Diversity and Adaptation of Riparian Cottonwoods and Hybrid Poplars - Exploration and Syntheses

杨树为北半球周围的一系列森林提供了基础。它们是加拿大最丰富和最广泛的树木，艾伯塔省南部提供了一个全球杨树生物多样性中心，有五个物种重叠，四种棉杨或河谷杨树杂交。棉杨还为人工杂交杨树提供亲本物种，这是加拿大和世界其他温带地区生长最快的树木。不幸的是，棉杉林一直在倒塌，这主要是由于河流筑坝和用于灌溉和其他用途的抽水，而气候变化放大了这一挑战。在这个研究计划中，我将扩大我们对北美杨树和一些柳树以及相关灌木的生理多样性和适应能力的调查。阿尔伯塔省南部的河岸森林提供了一个独特的自然实验室，不列颠哥伦比亚省和美国的研究将扩大地理范围。与大多数植物不同，杨树是雌雄异株的，无论是雄株还是雌株，我们将调查性别差异及其原因。我们的研究强调生理，形式和功能的融合，我们将比较和对比棉杨及其杂交品种。我们将通过测量树叶和树木的树液流量、光合作用和蒸腾作用，以及利用涡旋协方差通量塔测量整个生态系统，来研究生长和发育，扩大研究范围，从源水和木质部的同位素组成到研究成分。我们将调查对干旱和洪水的反应，并试图了解物种如何适应不同的环境，例如从山脉到草原的河谷环境。我们还在考虑遗传和遗传学，并操纵植物激素赤霉素的基因，赤霉素是树木形态和功能的主要调节者。这项研究将探索植物多样性和适应的基本性质，并揭示生理权衡。它可以识别有利于跨环境杨树种植和开垦的性状。它将有助于河流治理，以保护和恢复泛滥平原森林，这些森林提供了丰富的野生动物栖息地，并有利于水质。它还将有助于了解加拿大的落叶林可能如何应对气候变化，以及对诸如种植辅助移徙等预期反应的考虑。

Poplars, Populus trees, provide the foundations for a range of forests around the Northern Hemisphere. They are the most abundant and extensive trees in Canada, and southern Alberta provides a global centre of poplar biodiversity with five species that overlap and the four cottonwoods, or river valley poplars, hybridize. Cottonwoods also provide the parental species for artificial hybrid poplars, the fastest-growing trees in Canada and other temperate regions worldwide. Unfortunately, cottonwood forests have been collapsing, largely due to river damming and water withdrawal for irrigation and other uses, and climate change is amplifying this challenge.*******In this research program, I will extend our investigations into the physiological diversity and adaptations across the North American poplars, and some willows, related shrubs. The riparian forests of southern Alberta provide a unique natural laboratory and studies in British Columbia and the United States will extend the geographic scope. Unlike most plants, poplars are dioecious, either male or female, and we will investigate how the sexes differ, and why. Our studies emphasize physiology, the blending of form and function, and we will compare and contrast the cottonwood species and their hybrids. We will study growth and development, with up-scaling of study components from the isotopic composition of source and xylem water, through measurements of sap flow, photosynthesis and transpiration from leaves and trees, and up to whole ecosystem measurements with eddy covariance flux towers. We will investigate responses to drought and to flooding, and seek to understand how the species are adapted to the diverse environments, such as in river valleys from the mountains to the prairies. We are also considering inheritance and genetics, and manipulating genes for the phytohormone gibberellin, a master regulator of tree form and function. The research will explore the fundamental nature of plant diversity and adaptation, and reveal physiological trade-offs. It could identify traits to benefit poplar plantings across environments and for reclamation. It will contribute towards river regulation to conserve and restore floodplain forests, which provide rich wildlife habitats and benefit water quality. It will also assist in understanding how Canada's deciduous forests may respond to climate change, and considerations of prospective responses such as with plantings for assisted migration.***