Doctoral Dissertation Research: Spatial and Temporal Habitat Use of Elephants in the Serengeti Ecosystem: A Predictive Modeling Approach Using Multiscale Satellite Imagery

保护非洲剩余的大象种群及其栖息地已成为非洲大陆最大的野生动物管理挑战之一。在撒哈拉以南非洲的稀树草原生态系统中，大象是影响植被动态和结构的主要干扰源之一。在毗邻保护区的农村地区，大象也是人与野生动物冲突的主要贡献者。人类与大象之间的冲突(HEC)和大象对木本植物的影响都有可能加剧，因为大象数量在20世纪70年代和80年代的激烈偷猎后有所恢复，而以前的大象活动范围越来越受到人类住区的限制。位于坦桑尼亚北部和肯尼亚南部的25,000平方公里的塞伦盖蒂生态系统是世界上研究最深入的稀树草原生态系统之一。然而，近几十年来，关于大象种群动态或生态的研究很少，鉴于大象在塑造这一生态系统中的重要性，以及过去几十年发生的气候、植被覆盖以及人类和大象数量的变化，这是一个巨大的知识差距。该项目将结合实地测量的植被结构、光学和雷达遥感以及对坦桑尼亚塞伦盖蒂生态系统大象的卫星跟踪，绘制多个空间尺度的稀树草原结构图。这些绘制的变量将被用来在定量分布模型中预测大象的存在/不存在(通过卫星遥测获得)，这将提高对大象生态的以下方面的理解：1)影响稀树草原生态系统中大象栖息地选择的栖息地变量，以及这些变量的规模；2)预测大象使用人类主导的景观的因素，从而预测HEC。将使用时间序列雷达和光学卫星图像来识别研究区木本植物的变化模式。观察到的植被变化趋势将根据大象栖息地利用模型、遥感得出的火灾历史和气候数据进行评估，以更好地了解大象作为塞伦盖蒂生态系统变化因素的作用。本研究将使用新技术来调查大象栖息地选择及其对稀树草原林地结构的影响，为稀树草原生态学和野生动物-栖息地相互作用领域做出重大贡献。这将是首批在景观尺度上使用遥感技术来解决大象作为生态系统改良者的作用的研究之一。该项目将进一步促进以HEC为重点的不断扩大的研究领域，对导致大象使用人类占主导地位的地区的因素进行景观规模评估，并将提供对非洲最著名的野生动植物地区之一的适当生态系统管理至关重要的信息。这项研究的结果将使保护区管理人员能够将大象数量增长对稀树草原栖息地的影响以及HEC的生态相关性的信息纳入管理和缓解计划。该奖项由NSF的国际科学与工程办公室共同资助。

The conservation of Africa's remaining elephant populations and their habitats has emerged as one of the continent's greatest wildlife management challenges. In savanna ecosystems in sub-Saharan African, elephants are one of the major sources of disturbance influencing vegetation dynamics and structure. In rural areas adjacent to protected areas, elephants are also major contributors to human-wildlife conflict. Both human-elephant conflict (HEC) and the impacts of elephants on woody vegetation have the potential to intensify as elephant populations recover after the intense poaching of the 1970s and 1980s, while former elephant range becomes increasingly restricted by human settlement. The 25,000 square kilometer Serengeti ecosystem in northern Tanzania and southern Kenya is one of the best studied savanna ecosystems in the world. However, very few studies on elephant population dynamics or ecology have been conducted in recent decades, which represents a significant knowledge gap given the importance of elephants in shaping this ecosystem, and the changes in climate, vegetation cover and human and elephant populations that have occurred during the past decades. This project will employ a combination of field measurements of vegetation structure, optical and radar remote sensing, and satellite tracking of elephants in the Serengeti ecosystem of Tanzania to map savanna structure at multiple spatial scales. These mapped variables will be used to predict elephant presence/absence (obtained from satellite telemetry) within quantitative distribution models, which will improve understanding of the following aspects of elephant ecology: 1) the habitat variables that influence elephant habitat selection within a savanna ecosystem, and the scales at which these operate; 2) the factors that predict elephant use of human-dominated landscapes, and thus HEC. Time-series radar and optical satellite images will be used to identify patterns of woody vegetation change in the study area. The observed trends in vegetation change will be evaluated against models of elephant habitat use, remote sensing derived fire histories, and climate data to better understand the role of elephants as agents of change in the Serengeti ecosystem.This study will use techniques novel to investigations of elephant habitat selection and their impacts on savanna woodland structure, making significant contributions both to the fields of savanna ecology and wildlife-habitat interactions. It will be one of the first studies to use remote sensing technology at landscape scales to address the role of elephants as ecosystem modifiers. The project will further contribute to a growing field of study focused around HEC, by providing a landscape-scale assessment of the factors contributing to elephant use of human-dominated areas, and will provide information essential to appropriate ecosystem management in one of Africa's best-known wildlife areas. Results of the study will enable protected area managers to incorporate information both on the impacts of a growing elephant population on savanna habitats, and on ecological correlates of HEC, into management and mitigation plans.This award is co-funded by NSF's Office of International Science and Engineering.