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: 0717403
• 负责人: David Dettman
• 金额: $ 15.2万
• 依托单位: University of Arizona
• 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 2011-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0717403&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植物依赖于每年干旱期间由大型仙人掌和其他多肉植物提供的资源。例如，巨大的仙人掌的花和果实在一年中最干燥的时期为许多昆虫，鸟类和哺乳动物提供水，养分和能量。 saguaro的生长和繁殖对气候变异性和变化极为敏感，对依赖社区产生了潜在的重要影响。该项目开发了一种新的方法，用于评估气候波动，生长，压力反应和使用Saguaro Spine同位素组成中记录的信息的saguaro繁殖。 saguaro刺中的氧和碳稳定同位素比的变化记录了吸水和蒸发的模式，以及与水应激相关的光合作用过程的变化。由于刺是在仙人掌尖端生产的，并在植物上保留了多达100年或更长时间，因此任何Saguaro植物都可以使用长期，高分辨率的水平衡和光合应激记录。使用放射性碳（14C）约会技术来验证刺的年龄。这个新项目将在亚利桑那州的气候梯度中构建从萨瓜罗植物的整个生命中生长并保留的刺的高分辨率同位素记录。该项目假设1）刺的氧同位素比记录了水与萨瓜罗植物的来源和量以及蒸发条件下的变化； 2）碳同位素比反映了水应力对光合作用的影响。比较来自棘突的每年分辨同位素记录，其增长率，花/水果产量以及涵盖最近50年的气候记录将揭示Saguaro对局部和区域环境变化的反应。除两名博士后学生外，该提案还将资助原始的本科研究。该项目将针对现有的K-12外展计划开发有关仙人掌 - 水关系的课程单元。