Collaborative Research on Snow-Shrub Interactions in Alaskan and Canadian Tundra and their Potential for Positive Feedbacks to Vegetation and Climate Change

阿拉斯加和加拿大苔原雪灌木相互作用及其对植被和气候变化积极反馈潜力的合作研究

• 批准号: 0516509
• 负责人: Marion Bret-Harte
• 金额: --
• 依托单位: University of Alaska Fairbanks Campus
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-08-15 至 2010-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0516509&HistoricalAwards=false
• 关键词: Collaborative; Research; Snow; Shrub; Interactions

In the Arctic, a widespread transition from tundra to shrub-dominated vegetation appears to be underway. Winter processes could be critical to this tundra-to-shrub transition, because larger and denser shrubs trap more snow, which leads to warmer soil temperatures during winter and could permit greater decomposition and mobilization of nitrogen from soil organic matter. The goals of this research project include determining 1) whether snow trapped by shrubs in winter promotes biologically significant mobilization of nitrogen from soil, 2) whether shrubs take up nitrogen mobilized during winter and increase their growth, thus promoting shrub expansion, 3) whether shrub expansion promotes carbon loss from soil, as has been seen previously in fertilized tundra plots that have become dominated by shrubs, and 4) understanding how shrubs recover from being laid down by winter snow, and how snow affects their growth and mortality. These goals will be addressed by field experiments manipulating snow accumulation and shrub architecture, and by measuring plant and soil carbon and nitrogen where shrubs have naturally expanded over the last 50 years. Expansion of shrubs may be the most widespread land surface change in the Arctic as climate warms. Our results will help reveal the mechanisms underlying shrub expansion and their consequences for ecosystem cycling of carbon and nitrogen. Arctic and boreal regions have large stores of soil carbon that could greatly increase atmospheric CO2 concentration if released, promoting further climate warming.

在北极，从苔原到灌木为主的植被的广泛过渡似乎正在进行中。冬季过程可能对这种苔原到灌木的过渡至关重要，因为更大和更密集的灌木会捕获更多的雪，这导致冬季土壤温度升高，并可能使土壤有机质中的氮更大程度地分解和动员。 该研究项目的目标包括确定1）冬季被灌木困住的雪是否促进土壤中氮的生物学显著动员，2）灌木是否吸收冬季动员的氮并增加其生长，从而促进灌木扩张，3）灌木扩张是否促进土壤中的碳损失，正如以前在已被灌木占主导地位的施肥苔原地块中所看到的那样，4）了解灌木如何从冬季积雪中恢复，以及雪如何影响它们的生长和死亡。 这些目标将通过操纵积雪和灌木结构的实地实验来实现，并通过测量过去50年灌木自然扩展的植物和土壤碳和氮来实现。 随着气候变暖，灌木的扩张可能是北极最广泛的地表变化。 我们的研究结果将有助于揭示灌木扩张的机制及其对生态系统碳和氮循环的影响。 北极和北方地区有大量的土壤碳储存，如果释放出来，可能会大大增加大气中的二氧化碳浓度，促进进一步的气候变暖。