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

考古木材提供了从技术发展到经济和社会组织的人类存在的记录。这项博士论文资助的重点是木材，木材一直是并且仍然是过去和现在人类社会至关重要的资源。作为一种有机产品，木材也是一种环境档案，树木年代学已经利用它来重建过去的环境，可以追溯到数百年到数千年。如果已知有关树木的生长位置（来源），则可以最有效地利用这些信息。确定运输木材样本地理来源的多种不同方法已应用于考古木材，包括木材解剖特征、古代DNA和木材化学成分的研究，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，这项研究也适用于现在，因为它开发了一种方法，可以帮助识别非法采伐的木材，并通过对环境变化提供长期视角来应用于未来。这项研究的重点是三种特定元素的同位素：氧、硫和锶。这些同位素的自然比例在地理上是不同的，这意味着特定的地点有特定的同位素特征，这也反映在该地点生长的树木的木材中。为了了解这些特征是如何在空间上分布的，博士生和他的同事们通过测量已知位置的森林遗址的树木的同位素值来绘制同位素图（等温线）。然后可以对考古木材样本进行同样的测量，并将其与等高图进行比较，以确定树木可能来自哪些地区，也可能来自哪些地区。多种同位素的使用是以前考古溯源的一个关键发展，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不同地区和不同时期的多种木材。该项目进行了三个案例研究。第一种方法考虑的是松树样本，它们的产地可能来自很远的地方。第二组研究的是来自纽约州的铁杉样本，这些铁杉是在欧洲人在该地区扩张定居期间被砍伐的。第三个重点是橡树木材，它提供了900年的古气候记录。这三个案例研究捕获了一系列环境、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。该奖项反映了美国国家科学基金会的法定使命，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.