Ecophysiological Adaptations of Riparian Cottonwood Sexes, Species and Hybrids

杨树，杨树，为北半球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，阿尔伯塔南部提供了一个全球杨树生物多样性中心，有五种重叠的品种，四种棉杨树或河谷杨树杂交。白杨是加拿大和世界其他温带地区生长最快的树木，白杨是人工杂交杨树的亲本树种。不幸的是，棉杨林正在崩溃，这主要是由于河流筑坝和用于灌溉和其他用途的取水，而气候变化正在加剧这一挑战。在这个研究项目中，我将把我们的研究扩展到北美西部杨树的生理多样性和适应性。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，雄性或雌性，我们将研究性别差异的原因。我们的研究重点是生理学，形态和功能的融合，我们将比较和对比棉杨种及其杂交种。我们将利用无人机成像的新方法来补充野外研究和遥感、航空摄影和卫星图像，探索林地中雄性与雌性、不同物种和杂交物种的空间分布。我们将研究生长和发育，从源水和木质部水的同位素组成中扩大研究成分，通过测量树叶和树木的汁液流、光合作用和蒸腾，直至使用涡动相关通量塔测量整个生态系统。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，特别是在干旱地区的河谷洪泛平原，在那里，白杨提供了唯一的本土树木。我们也在考虑遗传和遗传学，以及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器。本研究将探讨杨树多样性的基本性质及其生理权衡。它可以识别出有利于杨树在不同环境下种植和开垦的性状。它将有助于河流管理，以保护和恢复洪泛区森林，这些森林提供了丰富的野生动物栖息地，并有利于水质。为此，我们已经成功地与拥有和运营大型水坝的机构合作，实施环境流动和监管制度，使棉杨能够生存、生长和繁殖。这些发现还将有助于了解加拿大的落叶林如何应对气候变化，并考虑可能的应对措施，如种植辅助迁移。

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 poplars of western North America. 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 explore the spatial distributions of males versus females and the different species and hybrids within woodland groves, using new methods of drone imaging to complement field studies and remote sensing with aerial photography and satellite imagery. 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, and especially river valley floodplains in dry regions, where cottonwoods provide the only native trees. 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 diversity across poplars and the 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. For this, we are already successfully working with agencies that own and operate large dams, to implement environmental flows, regulated regimes that enable cottonwood survival, growth and reproduction. The findings 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.