Eric Bird Purdue University Calumet Flora Richardson Fellowship Recipient

1. Investigating the mechanisms by which available nitrogen affects biodiversity of a plant community native to the Indiana Dunes National Lakeshore Eric Bird Purdue University Calumet Flora Richardson Fellowship Recipient

2. Concern • Atmospheric deposition of nitrogen is high in the Midwestern and Eastern United States • The Indiana Dunes receive approximately 15kg ha-1 y-1 nitrogen as wet deposition • Research has shown that increases in available nitrogen to low nitrogen ecosystems affects species composition and can have an overall negative affect on biodiversity

3. Preliminary research shows that ammonium nitrate treatment • Reduces the total biomass of some species • Alters how species allocate biomass (aboveground vs. belowground) • Reduces the germination success of some species

4. Setup • Use laboratory experiments to determine which species are hindered by nitrogen treatment and… • Use this information to predict which species will occur less frequently in a constructed native plant community grown in the field against a gradient of available nitrogen

5. Species investigated • Schizachyrium scoparium – little bluestem grass • Elymus canadensis – Canada wild rye • Panicum virgatum – switchgrass • Sorghastrum nutans – Indiangrass • Rudbeckia hirta – black eyed susan • Echinacea purpurea – purple cone flower • Dalea purpurea – purple prairie clover • Monarda punctata – dotted mint • Liatris aspera – rough blazing star • Lupinus perennis - lupine

6. Experiments • Biomass allocation – greenhouse • Germination – laboratory • Aboveground biomass production – field • Biodiversity – field • Competition – field

7. Biomass allocationgreenhouse • Purpose: to determine the relationship between available nitrogen and biomass allocation of ten native species

8. Biomass allocationgreenhouse • Hypothesis: if amount of ammonium nitrate increases then some species will allocate more biomass to aboveground growth while others will not.

9. Biomass allocationgreenhouse • Four treatment groups (n = 5): • control • 30kg ha-1 • 60kg ha-1 • 120kg ha-1 • Biomass will be harvested after approximately 6 months of growth.

10. Biomass allocationgreenhouse • Prediction 1: species that allocate more biomass to aboveground growth will outcompete other species in the field as available nitrogen increases

11. Competition and biomass allocationfield • Purpose: to determine whether aboveground or belowground biomass allocation increases the relative dominance of a species in a high nitrogen environment

12. Preliminary researchbiomass allocation • Table 1aboveground and belowground percent biomass for E. canadensis and S. scoparium(n = 5)

13. Competition and biomass allocationfield • Prediction 1: species that allocate more biomass to aboveground growth will outcompete other species in the field as available nitrogen increases • Hypothesis 1: if biomass allocation determines relative dominance then one of the two species should dominate at increased nitrogen levels • Hypothesis 2: if preliminary data and prediction 1 are correct then in high treatment groups S. scoparium will allocate more biomass to aboveground growth and will increase in relative dominance over E. canadensis

14. Competition and biomass allocationfield • Two species: E. canadensis, and S. scoparium • Four treatment groups (n = 5): • Control • 30kg ha-1 • 60kg ha-1 • 120kg ha-1 • Rectangular plastic containers are buried at the field site and half seeded with each of the two species. After one growing season the percent coverage by each species is determined

15. Germination laboratory • Purpose: to determine the relationship between the concentration of ammonium nitrate and the germination success of ten native species. • Hypothesis: if ammonium nitrate concentration is increased then the germination success of most species will be reduced

16. Preliminary research germination

17. Germination laboratory • Four treatments (n = 7): • Control • 1000ppm • 2000ppm • 4000ppm • Seeds germinated in petri dishes containing mineral sand at 22°C for 6 weeks • Number of germinated seeds recorded each week

18. Germination laboratory • Prediction 2: Species that are most successful at germinating at higher end of the spectrum should occur more frequently in the field as ammonium nitrate levels increase

19. Biodiversityfield • Purpose: to determine whether available nitrogen affects biodiversity of a plant community native to the Indiana dunes

20. Biodiversityfield • Prediction 1: species that allocate more biomass to aboveground growth will outcompete other species in the field as available nitrogen increases • Prediction 2: Species that are most successful at germinating at higher end of the spectrum should occur more frequently in the field as ammonium nitrate levels increase

21. Biodiversityfield • Hypothesis 1: if nitrogen levels increase then biodiversity will decrease • Hypothesis 2: if biodiversity decreases as a result of nitrogen additions then predictions 1 and 2 will be true

22. Biodiversityfield • Four treatment groups (n = 5): • Control • 30kg ha-1 • 60kg ha-1 • 120kg ha-1 • Species are seeded in 2x2m plots at field site. Percent coverage and aboveground biomass of each species is determined after two seasons.

23. Summary • It is expected that nitrogen additions will • Reduce germination of most species • Cause some species to allocate more biomass aboveground • Therefore • As nitrogen levels increase few species with high germination success and aboveground biomass allocation will begin to dominate and biodiversity will decline as a result