To elucidate the coupled effects of rugged terrain and forest litter on combustibility, this study examined common forest litter species—Cinnamomum camphora, Magnolia grandiflora linn, and Photinia. A small-scale combustion platform was constructed to simulate a compound terrain structure of "left-front gentle slope, right-front steep slope, left-rear concave groove, and right-rear gap." Combustion parameters, including temperature and thermal radiation, were systematically measured for single, binary, and ternary litter combinations. The Boltzmann function was introduced for quantitative fitting of temperature data, and new evaluation parameters were proposed. Results indicated that Cinnamomum camphora exhibited the strongest capacity to overcome terrain obstacles and propagate fire, with high thermal radiation and the highest burn rate (84.13%). In contrast, Photinia significantly suppressed combustion due to its high ash content; its inclusion in mixtures reduced thermal radiation across gaps by 30–50%, decreased A 2 by 47.7%, and halved the firebrand generation rate. Although the ternary mixture showed the fastest burn velocity (0.58 g/s), it achieved the lowest burn rate (56.56%) and produced short-duration, high-intensity fire peaks. This study reveals the critical regulatory role of terrain–species coupling in fire behavior and suggests that in complex terrains, Cinnamomum camphora should not be concentrated in steep slopes or gap areas. Instead, Photinia can be deployed along gap edges as natural fire-retardant units, enabling synergistic fire management based on terrain and species traits.
Zhong et al. (Fri,) studied this question.