The slow-moving flameless burning of wildland fuels (i.e. smouldering) can be difficult to detect and challenging to extinguish. Although previous research involving the smouldering of organic fuels (e.g. cotton, cellulose, peat) has investigated the influence of various fuel characteristics (e.g. moisture content, inorganic content, bulk density) on spread rate and surface temperatures, the smouldering behaviour of other common fuels is not well understood. This study expands on previous research to better understand how fuel characteristics influence the smouldering behaviour of duff from coniferous forests. Specifically, horizontal spread rates (0.5–19.5 cm h−1) and ground surface temperatures (258–392°C) were measured on 52 duff samples collected from underneath mature ponderosa pine trees (Pinus ponderosa) from sites in the Pacific Northwest, USA, and evaluated in terms of their moisture content (6–113%), inorganic content (3–42%), bulk density (34–130 kg m−3) and fuel depth (3.8–16.3 cm). The data suggested that horizontal spread rates decrease when inorganic content, inorganic loading and/or moisture loading of the duff increases. Surface temperatures decrease when inorganic bulk density and/or fuel loading increases. Conversely, surface temperatures decrease when moisture content increases for shallow duff. Higher fuel loading increases the likelihood of smouldering below the surface.

中文翻译：

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燃料特性对阴燃烟尘水平扩散率和地表温度的影响

野地燃料缓慢移动的无焰燃烧（即阴燃）很难被发现，也很难扑灭。尽管先前涉及有机燃料（例如棉花、纤维素、泥炭）阴燃的研究已经调查了各种燃料特性（例如水分含量、无机含量、堆积密度）对扩散率和表面温度的影响，但其他常见燃料的阴燃行为不是很好理解。本研究扩展了先前的研究，以更好地了解燃料特性如何影响针叶林中的达夫的阴燃行为。具体而言，对从太平洋西北部地区成熟的黄松树（Pinusponderosa）下收集的 52 个 duff 样品测量了水平扩散率（0.5-19.5 cm h-1）和地表温度（258-392°C），美国，并根据其水分含量 (6–113%)、无机含量 (3–42%)、堆积密度 (34–130 kg m-3) 和燃料深度 (3.8–16.3 cm) 进行评估。数据表明，当毛坯的无机含量、无机负载和/或水分负载增加时，水平铺展率会降低。当无机堆积密度和/或燃料负载增加时，表面温度降低。相反，当浅层的含水量增加时，表面温度会降低。较高的燃料负荷会增加在地表以下阴燃的可能性。当无机堆积密度和/或燃料负载增加时，表面温度降低。相反，当浅层的含水量增加时，表面温度会降低。较高的燃料负荷会增加在地表以下阴燃的可能性。当无机堆积密度和/或燃料负载增加时，表面温度降低。相反，当浅层的含水量增加时，表面温度会降低。较高的燃料负荷会增加在地表以下阴燃的可能性。