Abstract:

Based on 135 actual data by the investigation of 45 plots and 225 sample plots in Qinling to the maximum crown density (D) of easily burning layers, to the amount of the surface burning material(W) and to the absolute water-content ratio (μ) in the surface burning material, and by means of dissimilarity analysis method, 45 plots we have investigated can be obviously divided into 6 groups. According to differences among these groups, forest potential fire behavior in Qinling mountains crown fires can be divided into strong crown fire type, weak crown fire type and no crown fire type based on the maximum crow density of easily burning layers, separated by indices D 0.11 kg/m³ and 0.37kg/m³ respectively; the intensity of surface fire can be determined by the μ and W factors and be divided into 3 classes, the strong surface fire and the medium surface fire, separated by indices W 1.40 kg/m² and indices μ 40% respectively. According to those, all potential fire behaviors of forest in Qinling can be divided into 9 growps, the strong crown fire and strong surface fire(D>0.37 kg/m³,W≥1.40 kg/m², μ<40%), the strong crown fire and medium surface fire (D>0.37 kg/m³, W≥1.40 kg/m², μ≥40% or W<1.40 kg/m², μ<40%), the strong crown fire and weak surface fire(D>0.37 kg/m³,W<1.40 kg/m²,μ≥40%), the weak crown fire(0.11 kg/m³≤D≤0.37 kg/m³) and strong surface fire, the weak crown fire and medium surface fire, the weak crown fire and weak surface fire, no crown fire(D<0.11 kg/m³) and strong surface fire, no crown fire and medium surface, and no crown fire and weak surface fire respectively.

Key words: Qinling forest, Potential fire behavior of forest, Dissimilarity analysis, Indeces of classification