Collaborative Research: An Isotopic Record of Response to Climate Change in Spines of Saguaro Cactus

合作研究：仙人掌刺对气候变化响应的同位素记录

• 批准号: 0717395
• 负责人: David Williams
• 金额: $ 23.6万
• 依托单位: University of Wyoming
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-08-15 至 2010-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0717395&HistoricalAwards=false
• 关键词: Collaborative; Research; Isotopic; Record; Response

Wildlife species in the Sonoran Desert depend on resources supplied by large, water-storing cactuses and other succulents during periods of annual drought. The flowers and fruits of the giant saguaro cactus, for instance, provide water, nutrients and energy to numerous insects, birds and mammals during the driest periods of the year. Growth and reproduction of saguaro are extremely sensitive to climate variability and change, with potentially important impacts on dependent communities. This project develops a novel approach for assessing climate fluctuations, growth, stress responses, and reproduction of saguaro using information recorded in the isotope composition of saguaro spines. Variation in the oxygen and carbon stable isotope ratios in saguaro spines records patterns of water uptake and evaporation and changes in photosynthetic processes associated with water stress. Because spines are produced at the growing tip of the cactus and retained on the plant for up to 100 or more years, a long-term, high-resolution record of water balance and photosynthetic stress is potentially available for any saguaro plant. The age of spines is verified using radiocarbon (14C) dating techniques. This new project will construct precisely dated, high resolution isotope records from spines grown and retained throughout the life of saguaro plants across climate gradients in Arizona. The project hypothesizes that that 1) oxygen isotope ratios of spines record the source and amount of water to saguaro plants and variation in evaporative conditions; and 2) carbon isotope ratios reflect water stress effects on photosynthesis. Comparison of annually-resolved isotope records from spines with growth rates, flower/fruit production, and climate records covering the last 50 to 80 years will reveal saguaro's response to local and regional environmental variation. In addition to two post-doctoral students, the proposal will fund original undergraduate research. The project will develop a curriculum unit on cactus-water relations for an existing K-12 outreach program.

索诺兰沙漠中的野生动物物种在每年的干旱期间都依赖于大型蓄水仙人掌和其他多肉植物提供的资源。例如，巨大的仙人掌的花朵和果实在一年中最干旱的时期为许多昆虫、鸟类和哺乳动物提供水、营养和能量。仙人掌的生长和繁殖对气候变异和变化极为敏感，对依赖的社区可能产生重要影响。该项目开发了一种新的方法，用于评估气候波动，生长，压力反应，以及使用记录在仙人掌刺的同位素组成的信息的仙人掌的繁殖。氧和碳稳定同位素比值的变化在仙人掌刺记录模式的水分吸收和蒸发，并在光合作用过程中与水分胁迫的变化。由于刺是在仙人掌的生长顶端产生的，并保留在植物上长达100年或更长时间，因此任何一种仙人掌植物都有可能获得长期、高分辨率的水分平衡和光合作用压力记录。棘的年龄是用放射性碳（14 C）测年技术验证的。这个新项目将构建精确的日期，高分辨率的同位素记录从刺生长和保留在整个生命的仙人掌植物在亚利桑那州的气候梯度。该项目假设：1）刺的氧同位素比记录了水的来源和数量，以Saguaro植物和蒸发条件的变化;和2）碳同位素比反映了水分胁迫对光合作用的影响。将刺的年分辨同位素记录与过去50至80年的生长率、花/果产量和气候记录进行比较，将揭示仙人掌对当地和区域环境变化的反应。除了两名博士后学生外，该提案还将资助原创本科研究。该项目将为现有的K-12外展计划开发一个关于仙人掌-水关系的课程单元。