Wildfires thaw near-surface permafrost soils in the boreal forest, making previously frozen organic matter available to microbes. The short-term microbial stoichiometric dynamics following a wildfire are critical to understanding the soil element variations in thawing permafrost. Thus, we selected a boreal wildfire chronosequence in a region of continuous permafrost, where the last wildfire occurred 3, 25, 46, and >100years ago (set as the control) to explore the impact of wildfire on the soil chemistry, soil microbial stoichiometry, and the fungal-to-bacterial gene ratio (F:B ratio). We observed the microbial biomass C:N:P ratio remained constant in distinct age classes indicating that microbes are homeostatic in relation to stoichiometric ratios. The microbial C:N ratios were independent of the shifts in the fungal-to-bacterial ratio when C:N exceeded 12. Wildfire-induced reduction in vegetation biomass positively affected the fungal, but not the bacterial, gene copy number. The decline in microbial biomass C, N, and P following a fire, primarily resulted from a lack of soil available C and nutrients. Wildfire affected neither the microbial biomass nor the F:B ratios at a soil depth of 30cm. We conclude that microbial stoichiometry does not always respond to changes in the fungal-to-bacterial ratio and that wildfire-induced permafrost thawing does not accelerate microbial respiration.
1.Univ Helsinki, Dept Forest Sci, POB 27, FIN-00014 Helsinki, Finland 2.Nanjing Forestry Univ, Coll Forestry, Collaborat Innovat Ctr Sustainable Forestry China, Nanjing 210037, Jiangsu, Peoples R China 3.Univ Eastern Finland, Dept Environm & Biol Sci, Kuopio 70211, Finland 4.Univ Helsinki, Dept Food & Environm Sci, POB 56, FIN-00014 Helsinki, Finland 5.Univ Helsinki, Fac Agr & Forestry, Inst Atmospher & Earth Syst Res Forest Sci, Helsinki, Finland 6.Finnish Meteorol Inst, Climate Syst Res, POB 503, FIN-00101 Helsinki, Finland 7.Zhejiang A&F Univ, State Key Lab Subtrop Silviculture, Nurturing Stn, Linan 311300, Zhejiang, Peoples R China
Recommended Citation:
Zhou, Xuan,Sun, Hui,Pumpanen, Jukka,et al. The impact of wildfire on microbial C:N:P stoichiometry and the fungal-to-bacterial ratio in permafrost soil[J]. BIOGEOCHEMISTRY,2019-01-01,142(1):1-17