Wildfire alters the linkage between total and available soil C:N:P ratios and the stoichiometric effects on fine root growth in a Chinese boreal larch forest

Background and aims: Wildfire is a primary driver of forest ecosystem functioning, and fire-induced changes in nutrient cycling and the balance of multiple nutrients may influence plant growth response to burning. However, the relationship between total and available soil stoichiometry and stoichiometric effects on the growth of fine roots following forest fires remain unclear. Methods: We measured the total and available soil C, N, and P concentrations, their ratios, and fine root biomass (FRB) at unburned control, 1-year-postfire, and 11-year-postfire sites in a Chinese boreal larch forest. We analyzed the relationship between soil stoichiometry and FRB. Results: Wildfire significantly reduced the total and available soil C:N:P ratios and FRB immediately postfire. Eleven years postfire, most indicators recovered to the prefire levels except for total soil C:P and N:P ratios, and available C:N ratio. Wildfire increased the associations between total and available soil C:N:P ratios, as well as between FRB and soil C:N:P ratios, but reduced the relationship between FRB and soil nutrient supply. However, these effects became weaker over time. Conclusions: The effects of wildfire on biogeochemical processes in boreal ecosystems extend to the relationship between total and available soil stoichiometry. Wildfires strengthen the linkage between fine roots and soil stoichiometry but weaken the effects of soil nutrient supply in the Great Xing’an Mountains. Therefore, the effects of wildfire on the coupling of soil C, N, and P cycling can produce a more complex soil-plant interaction in the early succession stage of boreal larch forest.