U.S. Geological Survey, Western Ecological Research Center, Dixon Field Station, 800 Business Park Drive, Suite D, Dixon, CA, 95620, USA.
U.S. Geological Survey, Western Ecological Research Center, Dixon Field Station, 800 Business Park Drive, Suite D, Dixon, CA, 95620, USA.
J Environ Manage. 2023 Sep 1;341:117903. doi: 10.1016/j.jenvman.2023.117903. Epub 2023 May 3.
Escalated wildfire activity within the western U.S. has widespread societal impacts and long-term consequences for the imperiled sagebrush (Artemisia spp.) biome. Shifts from historical fire regimes and the interplay between frequent disturbance and invasive annual grasses may initiate permanent state transitions as wildfire frequency outpaces sagebrush communities' innate capacity to recover. Therefore, wildfire management is at the core of conservation plans for sagebrush ecosystems, especially critical habitat for species of conservation concern such as the greater sage-grouse (Centrocercus urophasianus; hereafter sage-grouse). Fuel breaks help facilitate wildfire suppression by modifying behavior through fuels modification and allowing safe access points for containment by firefighters. The Bureau of Land Management has proposed to roughly double the existing fuel break network in the western U.S., centered on the Great Basin. To our knowledge, no broad-scale examination of fuel break effectiveness or the environmental conditions under which fuel breaks are expected to be most effective has been conducted. We performed a retrospective assessment of probability of fuel break contributing to wildfire containment on recorded wildfire and fuel break interactions from 1985 to 2018 within the western U.S. We characterized environmental, fuels, and weather conditions within 500 m of wildfire contact, and within 5 km of the approaching wildfire. We used a binomial mixed model within a Bayesian framework to identify relationships between these variables and fuel break success. Fuel breaks were least successful in areas classified as having low resilience to disturbance and low resistance to invasion, in areas composed of primarily woody fuels, and when operating in high temperature and low precipitation conditions. Fuel breaks were most effective in areas where fine fuels dominated and in areas that were readily accessible. Maintenance history and fuel break type also contributed to the probability of containment. Overall results indicate a complex and sometimes paradoxical relationship between landscape characteristics that promote wildfire spread and those that impact fuel break effectiveness. Finally, we developed predictive maps of fuel break effectiveness by fuel break type to further elucidate these complex relationships and to inform urgently needed fuel break placement and maintenance priorities across the sagebrush biome.
美国西部野火活动的加剧对受威胁的薊草原（Artemisia spp.）生物群落产生了广泛的社会影响和长期后果。历史火灾模式的转变以及频繁干扰和入侵一年生草本植物之间的相互作用，可能会导致永久性的状态转变，因为野火的频率超过了薊草原群落的固有恢复能力。因此，野火管理是薊草原生态系统保护计划的核心，特别是对大角羊（Centrocercus urophasianus；以下简称大角羊）等受关注物种的关键栖息地至关重要。燃料隔离带通过燃料改性改变行为，并为消防队员提供安全的进入点来控制火势，有助于促进野火的抑制。美国土地管理局提议在美国西部，主要是在大盆地，将现有的燃料隔离带网络扩大一倍。据我们所知，尚未对燃料隔离带的有效性或预期燃料隔离带最有效的环境条件进行广泛的检查。我们对 1985 年至 2018 年美国西部记录的野火和燃料隔离带相互作用进行了回溯评估，评估了燃料隔离带对野火控制的贡献概率。我们描述了 500 米内野火接触点和即将到来的野火 5 公里范围内的环境、燃料和天气条件。我们在贝叶斯框架内使用二项混合模型来确定这些变量与燃料隔离带成功之间的关系。在被认为对干扰的抵抗力低和对入侵的抵抗力低的区域、主要由木质燃料组成的区域以及在高温和低降水条件下运行的区域，燃料隔离带的效果最差。在细燃料占主导地位的区域和易于到达的区域，燃料隔离带的效果最好。维护历史和燃料隔离带类型也有助于提高隔离的概率。总体结果表明，促进野火蔓延的景观特征与影响燃料隔离带有效性的特征之间存在复杂且有时矛盾的关系。最后，我们根据燃料隔离带类型开发了燃料隔离带有效性的预测图，以进一步阐明这些复杂关系，并为整个薊草原生物群落提供急需的燃料隔离带位置和维护优先级。
