Collaborative Research: Integrating paleoecological analysis and ecological modeling to elucidate the responses of tundra fire regimes to climate change

最近的气候变暖导致了北极地区深刻的环境变化，包括灌木覆盖面积扩大、永久冻土融化和海冰收缩。这些变化预示着，如果变暖趋势继续下去，将会发生更剧烈的影响。预测这些影响的主要挑战包括？惊喜吗在观测记录中保持相对稳定的系统组成部分（通常在北极地区过去几十年）。苔原燃烧可能是其中一个组成部分。现有证据表明，持续的气候和植被变化可能会大大增加冻土带燃烧。例如，初步调查结果揭示了温度和湿度阈值，这些阈值可能会被越过，导致燃烧率远远超过观测记录中所看到的燃烧率。此外，灌木丰富的显着增加正在改变北极地区的地貌结构，使未来的苔原火灾制度可能会大大不同于现代。因此，冻原燃烧正在成为快速变化的北极地区的一个关键过程，了解冻原火灾状况对气候变化的响应对于预测地球系统动态、制定生态系统管理战略以及北极居民为未来变化做好准备至关重要。以及未来气候和植被变化的可能性，极大地阻碍了我们评估苔原火机制如何响应未来气候和植被变化的能力。古生态学分析和生态学模拟避开了这些限制，并提供了获取这些信息的唯一途径。这项研究利用了古生态学和建模方法的互补特性，以（1）量化北美北极苔原生态系统中历史上的气候-植被-火灾关系，（2）对湖泊沉积物进行多代理分析，以重建晚冰期和全新世时期的苔原火灾状况，并采用气候和植被的新组合，（3）重新参数化ALFRESCO，一个景观生态系统模型，最初是为了研究亚北极植被对气候和火灾状况变化的响应而开发的，用于预测21世纪IPCC气候情景下的冻原火灾状况，（4）修改艾德，一个用于冻原生态系统研究的最先进的基于生理学的模型，（5）将艾德与ALFRESCO耦合，模拟与21世纪冻土带火状况变化相关的碳动力学。这些元素中的每一个都处于各自领域正在进行的研究的最前沿，它们共同承诺大大提高我们对过去，现在和未来苔原生态系统的气候-植被-火灾相互作用的认识。科学界很少考虑苔原生态系统中火灾制度改变的后果，这主要是因为苔原火灾在现代景观中很少发生。北极地区的火灾管理人员缺乏关于苔原生态系统火灾状况的最基本知识（例如，火灾返回间隔），用于设计和实施应急级火灾和燃料管理计划。这项研究直接解决了这个问题。预测模拟的21世纪世纪火灾制度将提供信息直接相关的火灾管理规划和政策在阿拉斯加。研究人员将通过这个项目与来自联邦管理机构的科学家合作。这种伙伴关系促进了联邦和州自然资源管理人员对过去、现在和未来气候-火灾关系范围的更好理解。

Recent climate warming has resulted in profound environmental changes in the Arctic, including shrub-cover expansion, permafrost thawing, and sea-ice shrinkage. These changes foreshadow more dramatic impacts that will occur if the warming trend continues. Among the major challenges in anticipating these impacts are ?surprises? in system components that have remained relatively stable in the observational record (typically past few decades in arctic regions). Tundra burning is potentially one such component. Available evidence suggests that ongoing climate and vegetation change could significantly increase tundra burning. For example, preliminary findings reveal temperature and moisture thresholds, which may be crossed to result in burning rates that far exceed those witnessed in the observational record. In addition, a marked increase in shrub abundance is changing the physiognomic structure of arctic regions such that future tundra fire regimes may differ vastly from modern. Thus tundra burning is emerging as a key process in the rapidly changing Arctic, and knowledge of tundra fire-regime responses to climate change is essential for projecting Earth system dynamics, developing ecosystem management strategies, and preparing arctic residents for future change.The short duration of observational fire records, paucity of fire-history studies, and possibility of novel future climate and vegetation greatly hinder our ability to evaluate how tundra fire regimes may respond to future climate and vegetation change. Paleoecological analysis and ecological modeling circumvent these limitations and offer the only ways to acquire such information. This research takes advantage of the complementary properties of paleoecological and modeling approaches to (1) quantify historic climate-vegetation-fire relationships in the tundra ecosystems of the North American Arctic, (2) conduct multi-proxy analyses of lake sediments to reconstruct tundra fire regimes during periods of the late Glacial and Holocene with novel combinations of climate and vegetation, (3) reparameterize ALFRESCO, a landscape ecosystem model initially developed to study the response of subarctic vegetation to changes in climate and fire regimes, for predicting tundra fire regimes under the suite of IPCC climate scenarios for the 21st century, (4) modify ED, a state-of-the-art physiologically-based model for tundra ecosystem studies, and (5) couple ED with ALFRESCO to simulate carbon dynamics related to 21st-century shifts in tundra fire regimes. Each of these elements is at the forefront of ongoing research in the respective areas, and together they promise to substantially advance our knowledge of climate-vegetation-fire interactions of tundra ecosystems for the past, present, and future.The consequences of altered fire regimes in tundra ecosystems are rarely considered by the scientific community, largely because tundra fires occur infrequently on the modern landscape. Fire managers in the Arctic lack the most fundamental knowledge about the fire regimes of tundra ecosystems (e.g., fire return intervals) for the design and implementation of landscape-level fire and fuels management plans. This research addresses this issue directly. The prognostic simulations of the 21st century fire regime will provide information directly relevant to fire management planning and policy in Alaska. The researchers will collaborate with scientists from federal management agencies through this project. This partnership promotes an improved understanding of the range of past, present, and future climate-fire relationships by federal and state natural resource managers.