Collaborative Research: RAPID: Mechanisms and fate of fire-induced carbonate formation in a cold desert ecosystem

旱地一直与野火联系在一起，但气候变化和植被的变化改变了这些敏感生态系统的火灾状态和碳平衡。野火消耗植被，释放储存的有机碳作为二氧化碳（CO2），一种温室气体。然而，最近在旱地野火之后，已经观察到盐以土壤碳酸盐（即无机碳）的形式积累。火灾诱发碳酸盐积累（FICA）的机制及其对碳长期储存的重要性尚不清楚。这项研究开始解决我们对火灾引起的土壤碳酸盐的起源、命运和影响的知识空白，因为干旱地区的野火活动处于历史最高水平。在这里，研究人员使用预定于2023年9月在美国农业部西北流域研究中心（NWRC）和关键区域观测站（CZO）已经密集测量的集水区进行的规定牧场火灾来描述火灾引起的碳酸盐堆积的环境控制。这项研究是一个跨学科研究小组的一部分，该小组由研究人员和土地管理人员组成，他们合作加强对野火的了解，以产生更大的区域影响。本研究将利用2023年9月在爱达荷州南部及周边地区的冷沙漠、山艾草草原生态系统特征中进行的实验火，表征导致火灾引起的碳酸盐积累（FICA）的非生物因素。土壤pH值、钙有效性、土壤二氧化碳（CO2）浓度和细胞外酶活性等因素的组合似乎导致了FICA，但所涉及的确切机制以及这些碳的来源和命运仍未解决。在牧场野火研究中不常见的是，该项目将1)在火灾发生前收集土壤样本，并将其与火灾后的条件进行对比，以促进未来对FICA控制的调查；2)在火灾发生前、发生期间和发生后9个月内测量土壤二氧化碳、湿度和温度条件——这是一个独特且易腐烂的数据集，也是研究由火灾引起的碳酸盐形成机制从未做过的事情。样本收集和传感器测量将在朝北和朝南的方面分层，以及烧伤严重程度处理（即植被类型），以了解FICA的景观控制。土壤样品也被认为是易腐的，并将存档，以备将来调查超出初始pH值，EC和碳酸盐测定。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Drylands have always been linked with wildfires, but climate change and shifts in vegetation have altered the fire regime and carbon balance of these sensitive ecosystems. Wildfires consume vegetation, releasing stored organic carbon as carbon dioxide (CO2), a greenhouse gas. Recently, however, the accumulation of salts in the form of soil carbonates (i.e., inorganic carbon) have been observed after dryland wildfires. The mechanisms of fire-induced carbonate accumulation (FICA) and its importance to long-term carbon storage remain unknown. This research begins to address a gap in our knowledge about the origin, fate, and impact of fire-induced soil carbonates as wildfire activity is at its historic highest levels in drylands. Here, researchers characterize the environmental controls on fire-induced carbonate accumulation using a prescribed rangeland fire slated for September 2023 in an already intensively instrumented catchment of the US Department of Agriculture’s Northwest Watershed Research Center (NWRC) and Critical Zone Observatory (CZO). The research is part of an interdisciplinary group of researchers and land managers collaborating to enhance understanding of wildland fires to create greater regional impact. This research will characterize the abiotic factors contributing to fire-induced carbonate accumulation (FICA) using an experimental fire in September 2023, located within the cold desert, sagebrush steppe ecosystem characteristic of southern Idaho and the surrounding region. A combination of factors including soil pH, calcium availability, soil carbon dioxide (CO2) concentration, and extracellular enzymatic activity appear to lead to FICA, but the exact mechanisms involved, and the source and fate of this carbon remain unresolved. Uncommon in rangeland wildfire studies, the project will 1) collect soil samples just before the fire, and contrast these with post-fire conditions to facilitate future investigation of controls on FICA, and 2) measure soil CO2, moisture, and temperature conditions before, during, and for 9 months after the fire – a unique and perishable dataset, and something that has never been done to study the mechanisms driving carbonate formation caused by fires. Sample collection and sensor measurements will be stratified across north- and south-facing aspects, and burn severity treatments (i.e., vegetation types) to understand landscape controls on FICA. Soil samples are also considered perishable and will be archived for future investigation beyond initial pH, EC, and carbonate determination.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.