CAREER: The end of winter: How changing snow conditions affect soil redox and biogeochemistry

职业：冬季结束：变化的雪况如何影响土壤氧化还原和生物地球化学

• 批准号: 2237128
• 负责人: Caitlin Hicks Pries
• 金额: $ 112.02万
• 依托单位: Dartmouth College
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-03-01 至 2028-02-29
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2237128&HistoricalAwards=false
• 关键词: CAREER; end; winter; How; changing

Winter is changing faster than other seasons. Regions that once had regular snow cover during winter now experience warm spells and rain-on-snow events that can cause snow to melt. Without consistent snow cover, soils will no longer be insulated from freezing temperatures or protected from water during the winter. Most research has focused on soils during the summer season when plants are growing, so little is known about how changes in winter conditions will affect soil processes like decomposition, greenhouse gas emissions, and nutrient export. This research uses an experiment that will melt snow, along with observations along a snow-cover gradient in the New Hampshire mountains, to understand how changes in snow cover will affect soil processes. This project provides graduate and undergraduate education in winter ecology, experiments, and data analysis. This project also involves community members, including public school students, to help monitor snow and soil conditions in the New Hampshire mountains and to help the public learn more about the effects of changes in winter on their communities.The loss of a persistent snowpack is increasing soil climate variability as snowmelt periodically raises soil moisture levels and leaves the soil vulnerable to episodic freezing. Recent measurements in upland forest soils indicate this winter variability is causing redox fluctuations. Increased redox fluctuations will have profound effects on soil biogeochemistry with implications for greenhouse gases, such as increased N2O fluxes and reduced CH4 uptake, and may increase nutrient exports to aquatic systems. This research will 1) construct a novel in situ experiment that manipulates winter climate with three treatments: melting 50% of snowfall, melting 100% of snowfall, and a control, where snow is not manipulated; and 2) use a natural gradient of snow conditions as a space-for-future-time substitution. Within the experiment and across the gradient, soil environmental variables (temperature, moisture, frost depth, O2, and redox potential), and biogeochemical fluxes, including greenhouse gas production (CO2, N2O, CH4) and the leaching of carbon, nutrients, and metals through the soil profile, will be measured. This research will generate the knowledge needed to fill the unaddressed gap of how midwinter snowmelt affects soil biogeochemistry through changes to moisture, temperature, and redox and quantify how this loss of snow affects soil.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.

冬季比其他季节变化得更快。曾经在冬季定期积雪的地区现在经历了温暖的时期和可能导致积雪融化的雨雪事件。如果没有持续的积雪，土壤将无法在冬季免受冰冻温度的影响或免受水的影响。大多数研究都集中在植物生长的夏季土壤，因此人们对冬季条件的变化将如何影响土壤过程（如分解、温室气体排放和养分输出）知之甚少。这项研究利用融雪实验以及沿新罕布什尔州山区积雪梯度的观测，来了解积雪的变化将如何影响土壤过程。该项目提供冬季生态学、实验和数据分析方面的研究生和本科生教育。该项目还涉及社区成员，包括公立学校的学生，帮助监测新罕布什尔州山区的雪和土壤状况，并帮助公众更多地了解冬季变化对其社区的影响。持续积雪的损失正在增加融雪导致土壤气候变化，周期性地提高土壤湿度，使土壤容易遭受间歇性冰冻。最近对高地森林土壤的测量表明，今年冬季的变化正在导致氧化还原波动。氧化还原波动的增加将对土壤生物地球化学产生深远的影响，对温室气体产生影响，例如氧化亚氮通量增加和甲烷吸收减少，并可能增加水生系统的养分输出。这项研究将 1) 构建一个新颖的原位实验，通过三种处理方式操纵冬季气候：融化 50% 的降雪、融化 100% 的降雪，以及不操纵降雪的对照； 2）使用雪况的自然梯度作为未来时间的空间替代。在实验中和整个梯度上，土壤环境变量（温度、湿度、霜深、O2 和氧化还原电位）和生物地球化学通量，包括温室气体产生（CO2、N2O、CH4）以及碳、养分和有机物的浸出。穿过土壤剖面的金属将被测量。这项研究将产生所需的知识，以填补仲冬融雪如何通过湿度、温度和氧化还原的变化影响土壤生物地球化学的空白，并量化降雪如何影响土壤。该奖项反映了 NSF 的法定使命，并被认为是值得的通过使用基金会的智力优势和更广泛的影响审查标准进行评估来提供支持。