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造成广泛的影响。例如，气候变化正在改变干扰机制，改变降水的季节模式，改变极端天气事件的频率，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的放大而加剧，这导致北极变暖的速度比中纬度地区快近2倍。北极迅速变暖正在导致高纬度生态系统的物理和生物组成部分发生变化。例如，在树状气候学领域，最近的研究指出，自1970-80年代以来，在一些高纬度地区，树木年轮温度的重建与测量的温度之间的偏差越来越大。实际温度和年轮研究重建的温度之间的偏差被称为“发散问题”。发散可能是生态系统对最近气候变化的反应，并挑战了这样的假设，即树木年轮年表可以作为过去气候的可靠预测因子。此外，分歧问题的空间范围在很大程度上还没有得到探索。我的研究将使用高度可分辨的代理数据源(树木年轮记录)来加深我们对加拿大北部气候和环境变化的理解。我将讨论加拿大年轮研究中的发散问题，特别是加拿大北部发散的空间发生情况以及导致发散的潜在因素。将进行调查的主要地理区域是加拿大西北部的因努维克和诺曼·威尔斯；加拿大中部树线附近的耶洛奈夫；以及哈德逊湾海岸树线附近的丘吉尔。这一研究项目的具体目标是：1：确定加拿大中北部林线上差异问题的空间特征。2：确定差异问题的原因(S)。3：使用不显示差异气候-生长关系的多个树轮数据来源，为三个研究区域建立长期、高分辨率的过去气候量化记录。加拿大北极/亚北极地区的千禧年气候记录很少。我将探索通过从湖底恢复淹没的原木来开发加拿大北部超长年轮年表的可能性。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替代指标的实用性。我的研究计划将在自然科学的许多研究领域(气候和生态系统建模师、生态学家、政策分析师)提供有用的见解，并增进我们对气候变化及其对北极影响的了解。

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.