Winter as a driver of nitrogen cycle responses to environmental change: responses of leguminous plants to variability in freezing

冬季作为氮循环对环境变化反应的驱动因素：豆科植物对冰冻变化的反应

• 批准号: RGPIN-2020-06486
• 负责人: Henry, Hugh
• 金额: $ 3.42万
• 依托单位: University of Western Ontario
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=741244
• 关键词: Winter; driver; nitrogen; cycle; responses

Nitrogen is a key soil nutrient for plant growth. Therefore, a thorough understanding of the factors that affect nitrogen availability is crucial for predicting plant responses to environmental variation. Changes in soil freezing resulting from variation in winter conditions can have a substantial influence on the activities of soil microbes and plant roots, and thus can alter nitrogen availability and uptake by plants over the following growing season. However, an important question is whether soil nitrogen responses to severe freezing events can persist over the longer term. Although populations of soil microbes and plant root systems disrupted by freezing can recover by the next year, freezing-driven changes in the types and abundances of different perennial plant species could have lasting effects on soil nitrogen, because the nitrogen content of decomposing plant material differs among species. Legumes, which are plants that can obtain nitrogen directly from the air by partnering with specialized bacteria, may be more sensitive to freezing than other plant species. Given that the decomposition of legumes can increase soil nitrogen substantially, changes in legume numbers in response to changing winters could have strong effects on soil fertility. Research on this topic is particularly timely and important given that warmer winters are resulting in decreased snow cover, which can increase the freezing of plants that overwinter in soil. The overarching objective of my research program is to address how limits to the freezing tolerances of legumes can influence the extent to which winter processes control soil nitrogen availability both in natural plant communities (e.g. grassland) and managed ecosystems (cropland). Using a combination of experiments under controlled growth conditions and in the field, I will test the novel hypothesis that increased freezing intensity reduces the survival and growth of legumes disproportionately relative to non-leguminous plants. I will then use larger scale, multi-year field experiments in combination with nitrogen tracer techniques to examine how lethal or sublethal freezing damage to legumes affect the amount and timing of nitrogen availability over subsequent plant growing seasons. In addition to providing important knowledge regarding changes in the soil fertility of natural environments in response to variation in weather and climate change, this research will contribute significantly to the effective use of legumes in applied scenarios, such as in agricultural cover crop mixtures and in the selection of species for the restoration of native plant communities. Although winter biology has been explored most extensively in alpine and arctic systems, my research will focus on plants in northern temperate regions, which include the most highly populated and agricultural regions of Canada.

氮是植物生长的关键土壤养分。因此，对影响氮可用性的因素的透彻理解对于预测植物对环境变化的反应至关重要。由于冬季条件变化而导致的土壤冷冻变化可能会对土壤微生物和植物根的活性产生重大影响，因此可以改变氮的可用性和植物在接下来的生长季节的吸收。但是，一个重要的问题是，土壤氮对严重冻结事件的反应是否可以长期持续。尽管在明年被冷冻破坏的泥浆微生物和植物根系系统可以恢复，但冻结驱动的多年生植物种类的类型和丰富性的变化可能会对土壤氮产生持久影响，因为分解植物材料的氮含量在物种之间的不同。豆类是可以通过与专门细菌合作直接从空气中获得氮的植物，可能比其他植物物种更敏感。鉴于豆类的分解可以大大增加土壤氮，因此豆类数量的变化会响应变化的冬季，可能会对土壤生育能力产生强大的影响。鉴于较温暖的冬季导致积雪减少，因此对该主题的研究特别及时且重要，这可能会增加越冬土壤中的植物的冻结。 我的研究计划的总体目的是解决豆类冻结公差的局限性如何影响冬季过程控制土壤氮的可用性，包括天然植物群落（例如草地）和托管生态系统（农田）。使用在受控生长条件下的实验结合，在现场，我将测试新的假设，即冻结强度的增加可降低豆科植物的存活率和生长，而相对于非卵形植物的生长和生长不成比例。然后，我将使用较大的多年野外实验与氮示踪剂技术结合使用，以检查豆类对豆类的致命或终极冻结损害如何影响随后的植物生长季节的氮可用性的数量和时机。除了提供有关自然环境的土壤生育能力的重要知识以应对天气和气候变化的差异之外，这项研究还将有助于有效利用豆科植物在应用的情况下，例如在农业覆盖的作物混合物以及选择物种以恢复本地植物社区的物种。尽管在高山和北极系统中对冬季生物学进行了最广泛的探索，但我的研究将重点放在北部温带地区的植物上，其中包括加拿大人口众多和人口最多的农业地区。