Study On Surface Fuel Loading And Influencing Factors Of Different Forest Types In Beijing Area

In this paper,the forest types of Pinus tabulaeformis,Platycladus orientalis,Quercus variabilis,Robinia pseudoacacia in ten districts and counties with abundant forest resources in Beijing were taken as the main research objects,and 85 sample plots were set up according to different site and stand factors(elevation,slope,DBH,tree height,crown width,first living branch height,first dead branch height,crown density).The forest stand,site factors and fuel loading of the sample plots were investigated.The correlation analysis of surface fuel loading with stand and site factors of different forest types was carried out.The multiple linear regression model of surface fuel loading and fine fuel loading(Fuels with stem-level or leaf thickness less than 0.6 cm in dead leaves,withered grass and 1 hour delay)was established by means of multiple stepwise regression analysis.The main results of this study were as follows:(1)The total surface fuel loading of Pinus tabulaeformis,Platycladus orientalis,Robinia pseudoacacia and Cortex variabilis forests were 16.358 t/ha,11.050 t/ha,11.835 t/ha and 11.297 t/ha,respectively.The total and fine fuel loading of Pinus tabulaeformis forest were the highest.The fuel loading of litter in the lower layer(The upper litter is mainly undecomposed withered leaves,the color is relatively light,the lower litter is decomposed or semi-decomposed,and the color is darker.)was the highest in all forest types.The fuel loading of shrub layer and litter in the upper layer accounted for a large proportion.The fuel loading of litter in 1 h and 10 h timelag branches was higher than that of herbaceous fuel.The fuel loading with 100 h timelag branches is the smallest.(2)Average DBH,average tree height,altitude,slope and crown density were the main factors affecting the fuel loading of four forest types.There was a significant negative correlation between crown density and herbaceous layer,and a positive correlation between the upper layer litter and crown density,There was a positive correlation between the lower layer fuels and total fuel loading with slope in herbaceous layer.The 1h timelag dead branches in different forest types showed a significant positive correlation with DBH.10h timelag dead branches were mainly positively correlated with elevation factors.(3)Multivariate linear regression models of total and fine fuel loading on the surface of different forest types were established by means of multiple stepwise regression analysis.In the models for estimating the fuel loading of different forest types,P-value was less than 0.01,R2 and R2 adjusted values were greater than 0.65,and the regression equation of fuel loading and research data had higher goodness of fit,and the response degree between independent variable and dependent variable is obvious.By studying the surface fuel loading of the different forest types in Beijing and combining with the influencing factors,the fuel loading estimation equation was established,which provided a reference for the fire prevention practice in Beijing.