Spatial heterogeneity in soil pyrogenic carbon mediates tree growth and physiology following wildfire

Pyrogenic carbon (PyC) is a ubiquitous legacy of wildfire in terrestrial soils, yet how it affects the growth and function of regenerating plants has received little research attention. We examined responses to a natural gradient of PyC deposition five years following a severe fire in a northern boreal forest, based on measurements of growth (height, basal area increment, and leader extension), physiological performance (Fv/Fm), and foliar nutrition (foliar C, N, P, K, Mg) of Pinus banksiana Lamb. We determined the concentration of PyC, expressed as a dosage (t·ha-1), in mineral soils collected from the rhizospheres of each sapling and used it as an independent factor to model trait responses to increasing PyC levels, in conjunction with measurements of soil physio-chemical properties (pH, EC, VOC, Ash, N, P, K, Ca, and Mg). Quantification and spatial analysis of PyC reveals heterogeneous deposition across the landscape with fine-grained patchiness at scale...