Surface Fuel Loading And Fire Danger Classification Of Main Forest Types In Laoshan Forest Farm Of Nanjing

In this study,11 typical stand types in Laoshan Forest Area of Nanjing were selected as the research object(including Pinus massoniana forest,Pinus taeda forest,Cunninghamia lanceolata forest,Quercus acutissima Carruth forest,Celtis sinensis forest,Quercus fabri forest,Liquidambar formosana forest,Picrasma quassioides forest,Meliosma beaniana forest,Platycladus orientalis forest,and Styrax dasyanthus forest).It investigated the stand factor and locality factor,measured the surface flammable load,including surface litter,shrubs and herbs in each sample,and collected samples.Measurement of physicochemical properties(including moisture content,ignition point,calorific value,ash content,extractives,and crude fiber)of various forest-type combustibles,and burning and propagation velocity of surface fuel were performed in the laboratory and correlation analysis was performed.The flammability of each stand type fuel was ranked and the fire danger classes were divided.The results of the research show that:The flammable load of each forest type is ranked as follows:Quercus fabri forest>Quercus acutissima forest>Celtis sinensis forest>Cunninghamia lanceolata forest>Picrasma quassioides forest>Meliosma beaniana forest>Pinus massoniana forest>Pinus taeda forest>Platycladus orientalis forest>Liquidambar formosana forest>Styrax dasyanthus forest;the highest effective fuel load of the forest surface is Quercus fabri forest,which is 10.306t/hm2.The Styrax dasyanthus forest with the effective load of the forest surface is the lowest.From the distribution of surface flammable materials,hackberry The surface flammables load of natural secondary forests such as Celtis sinensis forest and Quercus acutissima forest is generally higher than Pinus massoniana forest and Cunninghamia lanceolata forest etc.The surface fuel load of mixed forests is generally higher than that of pure forests;Through the weighted valuation analysis of the six physicochemical properties measured on the surface fuel of each stand type,the flammability ranking was:Pinus taeda>Pinus massoniana>Platycladus orientalis>Cunninghamia lanceolata>Quercus acutissima Carruth>Liquidambar formosana>Picrasma quassioides>Quercus fabri>Styrax dasyanthus>Celtis sinensis>Meliosma beaniana;The forest types are divided into three grades according to the flammability,that is,the flammable forest types are:Pinus taeda,Pinus massoniana,Platycladus orientalis,Cunninghamia lanceolata;Lateral Berlin and Chinese fir forest;The flammable forest types areQuercus acutissima Carruthy Liquidambar formosana,Picrasma quassioides,Quercus fabri;the non-combustible types are Styrax dasyanthus,Celtis sinensis,Meliosma beaniana;and physical and chemical properties of various combustibles are passed through SPSS 24.0.After correlation analysis of chemical properties,the ash content was negatively correlated with the calorific value,and the extraction was positively correlated with the calorific value;the indexes of caloric value,extractive content and cellulose content of the coniferous trees were higher than those of the broadleaf trees.Species,ash content is significantly lower than that of broad-leaved species;Through fuzzy clustering analysis methods,11 typical stand types in the forest area were used as clustering units to select effective surface fuel load capacity,Physical and chemical properties of combustibles(including moisture content,calorific value,ignition point)and combustible combustion spread rate.According to the clustering factor,the different fire danger grades in the forest area are classified into three grade I fire danger grade forest types:Quercus acutissima Carruth,Quercus fabri,andPinus massoniana;four grade II fire risk forest types,namely,Pinus taeda,Meliosma beaniana,Platycladus orientalis,Cunninghamia lanceolata;Grade III fire risk forest type 4,which are Celtis sinensis,Liquidambar formosana,Picrasma quassioides,and Styrax dasyanthus...