理解过去植被变化驱动机制是开展当前植被保护和恢复的理论依据。青藏高原东缘森林-草原过渡带植被对环境变化响应敏感，驱动机制复杂，而晚全新世人类活动的增强使其驱动机制更为复杂，且存在争议。为回答青藏高原大规模农牧业什么时间开始及其对植被影响强度如何这两个科学问题，本项目拟选取青藏高原东缘不同植被、不同土地利用形式和强度（包括牧场和农田）现代沉积物和动物（包括牲畜）粪便等样品，开展现代花粉和粪生真菌孢子现代过程研究，利用数理分析方法量化花粉及菌孢对植被和人类活动（畜牧业和种植业）的指示意义；通过开展甘肃碌曲县尕海和青海省玛多县星星海晚全新世湖泊沉积物的花粉、非花粉孢粉类型、古DNA及其它常规环境代用指标分析，重建该地区晚全新世高分辨率（分辨率30~40年/样品）的植被、环境及人类活动变化过程；并结合花粉和粪生真菌孢子现代过程研究成果，分析人类活动对植被影响强度。

Understanding of driving mechanism (natural and artificial) of past vegetation change is the theoretical basis for current vegetation protection and restoration. Vegetation is quite sensitive to environmental changes in forest-steppe transition zone on the east margin of Tibetan Plateau with complex driving mechanism; and the enhanced human activities complexes driving mechanism during the late Holocene. This project plans to perform modern pollen and spore of coprophilous fungi analyses across the east margin of Tibetan Plateau, to decide their indication of vegetation and human activities (grazing and farming) quantitatively. Simultaneously, we will reconstruct the past vegetation, environmental and land-use changes during the late Holocene (since ca. 7 cal ka BP) with high temporal resolution (ca. 30~40 years/sample), based on pollen, non-pollen palynomorph (NPP), ancient DNA and other environmental proxies analyses on the lacustrine sediment collected from the Xingxinghai Lake (Maduo County, Qinghai Province) and Gahai Lake (Luqu County, Gansu Province) in the forest-steppe transition zone, and investigate the intensity of human impacts on vegetation based on the conclusion of modern pollen and fungi spore investigations.