Abstract: In order to master the characteristics of forest humus smoldering temperature, the author took the surface humus combustible in Dingshan, Qixia District, Nanjing as the research object, and took the types of combustible, the combustion depth of combustible, water content and wind speed as independent variables respectively. Under the same condition of other variables, the author set up a preliminary smoldering spread model and obtained relevant experimental data. The data shows that the smoldering temperature of dry standing tree is up to 689 ℃; the deeper the smoldering burning depth is in the surface soil, the longer the smoldering duration will be; the transverse smoldering fire spreading on the soil surface determines the scope of smoldering forest fire; given the underground combustion characteristics of smoldering, it will burn out the combustible underground, but leave the surface unburnt, thus forms a hollow underground; when the water content is greater than 42.3%, the possibility of humus re-burning is very low; by comparing the results of orthogonal experimental table, the wind speed has the most significant effect on the smoldering re-ignition, while the combustion depth affects the smoldering time and range. The research provides partial theoretical basis and experimental data support for future forest fire fighting works.

Key words: humus, ground fire, smoldering, thermal infrared