University of California Irvine, Department of Civil and Environmental Engineering, Irvine, CA, United States.
University of California Irvine, Department of Civil and Environmental Engineering, Irvine, CA, United States.
Sci Total Environ. 2022 Aug 25;836:155723. doi: 10.1016/j.scitotenv.2022.155723. Epub 2022 May 11.
Prescribed (Rx) burns are conducted on days when the meteorological thresholds of maximum air temperature, relative humidity, and wind speeds are all met (burn window) in order to ensure safe Rx burn practices. Limited burn windows have been consistently identified as one of the most important constraints for conducting Rx burns in California. We investigate whether burn windows across California can be extended from the typical fall season to include other opportune seasons for facilitating specific management objectives. We quantify the seasonal Rx burn efficiencies by assessing the frequency and burned areas using an aggregate of Rx datasets, and we compute the seasonal spatiotemporal trends in the number of days the set of meteorological parameters are met over thirty-five years (1984 to 2019), using the gridMET 4 km dataset. Our results indicate that while fall burns are most frequently executed (40% of the time), the spring (and to a lesser extent winter) seasons yield efficient Rx burns similar to fall because greater acres are being consumed with less burns. In addition, winter and spring seasons experience burn window opportunities (70-90% of the time) over larger areas than the other seasons, and this is predominantly over forested regions in Northern California. Our results also indicate that burn windows in the winter and spring are decreasing at a rate of one day per year over a larger spatial area than that of summer and fall. This decrease is primarily driven by changes in the number of days the relative humidity thresholds are met. Policymakers recognize the critical importance that Rx burns have on a multitude of ecosystem restoration factors, fire behavior dynamics, and firefighter safety. Therefore, there is a need to capitalize on these additional burn windows before these opportunities become less feasible in the future.
处方（Rx）燃烧是在气象学上的最高气温、相对湿度和风速的阈值都得到满足的日子进行的（燃烧窗口），以确保安全的 Rx 燃烧实践。有限的燃烧窗口一直被认为是在加利福尼亚进行 Rx 燃烧的最重要限制之一。我们研究是否可以将加利福尼亚的燃烧窗口从典型的秋季延长到包括其他有利于实现特定管理目标的季节。我们通过使用 Rx 数据集的综合评估来评估频率和燃烧面积，从而量化季节性 Rx 燃烧效率，并通过使用 gridMET 4km 数据集计算三十五年（1984 年至 2019 年）中满足一组气象参数的天数的季节性时空趋势。我们的研究结果表明，尽管秋季燃烧最频繁（占 40%的时间），但春季（冬季次之）的 Rx 燃烧效率较高，与秋季相似，因为燃烧的面积较小，消耗的面积较大。此外，冬季和春季的燃烧窗口机会（70-90%的时间）比其他季节覆盖的区域更大，主要是在加利福尼亚北部的森林地区。我们的研究结果还表明，冬季和春季的燃烧窗口每年以一天的速度在比夏季和秋季更大的空间区域内减少。这种减少主要是由于满足相对湿度阈值的天数发生变化所致。政策制定者认识到 Rx 燃烧对生态系统恢复因素、火灾行为动态和消防员安全的至关重要性。因此，需要在未来这些机会变得不太可行之前，利用这些额外的燃烧窗口。
