Doctoral Dissertation Research: Mechanisms of shrubification in a changing Arctic

博士论文研究：变化中的北极灌木化机制

• 批准号: 2311256
• 负责人: Jonathan Levine
• 金额: $ 6.51万
• 依托单位: Princeton University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-04-15 至 2026-03-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2311256&HistoricalAwards=false
• 关键词: Doctoral; Dissertation; Research; Mechanisms; shrubification

Arctic tundra is made up of a variety of plants, including mosses, grasses, flowering herbs, and woody shrubs, which guard vast quantities of underground carbon frozen in Arctic soils. As the Arctic warms, shrubs are replacing other plant species, altering the carbon cycle. The driving mechanisms and impacts of this shift on Arctic soil carbon remains unclear. This research explores the reasons behind this shift by testing three hypothesized mechanisms that may explain shrubs' competitive advantage in a warmer climate. These hypotheses include increased photosynthesis, greater response to nutrients made available by warming, and larger gains from longer growing seasons. The project employs mathematical models, field experiments, and surveys of shrubs across Alaskan tundra landscapes to test these mechanisms. This research will improve our understanding of vegetation changes and carbon cycling in the rapidly warming Arctic. Results will be shared via a public-facing interactive website and incorporated into K-12 and college courses. The goal of this research is to determine the mechanisms by which changing climate enables shrub dominance in heterogeneous Arctic ecosystems. The research approach combines trait-based models of competing tundra species informed with field experimental manipulations of temperature, nutrient availability, and snowmelt date. The full factorial experimental manipulation of these three environmental factors will allow researchers to untangle the relative contribution of the hypothesized mechanisms to shrubification. Since different mechanisms may be driving shrubification across vast and variable Arctic landscapes, researchers will conduct surveys of shrub populations and warming experiments across natural environmental gradients on the North Slope of Alaska. By clarifying mechanisms driving shrubification at local and landscape scales, this research will aid future efforts to represent Arctic shrubs accurately in Earth System Models and reduce uncertainties in climate change projections.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.

北极苔原由各种植物组成，包括苔藓，草，开花草药和木本灌木，它们可以保护大量的地下碳在北极土壤中冷冻。随着北极的温暖，灌木正在替代其他植物物种，从而改变了碳循环。这种转变对北极土壤碳的驾驶机制和影响尚不清楚。这项研究通过测试三种假设的机制来探讨这种转变背后的原因，这些机制可以解释灌木在温暖的气候下的竞争优势。这些假设包括增加的光合作用，对升温提供的营养的反应更大，以及较长的生长季节的增长。该项目采用了整个阿拉斯加苔原景观的灌木的数学模型，现场实验和调查，以测试这些机制。这项研究将提高我们对快速变暖北极中植被变化和碳循环的理解。结果将通过面向公共的互动网站共享，并纳入K-12和大学课程中。这项研究的目的是确定气候变化可以使北极生态系统中的灌木占优势的机制。研究方法结合了基于特质的竞争性苔原物种模型，这些模型与温度，营养可用性和融雪日期的现场实验操作有关。对这三个环境因素的完整阶乘实验操作将使研究人员能够解开假设机制对灌肠化的相对贡献。由于不同的机制可能正在推动北极景观广阔和可变的灌木丛，因此研究人员将对阿拉斯加北坡的自然环境梯度进行灌木种群的调查和变暖实验。通过阐明在当地和景观量表上推动灌木化的机制，这项研究将有助于未来的努力在地球系统模型中准确地代表北极灌木，并减少气候变化预测中的不确定性。该奖项反映了NSF的法定任务，并通过评估该基金会的知识功能和广泛的影响来审查Criteria。