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植物和生态系统对气候变化的反应，以及北方温带地区工业和农业来源增加的大气氮污染。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，但它们之间的潜在相互作用尚不清楚。根据我之前使用NSERC探索基金进行的初步研究，我假设，虽然较长的生长季节可能会增加植物的生长，但气候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有机体，导致土壤氮流失增加和植物生长减少。我将在我在伦敦一块以草为主的田野上建立的长期实验的背景下，探索气候变暖和氮素添加的综合影响。除了监测植物对变暖(使用顶置加热器)和氮素添加的反应外，我还在研究土壤中氮素在处理过程中流失的途径。我还将研究植物在受控实验室条件下和田间条件下的冻结反应，以确定土壤冻结如何影响根的氮素吸收。除了我对植物和氮素的研究外，我还将在我的田间实验的背景下探索整个生态系统的反应。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性处理的反应的看法。我还将测量气候变暖和氮素增加在多大程度上改变了生态系统二氧化碳的释放和遏制。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尤为重要。总体而言，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可能如何变化以应对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.