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

Abstract

Background and aimsWildfire is a primary driver of ecosystem functioning, and the fire-induced changes in the cycling and balance of multiple nutrients may influence the response of plant growth to burning. However, the relationships between total and available soil stoichiometry and stoichiometric effects on the growth of fine roots following fire in forests remain unclear.MethodsWe measured the total and available soil C, N and P concentrations, their ratios and fine root biomass (FRB) at an unburned control, 1-year-postfire and 11-year-postfire sites in a Chinese boreal larch forest. The relationships between soil stoichiometry and FRB were analyzed.ResultsWildfire significantly reduced the total and available soil C:N:P ratios and FRB immediately postfire. Eleven years postfire, most indicators recovered to the pre-fire levels except total soil C:P and N:P ratios, and available C:N ratio. Wildfire immediately increased the correlations between total and available soil C:N:P ratios, as well as between FRB and soil C:N:P ratios, but reduced the correlations between FRB and soil nutrient supply. These effects became weaker over time.ConclusionsThe effects of wildfire on biogeochemical processes in boreal ecosystems extend to the relationships between total and available soil stoichiometry. Wildfire strengthens the linkage between fine roots and soil stoichiometry, but weakens 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 postfire early succession stage of boreal larch forest.