Harris Matthew P, Coop Jonathan D, Balik Jared A, McFarland Jessika R, Parks Sean A, Stevens-Rumann Camille S
Clark School of Environment and Sustainability, Western Colorado University, Gunnison, Colorado, USA.
Aldo Leopold Wilderness Research Institute, Rocky Mountain Research Station, USDA Forest Service, Missoula, Montana, USA.
Ecol Appl. 2025 Jul;35(5):e70061. doi: 10.1002/eap.70061.
Aspen (Populus tremuloides) forests are generally thought to impede fire spread, yet the extent of this effect is not well quantified in relation to other vegetation types. We examined the influence of aspen cover on interpolated daily fire spread rates, the relative abundance of aspen at fire perimeters versus burn interiors, and whether these relationships shifted under more fire-conducive atmospheric conditions. Our study incorporated 314 fires occurring between 2001 and 2020 in the southwestern United States and a suite of gridded vegetation, topography, and fire weather predictor variables. We found that aspen slows fire progression: as aspen cover on the landscape increased, daily area burned and linear spread rate decreased. Where aspen cover was <10%, daily fire growth averaged 1112 ha/day and maximum linear spread was 2.1 km/day; where aspen exceeded 25%, these values dropped to 368 ha/day and 1.3 km/day. Aspen also serves as a barrier to fire spread, demonstrated through a higher proportion of aspen cover at fire perimeters than in burn interiors. Finally, though favorable fire weather conditions increased fire growth rates, differences between aspens and conifers persisted. Our results affirm that aspen stands can act as a firebreak, with clear applications for vegetation management. For example, interventions that shift conifer to aspen cover could lessen the risk of fire for nearby values at risk (e.g., communities, infrastructure) but still support forest ecosystem function. Further, wildfire-driven conversion from conifer to aspen forest types in some landscapes may produce a negative feedback that could dampen expected increases in fire activity under a warmer and drier climate.
人们普遍认为颤杨（Populus tremuloides）林会阻碍火势蔓延，然而相较于其他植被类型，这种影响的程度并未得到很好的量化。我们研究了颤杨覆盖度对插值每日火势蔓延速度的影响、火灾周边与火烧区域内部颤杨的相对丰度，以及这些关系在更有利于火灾发生的大气条件下是否会发生变化。我们的研究纳入了2001年至2020年间在美国西南部发生的314起火灾，以及一系列网格化的植被、地形和火灾天气预测变量。我们发现颤杨会减缓火势蔓延：随着景观中颤杨覆盖度的增加，每日烧毁面积和线性蔓延速度会降低。当颤杨覆盖度小于10%时，每日火灾增长平均为1112公顷/天，最大线性蔓延速度为2.1千米/天；当颤杨覆盖度超过25%时，这些数值降至368公顷/天和1.3千米/天。颤杨还起到了阻止火势蔓延的屏障作用，这体现在火灾周边的颤杨覆盖度比例高于火烧区域内部。最后，尽管有利的火灾天气条件提高了火灾增长率，但颤杨和针叶树之间的差异仍然存在。我们的研究结果证实，颤杨林可以起到防火带的作用，这在植被管理方面有明确的应用。例如，将针叶林转变为颤杨覆盖度更高的区域的干预措施，可以降低附近受威胁区域（如社区、基础设施）的火灾风险，但仍能支持森林生态系统功能。此外，在某些景观中，野火驱动的从针叶林到颤杨林类型的转变可能会产生负面反馈，这可能会抑制在更温暖、更干燥气候下预期的火灾活动增加。
