Landscape ecology of microbes in peatlands under different management regimes

Peatlands are essential ecosystems that play a significant role in the sequestration of carbon, water provisioning and global biodiversity. However, human activities are threatening their ability to sustain important ecosystem services. Soil microbial activity supports ecosystem processes in peatlands, but little is known about the main drivers of microbial community dynamics and their association with ecosystem functioning. Therefore, to better forecast the response of the microbiome to management regimes, a deeper understanding is required. The overall goal of this thesis is to identify the environmental drivers of peatland soil microbial communities and to investigate the effects of land management on community composition, function and resistance to habitat change. The study was based on the analysis of a pre-existing data set on microbial communities regarding land reclamation in Canada and on original data collection and analysis regarding burning regimes at Moor House Nature Reserve, UK. The Canadian data were used to determine how microbial communities and function change along three natural fens and a constructed fen in the Athabasca oil sands region of Alberta and assess the impact of this reclamation practice. The UK research focused on investigating how prescribed burning affects soil properties, microbial community structure and microbial N-cycling using a range of approaches including next-generation sequencing and qPCR. Overall, results show first, total substrate respiration was significantly higher in the constructed fen, yet, the diversity of fungi and prokaryotes was higher in the treed-rich fen and community composition was significantly different between fens. However, prokaryote community composition was similar in the constructed fen to the treed-rich fen showing a resilience of the community to soil transfer. Second, there were changes in archaeal, bacterial and fungal diversity and community composition between burn treatments and soil profiles. Fungal diversity showed a more drastic change across burn treatments throughout the soil profile and there was also a shift in the relative abundance of trophic modes. Co-occurrence network analysis revealed that the non-burn topsoil had a larger and more complex network structure with more positive links than those under rotational burns. Third, amoA-AOA, amoA-AOB and nifH were higher in the topsoil of the non-burn control while the abundance of nirK was higher in plots under short rotation and long rotation regimes. ChiA abundance was greater in plots under a short rotation burn regime and decreased with soil depth. This result suggests that microbial N turnover potential is affected by the practice of burning. The changes in microbial communities and function are anticipated to have an impact on important peatland ecosystem services.