Yukon-Kuskokwim Delta fire: decomposition rates, Yukon-Kuskokwim Delta Alaska, 2016

The summer of 2015 was an extraordinary year for fire in the Arctic, including in the Yukon-Kuskokwim Delta, presaging a future where tundra and boreal fire is far more common. Remarkably, the area burned in the YK Delta in 2015 exceeds the total area burned from 1940-2014 combined. The response of the YK Delta in the first year post-fire will set the stage for longer-term changes in delta carbon storage and transport among tundra, aquatic and marine systems, and to the atmosphere. Quantifying carbon export and understanding the immediate ecosystem response to fire is critical because long-term recovery is, to a considerable degree, dependent on short-term responses. A major question that this research will address is how fire influences the amount and form of carbon transported from delta ecosystems seasonally and in the first year following fire. Ultimately, these results will inform long-term trajectories of the vulnerability and fate of delta carbon pools. This research will significantly improve our understanding of the role of fire in the loss of both modern and ancient carbon from arctic river deltas, which contain >10% of the Arctic’s massive permafrost carbon store. Arctic river deltas are hotspots for carbon storage, occupying <1% of the pan-Arctic watershed but containing >10% of carbon stored in arctic permafrost. They are also heterogeneous mosaics of linked terrestrial and aquatic ecosystems, and are susceptible to changes in land, river, and marine systems. The vulnerability of carbon stored in arctic river deltas is a major unknown and is critically important as climate warming and increasing fire frequency may make this carbon vulnerable to transport to aquatic and marine systems and to the atmosphere. The goal of this proposal is to examine the immediate effects of fire on carbon storage in the Yukon-Kuskokwim Delta and exchange between terrestrial and aquatic components of the Delta. By extension this work will yield critical insights into how the carbon balance of deltas in the arctic system will change over the coming decades as warming continues and fire frequency increases. This dataset includes in situ soil decomposition rates from buried cellulose experiments.

2015年夏季是北极野火形势极为特殊的一年，育空-库斯科奎姆三角洲（Yukon-Kuskokwim Delta，以下简称YK三角洲）亦受波及，这一事件预示着未来苔原（tundra）与北方林野火（boreal fire）将愈发普遍。值得关注的是，2015年该区域的过火面积超过了1940年至2014年的总过火面积之和。火灾后第一年YK三角洲的生态响应，将为三角洲碳储量、苔原-水生-海洋系统间的碳输运以及碳向大气的排放等长期变化奠定基础。

量化碳输出量并厘清野火对生态系统的即时响应至关重要，因为长期恢复在很大程度上依赖于短期响应。本研究拟解决的核心问题之一是：野火如何季节性地以及在火灾后第一年，影响三角洲生态系统的碳输运总量与碳赋存形态。最终，这些研究结果将为解析三角洲碳库的长期演化轨迹及其脆弱性与归宿提供依据。本研究将大幅增进我们对野火在北极河流三角洲现代与古老碳损失过程中所起作用的理解——这类三角洲储存了北极地区超过10%的巨型永久冻土（permafrost）碳库。

北极河流三角洲是碳储存的热点区域，仅占泛北极流域不足1%的面积，却储存了北极永久冻土中超过10%的碳。它们同时也是连接陆地与水生生态系统的异质性镶嵌体，易受陆地、河流与海洋系统变化的影响。北极河流三角洲储存的碳的脆弱性仍是一大未知，但这一问题极为关键：气候变暖与野火频率上升可能使这类碳更易被输运至水生、海洋系统以及大气中。

本研究的目标是探究野火对YK三角洲碳储量的即时影响，以及三角洲陆地与水生组分间的碳交换过程。进一步而言，这项工作将为解析未来数十年间，随着气候持续变暖与野火频率增加，北极系统内三角洲碳平衡将如何变化提供关键见解。

本数据集包含埋置纤维素实验得到的原位（in situ）土壤分解速率数据。