The Impact of Simulated Climate Change on Sugar Maple at the Hardwood/Boreal Forest Ecotone

森林对气候变化的反应有据可查。 对植物群落的研究表明，在最近的冰河时代之后的18,000年里，北美的植物物种因自然气候变暖而改变了分布范围。 在这段变暖期间，温度上升的速度是中等的，植物物种迁移几乎没有困难。 然而，对未来几百年人类引起的气候变化的预测表明，变暖可能比树木物种以前经历的要快得多。这种快速的气候变化可能会严重影响许多物种的繁殖能力，并在目前发现它们的地区继续生存下去，最重要的是，许多物种最终可能无法迁移到更适合其环境需要的地方。 总的来说，这一问题可能导致改变森林群落，主要由具有广泛环境耐受性的物种主导。 该研究项目的重点是评估人类引起的气候变化对北美北方糖枫幼苗和种子的影响。 研究人员将评估糖枫树幼苗对空气温度和土壤湿度条件变化的敏感性。作为北美东部森林中的优势物种，糖枫可能会影响人类改变气候下的大部分生态变化。 研究人员将研究哪些气候变量（温度和/或降水）控制生长并导致植物胁迫或死亡，最终危及糖枫在这些森林中的持续存在，并扩展到整个北方部分糖枫在北美东部的范围。 该项目有两个目标：（1）确定未来的空气温度和降水状况可能对现有的糖枫幼苗在糖枫的当前北方限制在加拿大中部安大略，和（2）确定的程度，种子从两个地区（安大略和伊利诺伊州）发芽和生长在田间条件下，在温暖和凉爽的气候在糖枫的当前范围。 这些问题将从两个方面加以解决。 首先，红外线加热灯和防雨结构将被用来改变温度和降水制度的自然发生的糖枫树幼苗在中部安大略模拟模拟气候条件预测的研究领域在2060年代。 其次，调查人员将从两个代表糖枫目前温度范围内极端温度条件的地点收集和分散糖枫种子。糖枫的未来具有重要的生态和经济意义。 人类可能有必要作为种子传播者对那些种子传播有限的物种进行干预，如糖枫。 该项目将开始确定在需要人工辅助种子传播的情况下可作为种子来源的种群。 因此，该项目将增加生物地理学和森林生态学领域虽小但不断增长的知识库，该知识库调查气候变化对自然生态系统的影响，最终目标是为人类在植物无法适应（或无法适应）的情况下进行干预做好准备。远距离）适应快速变化的条件。 项目结果将提供关于是否存在糖枫可能无法生存的生态阈值的信息，以便森林管理人员、建模人员和决策者能够开始考虑环境变化何时可能变得不可挽回的有害，并监测这些变化即将发生的迹象。

Forest response to climate change is well documented. Studies of plant communities demonstrate that plant species in North America shifted range in response to natural climate warming over the past 18,000 years following the most recent ice age. During that warming period, rates of temperature increases were moderate and plant species migrated with little difficulty. Projections of human-induced climate change over the next several hundred years suggest, however, that warming may be much faster than tree species experienced previously. This rapid rate of climate change may severely impact the ability of many species to reproduce and persist in regions where they are currently found. Most significantly, numerous species may ultimately be unable to migrate to locations more suited to their environmental needs. Collectively, this problem may result in altered forest communities dominated largely of species with broad environmental tolerances. The focus of this research project is to evaluate the impact of human-induced climate change on sugar maple seedlings and seeds at the species' northern limit in North America. The investigators will assess the sensitivity of sugar maple seedlings to alterations in air temperature and soil moisture conditions. As a dominant species in forests throughout eastern North America, sugar maple may influence much of the ecological change under human-modified climates. The investigators will examine which climate variables (temperature and/or precipitation) control growth and lead to plant stress or death, ultimately jeopardizing the continued presence of sugar maple in these forests and, by extension, across the northern portion of sugar maple's range in eastern North America. This project has two objectives: (1) To determine the impact that future air temperature and precipitation regimes may have on existing sugar maple seedlings at sugar maple's current northern limit in central Ontario, Canada; and (2) To determine the degree to which seeds from two regions (Ontario and Illinois) germinate and grow under field conditions in warmer and cooler climates within sugar maple's current range. These questions will be addressed in two ways. First, infrared heat lamps and rain-exclusion structures will be employed to alter the temperature and precipitation regimes of naturally occurring sugar maple seedlings in central Ontario to mimic modeled climate conditions projected for the study area in the 2060s. Second, the investigators will collect and reciprocally disperse sugar maple seeds from two sites representing extreme temperature conditions within sugar maple's current range.The future of sugar maple is of great ecological and economic importance. It may be necessary for humans to intervene as seed dispersers for those species with limited long-range seed dispersal, like sugar maple. This project will begin the process of identifying populations that may act as seed sources in the event that human-aided seed dispersal becomes necessary. This project therefore will add to the small but growing knowledge base in biogeography and forest ecology that investigates the impact of climate change on natural ecosystems with the eventual goal of preparing humans to intervene in the event that plants fail to adapt (or are unable to disperse long-distances) to the rapidly changing conditions. The project results will provide information regarding whether ecological thresholds exist beyond which sugar maple may not survive so that forest managers, modelers, and policy makers can begin to consider when environmental changes may become irreparably detrimental and monitor for indications that those changes are imminent.