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A comprehensive understanding of modern pollen transport processes is a prerequisite for utilizing fossil pollen to elucidate the evolution of palaeoclimates and palaeoenvironments, especially in areas such as southwestern China where complex mountainous topography results in vegetation heterogeneity. In this paper, we selected four vertical profiles in mountainous regions of southwestern China, each with distinct plant communities, to investigate the relationship between modern pollen rain, vegetation types and vegetation cover, and to quantify the influence of environmental factors. Results show that pollen assemblages are generally representative of regional plant communities, although long-distant transport of arboreal pollen by valley winds can introduce signals from a much wider area. The calibrated arboreal pollen percentage (AP) and ratio of arboreal pollen to non-arboreal pollen (AP/NAP) serves as reliable quantitative proxies for vegetation cover, highlighting the importance of appropriate calibration when interpreting fossil pollen assemblages. Climate is the primary determinant of pollen distribution across these mountains, with mean temperature of the coldest month (MTCM) playing the most prominent contribution. Additionally, the impact of vegetation cover and soil nutrients on pollen distribution are also significant. Our modern study improves the accuracy of pollen interpretation for palaeoenvironmental reconstruction in mountainous regions of southwestern China. • Pollen assemblages can effectively depict the characteristics of mountain vegetation communities. • The calibrated AP percentage and AP/NAP can quantitatively indicate arboreal cover. • MTCM controls pollen distribution in different mountains of southwestern China. • Climate dominates pollen distribution below treeline and vegetation cover controls above treeline. [ABSTRACT FROM AUTHOR]

The sedimentary sequences of the Yangtze River delta comprise important Quaternary records of tectonics, sea-level oscillation, and climatic change; however, analysis is hampered by a lack of a reliable chronological framework. In this paper, we present an integrated chronology for two sedimentary sequences (core ZKW2 and ZKW4) on the southern side of the Yangtze River delta, based on magnetostratigraphy and absolute methods (OSL, 14C, and ESR dating). The basal ages of the core ZKW2 and ZKW4 are ca. 2.25 Ma and 2.96 Ma, respectively. The integrated chronology indicates significant increases in the sedimentary accumulation rate at ∼0.15 Ma, rather than the Matuyama-Brunhes boundary as indicated by magnetostratigraphy alone. The observed sedimentary transition is possibly controlled by regional subsidence of the Zhe-Min Uplift, and climate evolution during the last interglacial period. • High-quality magnetostratigraphy is obtained for the Quaternary sediments in the YRD. • The SARs of the YRD sediments significantly enhanced since ∼0.15 Ma. • Tectonics and climate factors jointly control the sedimentary evolution in the YRD. [ABSTRACT FROM AUTHOR]

Grain size is commonly used as a proxy to reconstruct past lake hydrology; however, published research rarely links grain size with modern processes, and uncertainties exist for interpretation. In this paper, we decompose the grain size frequency distributions (GSFD) for 196 lake surface sediments from 61 lakes and 9 reservoirs across the Inner Mongolia Plateau and adjacent areas and divide them into five GSFD components. We statistically analyze the relationship between the GSFD components and influencing variables to determine the taphonomic dynamics and their environmental implications. Within individual lakes, we found that GSFD component 4 (74.00–209.30 μm) and GSFD component 5 (209.30–592.00 μm) dominate near the lake margin and reduce toward the lake center in proportions. By contrast, GSFD component 2 (2.75–15.56 μm) increases toward the lake center. Therefore, the proportions of GSFD component 2, 4, and 5 reflect the relative distance to the lakeshore and allow inferences about lake area changes. We apply this large modern dataset to a sediment core obtained from Lake Wulanhushao (WLHS) on the Inner Mongolia Plateau and link the lake surface sediment-based GSFD components to BEMMA end-members of grain size records to define their environmental implications over the last 18.59 cal. kyrs BP. We found that the Lake WLHS has responded to the orbital and suborbital climate changes since the last deglaciation. Specifically, maximum lake transgression prevailed during the early to middle Holocene (11.70–7.10 cal. kyr BP), medium lake transgression dominated during 17.05–15.80 cal. kyr BP, and weak transgression developed during 14.60–12.90 cal. kyr BP. Maximum lake regressions prevailed before 17.05 cal. kyr BP, during 15.80–14.60 cal. kyr BP and 12.90–11.70 cal. kyr BP. Our reconstructed early Holocene maximum lake area is consistent with regional abiotic proxy-based moisture records, but contrasts with the regional biotic proxy-based moisture records, which reconstruct increasing moisture conditions. Our new method to determine lake area changes will provide valuable data to understand the climate dynamics of northern China. • We numerically revealed the environmental implications of grain size components of lake surface sediment. • Linking lake surface sediment grain size component to core end members provide basis for interpretations. • Maximum lake transgression prevailed during the early Holocene in northern China. • Abiotic proxies-based early Holocene lake transgression is distinct with biotic proxies' reconstructions. [ABSTRACT FROM AUTHOR]

