Doctoral Dissertation Research: Method to Determine the Geographic Distribution of Timber

考古木材提供了人类存在的记录，从技术发展到经济和社会组织。这篇博士论文资助的重点是木材，它过去和现在都是对人类社会具有根本重要性的资源。作为一种有机产品，木材也是一种环境档案，树木年代学的科学已经利用它来重建可以追溯到几百到几千年前的过去环境。如果知道有关树木的生长地点（种源），就可以最有效地利用这一信息。多种不同的方法来确定运输木材样品的地理来源已被应用于考古木材，包括木材解剖特征，古代DNA和木材的化学成分的研究，但都面临着限制其适用性的缺点。该项目开发了一种新的来源方法，重点是使用多种同位素来帮助限制考古木材样本可能起源的区域。除了对过去人类社会和气候的洞察之外，这项研究还可以通过开发一种有助于识别非法砍伐木材的方法来应用于现在，并通过对环境变化的长期展望来应用于未来。研究重点是三种特定元素的同位素：氧，硫和锶。这些同位素的天然比例在地理上各不相同，这意味着特定的位置具有特定的同位素特征，这也反映在该位置生长的树木的木材中。为了了解这些特征在空间上是如何分布的，博士生和同事们通过测量具有已知位置的森林站点的树木的同位素值来开发同位素地图（isoscape）。然后可以对考古木材样本进行同样的测量，并与isoscape进行比较，以确定树木可能来自哪些地区。多种同位素的使用是以前考古学起源的一个关键发展，因为它允许考虑更多的化学变化，并确定更精确的生长位置。该项目的一个关键目标是开发的方法可以应用于来自不同地区和时间段的多个木材品种。该项目进行了三个案例研究。第一种考虑的是松树样本，它们可能来自遥远的地方。第二种是来自纽约州的铁杉样本，这些样本是欧洲人在该地区扩张定居时砍伐的。第三个重点是橡树木材，提供了900年的古气候记录。这三个案例研究捕捉了一系列环境、生物和时间因素，从而允许开发一种强大而通用的方法，这将有助于实现考古木材的潜力。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Archaeological wood provides a record of human existence ranging from technological development to economic and social organization. This doctoral dissertation grant focuses on wood which has been and remains a resource of fundamental importance to human societies past and present. As an organic product, wood is also an environmental archive which the science of dendrochronology has harnessed to reconstruct past environments dating back hundreds to thousands of years. This information can be most effectively utilized if the growth-location (provenance) of the trees in question is known. Multiple different approaches to determine the geographic origin of transported wood samples have been applied to archaeological wood, including the study of wood anatomical features, ancient DNA, and the chemical composition of wood, but all have faced drawbacks which limit their applicability. This project develops a new approach to provenance focused on the use of multiple isotopes to help constrain the area from which archaeological wood samples could have originated. As well as insight on past human societies and climates, this research is also applicable in the present through the development of a method which can help to identify illegally logged timber, and the future by contributing a long-term perspective on environmental change.The research focuses on the isotopes of three specific elements: oxygen, sulfur, and strontium. The natural ratios of these isotopes vary geographically, meaning that specific locations have a particular isotopic signature which is also reflected in the wood of trees growing in that location. To understand how these signatures are distributed spatially, the doctoral student and colleagues develop isotope maps (isoscapes) by measuring the isotope values of trees from forest sites which have a known location. The same measurements can then be made on archaeological wood samples and compared to the isoscapes to determine which areas the trees could and could not have come from. The use of multiple isotopes is a key development on previous archaeological provenancing as it allows more chemical variation to be considered and a more precise growth-location to be identified. A key goal of this project is that the method developed can be applied to multiple wood species from diverse regions and time periods. The project conducts three case studies. The first considers pine samples whose origin could be from far afield. The second considers hemlock samples from New York State which were felled during the expansion of European settlement in the region. The third focuses on oak timbers which provide a 900-year palaeoclimate record. The three case studies capture a range of environmental, biological, and temporal factors, thereby allowing the development of a robust and versatile method which will help to realize the potential of archaeological wood.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.