2. Impact of varied precipitation and N deposition on grassland soil microbial communities and GHG flux Emma L. Aronson Allison lab UC Irvine May 17, 2012

3. Precipitation hypotheses Indicates level of soil bacterial biodiversity Decreased Rainfall ControlIncreased Rainfall Indicates rate of CO 2 and N 2 O release, CH 4 consumption

4. N amendment hypotheses Control Indicates level of soil bacterial biodiversity Indicates rate of CO 2 and N 2 O release, CH 4 consumption N Added NNNNNN

5. In March, N and H 2 O- increased CH 4 uptake production uptake

6. H 2 O- increased CH 4 uptake production uptake

7. N increased CH 4 uptake production uptake

8. Rain decreased, then increased uptake production uptake

9. CH 4 flux correlates with initial [CH 4 ] 500 1000 1500 2000 2500 3000 3500 80 60 40 20 0 -20 -40 -60 -80 CH 4 Flux (ppb min -1 ) production uptake

10. H 2 O- decreased respiration

11. Time interacts with precipitation

13. Rainfall increases respiration Courtesy of Greg Winston CO 2 Flux (mg m -2 h -1 ) Precipitation (in d -1 ) Day of Study Precipitation CO 2 Flux

14. N increases N 2 O release

15. Time interacts with N treatment

17. Rain Effect?

18. Drought changed bacterial community Ambient RainfallReduced Rainfall Significantly Different Phyla

19. Reduced rainfall decreases variability in microbial richness at OTU level

20. Drought decreased respiration and variability in bacterial diversity, increased CH 4 uptake Decreased Rainfall ControlIncreased Rainfall Indicates rate of CO 2 release, CH 4 consumption microbial community variability

21. N amendment increased N 2 O release, CH 4 uptake N AddedControl NNNNNN Indicates rate of N 2 O release, CH 4 consumption

22. Research in progress Further 16S 454 sequencing – for all dates of gas analysis Shotgun metagenomic DNA sequencing GeoChip functional microarrays or qPCR Gene expression of soil N and C cycling functions

23. Questions?