Results/Conclusions

Controlling for temperature and soil moisture, there were no significant effects of plant type or site on soil respiration, measured in situ. Significantly lower water content was observed in the highly invaded site, especially in gaps between shrubs where invasive grasses flourished. Glucose and salicylate SIR were not significantly affected by site or vegetation type.  However, microbial biomass C was found to be lower in the highly invaded site relative to the less invaded site. Interestingly, this reduction in microbial biomass C was compensated by an increase in the biomass-specific activity of the biomass, as shown by a higher ratio of glucose SIR to microbial biomass C in the invaded site. These results show evidence for the alteration of the habitat by invasive plants, particularly in terms of the water cycle, the microbial community and how it processes plant litter. These alterations could have important implications for how the plant community and C balance of CSS ecosystems interact with climate change in the future.