Tree rings as indicators of hydrological changes and past climate

树木年轮分析在提供环境指标（如温度、干旱、虫害爆发）方面有着悠久的历史。在加拿大，树木每年产生年轮，它们分布广泛，通常能活几个世纪。因此，我们可以使用树木年轮特征来重建仪器记录之前的条件。我研究的一个长期目标是发现新的树木年轮特征，并评估它们作为替代指标的用途。近年来，树木年轮的解剖异常已被广泛用作极端气候事件的指标。例如，霜环和光环提供了有关温度异常的信息，它们可以根据过去和现在的气候帮助估计未来的气候预测。有趣的是，光环与最大晚木密度呈负相关，晚木密度是广泛使用的夏季温度指标。最大木材密度也可以通过测量树木年轮的蓝色反射率来近似计算；这种技术在北美基本上没有得到充分利用。温尼伯大学树木生态学实验室正在产生重大影响的另一个领域是树木水文学。我们在使用洪水环和早期船只的年度测量来研究北方系统的长期水文变化方面处于领先地位。我们对扩散多孔物种的最新研究使我们能够以周期性切向带的形式确定一种新的水文代理。拟议的研究将沿着两条主线发展。第一个是树木水文。我们将在时间上、地理上、物种上和水文制度上扩大我们的工作。其次，我们将利用我们大量的木材收集来探索加拿大树木气候学中蓝色反射率的效用。将对马尼托巴的水文系统进行两项研究，包括温尼伯湖。另一项研究将决定美国榆树对洪水的反应。第四项研究将评估重建渥太华河上游历史洪水的可能性。第五项研究将关注扩散多孔物种对洪水的响应。第六个项目的目标是重建全新世的洪水动态，重点是魁北克省杜帕奎特湖的支流。至少有四个项目也将涉及蓝色反射，并要求学生完成一篇荣誉论文。总之，这项研究将有助于更好地了解树木的生长情况，并更好地了解人类活动和/或自然变化带来的未来环境变化如何影响加拿大人及其环境。这将有助于加拿大水电部门和水资源管理人员。这个研究项目将为本科生和硕士生提供许多项目。鉴于它是实验室密集型的，它也将提供许多培训和就业机会。鉴于温尼伯大学对校园本土化的坚定承诺，我的一部分研究时间也将为土著学生提供培训机会。

Tree-ring analysis has a long history of providing environmental proxies (e.g., temperature, drought, insect outbreak). In Canada, trees produce annual tree rings, they are widely distributed and often live for centuries. We can thus use tree-ring traits to reconstruct conditions prior to instrumental records. A long-term objective of my research is to uncover new tree-ring traits and to evaluate their use as proxies. In recent years, anatomical abnormalities in tree rings have become widely used as indicators of extreme climate events. For example, frost and light rings provide information about temperature anomalies and they can help gauge future climate projections in light of past and current climates. Interestingly, light rings are inversely related to maximum latewood density, a widely used summer temperature proxy. Maximum latewood density can also be approximated by measuring the blue reflectance of trees rings; a technique largely underutilized in North America. Another area in which the University of Winnipeg DendroEcology Laboratory is having significant impacts is dendrohydrology. We are leaders in the use of flood rings and year-to-year measurements of earlywood vessels to study long-term hydrological variability in boreal systems. Our latest work with diffuse-porous species has allowed to identify a novel hydrological proxy in the form of periodic tangential band of vessels. The proposed research will develop along two main axes. The first is dendrohydrology. We will expand our work temporally, geographically, across species and hydrological regimes. Second, we will explore the utility of blue reflectance in Canadian dendroclimatology taking advantage of our large wood collection. Two studies will be led on hydrological systems in Manitoba including Lake Winnipeg. Another will determine how ring-porous species American elm respond to flooding. A 4th one will evaluate the possibility to reconstruct historical flooding for the upper Ottawa River. A 5th study will focus on the response of diffuse-porous species to flooding. A 6th one will aim at reconstructing the Holocene flood dynamics focusing on Lake Duparquet's tributaries, Quebec. At least, four projects will also deal with blue reflectance and involve students completing an honours thesis. In conclusion, this research will allow to better understand tree growth and to better visualize how future environmental changes brought by human activities and/or natural variations may impact Canadians and their environment. It will be helpful to the Canadian Hydropower sector and water resource managers. This research program will provide many projects for both undergraduate and MSc students. Given it is laboratory intensive, it will also provide many training and employment opportunities. Given the strong commitment of the University of Winnipeg towards campus indigenization, a portion of my research time will also be going to provide training opportunities to Indigenous students.