Fungal responses to elevated temperature and soil nitrogen availability

The soil microbial community controls decomposition of organic residues which constitute a large portion of soil organic matter. Microbial growth is impacted by global changes such as warming and soil nitrogen (N) availability. Carbon use efficiency (CUE) is an important parameter that influences soil C dynamics by partitioning organic matter between soil C and CO2 pools. This research focuses on the growth of different fungal species' exposed to varying temperatures and N availabilities, while quantifying respiration (CO2 flux) and microbial growth. To assess individual fungal isolates, we constructed a sterilized artificial soil medium to mimic a sandy loam soil by mixing 70% sand, 20% silt, and 10% clay. Several fungal species of the phyla Ascomycota and Basidiomycota were individually grown in this media at different temperatures (15 and 25°C) and N levels. Soil respiration was measured over the incubation period. Fungal biomass was estimated by chloroform fumigation extraction and qPCR of the fungal ITS region. Our results indicate that fungi were able to grow effectively and reproducibly in the artificial soil medium, demonstrating that using an artificial soil is an effective method for assessing individual species responses. Temperature and N availability had a positive affect on C mineralization and biomass. CUE varied among fungal species and, in general, declined with temperature.