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。气候和人类影响的微妙变化引发了火灾制度的变化，对生态系统有潜在的重大影响。目前气候变化的速度和幅度有可能危及生态恢复能力，使受到干扰的生态系统无法恢复。考虑到气候变化的潜在后果，了解火灾制度及其驱动因素对于适应气候变化至关重要。在世界范围内，剧烈和快速移动的特大火灾已经燃烧了严重的社会，经济和生态影响。2017年不列颠哥伦比亚省破纪录的野火烧毁了120万公顷土地，其中大部分是山地森林。这些快速移动、强烈的火灾具有高度严重的影响，即使在山地森林中，也有强有力的证据表明过去存在低严重的地表火灾制度。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出了历史极限？森林抵御火灾的能力是否受到损害？我们如何调整管理以提高森林恢复力？我的研究表明，山地森林的火灾制度与北方森林的火灾制度有很大的不同。混合严重程度的火灾制度包括频繁的地表火灾和周期性的树冠火灾，以及不列颠哥伦比亚省和阿尔伯塔省山麓地区历史上主要的山地森林。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旱的森林。我们将使用多行树木年轮证据来比较这些研究区域的火灾历史。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土著知识结合起来，全面了解文化之火及其生态影响。第三阶段解决了从森林林分和景观中消除地表火灾的后果。结合实地调查和航空照片分析以及火灾行为模型，我们将量化已经积累的燃料的数量以及森林作为高强度林冠火灾燃烧的可能性。这项研究的最后阶段评估了气候变化如何加剧了这些问题。3名博士，3名硕士和c.14名本科生将全面参与本研究。最终，我们将获得关于历史火灾制度驱动因素的新知识，它们的变化程度，以及对森林恢复力的影响。我们的工作将有助于确定缓减燃料和恢复生态的优先领域。它还提供了一个急需的基线，以确保适应性管理有效地提高森林对气候变化的抵御能力。

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.