Browsing by Author "Viitamäki, Sirja"

Soil microbial communities have a critical role in the biogeochemical processes on Earth, but their response to the ongoing climate change is poorly understood. Arctic permafrost harbors approximately 50% of Earth’s below ground carbon, and warmer climate leads to increased rate of microbial decomposition of soil organic matter in polar regions. Without a comprehensive understanding of the soil microbial ecology, the overall impact of climate change to nutrient cycles and greenhouse gas emissions is difficult to predict. My aim was to improve the knowledge of active microbes and their energy sources in subarctic soil. I studied the activity and functions of soil microbial communities by applying metatranscriptomics to soils along a natural climate gradient in subarctic Kilpisjärvi, northwestern Finland. The gradient represents the possible soil conditions, that microbial communities live in as the climate changes. Additionally, I studied the relationship of microbial activity and various environmental factors, including pH and soil organic matter. Results of the thesis showed that the active microbial communities in subarctic soils are diverse taxonomically and by their energy metabolism, and that pH, soil organic matter content and moisture are the main drivers of soil microbial activity and functions.