Doctoral Dissertation Research: Holocene History of Atlantic Tropical Forest and Cerrado in Southeastern Brazil: The Role of Climate, Fire, and Human Disturbance

巴西东南部的大西洋森林是世界上受威胁最大的热带森林之一。关于这片多种多样的热带森林的历史和生态的许多方面仍然未知，尽管它正在迅速被清除。该项目将从气候变化、火灾发生和人类干扰的背景下研究巴西东南部自中全新世以来植被变化的历史。圣保罗州的生态敏感地区主要是大西洋季节性热带森林，但也有最南端分布的塞拉多(巴西稀树大草原)，这种植物以自然斑块的形式散布在季节性森林中。该地区被美洲原住民占领了数千年，但在过去150年里，密集的森林砍伐使大西洋森林变成了大小不一的孤立碎片。这片广阔的森林/塞拉多交错带和一些森林碎片中的三个湖泊将被取芯进行孢粉研究。将对沉积物中的花粉和微观木炭进行分析，以详细记录过去几千年的植被变化和火灾历史，特别是自欧洲接触以来的最后几百年。这项研究将产生与全新世气候变化、自然和人为火灾以及人类干扰有关的森林/塞拉多交错带发展的古生态记录。它将讨论大西洋热带森林森林碎片化造成的生物多样性丧失和生态退化问题，并将深入了解热带地区保护生物学和环境规划方面的关键问题。这项研究还将促进热带孢粉学的发展，特别是在人类对热带植被影响的研究中的应用。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。

The Atlantic forest in southeastern Brazil is one of the most threatened tropical forests in the world. Many aspects concerning the history and ecology of this diverse tropical forest are still unknown, even as it is being cleared at a rapid rate. This project will study the history of vegetation changes in southeastern Brazil since the middle Holocene in the context of climatic changes, fire occurrence, and human disturbance. The ecologically sensitive region in the state of Sao Paulo is occupied mainly by Atlantic seasonal tropical forest, but it also contains the southernmost distribution of cerrado (Brazilian savanna), which occurs as natural patches interspersed within the seasonal forest. The region has been occupied by native Americans for thousands of years, but intensive deforestation over the last 150 years has reduced the Atlantic forest into isolated fragments of various sizes. Three lakes within this broad forest/cerrado ecotone and in some of the forest fragments will be cored for palynological study. The sediments will be analyzed for pollen and microscopic charcoal to produce detailed records of vegetational changes and fire history for the last several millennia, especially focusing on the last several hundred years since the European contact. This study will produce paleoecological records on the development of the forest/cerrado ecotone in relation to Holocene climatic changes, natural and anthropogenic fires, and human disturbance. It will address questions concerning the loss of biodiversity and ecological degradation due to forest fragmentation in the Atlantic tropical forest, and it will provide insight into key issues in conservation biology and environmental planning in the tropics. This study will also advance the science of palynology in the tropics, especially its application in the study of human impacts on tropical vegetation. 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.