Finnish ICOS 16S rRNA and ITS amplicons
Soils in northern latitudes are warming, resulting in changes to soil abiotic conditions. Slight changes in soil conditions can alter microbial activity, observed through respiration measurements and extracellular enzyme activity (EEA) analyses. To understand the effects of soil temperature and moisture on microbial activity and community composition, we prepared soil collected from a Finnish boreal forest for a laboratory incubation study. The soil was wetted to a range of matric potentials and incubated at different temperatures to mimic a range of soil conditions throughout a growing season at our site. We hypothesized that temperature would be positively correlated to microbial respiration and potential EEA due to faster reaction rates and metabolic activity. Conversely, we expected soil moisture to limit activity when too dry or wet. Lastly, we expected temperature to drive shifts in the microbial taxonomy. Respiration and potential EEA were both significantly impacted by increased soil temperature. Conversely, the effect of matric potential was not significant across the whole dataset, only within each incubation temperature. Only the nitrogen degrading potential EEA values significantly increased by both temperature and moisture conditions, with peak activity occurring at -10 kPa. Both bacterial and fungal community composition shifted with temperature. There were more abundant bacterial taxa at warmer temperatures and more abundant fungal taxa colder temperatures. These results reveal the potential for future CO2 emissions and increased seasonal nutrient cycling in these regions.