RAPID: Fire Effects on Soil and Aquatic Organic Matter in a Southern Appalachian Hardwood Forest.

森林火灾的影响通常是根据失去的树木面积或对野生动物的影响来考虑的。但火灾也可能对森林土壤中有机物质的数量、种类和运输产生重要影响，可能会对森林生产力产生巨大影响。然而，研究野火的影响是非常困难的，因为火灾后环境发生了迅速的变化，而且最近发生火灾的地点往往缺乏可靠的火灾前数据。该项目将利用最近在大烟山国家公园火灾之前和之后收集的关于土壤有机碳的数据，以检查火灾对陆地-水生界面有机碳循环的即时影响。这场大火烧毁了公园的两个地点，这两个地点是国家生态观测站网络的一部分，因此有可能将火灾前对土壤碳的详细评估与相同地点的火灾后变化结合起来。通过这样做，这个项目将填补我们对火如何影响美国东部森林生态系统的了解的空白。火将一系列热变化碳(C)引入陆地、大气和水生系统，如黑C(有机物不完全燃烧产生的稠合芳烃残留物)、多环芳烃(PAHs)和低分子有机酸(LMWOA)。这种热蚀变物质可以对土壤有机质(SOM)的数量和质量以及陆地和水生生态系统功能产生重要影响。火灾对土壤储量和溶解有机质(DOM)质量的影响知之甚少，但许多溪流在火灾后DOM浓度较高，这表明土壤DOM浓度增加，并在土壤剖面中移动。对于这种高度不稳定的亲水性DOC，有几种途径可用，包括：(1)高效地输送到溪流，在那里它可能成为水生生物的重要碳源；(2)高效输送到土壤剖面的更深部分，在那里裸露的矿物表面占主导地位，吸附能力最高，因此这种材料可以作为深层土壤碳被固定。DOC在这些途径之间的分配对于预测火灾对生态系统功能和服务的影响具有重要意义，包括饮用水质量和土壤固碳。这些固体残留物的火灾后并入过程可能相当迅速，但仍然知之甚少。这项工作是第一批考察相邻土壤和水生系统中颗粒和溶解的热蚀变碳的火灾后动态的研究之一。

The effects of forest fires are often thought of in terms acreage of trees lost or impacts on wildlife. But fires can also have an important influence the amount, kinds, and transport of organic matter that is in forest soil, with potentially large ramifications for forest productivity. However, studying the effects of wildfire is very difficult due to the rapid post-fire changes to the environment and often the lack of robust pre-fire data in locations that have recently burned. This project will take advantage of data on soil organic carbon collected prior to and immediately after the recent fire in the Great Smokey Mountains National Park to examine immediate post-fire effects on organic carbon cycling across the terrestrial-aquatic interface. The fire burned two sites with the park that are part of the National Ecological Observatory Network so it will be possible to couple a detailed pre-fire assessment of soil carbon with post-fire changes in the same locations. In doing so, this project will fill in gaps in our understanding of how fire affects forest ecosystems in the Eastern United States.Fire introduces a spectrum of thermally-altered carbon (C) such as black C (condensed-aromatic residue produced from incomplete combustion of organic matter), poly-aromatic hydrocarbons (PAHs), and low molecular weight organic acids (LMWOA) to terrestrial, atmospheric, and aquatic systems. This thermally-altered material can have important effects on quantity and quality of soil organic matter (SOM) as well as terrestrial and aquatic ecosystem function. The effects of fire on soil stocks and quality of dissolved organic matter (DOM) are poorly understood, however many streams have higher DOM concentrations post-fire, suggesting that soil concentrations of DOM increase and are mobile within the soil profile. Several pathways are available to this highly labile, hydrophilic DOC, including: (1) efficient transport to a stream where it may become an important source of carbon to aquatic organisms; and (2) efficient transport to deeper parts of the soil profile where naked mineral surfaces dominate and the sorptive capacity is highest and therefore this material can be sequestered as deep soil carbon. The partitioning of DOC between these pathways has important implications for predicting the impacts of fire on ecosystem function and services including, drinking water quality and soil carbon sequestration. The process of post-fire incorporation of these solid residues can be quite rapid but remains poorly understood. This work represents one of the first studies to examine the immediate post-fire dynamics of both particulate and dissolved classes of thermally-altered C in adjoining soils and aquatic systems.