Detecting Wild Rice in Lake Sediments by Phytoliths and Cuticle Analysis: A Pilot Study in the Great Lakes Bioregion

野生稻（Zizania spp.）是北美历史上重要的动物和人类食物来源。美国土著社区和生态学家努力了解其最近在部分地理范围内减少的原因，并制定合适的恢复策略。目前需要一种可靠的方法，根据湖泊沉积物估计其过去的分布。该项目将通过比较来自该地区的现代植物宏观和微观化石收集与来自湖泊核心的数据来研究重建野生稻地理分布的方法，其中基于花粉数据假设了野生稻存在的证据。从地理上讲，研究区域将集中在明尼苏达州东北部和中部，苏必利尔湖以西和米勒湖以南。之所以选择这个地区，是因为它靠近目前北方野生稻分布的北部边界，并且有很好的可获得的年代湖芯覆盖。将在光镜和扫描电子显微镜下对现存的四种齐扎尼亚植物（三种在北美，一种在亚洲）的现代植物样本进行检查，以确定诊断性植物岩和草角质层的存在。现代沉积物样本将从一系列湖泊中采集，这些湖泊中现在有野生水稻，以评估不同大小和结构的湖泊中现代微化石的分布范围。该数据集将用于重新分析六个现有的湖芯，这些湖芯已经确定了花粉的年代并进行了分析，其中花粉丰度的峰值被解释为野生水稻丰度的峰值，但从未得到证实。此外，将从目前存在野生稻或根据考古证据被认为存在野生稻的湖泊中收集3至6个新的岩芯，以制作研究区域自冰期晚期至今（距今约15,000年）过去野生稻分布和丰富程度的点图。本研究将开发一种新的、简单的方法，利用简单的取芯装置和光学显微镜来估计湖泊沉积物中野生稻的存在和丰度。这将是首次在湖泊沉积物和其他一些发生在大湖生物区的湿地草中寻找齐扎尼亚和Leersia二氧化硅微/大化石的区别特征的系统努力。这项研究将为从事野生水稻恢复工作的考古学家、生态学家和生物地理学家提供一种新的、快速的方法来独立验证过去湖泊林分中野生水稻的存在。研究结果将通过出版物、图像网络档案、报告和讲习班向自然资源专业人员和美洲土著部落代表广泛传播。它将进一步培训一名研究生和两名本科生（后者来自美洲土著背景），学习一种快速分析沉积物中野生水稻的新方法。该数据集将对美国、加拿大和亚洲的古生态和考古界产生重大影响。

Wild rice (Zizania spp.) is a historically important food source for animals and humans in North America. Native American communities and ecologists struggle to understand reasons for its recent decline over portions of its geographical range and to develop suitable restoration strategies. A need exists to have a reliable method of estimating its past distributions based on lake sediments. This project will examine methods of reconstructing the geographic distribution of wild rice by comparing a modern plant macro- and microfossil collection from the region with data from lake cores, in which evidence of wildrice presence had been postulated based on pollen data. Geographically the area of study will focus on northeastern and central Minnesota, west of Lake Superior and south to Lake Mille Lacs. This region is chosen because it is near a northern limit of the present northern wild rice distribution and has a good coverage of available dated lake cores. Modern plant samples of four extant Zizania species (three in North America and one in Asia) will be examined under light and SEM microscope for presence of diagnostic phytoliths and grass cuticles. Modern sediment samples will be taken from a range of lakes, where wild rice is present today to assess modern range of microfossil distribution within lakes of different size and configuration. The dataset will be used to reanalyze six existing lake cores that had been dated and analyzed for pollen, in which spikes in pollen abundance had been interpreted, but never proven, as spikes in wild rice abundance. Additionally three to six new cores will be collected from lakes where wild rice is currently present or is believed to have existed based on archeological evidence to produce a point map of past distribution and abundance of wild rice in the study area since the late glacial to present (approximately 15,000 years before the present to today). This study will develop a new and simple method of estimating presence and abundance of wild rice in lake sediments using simple coring devices and a light microscope. It will be a first-of-its kind systematic effort to look for distinguishing characteristics of Zizania and Leersia silica micro/macrofossils in lake sediments and some other wetland grasses that occur in the Great Lakes bioregion. This study will benefit archeologists, ecologists, and biogeographers working on wild rice restoration by providing a new quick way of independently verifying past presence of wild rice in stands in a lake. The results will be broadly disseminated via publications, web archive of images, presentations and workshops to natural resource professionals and Native American tribal representatives. It will further train one graduate and two undergraduate students (the latter from Native American background) with a new method of rapid wild rice analysis in sediments. The dataset will be of significant benefit to the paleoecological and archaeological communities in the U.S., Canada, and Asia.