MSB-ECA: A Lengthening Vernal Window: How Vernal Asynchronies in Energy, Water, and Carbon Fluxes Impact Ecosystem Function

MSB-ECA：延长的春季窗口：能源、水和碳通量的春季异步如何影响生态系统功能

• 批准号: 1802726
• 负责人: Elizabeth Burakowski
• 金额: $ 29.86万
• 依托单位: University of New Hampshire
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-01 至 2022-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1802726&HistoricalAwards=false
• 关键词: MSB; ECA; Lengthening; Vernal; Window; MSB; ECA; Lengthening; Vernal; Window

The vernal window is the transitional period between winter and spring in the northeastern US, when air temperatures warm above freezing, snow melt begins, and forest canopies fully leaf out. The sequential order and timing of physical changes during this window plays a key role in the healthy functioning of seasonally snow-covered ecosystems. The vernal window is shorter following cold, snowy winters but lengthens when winters are warmer and snow packs are shallow or melt multiple times through the winter. When the vernal window gets longer, it can lead to a mismatch in the timing of key ecosystems processes. For example, earlier snowmelt in the spring can flush nutrients from soils before trees emerge from dormancy, preventing trees from accessing those vital nutrients during early spring growth. The vernal window is expected to lengthen given documented warming trends in winter climate, and, under higher emission scenarios may be eliminated altogether in more southerly locations. This study will integrate observations of snow, streamflow, and forest health to document historical changes in the length of the vernal window and use simulations to project future changes in the vernal window. Results will be use to assess the impact on key energy, water, and carbon transitions on ecosystem function, using the northeastern United States forests as a testbed. In collaboration with a local high school classroom, the investigators will develop a low-cost instrumentation suite constructed by students through an inquiry-based lab course that will allow students to track changes in the vernal window in their school yards. A Next Generation Science Standard compliant curriculum with units on energy balance, the carbon cycle, and hydrology will accompany the instrument kit, laying the groundwork for outdoor classroom inquiry on the environment. Previous studies have demonstrated the importance of winter coldness or snowpack as drivers of spring onset, however, it remains unclear how antecedent winter temperature and snowpack properties interact to influence the timing and duration of the vernal window. In addition, previous work has not investigated explicitly how biogeochemical asynchronies that result from longer lags between transitions in the longer vernal window can impact ecosystem function, which is essential for understanding the impact of environmental change. Rapid changes in winter conditions could lead to vernal asynchronies that have strong potential to alter energy, water, and carbon balances. The most extreme case is a shift into a snow-free regime in which the vernal window ceases to exist and is replaced by a prolonged period of increased net radiation into terrestrial and aquatic ecosystems between senescence and leaf out that may fundamentally alter ecosystem function. The work proposed here brings together large existing datasets and process-based models that will be used to investigate explicitly 1) the relative importance of winter coldness and snowpack in altering the vernal window; 2) how longer vernal lags and windows impact ecosystem energy, water, and carbon balance; and 3) how future winter coldness and snowpack characteristics might lead to additional changes in the vernal window. The outcome of this process will be a regional, 30-year historical analysis of changes to energy, carbon, and water balances during the vernal window. Insight gained from this historical analysis will provide the ability to project future changes in not only vernal window length, but also the impact of changing energy, carbon, and water balances during the vernal window on ecosystem function.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.

春季的窗户是美国东北部冬季和春季之间的过渡时期，当时空气温度在冰冻，雪融化开始时，森林檐篷完全叶出来。在此窗口中，物理变化的顺序顺序和时间在季节性雪覆盖的生态系统的健康功能中起着关键作用。在寒冷的冬季冬天，春季的窗户较短，但是当冬季变暖时，降雪量会延长，整个冬季降雪或多次融化。当春季窗口更长时，它可能会导致关键生态系统过程的时间不匹配。例如，在春季的较早融雪可以从树木从休眠中浮出水面之前从土壤中冲洗养分，从而阻止树木在早春生长期间获得这些重要的营养。预计在冬季气候中，春季窗口有望延长给定的变暖趋势，在更南方的位置可以完全消除较高的排放场景。这项研究将整合雪，流量和森林健康的观察结果，以记录春季窗口长度的历史变化，并使用模拟在春季窗口中投射未来的变化。结果将用于评估对关键能量，水和碳过渡对生态系统功能的影响，并使用美国东北森林作为测试床。调查人员与当地的高中教室合作，将通过基于询问的实验室课程来开发由学生建造的低成本仪器套件，该课程将使学生能够跟踪他们学校院子里的春季窗口中的变化。下一代科学标准的课程，具有能源平衡，碳循环和水文学单位的单元将伴随仪器套件，为环境室外教室查询奠定基础。先前的研究表明，作为春季发作的驱动因素，冬季寒冷或积雪的重要性尚不清楚冬季温度和积雪特性如何相互作用以影响春季窗口的时间和持续时间。此外，先前的工作尚未明确研究由较长的春季过渡之间较长滞后产生的生物地球化学异步如何影响生态系统功能，这对于理解环境变化的影响至关重要。 冬季条件的快速变化可能导致阳性异步具有强大的能量，水和碳平衡的潜力。最极端的情况是转移到一个无雪的状态，在这种状态下，春季窗户不再存在，并被延长的净辐射增加到衰老和叶片之间的陆地和水生生态系统的长时间，这可能从根本上改变了生态系统功能。这里提出的工作汇集了大型现有数据集和基于过程的模型，这些模型将用于显式研究1）冬季寒冷和积雪在更改春季窗口中的相对重要性； 2）春季滞后和窗户影响生态系统能量，水和碳平衡的时间； 3）未来的冬季寒冷和积雪特征如何导致春季窗户的其他变化。该过程的结果将是对阳台窗口期间能量，碳和水平衡变化的区域性，30年的历史分析。从这种历史分析中获得的洞察力将提供能够在春季窗口对生态系统功能期间的能量，碳和水平变化的影响中投射未来变化的能力。该奖项反映了NSF的法定任务，并认为通过基金会的智力和更广泛的影响，可以通过评估通过评估来进行支持，这是值得的。