Study On Classification And Load Estimation Of Forest Fuel In Liannan County,Guangdong Province

Forest fuel is the material base of combustion.Scientific classification of forest fuel types can not only provide basic data for forest fire prevention and fire fighting,but also provide decision support for attacking fire.The study on the dynamic characteristics of moisture content of forest fuel and its response process to forest environment has certain practical significance for improving the accuracy of forest fire prediction.At present,there are many methods to determine the moisture content of forest fuel at home and abroad,such as meteorological element regression method,equilibrium moisture content method,remote sensing estimation method,empirical model method and process model method and so on.According to different sources or view of research,there are two kinds of fuel moisture content prediction models in summary:empirical model and process model.The species and moisture content of combustibles are closely related to the behavior of forest fire,and the moisture content affects the ignition of combustibles and the spread of forest fire.The load of forest fuel affects the fire intensity.This study can provide a basic method for fire behavior prediction by mathematical model for prediction of fuel load.Findings are showed as follows:(1)Using key variables including the thickness and load of the humus layer,the 1-hour lagged flammable material load,and the height of shrubs,a clustering analysis was conducted on significantly different flammable material parameters using the systematic clustering method.As a result,the forest types in Lian Nan County were divided into three main categories and five subcategories:coniferous forest(with two subcategories,namely,Chinese fir forest and Pinus massoniana forest),conifer-broadleaf mixed forest(with two subcategories,namely,Chinese fir-broadleaf mixed forest and Pinus massoniana-broadleaf mixed forest),and shrub forest.(2)There were significant differences(P<0.05)in the moisture content of dead flammable materials in Pinus massoniana forests and live flammable materials in Chinese fir forests between the shady and sunny slopes,but no significant differences(P>0.05)in the moisture content of forest flammable materials between the slopes for the other forest types.There was no significant relationship(P>0.05)between the moisture content of live flammable materials and meteorological factors,but the moisture content of dead flammable materials showed strong correlations with humidity,temperature,wind speed,and rainfall,which are all meteorological factors.(3)Four meteorological factors,namely humidity,temperature,wind speed,and rainfall,were used as independent variables to construct models to estimate the moisture content of flammable materials on the shady and sunny slopes in Chinese fir forests,Pinus massoniana forests,and Chinese fir-Pinus massoniana mixed forests.The coefficient of determination of the estimation models ranged from 0.10 to 0.65,with most models having high accuracy and being able to accurately estimate the moisture content of flammable materials.(4)Single-factor and multiple-factor estimation models were constructed for flammable material load in Chinese fir forests and Pinus massoniana forests using four variables,including mean diameter at breast height,mean height,mean age,and crown density,either individually or in combination.The coefficient of determination for the flammable material load estimation model in Chinese fir forests ranged from 0.14 to 0.70,while the coefficient of determination for the flammable material load estimation model in Pinus massoniana forests ranged from 0.10 to 0.88.These results indicate that it is possible to accurately estimate the flammable material load in Chinese fir forests and Pinus massoniana forests based on forest mensuration variables in reality.