Research On Forest Fuel Loads And Potential Fire Behavior In Jiangxi Dagangshan Area

Study on11major vegetation types in Jiangxi Dagangshan area, the site factors and stand factors are surveyed. Measuring surface fuel load, including litter, grass and hay, andl,10,100h surface dry twigs load are measured in every quadrat; Canopy vertical distribution of combustible materials, with the method of the the standard sticks to determining the crown Fuel Load (combustibles space density),and samples were collected.The calorific value extract, ash and crude fiber mass fraction of combustible material are measured in forest fire laboratory, and proceed correlation analysis.Based on the famous of the spread of the Rothermel forest fire model in the United States and Byram fire intensity formula, according to the spread of BehavePlus forest fire systems, to calculate the potential fire behavior. The potential fire behavior including surface fire and crown fire, the main fire behavior indicators contain forest fire spread rate, fire intensity and flame length.The study concluded, The surface active fuel loads of Castanopsis rargesn forest are highest,7.755t/hm2; the lowest of fuel loads is Alnus cremastogyne Burk. forest,1.904t/hm2. that the order of each forest type surface fuel load are:Castanopsis rargesn forest> Pinus massoniana Lamb forest> Evergreen broadleaf forest> Machilus pauhoi kaneh forest>Cryptomeria fortune forest> Schima superba Gardn et Champ forest> Cupressus funebris forest> Metasequoia glyptostroboides forast>Hard mixed forest>Rhododendron latoucheae Franch. Forest> Alnus cremastogyne Burk.forest. Each forest type canopy combustible average density is differently, the Pinus massoniana Lamb forest is maximum, which the crown fuels average density is0.71kg/m; the Metasequoia glyptostroboides forest sparse, with an average density of0.05kg/m3.The combustibles average density of each forest type canopy sort as follows:Pinus massoniana Lamb forest> Rhododendron latoucheae Franch. forest> Evergreen broadleaf forest>Cupressus funebris forest> Castanopsis rargesna forest> Schima superba Gardn et Champ forest> Cryptomeria fortune forest> Hard mixed forest> Alnus cremastogyne Burk.forest> Machilus pauhoi kaneh forest> Metasequoia glyptostroboides forest. View from combustible material distribution, natural forests generally larger than the plantation, mixed forest is generally greater than Chunlin.Surface fire spread rate in addition to the close contact with the surface fuel load, was positively correlated with the wind speed. In different conditions of forest fire spread rate, fire intensity and flame length is closely related. The surface fire behavior indicators of each forest sort as follows:Castanopsis rargesn fores t> Pinus massoniana Lamb forest> Evergreen broadleaf forest> Machilus pauhoi kaneh forest>Cryptomeria fortune forest> Schima superhu Gardn et Champ forest> Cupressus funehris forest>Melasequoia glyplostroboides foresl>Hard mixed forest>Rhododendron latoucheae Franch. Forest> Alnus cremastogyne Burk.forest.The crown fire spread rate in horizontal direction are increases exponentially with the wind speed, the average density and moisture content of the canopy combustibles, woodland slope are important factors to influence crown fire intensity and flame length. The fire behavior indicators of each forest canopy sort is as follows:Pinus massoniana Lamb forest> Rhododendron latoucheae Franch. Forest> Rhododendron latoucheue Franch. Forest> Caslanopsls rargesn forest> Hard mixed forest> Cryptomeria fortune forest> Evergreen broadleaf forest> Machilus pauhoi kuneh forest> Schima superha Gardn et Champ forest> Metasequoia glyptostroboides forest> Alnus cremastogyne Burk.forest. According to the fire behavior indicators cluster analysis, Based on the combustible fire behavior indicators, the different forest types can be divided into three categories, Pinus massoniana Lamb forest have higher fire danger index, as first class; Rhododendron laloucheae Franch. Forest, Rhododendron latoucheae Franch. Forest, Castanopsis rargesn forest and Evergreen broadleaf forest,those4types of Forests fire behavior indicators medium, as second class; and the remaining six forest types as third class.Under normal circumstances, the fire behavior indicators of natural forest is greater than the plantations. The fire behavior indicators of coniferous forest is larger than the broad-leaved forest, the fire behavior indicators of pure forest is greater than mixed forest, deciduous broadleaf forest is greater than evergreen broadleafforest. By comparing the potential surface fire and crown fire behavior indicators of each forest types, to make the evaluation of the harm may caused by forest fire behavior, and then proposed the decision-making of the forest fire prevention.