Temporal and spatial evolution of Holocene vegetation and lake hydrological status, China

Studying past climate change has important scientific significance in exploring long-term climatic variability, assessing the nature and human’s contribution to climate warming, and predicting future climate change. Here, we presented a data synthesis of pollen records, organic geochemical proxies, as well as lake-level records, along with numerical climate classification and lake-level simulations to show temporal and spatial evolution of past vegetation and hydrologic change during the Holocene in China. Both geological data and numerical modeling indicated that the evolution of vegetation shows out-of-phase relationships with lake hydrological status in various regions. China as a whole experienced optimal vegetation cover in the mid-Holocene. However, areas dominated by the Asian monsoon and the Westerlies did not uniformly show an early Holocene hydrological optimum. For the Westerlies-controlled regions, optimal conditions prevailed during the mid-Holocene. These apparent contradictions were closely related to various driving factors in different geographical regions. Precipitation has been recognized as a major influence on lake hydrological status of arid and semi-arid in northeast China, whereas in other regions of China, the combined effect of evaporation and precipitation was more influential. Likewise, the limiting factor of vegetation conditions was asynchronous in China, for example, moisture in northwestern China, temperature in the Qinghai-Tibet Plateau, as well as moisture and temperature in the monsoon marginal zones and monsoonal regions. The results provide insights into the underlying climate-forcing mechanisms, and demonstrate a new perspective on Quaternary environment change research.