Study On The Prediction Model Of Surface Dead Fuel Moisture Content Of Typical Forest Stands In Maoershan

Forest fire is one of the more serious natural disasters facing the world,and it is also an important factor that disturbs the global ecosystem.As the global warming will lead to more frequent occurrences of forest fires,the prevention and strict control of forest fires has become the focus of human attention.It is of great significance to improve fire risk prediction,reduce the possibility and potential hazards of fire,and thus reduce the loss caused by fire.Therefore,it is particularly important to strengthen forest fire management and improve forest fire forecasting fuels.Forest fire is one of the important factors affecting the forest ecosystem.The spread and development of forest fires are deeply affected by the moisture content of forest fules,especially the occurrence of forest fires is directly affected by the moisture content of dead fules on the ground.Therefore,accurately predicting the moisture content of the dead fules on the forest surface is the key to predicting forest fire risk and fire behavior,and it is the key to strengthen the research on the moisture content prediction models of the dead fules.Therefore,this paper takes Maoershan in Heilongjiang Province as the research area and selects typical representative tree species(Pinus koraiensis、Pinus sylvestris var、Larix gmelinii、Betula platyphylla)of the northern forest ecosystem.Through indoor fuel moisture content simulation experiments and long-term field observation experiments,based on the dynamic changes of fule moisture content,the forest surface dead fules are constructed.Moisture prediction model,and use different site conditions as variables to explore the applicability of the same forest stand in artificial forests and natural forest models.The main conclusions are as follows:(1)Under the same temperature and humidity conditions,as time changes,the moisture content of fules gradually reaches the equilibrium moisture content.During this water loss process,the water loss rate of Pinus sylvestris is significantly faster than that of Pinus koraiensis,Larix gmelinii,and faster than Betula platyphylla;and when When the relative humidity is constant,the equilibrium moisture content is negatively correlated with the air temperature.When the temperature is constant,the equilibrium moisture content is positively correlated with the relative humidity.This study found that the temperature is 10℃ and the relative humidity is 45%.All types of fules have the lowest equilibrium moisture content.This condition seems to be more conducive to the management of forest fules.(2)Based on the equilibrium moisture content method(Simard method,Nelson method,Van Wagner method and Anderson method),the indoor equilibrium moisture content model is constructed.The results show that the fitting effect of Van Wagner method and Anderson method is better than Simard method and Nelson method;In the Simard method,when the relative humidity is higher than 50%,the fitting accuracy is higher,when the relative humidity is lower than 50%,the fitting accuracy is lower;choose any model form to fit the equation,the fitting effect of Larix gmelinii The best,the worst of Betula platyphylla.(3)The prediction model of surface dead combustible moisture content of artificial forest was constructed based on the field estimation method.The results showed that the effect of Simard prediction model was better,followed by Nelson,and the prediction accuracy of meteorological element regression model was low.And whether in the Simard prediction model or the Nelson prediction model,the prediction accuracy of the four types of fuel moisture content from high to low are Betula platyphylla>Pinus sylvestris>Larix gmelinii>Pinus koraiensis.(4)Based on the analysis of the dynamic changes of the moisture content of fules under natural forest site conditions,it is concluded that the dynamic changes of the moisture content are similar to the plantation forests.The dynamic changes of the moisture content are affected by many aspects,and have a significant positive correlation with temperature,a significant negative correlation with relative humidity,and a significant relationship with rainfall.Positive correlation.Since the regression model of meteorological elements based on plantation forests is inferior,no comparison is made in natural forest stands.Only comparing the Simard model and the Nelson model,the results show that the Simard model is always slightly better than Nelson.And under the two models,the model fitting effect is Betula platyphylla>Pinus koraiensis>Pinus sylvestris>Larix gmelinii,which is different from the plantation.But it also shows that the equilibrium moisture content model is more applicable to birch forests.(5)Comparing the prediction models of fule moisture content between plantation forest and natural forest.The conclusion is:whether it is the Nelson model or the Simard model,the fitting effect of the artificial forest is better than that of the natural forest.Under plantation site conditions,Pinus koraiensis had the worst fitting effect,and Larix gmelinii had the worst fitting effect in natural forests.In addition,Betula platyphylla had the highest prediction accuracy for both plantations and natural forests.