Freeze-Thaw Cycles and Summer Drought: Constraints on WaterFlow in Related Rhododendron Taxa across two LTER sites

冻融循环和夏季干旱：两个 LTER 站点相关杜鹃类群水流的限制

• 批准号: 9630791
• 负责人: Erik Nilsen
• 金额: $ 16.86万
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-07-15 至 1999-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9630791&HistoricalAwards=false
• 关键词: Freeze; Thaw; Cycles; Summer; Drought

9630791 Nilsen The water conducting ability of plant stems must be sufficient to supply water to leaves for growth and other physiological processes. However, thewater conducting ability of the stem can be reduced when air bubbles formwithin the cells that normally conduct water. These bubbles can occur during drought when the tension, which pulls water through the plant from the soil to the leaves, becomes too great and the water column breaks. Also, during the winter, freezing of the water inside these cells causes air dissolved in the water to form bubbles which can expand and block water flow during periods of thaw. We will be studying the impact of the frequency and duration of drought and winter freeze-thaws on the water conducting ability of stems of related Rhododendron species. We will be utilizing the natural variation in winter freeze-thaw frequency and intensity of summer drought provided by two Long Term Ecological Research (LTER) sites to evaluate these following objectives: 1) determine the physical factors which control the maximum potential water flow through these plants, 2) to examine possible limits to water transport in relation to plant response to climatic patterns of water availability, and 3) to determine the structural/physiological adaptations of these species which may prevent or lessen the potential for the development of air blockages in their water conducting cells. This study will provide a cross-LTER comparison of the ecological physiology of closely related taxa, provide information of the controls of water flow through plants, and provide information about the water use of understory plants to be used in models of ecosystem water use budgeting.

小行星9630791 植物茎的导水能力必须 足以供水 到 叶子生长和其他 生理过程。 然而，当气泡形成在通常导水的细胞内时，茎的导水能力会降低。 这些气泡可能发生在干旱时，当张力，其中拉水通过植物从土壤到叶子，变得太大，水柱打破。 此外，在冬季，这些细胞内的水冻结导致溶解在水中的空气形成气泡，这些气泡可以在解冻期间膨胀并阻止水流。 我们将研究干旱和冬季冻融的频率和持续时间对相关杜鹃属植物茎导水能力的影响。 我们将利用 冬季冻融频率和夏季干旱强度的自然变化由两个长期生态研究（LTER）站点提供，以评估以下目标：1）确定控制通过这些植物的最大潜在水流量的物理因素，2）研究与植物对水可用性的气候模式的反应有关的水运输的可能限制，和3）确定这些物种的结构/生理适应性，这些适应性可能会防止或减少 导水细胞中出现空气堵塞。 这项研究将提供一个交叉LTER比较密切相关的类群的生态生理，提供信息的控制水流通过植物，并提供信息的林下植物的用水量用于生态系统用水预算模型。