Abstract: Forest surface fuel is an important causing factor for forest fire. Understanding the impact factors of forest surface fuel load can provide scientific basis for forest combustible management. In this study, we conducted correlation analysis and stepwise regression analysis between surface fuel load and topographical, forest stand and ground cover factors ofPinus tabuliformis forest in Beijing Songshan National Nature Reserve. The contribution of those three types of factors to the changes of fuel load was calculated. Results showed that: (1) The total amount of surface fuel load had a significant relationship with the herb coverage. The live surface fuel load was significantly positively correlated with altitude and shrub coverage, but negatively correlated with herb coverage. The dead surface fuel load was significantly positively correlated with canopy density, stand density, and average tree height, but negatively correlated with altitude. (2) Results of multivariable linear regression analysis showed that altitude, canopy coverage, and shrub coverage were the most significant factors affecting the live surface fuel load. The dead surface fuel load was most closely related to altitude and canopy density. (3) Among the explanatory factors of live surface fuel load, the contribution rate was in order of ground cover factor>stand factor> topographical factor, with the interaction of ground cover factor and topographical factor being the most significant, followed by interaction of ground cover factor and stand factors. For the dead surface fuel load, the contribution rate was in order of stand factor> topographical factor> ground cover factor, with the interaction of stand factor and topographical factor being significant, followed by the interaction of stand factor and ground cover factor. Affecting factors depended on the types of surface fuel. Therefore, it is necessary to differentiate affecting factors in surface fuel management, forest fire prevention, and stand regulation.

Key words: heavy metal pollution in farmland, Cd, Amaranthus hypochondriacus., maize, intercropping remediation