『Abstract
　After vegetation fires considerable amounts of severely or partly charred necromass (referred to here as char) are incorporated into the soil, with long-term consequences for soil C and N dynamics and thus N availability for primary production and C and N transport within the soil column. Considering results reported in the pyrolysis literature in combination with those obtained from controlled charring of plant materials and soil organic matter (SOM), it has become clear that common models claiming char as a graphite-like material composed mainly of highly condensed polyaromatic clusters may be oversimplified,. Instead, I suggest a concept in which char is a heterogeneous mixture of heat-altered biopolymers with domains of relatively small polyaromatic clusters, but considerable substition with N, O and S functional groups. Such a concept allows fast oxidation facilitating both microbial attack and dissolution. although, char is commonly believed to degrade more slowly than litter, over the long term and under oxic conditions, char may degrade to an extent that it becomes indistinguishable from naturally formed SOM. Oxygen depletion or environments with low microbial activity may be necessary for char to survive without major chemical alteration and in considerable amounts for millennia or longer/

Keywords: Pyrolysis; Charcoal; Black carbon; Black nitrogen; Aromatic; Alkyl』

Introduction
Ecological importance of vegetation fires past and present
Fire severity spectrum and temperature regime
Impact of fire on soil properties
　Liming effect
　Nutrient availability
　Accumulation of hydrophobic compounds
Impact on soil biology and enzyme activity
Impact of fire on SOM content
Impact of fire on SOM quality
　Cellulose and pectin
　Lignin and chlorogenic acid
　Proteins and amino acids
　Maillard reaction
　Charring of plants residues and SOM
Char content in soils
Chemical alteration of SOM in fire-affected soils
　Direct effects on bulk soil organic carbon
　Solubility of SOM
　Alteration of the organic N fraction
　Impact of recovery time
Stability of char
Conclusions
　Molecular structure of char and its impact on char quantification in SOM
　Importance of “black nitrogen”
　Charcoal structure and its short-term impact on SOM properties
　Impact of char input on quality and quantity of SOM
　Degradability and solubility of char residues
References