Dead fuel moisture influences the risk of fire ignition events, with implications for fire hazards, risk mitigation, and the design of prescribed burning activities. Because direct fuel moisture measurements are rarely available, fuel moisture must be estimated when evaluating fire risks. Most estimates rely primarily on atmospheric conditions and ignore the interaction of fuels with the soil surface with which they are in hydraulic contact. In this study we explore whether dead fuel moisture predictions can be improved with information about surface soil moisture. Despite the likelihood that dead fuels would exchange water with underlying soil, the influence of soil moisture on fuel moisture has been poorly studied. An analysis of 202 observations of co-located soil moisture, 1 and 10 h fuel moisture measurements, with environmental and meteorological covariates, showed that soil moisture had a small but significant effect on fuel moisture across all sampled conditions. The influence of soil moisture on fuel moisture was the most important among all other environmental factors for wet soil conditions and 10-h fuels, where a 1% increase in soil moisture content led to approximately a 0.6% increase in fuel moisture. The effect of soil moisture on 1-h fuel moisture although significant was small. Incorporating spatio-temporal variability of soil moisture into time-series or spatial predictions of fuel moisture tended to (i) reduce the seasonal duration in which fuels had a high probability of ignition by an average of 52–60 days across the tested years, and (ii) increased the heterogeneity of the probability of ignition through space, compared with similar models that did not incorporate soil moisture information.

死燃料水分影响着火事件的风险，对火灾危险、风险缓解和规定的燃烧活动的设计产生影响。由于很少能直接测量燃料水分，因此在评估火灾风险时必须估计燃料水分。大多数估计主要依赖于大气条件，而忽略了燃料与其液压接触的土壤表面的相互作用。在这项研究中，我们探讨了是否可以利用有关表层土壤水分的信息来改进对死燃料水分的预测。尽管死燃料可能会与下面的土壤交换水分，但土壤水分对燃料水分的影响研究甚少。对 202 次同地土壤水分观测、1 小时和 10 小时燃料水分测量的分析，与环境和气象协变量的研究表明，在所有采样条件下，土壤水分对燃料水分的影响很小但很显着。在潮湿土壤条件和 10 小时燃料的所有其他环境因素中，土壤水分对燃料水分的影响是最重要的，其中土壤水分含量增加 1% 导致燃料水分增加约 0.6%。土壤水分对 1 小时燃料水分的影响虽然显着，但影响很小。将土壤水分的时空变异性纳入燃料水分的时间序列或空间预测倾向于 (i) 将燃料具有高点燃概率的季节性持续时间在整个测试年份平均减少 52-60 天，以及(ii) 增加了通过空间点燃的可能性的异质性，