SGER: Determining Seed Bank Age Structure with Tandem Accelerator Mass Spectrometry C14 Dating

在纯生态学和应用生态学中有许多问题，对种子库动态和种子年龄结构的理解是至关重要的。这些包括对演替、灭绝和殖民动态、植被恢复政策和杂草管理的理解。传统上，确定种子库年龄结构的唯一方法是对种子队列进行多年跟踪。该项目将使用包括串联加速器质谱（TAMS）在内的新技术来测定现代种子库的14C含量。这项技术，再加上1963年核弹试验造成的大气中碳含量的变化，应该可以准确估计过去30年里产生的种子的年龄。这个程序将用索诺兰沙漠一年生植物的种子进行测试。测年程序将用已知年龄的种子进行校准，然后用来测定这个沙漠一年生植物的种子库的年龄。人们普遍认为，长寿命种子库在沙漠年生植物的生态中起着重要作用，沙漠年生植物作为模式生物在我们对环境变异的适应和变环境下的群落动态的理解中发挥了重要作用。研究地点的沙漠年刊可获得长期人口统计数据。长期数据将有助于解释14C年代，因为过去14年种子产量的差异可以与它们被纳入种子库进行比较。同样，14C测年将有助于解释长期数据，可以估计种子保留在种群动态中的作用。这项探索性研究小额资助计划的研究将导致技术发展的重要突破，从而深入了解长期的社区动态和多样性。种子库年龄结构在许多生境中对许多生态问题至关重要，而TAMS 14C对种子长达30年的老化将构成一项重大的方法突破。

9520888 Venable There are many questions in both pure and applied ecology for which an understanding of seed bank dynamics and seed age structure is critical. These include an understanding of succession, extinction and colonization dynamics, revegetation policies, and weed management. Traditionally, the only way to determine seed bank age structure has been to follow seed cohorts for many years. This project will use new techniques involving Tandem Accelerator Mass Spectrometry (TAMS) to date modern seed banks with 14C. This technology, in conjunction with the variable levels of atmospheric 14C as a result of nuclear bomb testing which peaked in 1963, should permit accurate estimates of the ages of seeds produced over the last 30 years. This procedure will be tested with seeds of a Sonoran Desert annual plant. The dating procedure will be calibrated with seed of known age and then utilized to age a carefully sampled seed bank of this desert annual. It is widely believed that long-lived seed banks play an important role in the ecology of desert annuals and desert annuals have played an important role as model organisms in the development of our understanding of adaptation to environmental variability and community dynamics in variable environments. Long-term demographic data are available for desert annuals at the study site. The long-term data will aid in the interpretation of the 14C dates, because differences in production of seeds over the last 14 years can be compared to their incorporation into the seed bank. Likewise, the 14C dates will aid in the interpretation of the long-term data by permitting estimation of the role of seed retention in population dynamics. The research in this Small Grant for Exploratory Research proposal will lead to important breakthroughs in the development of technology that will permit in-depth understanding of long-term community dynamics and diversity. Seed bank age structure is critical in many habitats for many ecological questions, and TAMS 14C aging of seeds for up to 30 years of age would constitute a major methodological breakthrough.