Mechanisms of plant and ecosystem responses to climate warming and increased atmospheric nitrogen deposition in temperate regions

我的研究目标是确定北温带地区植物和生态系统对气候变化和工业和农业大气氮污染增加的响应。虽然这两个因素预计将在下个世纪对植物和生态系统产生重大影响，但它们之间潜在的相互作用尚不清楚。根据我之前使用NSERC发现基金进行的初步研究，我假设，虽然生长季节变长可能会促进植物生长，但由于变暖和更极端的气候事件导致的积雪减少可能会增加土壤冻结的强度，这可能会损害植物和土壤生物，导致土壤氮损失增加，植物生长减少。我将在我在安大略省伦敦的一片草地上建立的长期实验中，探索变暖和氮添加的综合影响。除了监测植物对变暖（使用顶部加热器）和氮添加的反应外，我还在研究氮在处理后从土壤中流失的途径。我还将在受控的实验室条件下和实地研究植物的冻结反应，以确定土壤冻结如何影响根系对氮的吸收。除了我对植物和氮的研究外，我将在我的野外实验的背景下探索整个生态系统的响应。我将研究食草动物和分解者的活动如何改变我们对植物对实验处理的反应的看法。我还将测量气候变暖和氮含量增加对生态系统释放和遏制二氧化碳的影响程度。这些数据对于预测气候变化的生物反馈将如何影响未来的温室气体浓度特别重要。总的来说，我的研究将对自然植物群落和农业系统的管理以及预测生态系统服务如何响应下个世纪的全球变化具有重要意义。

My research objective is to determine plant and ecosystem responses to climate change and increased atmospheric nitrogen pollution from industrial and agricultural sources in northern temperate regions. While both of these factors are expected to have substantial effects on plants and ecosystems over the next century, their potential interactions remain unclear. Based on preliminary studies conducted using my previous NSERC Discovery Grant, I hypothesize that while a longer growing season might be expected to increase plant growth, reduced snow cover caused by warming and more extreme climate events will likely increase the intensity of soil freezing, which can damage plants and soil organisms, leading to increased soil nitrogen losses and reduced plant growth. I will explore the combined effects of warming and nitrogen addition in the context of a long-term experiment I have established in a grass-dominated field in London, ON. In addition to monitoring the plant responses to warming (administered using overhead heaters) and nitrogen addition, I am examining the pathways by which nitrogen is lost from the soil in response to the treatments. I will also study plant freezing responses under controlled laboratory conditions and in the field to determine how soil freezing influences root nitrogen uptake. In addition to my research on plants and nitrogen, I will explore entire ecosystem responses in the context of my field experiment. I will examine how the activities of herbivores and decomposers alter our perception of how the plants respond to the experimental treatments. I will also measure the extent to which warming and increased nitrogen alter the release and containment of carbon dioxide by the ecosystem. These data are particularly important for predicting how biological feedbacks to climate change will influence future greenhouse gas concentrations. Overall, my research will have important implications for the management of natural plant communities and agricultural systems and for predicting how ecosystem services may change in response to global change over the next century.