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

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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.