Forest wildfires lead to the production of chemically altered biomass residues known as pyrogenic organic matter (pyOM), which has been thought to be highly resistant and contribute to soil organic carbon (SOC) sequestration. A significant portion of pyOM may, however, be utilized by soil biota and as such may be fragmented, digested, and released as carbon dioxide into the atmosphere or stabilized in the soil. In addition, soil succession after the fire event and climate change may have a significant effect on all of the biotic processes. Here, we will observe successional changes in the soil properties on a 100-year post-fire chronosequence in pine forests in the Mediterranean, temperate, and boreal zones and along the soil profile. The focus will be on the effect of increased temperature on the transformation and stabilization of pyOM by soil faunal and microbial communities. We will perform field samplings and observations, 13C-labelled pine litter and pyOM production, as well as a slightly manipulated field experiment and a heavily manipulated laboratory experiment.