Doctoral Dissertation Research: Long-Term Reconstruction of Oak Mast in the Southern Appalachian Region

美国东南部阿巴拉契亚山脉南部的橡树（栎属）在大多数年份结出橡子形状的果实。然而，在某些年份，橡子（也称为桅杆）的生产对一个地区的所有橡树来说都是特别沉重的。这些极端桅杆事件代表了树木的重大资源消耗，它们对野生动物和野生动物动态产生了深远的影响。在南阿巴拉契亚地区详细的测深纵向记录的发展正在提供资料，使人们能够对长期测深周期的动态进行科学检查，以及是否因气候变化或其他因素而发生了任何变化。本博士论文研究项目将采用树突年代学的树突重建新方法，探索南阿巴拉契亚地区橡树树突的空间特征。在阿巴拉契亚山脉南部的几个地点，将开发一百年的桅杆历史，这些重建将用于检查桅杆生产的时间趋势，探索气候与桅杆事件之间的联系，并调查桅杆事件的空间动态。该项目将生成一套长时间的橡树年表，这些年表在空间上分布在整个阿巴拉契亚山脉南部。多种年表将通过与整个地区20个美国历史气候网络（USHCN）气象站的单独林分记录进行比较，从而实现气候对树木生长影响的空间分析。该项目将对树木年代学技术的发展作出广泛贡献。通过该项目开发的长期桅杆重建将使森林学家、生态学家和生物地理学家能够通过回顾过去，更好地了解桅杆生态。该项目还将增加对自然系统动态中规模作用的见解。在不同尺度上对桅杆的分析将增强对桅杆动力学中驱动机制作用的理解。野生动物管理人员也可以使用桅杆记录来检查桅杆在过去野生动物种群波动中的作用，生态学家也可以使用这些记录来检查极端桅杆事件如何对橡树建立脉冲做出贡献。作为博士论文研究改进奖，该奖项还将提供支持，使有前途的学生建立一个强大的独立研究生涯。

Oak trees (Quercus spp.) in the southern Appalachians of the southeastern U.S. produce fruit in the form of acorns in most years. During some years, however, the production of acorns (also known as mast) is especially heavy for all oak trees in an area. These extreme mast events represent a significant resource expenditure for the trees, and they have profound impacts on wildlife and wildlife dynamics. The development of detailed longitudinal records of masting in the southern Appalachians is making available information that permits scientific examination of the dynamics of longer-term masting cycles and whether any changes have occurred in response to climate change or other factors. This doctoral dissertation research project will employ new methods for dendrochronological mast reconstruction to explore spatial aspects of masting in oaks in the southern Appalachians. One hundred-year mast histories will be developed for several locations in the southern Appalachians, and these reconstructions will be used to examine temporal trends in mast production, to explore links between climate and mast events, and investigate the spatial dynamics of mast events. The project will generate a set of long-duration oak chronologies that are spatially distributed throughout the southern Appalachians. Multiple chronologies will enable a spatial analysis of the effect of climate on tree growth by comparing individual stand records with twenty U.S. Historical Climate Network (USHCN) meteorological stations throughout the region. This project will contribute broadly to the development of dendrochronological techniques. The long-term mast reconstructions developed through this project will allow foresters, ecologists, and biogeographers to better understand mast ecology by looking back in time. The project also will add insights into the role of scale in the dynamics of natural systems. The analysis of masting at different scales will enhance understandings of the roles of driving mechanisms in mast dynamics. The mast records also can be used by wildlife managers to examine the role of mast in past wildlife population fluctuations and by ecologists to examine how extreme mast events contribute to oak-establishment pulses. As a Doctoral Dissertation Research Improvement award, this award also will provide support to enable a promising student to establish a strong independent research career.