A comparison of two warming treatments and their effects on plant growth and ecosystem CO2 exchange, and a concurrent study of seasonal variation in the soil microbial community

This study compared the effects of two different warming treatments (open-top chambers and infrared heaters) on the environmental conditions in native prairie grassland. Both treatments increased average air temperature, with infrared heaters providing a more consistent warming than open-top chambers, but also a more significant decrease in soil moisture. Additionally, the effects of warming on plant biomass and ecosystem CO2 exchange were examined. No significant effects of increased temperature were found, although 2013 had higher precipitation than normal and produced more aboveground biomass than average years, with correspondingly low δ13C and δ18O values. Finally, a concurrent study examined the seasonal variation in soil microbial activity, as controlled by the direct and indirect effects of soil temperature and soil moisture. Significant seasonal patterns were found in soil respiration, soil microbial biomass, extracellular enzyme activity and the species composition of the soil bacterial community