The impact of changing climate on ecosystem processes is currently a ‘black box’ scenario with soil microbial communities representing a core module. To investigate the components of this complex and dynamic microbial module, accurate, sensitive and high-throughput technologies are required. We have developed and applied a 500,000 probe high-density phylogenetic DNA microarray to determine the microbial population response to simulated climate change (precipitation gradients). Using these metagenome and metatranscriptome scale measurements, our goal is to connect this microbial module with key ecosystem-process modules and focused plant-response modules.
Preliminary data demonstrates that 1-22% of the prokaryotic population detected was significantly impacted by altered precipitation depending on soil type. The most significantly impacted microbial phylum was the Actinobacteria, with more than 20 different families showing decreased abundance in response to elevated precipitation. These include cellulolytic species such as Cellulomonas. Similarly, Clostridia and Bacilli were also negatively impacted by elevated precipitation and included xylanolytic species, while many free-living nitrogen-fixing bacteria within the Rhizobiales and Bradyrhizobiales also declined. Surprisingly, very few organisms responded positively to increased precipitation in these soils with the exception of the understudied Verrucomicrobia. These results demonstrate the power of high-density microarrays in determining climate change impacts on the entire soil microbial population and also highlight the potential impacts of increased precipitation on both carbon and nitrogen transformations in annual grasslands.