Forest resilience in the 21st century: Adapting to altered fire regimes and climate change

野火是影响全球森林的最重要的自然干扰因子。由气候和人类影响的微妙变化引发的火灾状况的变化可能对生态系统产生重大影响。目前气候变化的速度和规模有可能危及生态复原力，使受到干扰的生态系统无法恢复。鉴于气候变化的潜在后果，了解火灾状况及其驱动因素对于适应至关重要。 在世界范围内，强烈和快速移动的特大火灾带来了严重的社会，经济和生态影响。2017年，不列颠哥伦比亚省发生了创纪录的野火，烧毁了120万公顷土地，其中大部分是山地森林。这些快速移动，激烈的火灾有很高的严重性影响，即使在山区森林与过去的低严重性地表火灾制度的有力证据。这些极端的野火引发了三个生态问题： 火灾制度的改变是否超越了历史极限？ 森林对火灾的抵御能力是否受到损害？ 我们如何调整管理以提高森林复原力？ 我的研究表明，山地森林的火灾状况与北方森林的火灾状况有很大的不同。混合严重的火灾制度包括频繁的地表火灾和周期性的树冠火灾和历史上占主导地位的山地森林在不列颠哥伦比亚省和阿尔伯塔的山麓。迫切需要更好地了解混合严重火灾制度的动态和驱动因素，以确保这些森林的复原力。 在接下来的5年里，我和我的研究团队将完成一系列相互关联的研究项目： 第一阶段将把我们的火灾历史重建网络扩展到不列颠哥伦比亚省最干燥的森林。我们将使用多行的树木年轮证据来比较这些研究领域之间的火灾历史。我们将确定历史火灾制度的变化是否在气候区域中普遍存在，以及对森林组成和结构的影响。 第二阶段将西方科学与本土知识相结合，全面了解文化火及其生态影响。 第三阶段处理消除森林林分和地貌表面火灾的后果。 结合实地调查和航空照片分析与火灾行为建模，我们将量化已经建立的燃料数量和森林燃烧为高强度树冠火灾的概率。 这项研究的最后阶段评估了气候变化如何加剧这些问题。 三个博士，3个硕士和c.14本科生将整体参与这项研究。 最终，我们将产生关于历史火灾制度的驱动因素，它们变化的程度以及对森林恢复力的影响的新知识。我们的工作将有助于优先考虑燃料缓解和生态恢复领域。它还提供了一个急需的基线，以确保适应性管理能够有效地提高森林对气候变化的适应能力。

Wildfire is the most important natural disturbance agent affecting global forests. Changes to fire regimes, triggered by subtle changes in climate and human impacts, have potential major impacts on ecosystems. The current rate and magnitude of climate change have the potential to jeopardize ecological resilience so that disturbed ecosystems are unable to recover. Understanding fire regimes and their drivers is essential to adapt, given the potential consequences of climate change. Worldwide, intense and fast-moving megafires have burned with severe social, economic, and ecological impacts. The record-breaking wildfires of 2017 in British Columbia burned 1.2 million hectares, mostly in montane forests. These fast-moving, intense fires had high-severity effects, even in montane forests with strong evidence of past low-severity surface fire regimes. These extreme wildfires incite three ecological questions: Have fire regimes been altered beyond historical limits? Is forest resilience to fire compromised? How do we adapt management to improve forest resilience? My research shows that fire regimes in montane forests differs from those in boreal forests in meaningful ways. Mixed-severity fire regimes include frequent surface fires and periodic crown fires and historically dominated montane forests in British Columbia and the foothills of Alberta. Improved understanding of the dynamics and drivers of mixed-severity fire regimes is urgently needed to assure the resilience of these forests. Over the next 5 years my research team and I will complete a series of inter-related research projects: Phase 1 will expand our network of fire history reconstructions into the driest forests in BC. We will use multiple lines of tree-ring evidence to compare fire history among these study areas. We will determine if changes to historic fire regimes are pervasive among climatic regions and the consequences for forest composition and structure. Phase 2 combines western science with Indigenous knowledge for a comprehensive understanding of cultural fire and its ecological effects. Phase 3 addresses the consequences of eliminating surface fires from forest stands and landscapes. Combining fieldwork and air photograph analysis with fire behaviour modelling, we will quantify the amount of fuels that have built up and the probability of forests to burn as high intensity crown fires. The final phase of this research assesses how climate change exacerbates these problems. Three PhD, 3 MSc and c.14 undergraduate students will be integrally involved with this research. Ultimately, we will generate new knowledge on the drivers of historical fire regimes, the degree to which they have changed, and the consequences to forest resilience. Our work will help prioritize areas for fuels mitigation and ecological restoration. It also provides a much-needed baseline to ensure adaptive management is effective at improving forest resilience to climate change.