Study On Combustibility Of Several Main Tree Species In Hei Longjiang Province

The combustibility of the main conifer and broadleaves tree species in Heilongjiang Province was studied by cone calorimetric analysis at a heat flux of 50kW·m^-2and a gas flow rate of 24L·s^-1.The fifteen species were Pinus koraiensis,Pinus sylvestris var.mongolica,Picea koraiensis,Larix gmelini,Phellodendron amurense,Juglans mandshurica,Quercus monglica,Acer tegmentosum,Fraxinus mandshurica,Populus davidiana,Betula platyphylla,Acer mono,Alnus hirsute,Tilia amurensis and Populus ussuriensis.The thermal characteristics of leaves and bark were analyzed simultaneously with testing and recording the data of heat release,mass loss,smoke formation and the composition of tail gas. And the effect of oxygen concentration on the burning of the samples was taken into account.It indicates that all the combustion process of the samples can be divided into three stages generally:initial smoldering stage,flaming stage and after-glowing stage.The changes regularity of samples on heat release rate(HRR),mass loss rate(MLR),rate of smoke release (RSR)and rate of CO₂ production(PCO₂)appeared isochronous,and all of these parameters come to their peaks when flaming combustion was the most acutely.At the same time,we found that the mass loss,heat release,smoke release and CO₂ production of the most species occurred in flaming stage and the process of CO releasing was comparatively complex owing to the influence of oxygen concentration and fire-retardant treatment.As a whole,CO releasing mainly occurs in the stage of after-glowing,which was induced by partial oxidation of wood charcoal.Above all,the fire-resistance of Acer tegmentosum was the best,and recommended as fire resistance species for fire-preventing forest belts.Reversely the fire-resistance of Betula platyphylla and Phellodendron amurense were the worst of the fifteen tree species.All the burning indexes of Larix gmelini Rupr.were at middle level,it was an stronger anti-fire conifer species.Because of high fire-resistance of bark but poor fire-resistance of leaves,Quercus mongolica and Pinus sylvestris Var.mongolica Litv were not recommended for fire-preventing forest belts.And so the ordering of fire resistance of the fifteen tree species was Acer tegmentosum＞Populus ussuriensis＞Acer mono＞Quercus monglica＞Fraxinus mandshurica＞Larix gmelini＞Juglans mandshurica＞Tilia amurensis＞Populus davidiana＞Alnus hirsute＞Picea koraiensis＞Pinus sylvestris var.mongolica＞Phellodendron amurense＞Pinus koraiensis＞Betula platyphylla.