Role of Winter Water Relations in Determining the Upper Elevational Limits of Three New England Conifers

冬季水关系在确定三种新英格兰针叶树海拔上限中的作用

• 批准号: 9603860
• 负责人: Richard Boyce
• 金额: $ 18.99万
• 依托单位: University of Denver
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-02-01 至 1999-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9603860&HistoricalAwards=false
• 关键词: Role; Winter; Water; Relations; Determining

9603860 Boyce Evergreen conifers, unlike diciduous trees, must keep their foliage alive during the winter. In addition to freezing stress, they must deal with drought, or desiccation. A lot of water is found in the winter environment, but it is usually locked up as snow and ice and is unavailable to plants. Conifer foliage is adapted to minimize water loss during the winter; losses are replaced during above-freezing periods, when water stored in the wood melts and can flow into the foliage. Shorter growing seasons at high elevations decrease foliar resistance to winter water loss, while the frequency and duration of warm periods in the winter also decreases. Thus, the amount of water lost increases, while the ability to replace it decreases. Winter desiccation appears to cause alpine treeline in some places. However, its role in setting the upper elevational limits of conifers that do not extend all the way to treeline is poorly known. This study will examine the foliar winter water relations, or water balance, of three important New England conifers that differ in location preferences and growth strategies: white pine, eastern hemlock and red pine. Our preliminary data suggest that the older foliage in these species may experience damaging water levels during the winter. We will use physiological measurements of trees collected near their upper elevational limit to determine desiccation stress. These data will be coupled with climatic data collected at the research sites to predict water relations. This approach may be extended to other species and under conditions imposed by a changing climate.

9603860博伊斯 万年青针叶树不像落叶树，必须在冬天保持叶子的活力。 除了冰冻压力，它们还必须应对干旱或干燥。 在冬季环境中发现了大量的水，但它通常被冰雪锁住，植物无法利用。 针叶树的叶子适合在冬季尽量减少水分流失;在冰点以上的时期，当储存在木材中的水分融化并流入森林时，损失会得到补充。 树叶 较短的生长季节 在 高海拔降低了叶片对冬季水分流失的抵抗力，而冬季温暖期的频率和持续时间也减少了。 因此，失去的水量增加，而补充的能力降低。 冬季干燥似乎导致高山树线在一些地方。 然而，它在设定不延伸到树线的针叶树的海拔上限方面的作用却知之甚少。 本研究将探讨叶冬季水分关系，或水分平衡，三个重要的新英格兰针叶树，不同的位置偏好和增长战略： 白松、铁杉和红松。 我们的初步数据表明，这些物种的老叶可能会经历破坏性的水位 在冬天。 我们将使用生理测量的树木收集接近其海拔上限，以确定干燥应力。 这些数据将与在研究地点收集的气候数据相结合，以预测水的关系。 这种方法可以扩展到其他物种，并在气候变化的条件下。