Doctoral Dissertation Research: Holocene Environmental Change in the Northern Peten and its Implications for Maya Prehistory

在过去的40年里，在墨西哥南部和危地马拉的玛雅低地进行了几项古生态和地球化学研究。这些研究表明，在晚更新世和全新世期间，这一重要考古区的气候在不同的时间尺度上发生了变化。一些记录还表明，与农业活动和城市化有关的人类影响造成了大量的森林砍伐和土壤侵蚀。然而，在大多数情况下，无法区分自然和人类引起的环境变化。这导致了关于玛雅低地人口增长和下降的主要原因的不确定性。这一博士论文研究项目将详细记录危地马拉北半球全新世晚期的环境变化，该地区在前古典主义时期人口稠密，但现在几乎没有人居住。这项记录将基于对2001年从两个相对较小的湖泊--阿图罗港和春图基--回收的沉积物岩心的分析。将对岩心进行分析，以确定沉积物化学、化石花粉、微观木炭、磁化率和稳定同位素的变化。将通过对木炭和陆地植物材料进行16次放射性碳测定(每个湖8次)来提供时间控制。初步结果表明，阿图罗港核覆盖了全新世的大部分地区，而春图基核则覆盖了过去1350年的大部分时间。因此，阿图罗港岩芯将提供一个长期的记录，而春图基岩芯将提供一个高分辨率的记录，记录晚期经典玛雅人的遗弃。玛雅低地的戏剧性人口变化导致学者们猜测环境退化和气候变化可能起到的作用。该项目将尝试通过使用广泛的分析技术来区分人类引起的环境变化和自然环境变化的相对重要性。在玛雅低地南部的佩滕-伊察湖也曾尝试过类似的方法，但由于该湖的面积很大，结果并不确定。这项研究的作者得出结论，北冰洋较小的湖泊可以提供更敏感的记录。因此，这篇论文研究的学术价值在于它有可能填补我们在玛雅低地古环境变化方面的一个重要空白。从更广泛的意义上说，这项研究的结果将对当前的土地利用政策有用。了解玛雅低地环境变化的原因和影响将有助于制定合理的资源管理政策。从公元前2500年到公元前1000年，北腾地区支持着人口稠密的地区，由此对自然资源的压力很可能导致了该地区的前古典和古典时期的遗弃。对史前玛雅农业的研究表明，森林砍伐和侵蚀随着人口的增长而增加。近几十年来，北电的人口呈爆炸式增长，因此也需要一种考虑到环境变化历史的资源政策。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。

During the last 40 years, several paleoecological and geochemical studies have been carried out in the Maya lowlands of southern Mexico and Guatemala. These studies have shown that climate in this important archaeological area has changed on a variety of time scales during the late Pleistocene and Holocene. Some records also indicate that human impacts associated with agricultural activity and urbanization caused significant forest clearance and soil erosion. In most cases, however, it has not been possible to distinguish between natural and human-induced environmental change. This has led to uncertainty regarding the primary causes of population growth and decline in the Maya lowlands. This doctoral dissertation research project will provide a detailed record of late Holocene environmental change in the northern Peten of Guatemala, an area that was densely populated during the Preclassic period but now is virtually uninhabited. The record will be based on the analysis of sediment cores recovered in 2001 from two relatively small lakes: Puerto Arturo and Chuntuqui. The cores will be analyzed to determine variations in sediment chemistry, fossil pollen, microscopic charcoal, magnetic susceptibility and stable isotopes. Chronological control will be provided by 16 radiocarbon determinations (eight per lake) on charcoal and terrestrial plant material. Initial results suggest that the Puerto Arturo core covers most of the Holocene and the Chuntuqui core the last 1,350 years. The Puerto Arturo core therefore will provide a long-term record and the Chuntuqui core a high-resolution record of the Late Classic Maya abandonment.The dramatic population changes in the Maya lowlands have led scholars to speculate on the possible roles of environmental degradation and climate change. This project will attempt to separate the relative importance of human-induced and natural environmental change by using a wide range of analytical techniques. A similar approach has been attempted at Lake Peten-Itza in the southern Maya lowlands, the results of which were inconclusive because of the large size of the lake. The authors of that study concluded that smaller lakes in the Peten could provide more sensitive records. The intellectual merit of this dissertation research therefore lies in its potential ability to fill an important gap in our knowledge of paleoenvironmental change in the Maya lowlands. In a broader sense, the findings of the study will be useful to current land-use policies. Understanding the causes and effects of environmental change in the Maya lowlands will help develop sound policy for resource management. The Peten supported dense populations from 2500 to 1000 BP, and the resulting pressure on natural resources may well have led to the Preclassic and Classic period abandonments of the area. Studies of prehistoric Maya agriculture have shown that deforestation and erosion increased with population growth. Population has exploded in the Peten in recent decades, and so too has the need for a resource policy that takes into account the history of environmental change. 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.