From cells to biomes: the impacts of recent climate change on northern ecosystems

气候变化正在通过改变温度和降水模式对全球生态系统产生广泛的影响。例如，气候变化正在改变扰动机制，改变降水的季节模式，改变极端天气事件的频率，并改变物种分布和物候模式。在北部地区，气候变化的影响由于北极放大而加剧，北极变暖的速度比中纬度地区快近2倍。北极地区的快速变暖正在导致高纬度生态系统的物理和生物成分发生变化。例如，在树木气候学领域，最近的研究指出，自20世纪70年代至80年代以来，在一些高纬度地区，树木年轮温度重建与测量温度之间的偏差越来越大。实际温度与树木年轮研究重建的温度之间的这种偏差被称为“散度问题”。分化可能是生态系统对近期气候变化的一种反应，它挑战了树木年轮年表可以作为过去气候可靠预测指标的假设。此外，发散问题的空间范围在很大程度上尚未被探索。我的研究将利用高分辨率的代理数据源（树木年轮记录）进一步加深我们对加拿大北部气候和环境变化的理解。我将讨论加拿大树木年轮研究中的辐散问题，特别是加拿大北部地区辐散的空间发生和导致辐散的潜在因素。将调查的主要地理区域是加拿大西北部的Inuvik和Norman Wells；靠近加拿大中部林木线的黄刀；以及哈德逊湾海岸附近的丘吉尔。本研究项目的具体目标是：1 .确定加拿大中北部树木线辐散问题的空间特征；2 .确定辐散问题的原因；3 .利用不显示辐散气候-生长关系的多种来源的树木年轮数据，为三个研究区域开发长期的、高度解决的过去气候定量记录。加拿大北极/亚北极地区很少有年际确定的千年气候记录。我将探索通过从湖底回收淹没的原木，为加拿大北部开发超长树木年轮年表的可能性。4：探索木材解剖特征（管腔面积，细胞壁厚度）作为重建树线地点过去气候条件的代理的效用。我的研究项目将为自然科学（气候和生态系统建模者、生态学家、政策分析师）的许多研究领域提供有用的见解，并推进我们对气候变化及其对北极影响的认识。

Climate change is leading to broad scale impacts on global ecosystems through changing temperature and precipitation patterns. For example, climate change is altering disturbance regimes, changing the seasonal patterns of precipitation, altering the frequency of extreme weather events, and changing species distributions and phenological patterns. In northern regions, the impacts of climate change are heightened due to Arctic amplification which has caused the Arctic to warm nearly 2X faster than mid-latitude regions. The rapid warming in the Arctic is leading to changes to physical and biological components of high-latitude ecosystems. For example, within the field ofdendroclimatology, recent studies have noted that since the 1970-80s, there has been an increasing off-set between tree-ring temperature reconstructions and measuredtemperatures at some high-latitude sites. This offset between actual temperatures and those reconstructed from tree ring studies is known as the "Divergence Problem".Divergence is potentially an ecosystem response to recent climate change and challenges the assumption that tree ring chronologies can be used as a reliablepredictor of past climate. In addition, the spatial extent of the Divergence Problem is largely unexplored. My research will further our understanding of climate and environmental change in northern Canada using highly-resolved proxy data sources (tree ring records). I will address the Divergence issue in tree ring research in Canada, especially the spatial occurrence of divergence across northern Canada and the potential factors leading to divergence. The main geographic areas that will be investigated are Inuvik and Norman Wells in northwest Canada;Yellowknife near the central Canadian treeline; and Churchill, MB near treeline on the coast of Hudson Bay. The specific objectives of this research project are:1: Determine the spatial signature of the Divergence Problem across treeline in north-central Canada.2: Determine the cause(s) of the Divergence Problem.3: Develop long, highly resolved quantitative records of past climate for the three study regions using multiple sources of tree ring data that do not display diverging climate-growth relations. Few annually-resolved millennial length records of climate exist for Arctic/subArctic regions of Canada. I will explore the possibilityof developing supra-long tree ring chronologies for northern Canada by recovering submerged logs from the bottom of lakes.4: Explore the utility of wood anatomical features (lumen area, cell wall thickness) as proxies for reconstructing past climatic conditions at treeline sites. My research program will provide insights useful in a number of fields of study within the natural sciences (climate and ecosystem modellers, ecologists, policy analysts) and advance our knowledge of climate change and its impacts in the Arctic.