (Ashman 2004) • Plants shown to compete for pollinators = limited resource (Campbell 1985)

  21. Seed number Visitation rate CO2 N Reward C:N λ Seed quality Visitationduration Flower longevity Grand Scheme Environmental Change factor Floral traits Pollination success Reproductive success Population growth Floral Output + ? + + - ? + +

  22. Seed number Visitation rate CO2 N Reward C:N λ Seed quality Visitationduration Flower longevity Grand Scheme Environmental Change factor Floral traits Pollination success Reproductive success Population growth Floral Output + +

  23. Seed number Visitation rate CO2 N Reward C:N λ Seed quality Visitationduration Flower longevity Grand Scheme Environmental Change factor Floral traits Pollination success Reproductive success Population growth Floral Output + + + -

  24. Seed number Visitation rate CO2 N Reward C:N λ Seed quality Visitationduration Flower longevity Grand Scheme Environmental Change factor Floral traits Pollination success Reproductive success Population growth Floral Output + + + - + +

  25. Seed number Visitation rate CO2 N RewardC:N λ Seed quality Visitationduration Flower longevity Grand Scheme Environmental Change factor Floral traits Pollination success Reproductive success Population growth Floral Output + + + - + +

  26. Seed number Visitation rate CO2 N Reward C:N λ Seed quality Visitationduration Flower longevity Grand Scheme Environmental Change factor Floral traits Pollination success Reproductive success Population growth Floral Output + + + - + +

  27. Seed number Visitation rate CO2 N Reward C:N λ Seed quality Visitationduration Flower longevity Grand Scheme Environmental Change factor Floral traits Pollination success Reproductive success Population growth Floral Output + + + - + +

  28. Methods • Trifolium repens (white clover) • Legumous perennial w/ rhizobium • Self-incompatible • Generalist pollinated • Chamber experiment

  29. Floral Measurements Days to flower Inflorescence width, number per plant Flower height, number per inflorescence Inflorescence longevity Pollinator Observations 20 minute visual observations Pollinator type Visit duration Flight pattern C:N measurements Methods

  30. Results C sig N sig CxN sig C sig N sig CxN sig C S N S CxN S S: p ≤ 0.05 MS: 0.1 ≤ p ≤ 0.05 NS: p ≥ 0.1

  31. Results C S N NS CxN NS

  32. Results C S N S CxN S

  33. Results C MS N MS CxN MS

  34. Results C MS N NS CxN NS

  35. Conclusions • Pollinator behavior is altered in response to Trifolium repens grown under elevated CO2 but not enhanced N • Hypothesis: response of pollinators due to increase in floral output and possibly alteration of nectar quality • Potentially influence seed output and reproductive success => plant demography

  36. Discussion • Differential response => pollinator composition in an area may shift with environmental change • Pollinators depend on nectar and pollen consumption for dietary needs => could be indirectly influenced by environmental change (Mevi-Shütz et. al. 2003) • Species of concern often pollen limited => interaction with pollinators could be important to survival (Rymer et. al. 2005)

  37. Acknowledgments Knight lab Chase lab Alex Harmon-Threatt Carla Fresquez Pete Van Zandt Danforth Plant Sciences Center greenhouse staff National Science Foundation

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