1. Some slides on warming, precipitation, and biomass harvesting experiments in Oklahoma Yiqi Luo Department of Microbiology and Plant Biology University of Oklahoma, USA http://ecolab.ou.edu

2. C3 dominant C4 dominant 14-year warming and clipping experiment 4-year warming, precipitation and clipping experiment

3. Long-term: 14 years Warming: 2 o C Clipping: Yearly

4. warming x Precipitation x Bioenergy

5. Plant community C 4 /C 3 species Leaf Ps Phenology Growing season Plant growth Microbial community Fungi/bacteria Plant N uptake Plant & soil C Available N Quality of bulk litter Respiration NUE Litter Decomposition Luo, 2007. Ann. Rev. Ecol. Evol. System

6. Plant community C 4 /C 3 species Leaf Ps Phenology Growing season Plant growth Microbial community Fungi/bacteria Plant N uptake Plant & soil C Available N Quality of bulk litter Respiration NUE Litter Decomposition Sherry et al. 2007, PNAS Zhou et al. 2007a, JIPB Zhou et al. 2006, GBC; 2007b, GCB Luo et al. 2001, Nature Zhang et al. 2005 GCB Zhou et al. 2012 NCC An et al. 2005, GCB Cheng et al. 2010 Agric Ecosystems Wan et al. 2005, GBC Luo et al. 2009, GCB-E Sherry et al. 2008, GCB Niu et al. 2010, Ecology Sherry et al. 2010, 2011, 2012

7. Warming effects on C & N storages Plant C increased, but plant and soil N didn’t change Niu et al. 2010 Ecology

8. Niu et al. 2010 Contributions of N and NUE

9. Mechanism: species composition changes

10. W: +12~25% W: -26~53% W: +4~9% W: +32% W: -18~19% W: -8~18% Contrast warming effects between C3 and C4 vegetation C4 grasslandC3 grassland Niu et al. 2013

11. C3 & C4 composition determines warming effects! Niu et al. 2013

12. Mechanism: different optimum temperature Niu et al. 2013

13. Luo et al. 2001 Nature Acclimation of soil respiration to warming

14. Sherry et al. 2007 PNAS