Analysis of fire suppression and increasing environmental variability on wildfire intensity

野火正在以几代人未曾见过的规模和强度燃烧，对流域、生态系统和人类社区产生潜在的破坏性影响。调查人员计划分析400年的树木年轮火灾记录和1000年的热敏考古文物，以确定今天的火灾是否比历史上燃烧得更热。经过一个多世纪的灭火，森林里到处都是灌木丛、死燃料和过于密集的树木。温暖的气温和严重的干旱使这些森林易燃易爆。由于这些混杂因素，很难理清环境变化和灭火对野火的相对贡献。将最近在凉爽天气条件下发生的火灾与仅使用灭火前燃料燃烧的火灾进行比较，将使这些科学家能够将环境变化的影响与灭火的影响区分开来。该项目培训美洲原住民学生，使土地管理者能够更好地将资源分配到减轻野火的活动中。由于一个世纪以来的灭火工作，许多森林以落叶、枯枝和倒下的树木以及幼树和灌木的密度不断增加的形式积累了燃料。更高的温度和普遍的干旱使这些积累的燃料更容易燃烧，并导致极端的火灾行为，包括火灾龙卷风。越来越大的“特大火灾”已经影响了供水、生态系统，并摧毁了成千上万的房屋。在这些情况下，很难分析环境变化和灭火的相对贡献，因为它们同时起作用。然而，了解每一种资源的相对重要性将有助于土地管理者和政策制定者分配资源来缓解这种情况。在这个项目中，研究人员使用了一种创新的方法，将热敏考古代用品与人工制品年代测定、木炭分析和树木年轮科学相结合，以确定一个世纪以来的灭火积累的燃料是否足以推动过去500- 1000年来前所未有的火灾强度的增加。他们调查了在灭火前经常燃烧的地点，以建立历史条件的基线（灭火前的地点）和在一个世纪的灭火后在寒冷季节条件下燃烧的地点（灭火后的地点）。通过将灭火和燃料对火灾事件温度和持续时间的影响隔离开来，将重点放在冷季灭火后的火灾上，可以减少环境变化的影响。这项研究的结果有助于土地利用和火灾规划，使政策制定者能够更好地权衡集约化森林间伐和规定焚烧的机会成本。缓解环境和保护家园。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Wildfires are burning at scales and intensities not seen in generations with potentially devastating impacts on watersheds, ecosystems, and human communities. Investigators plan to analyze 400 years of tree-ring fire records and 1,000 years of heat sensitive archeological artifacts to determine if fires today are burning hotter than they have historically. After more than a century of fire suppression, forests are full of undergrowth, dead fuel, and overly dense stands of trees. Warmer temperatures and severe drought make these forests explosively combustible. It is difficult to disentangle the relative contributions of environmental change and of fire suppression to wildfires because of these confounding factors. Comparing recent fires under cool weather conditions versus those that only burned in pre-fire suppression fuels will enable these scientists to separate the influences of environmental change from those of fire suppression. This project trains Native American students and enables land managers to better allocate resources to activities that mitigate wildfires.As a result of a century of fire suppression, many forests have accumulated fuels in the form of leaf litter, dead and down branches and trees, and an increasing density of young trees and shrubs. Hotter temperatures and pervasive droughts make these accumulated fuels more combustible and are driving extreme fire behavior including fire tornados. Increasingly large "megafires" have impacted water supplies, ecosystems, and destroyed thousands of homes. It is difficult to parse the relative contributions of environmental change and fire suppression in these contexts because they are operating simultaneously. However, knowing the relative importance of each would aid land managers and policy makers to allocate resources to mitigate the situation. In this project researchers use an innovative integration of heat sensitive archaeological proxies in artifact dating and charcoal analysis, and tree-ring science to determine if fuels accumulated from a century of fire suppression alone are enough to drive increases in fire intensity that are unprecedented in last 500-1,000 years. They investigate sites that burned frequently prior to fire suppression to establish a baseline for historical conditions (pre-suppression sites) and sites that burned in cool-season conditions after a century of fire suppression (post-suppression sites). By focusing on cool-season post-suppression fires, the impact of environmental change can be reduced by isolating the impacts of fire suppression and fuels on the temperature and duration of fire events. The results of this study contribute to land-use and fire planning by allowing policymakers to better weigh the opportunity costs of intensive forest thinning and prescribed burning versus. environmental mitigation and home protection.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.