Reconstructing Holocene landscape development in Mongolia influenced by climate and pastoralism, based on geomorphological archives

基于地貌档案重建受气候和畜牧业影响的蒙古全新世景观发展

• 批准号: 429299280
• 负责人: Professor Dr. Manfred Anton Frechen
• 金额: --
• 依托单位: Leibniz-Institut für Angewandte Geophysik (LIAG)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/429299280?language=en
• 关键词: Reconstructing; Holocene; landscape; development; Mongolia

The key question of this project, i.e., since when and to what extent humans have influenced the vegetation pattern in the semihumid to arid forest steppe and steppe regions of Mongolia, has not yet been finally resolved. The archeological record provided by graves and sacral buildings only starts with the Bronze Age (3.5 ka BP). At that time, the nomadic lifestyle, including the whole spectrum of herd animals, was already fully established. However, the preceding period of the transition from the lifestyle of hunters and gatherers to stockbreeding is poorly documented, as artefacts of this period are rare. This project is based on the hypothesis that the development of pastoralism since the end of the Neolithic period led to a substantial change in the vegetation, which in turn triggered an intensification of geomorphological processes. In this project, we will develop and apply an innovative scientific approach that will allow us to identify the spatial and temporal patterns of the onset of human-induced landscape changes at local and regional scale. The approach will include a combination of geomorphological-pedological field and laboratory analysis, numeric dating, charcoal and biomarker analyses. The involved geomorphological-pedological methods are based on the following causal chain: Human activities such as woodcutting, fire-setting and wood pasture caused reduction of forest area and degradation of steppe vegetation by overgrazing. These anthropogenic impacts on the landscape resulted in increased soil erosion, as well as fluvial and eolian sediment redistribution. This causal chain led to a strikingly extensive distribution of stratified sediments in this landscape, containing organic layers, paleosols and charcoal. These sediments represent excellent archives for the reconstruction of the Holocene geomorphodynamics and their chronological course in this landscape. They will be the key study objects of this project. Direct evidence for the first occurrence of domestic livestock and corresponding pastoral economy will be obtained from the analysis of lipid biomarkers. In particular, fecal steroids that are preserved as stable compounds in paleosols and sediments, will serve as indicators of the local presence of relevant animal species such as horse, yak, cattle, sheep and goat.The successful implementation of the intended combination of geomorphological, pedological and geochemical methods will also contribute an important new approach to the identification of anthropogenic signals in paleoclimate reconstructions. This contribution will be highly relevant, as the existing uncertainties in the reconstruction of the late Holocene paleoclimatic development of Mongolia derive mainly from the interference of climatic and anthropogenic signals in the proxy data that are hardly separable by existing methods.

该项目的关键问题，即人类何时以及在多大程度上影响了蒙古半湿润至干旱森林草原和草原地区的植被格局，尚未最终解决。坟墓和祭祀建筑提供的考古记录仅始于青铜时代（3.5 ka BP）。那时，包括各种畜群在内的游牧生活方式已经完全确立。然而，关于从狩猎采集生活方式向畜牧业转变的前一个时期的记载很少，因为这一时期的文物很少。该项目基于这样的假设：新石器时代末期以来畜牧业的发展导致植被发生了重大变化，进而引发了地貌过程的加剧。在这个项目中，我们将开发和应用一种创新的科学方法，使我们能够识别当地和区域范围内人类引起的景观变化的空间和时间模式。该方法将包括地貌土壤学领域和实验室分析、数值测年、木炭和生物标志物分析的结合。所涉及的地貌土壤学方法基于以下因果链：伐木、放火和木材牧场等人类活动导致森林面积减少和过度放牧导致草原植被退化。这些人为对景观的影响导致土壤侵蚀加剧，以及河流和风成沉积物的重新分配。这一因果链导致了该景观中层状沉积物的广泛分布，其中包含有机层、古土壤和木炭。这些沉积物为重建全新世地貌动力学及其在该景观中的年代进程提供了极好的档案。他们将是本项目的重点研究对象。通过脂质生物标志物的分析，可以获得家畜首次出现和相应的畜牧经济的直接证据。特别是，在古土壤和沉积物中以稳定化合物形式保存的粪便类固醇，将作为当地存在相关动物物种（如马、牦牛、牛、绵羊和山羊）的指标。土壤学和地球化学方法也将为古气候重建中识别人为信号提供重要的新方法。这一贡献将具有高度的相关性，因为重建蒙古全新世晚期古气候发展的现有不确定性主要源于代理数据中气候和人为信号的干扰，而这些信号很难通过现有方法分开。