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

该项目的关键问题，即人类从何时起以及在多大程度上影响了蒙古半湿润到干旱的森林草原和草原地区的植被格局，尚未最终得到解决。坟墓和祭祀建筑提供的考古记录只始于青铜时代(3.5ka BP)。当时，游牧生活方式，包括整个牧群动物的范围，已经完全确立。然而，从狩猎者和采集者的生活方式向畜牧业转变的前一个时期记录很少，因为这一时期的人工制品很少。该项目基于这样一种假设，即新石器时代末期以来牧业的发展导致植被发生重大变化，进而引发地貌过程的加剧。在这个项目中，我们将开发和应用一种创新的科学方法，使我们能够确定局部和区域尺度上人类引起的景观变化的时空模式。该方法将包括地貌-土壤场和实验室分析、数字测年、木炭和生物标志物分析相结合。所涉及的地貌-土壤学方法基于以下因果链：人类活动，如伐木、放火和放牧，导致过度放牧导致森林面积减少和草原植被退化。这些对景观的人为影响导致土壤侵蚀加剧，以及河流和风沙沉积物的重新分布。这种因果链导致了层状沉积物在这一景观中的广泛分布，包括有机层、古土壤和木炭。这些沉积物是重建全新世地貌动力学及其在该地貌中的年代学过程的极好档案。他们将是本项目的重点研究对象。通过对脂类生物标志物的分析，将获得首次出现家畜和相应的牧区经济的直接证据。特别是，作为稳定化合物保存在古土壤和沉积物中的粪便类固醇，将作为马、牦牛、牛、绵羊和山羊等相关动物物种在当地存在的指示器。地貌学、土壤学和地球化学方法的成功结合也将为识别古气候重建中的人为信号贡献一种重要的新方法。这一贡献将具有重要意义，因为重建蒙古晚全新世古气候发展的现有不确定性主要来自替代数据中气候和人为信号的干扰，而现有方法很难将这些干扰分开。

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.