Objective This paper aims to study the surface fuel load and influencing factors of Pinus yunnanensis forest in Xichang City, Sichuan Province of southwestern China to provide a basis for the scientific fuel management and reduce forest fire risk level.

Method P. yunnanensis forest in Xichang City was taken as the research object. A typical and representative P. yunnanensis forest was selected to set up 16 standard plots with the size of 20 m × 30 m, and the surface load of different type fuels (herbs, shrubs, surface withered leaves, 1 h time-lag dead twigs, 10 h time-lag dead twigs, 100 h time-lag dead twigs) were investigated in the sample plots. RDA redundancy analysis and multivariable linear regression analysis were used to determine the relationship between fuel load and stand factors (DBH, tree height, average undershoot height, canopy density) and topographic factors (altitude, slope, slope aspect, slope position), and to determine the key influencing factors of surface fuel load.

Result (1) The total surface fuel load of P. yunnanensis forest was 7.82−33.53 t/ha, with an average of 22.25 t/ha. The average combustible load was 10.68 t/ha, accounting for 48.00% of the total surface fuel load. (2) RDA analysis showed that total fuel load was positively correlated with canopy density (P < 0.01), and negatively correlated with altitude (P < 0.05). The total and flammable fuel load of P. yunnanensis on shady slope was higher than that on sunny slope (P < 0.01). (3) Multivariate linear regression analysis showed that slope aspect was the main factor affecting the total combustible and combustible load of P. yunnanensis.

Conclusion The fuel load of P. yunnanensis forest was affected by both the topographic factors, mainly including slope aspect, and altitude and the stand factors mainly including canopy density. In the aerial seeding forest area of P. yunnanensis in Xichang City, the total surface fuel load is high, and the proportion of combustible fuel is large, so there is a large fire hazard.