Original Article

Subject Category: Microbial ecosystem impacts

The ISME Journal (2011) 5, 1692–1700; doi:10.1038/ismej.2011.32; published online 31 March 2011

Effect of warming and drought on grassland microbial communities

Cody S Sheik1,2, William Howard Beasley3, Mostafa S Elshahed4, Xuhui Zhou1, Yiqi Luo1 and Lee R Krumholz1,2

  1. 1Department of Botany and Microbiology, University of Oklahoma, Norman, OK, USA
  2. 2The Institute for Energy and the Environment, University of Oklahoma, Norman, OK, USA
  3. 3Department of Psychology, University of Oklahoma, Norman, OK, USA
  4. 4Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, USA

Correspondence: LR Krumholz, Department of Botany and Microbiology, University of Oklahoma, 770 Van Vleet Oval, Norman, OK 73019, USA. E-mail: krumholz@ou.edu

Received 23 September 2010; Revised 8 February 2011; Accepted 21 February 2011; Published online 31 March 2011.



The soil microbiome is responsible for mediating key ecological processes; however, little is known about its sensitivity to climate change. Observed increases in global temperatures and alteration to rainfall patterns, due to anthropogenic release of greenhouse gases, will likely have a strong influence on soil microbial communities and ultimately the ecosystem services they provide. Therefore, it is vital to understand how soil microbial communities will respond to future climate change scenarios. To this end, we surveyed the abundance, diversity and structure of microbial communities over a 2-year period from a long-term in situ warming experiment that experienced a moderate natural drought. We found the warming treatment and soil water budgets strongly influence bacterial population size and diversity. In normal precipitation years, the warming treatment significantly increased microbial population size 40–150% but decreased diversity and significantly changed the composition of the community when compared with the unwarmed controls. However during drought conditions, the warming treatment significantly reduced soil moisture thereby creating unfavorable growth conditions that led to a 50–80% reduction in the microbial population size when compared with the control. Warmed plots also saw an increase in species richness, diversity and evenness; however, community composition was unaffected suggesting that few phylotypes may be active under these stressful conditions. Our results indicate that under warmed conditions, ecosystem water budget regulates the abundance and diversity of microbial populations and that rainfall timing is critical at the onset of drought for sustaining microbial populations.


climate change; microbial diversity; drought; warming