SGER: Measuring and Interpreting Nitrogen in Tree Rings

摘要00-87007谢泼德SGER：测量和解释树木年轮中的氮目前，科学家们不能明确地解释树木年轮中的氮浓度。 这样做的能力将大大提高了解氮循环，包括最近的大人为增加氮沉降的影响。 解释树木年轮中N浓度的一个困难是N在植物组织中是众所周知的移动的，使其在年轮形成时作为环境可用性指标的简单可解释性受到质疑。另一个困难，混淆了树木年轮氮浓度的简单解释是，它对氮的可用性和吸收的变化的反应仍然是不确定的。这项探索性的研究有两个目标：精确测量树木年轮中的N和占可能的氮跨环易位，并校准响应树木年轮中的N浓度已知的变化，N的可用性，以完善技术。

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.