SGER: Measuring and Interpreting Nitrogen in Tree Rings

摘要00-87007谢泼德·斯盖尔：测量和解释年轮中的氮目前，科学家们还不能明确地解释年轮中的氮浓度。这样做的能力将极大地提高对N循环的理解，包括最近N沉积的人为大幅增加的影响。解释树木年轮中N浓度的一个困难是，N在植物组织中的移动性是出了名的，这使得它在树木年轮中作为年轮形成时环境可获得性的简单指示器的可解释性受到质疑。另一个困扰对树轮N浓度的简单解释的困难是，它对N有效性和吸收变化的反应仍然不确定。这项探索性研究有两个目标：改进准确测量树木年轮中N的技术，并考虑N在年轮之间可能的转移，以及校准树木年轮中N浓度对已知N有效性变化的响应。

Abstract 00-87007 Sheppard SGER: Measuring and interpreting nitrogen in tree rings Presently, scientists cannot unequivocally interpret nitrogen concentrations in tree rings. The ability to do this would greatly improve understanding of N cycling, including the effects of recent large anthropogenic increases in N deposition. One difficulty in interpreting N concentration in tree rings is that N is notoriously mobile across plant tissues, rendering questionable its simple interpretability in tree rings as indicators of environmental availability at the time of ring formation. Another difficulty that has confounded simple interpretations of tree-ring N concentration is that its response to changes in N availability and uptake is still uncertain. This exploratory research has two objectives: to refine techniques for accurately measuring N in tree rings and accounting for possible translocation of N across rings, and to calibrate the response of N concentration in tree rings to known changes in N availability.