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The investigation of two profiles (DYS1 and DYS5) from the Daiyun Mountains in southeastern China sheds new light on the history of regional climate changes and the variability of the intensity of the East Asian Summer Monsoon (EASM) over the past 10350 years based on the degree of peat humification, loss on ignition (LOI), magnetic susceptibility (MS) and geochemical (Rb, Zr and Zr/Rb) data. The records indicate that three main climatic regimes have occurred over the past 10350 years: 1. relatively warm and wet conditions from ~10350 to 8800 cal BP; 2. a warmer and wetter climate from 8800 to 3000 cal BP that was interrupted by four cold episodes at 7500, 6400, 5400, and 4400 cal BP; and 3. a dry and cool climate after ~3000 cal BP. These climatic changes were probably associated with a weak EASM, which was related to the latitudinal movement of the Intertropical Convergence Zone (ITCZ). Other important influences include solar radiation, etc. [ABSTRACT FROM AUTHOR]

The Yangtze River Basin is a crucial region in the monsoon region of China, and reconstructing its hydrological and precipitation evolution is important for developing a more robust understanding of the evolution of the East Asian Summer Monsoon. A pollen record from a strata profile (JZ2010) in the Jianghan Basin of Central China reveals variations in paleovegetation and paleoenvironmental and paleoclimatic conditions covering the last 24 cal kyr BP at ∼90 years resolution. We perform a quantitative precipitation reconstruction (based on a weighted averaged partial least squares method). Results of the study show that the vegetation in the region experienced a succession from coniferous and broad-leaved mixed forest to evergreen and deciduous mixed forest and then to secondary coniferous forest. Over the past 24 kyr, the climate was relatively dry during the deglacial period, particularly during HS1 and the Younger Dryas cold event, interrupted by a warm and humid Bølling-Allerød. Precipitation in the early Holocene was at its maximum, peaking between 10.0 and 7.0 cal kyr BP followed by drier conditions between 6.5 and 4.5 cal kyr BP. Subsequent wetter conditions lasted until 3.8 cal kyr BP, after which precipitation gradually declined. Overall, the quantitative precipitation reconstruction is consistent with other proxy-based precipitation reconstructions in the Yangtze River region. However, the temporal pattern of variations in precipitation is distinct from that of the northern China monsoon region, where the precipitation peak occurred during the mid-Holocene. The study suggests that, prior to the Holocene, climate change was controlled by insolation dynamics and high latitude teleconnections, while during the Holocene it was primarily influenced by low latitude teleconnections, including the El Niño-Southern Oscillation, which controlled the dipolar rainfall pattern in the monsoon region of China. The high resolution record of changing climate in the East Asian monsoon region over a period spanning the LGM and Holocene provides a useful benchmark for modelling future precipitation change in southern and northern China against the background of global warming. • The study provides a high resolution pollen record of regional vegetation, climate, quantitative monsoon precipitation and environmental reconstruction since 24 cal kyr BP in Central China. • Results showed a peak in precipitation during the early Holocene which contrasts with northern China. • Prior to the Holocene, climate change was controlled by insolation dynamics and high latitude teleconnections, while during the Holocene it was primarily influenced by low latitude teleconnections. [ABSTRACT FROM AUTHOR]

Since the Holocene, long–term human activities have altered the composition, structure, and function of ecosystems, yet uncertainty remains regarding the underlying mechanism of a variety of vegetation responses to both natural and anthropogenic forces. In this study, we collected and categorized 37 fossil pollen records from Zhejiang, a region characterized by continuous Neolithic Cultures in eastern China, into natural and human–impacted sites. The aim was to reconstruct past long–term changes in plant traits and to investigate variations in ecosystem functioning under the pressure of natural climate shifts and anthropogenic disturbances. Our findings reveal that, during the Holocene, plant functional traits at natural sites gradually adapted to warmer and wetter conditions, with the natural functional dispersion (FDis) showing a steady decrease between 9.0 and 4.0 cal ka BP. At human–impacted sites, intensified human activities gradually transformed the landscape from forest to grassland and shrubland, allowing light–demanding vegetation to thrive due to extended canopy gaps. Pioneer plants flourished in the secondary succession, leading communities to exhibit more aggressive resource acquisition strategies compared to a natural community. With the progression of agriculture towards intensive practices, ancestors might have expanded their original ecological niches by shaping a landscape encompassing a gradient of grasslands, shrublands, and forests, leading to an increase in plant diversity and a reversal in the trend of decreasing FDis. Higher functional diversity is considered a potential factor in maintaining ecosystem stability. Neolithic human activities, by modifying plant composition, community structure, and shaping landscape gradients, probably contributed to enhancing the stability of past terrestrial ecosystems. [Display omitted] • The Holocene long-term climatic trends forced a convergence of vegetation functions. • The intensive agricultural practice had shaped new landscapes and increased functional diversity. • Human activities induced responses to plant trait changes by directly altering plant components. • Neolithic human activities resulted in vegetation adopting more aggressive resource acquisition strategies. [ABSTRACT FROM AUTHOR]

The Holocene Temperature Conundrum refers to the mismatch between proxy-based temperature records and those based on climate model simulations. A possible reason for this mismatch is a putative proxy-based bias in reconstructed summer temperatures, and therefore, regional reconstructions of seasonal temperature are crucial for resolving the conundrum. In this paper, we reconstruct vegetation and climate changes over the last ∼10,000 years BP based on a high-resolution pollen record from Gushantun peatland, Changbai Mountains, Northeast China. Multiple quantitative reconstruction approaches were used and weighted averaging partial least squares regression (WAPLS) was found to be the most appropriate method for reconstructing Holocene temperature and precipitation. The reconstructed climate record shows that the Holocene Climate Optimum occurred between 8 ka and 6 ka and exhibited a cold month mean temperature that was 3 °C warmer than modern temperatures. Climate gradually cooled during late Holocene with a minimum cold month temperature of −19.6 °C. Four prominent cold events occurred around 8.7 ka BP, 7.8 ka BP, 5.7 ka BP, and 2.5 ka BP with an amplitude variation up to 3 °C. The synthesized seasonal temperature time series and a comparison with other proxies show that the decreasing trend in mean annual temperature is not a seasonal bias caused by summer temperature change. This study provides evidence of a Holocene seasonal temperature change at a regional scale and insights for further understanding of the Holocene Temperature Conundrum. • Reconstructed seasonal temperature changes based on a new high-resolution fossil pollen record in the Changbai Mountains • Synthesized climatic series in Northeast China to investigate the characteristics of regional temperature changes and their driving factors • Reconstructed winter temperature as evidence to address the alleged seasonal bias for the Holocene temperature conundrum [ABSTRACT FROM AUTHOR]