The end Permian to Middle Triassic interval (∼252–242 Ma) witnessed the largest marine mass extinction and the most delayed recovery in the Phanerozoic. The nature and mechanism of these biotic and environmental changes remain unclear. This special issue focuses on the Triassic marine sediments in South China, which provide unique documentation of the collapse and recovery of marine ecosystems. Six papers focus on biotic changes and their ecological significance in Early and Middle Triassic times, documenting evidence from bivalves, marine reptiles, stromatolites, hybodontid teeth, vertebrate coprolites, and other putative fossils. Two papers study conodont biostratigraphy across the Permian-Triassic boundary (PTB) and Induan-Olenekian boundary. Two papers reconstruct the palaeoenvironments of the Early Triassic Chaohu Fauna and Middle Triassic Luoping Biota. Two further papers present new marine δ13C records and biomarker data and link them to volcanic eruptions in Early Triassic times. These new findings are important for understanding the co-evolution between biotic and environmental changes in the aftermath of Permian-Triassic boundary mass extinction. [ABSTRACT FROM AUTHOR]

Human impact on the coastal plain of Southeast China has been well studied over late Holocene timescales; however, an understanding of anthropogenic impact in mountainous regions is still lacking. In this paper, we present records of vegetation, fire, and human impact, spanning the past 4000 years, with a resolution of ∼40 years, obtained from an upland peatland in Southeast China. The results reveal that climate change (dominated by the evolution of the East Asia Monsoon) was the most critical factor controlling vegetation before 1.0 cal kyr BP, while human impact gradually emerged as the primary driver after 1.0 cal kyr BP in the mountains of Southeast China. As such, the record of anthropic impact in mountainous regions lagged behind the signal from the coastal plains by some 2000–4000 years. As the population migrating from northern China dispersed into the mountainous regions of Southeast China, demand for agricultural land promoted slash-and-burn cultivation and the destruction of broad-leaf forest. • Three climatic stages identified spanning 4.0 cal kyr BP based on pollen and charcoal analysis. • Significant anthropogenic impact on mountain vegetation of Southeast China occurred in 1.0 kyr BP, lagged coastal plains by 2000–4000 years. • The population migrating from northern China dispersed into the mountainous regions of southeastern China in 1.0 kyr BP, urgent demand for cultivated land. [ABSTRACT FROM AUTHOR]

The decline of ancient societies has been often associated with hydroclimate instabilities. In this paper, we report phytolith records from the Yangtze River Delta of China, to reconstruct middle and late Holocene climate dynamics, and understand societal impacts. Our findings reveal that the area experienced a consistent decline in temperature and humidity punctuated by several rapid climate shifts. A distinct dry episode from 7000 to 6000 cal yr BP likely developed in response to weakened Atlantic Meridional Overturning Circulation (AMOC) and a southward shift of the intertropical convergence zone (ITCZ), resulting in a weakened East Asian summer monsoon (EASM) and a strengthened East Asian winter monsoon (EAWM). This dry condition would have favoured the emergence of dryland and facilitated rice cultivation in the lower Yangtze region. Another dry episode at 4500–4000 cal yr BP, which was probably associated with the widespread 4.2 ka climate event, and linked to a further retreat of the ITCZ and highly variable ENSO intensity, led to highly unstable hydroclimate conditions in the region. We argue that this event disrupted social resilience and culminated in the cultural collapse at the end of Liangzhu Culture. • Cooling trend since 8000 cal yr BP in response to decline of summer insolation. • Dry episodes at 7000–6000 and 4500–4000 cal yr BP. • Strength of AMOC and position of ITCZ jointly modulates the EASM. • Neolithic societal resilience shows varied responses to each dry episode. [ABSTRACT FROM AUTHOR]

Discriminating the provenance of fine-grained sediments is crucial for reconstructing paleogeography, sedimentary processes, and paleoclimate. In this paper, we investigate the South Bohai Coast to better understand source-to-sink systems in East Asia. This region is influenced by both distant sources such as the large-scale Yellow River and small local river sources flowing from the Luzhong Mountain area. Two Holocene sedimentary cores, dated using optically stimulated luminescence (OSL) and accelerator mass spectrometry (AMS) 14C chronology, were used to investigate the provenance of the fine-grained sediments over the last 7 kyrs. Clay mineralogy and relevant non-linear modeling were employed for provenance discrimination. The results show that the fine-grained sediments along the South Bohai Coast were mainly derived from the Yellow River during the periods of 7.0–5.4 ka and 4.5–2.6 ka, respectively, while the input from the Luzhong Mountain-derived rivers was greater during 5.4–4.5 ka and 2.6–0.2 ka, respectively. Fluvial activities and marine-terrestrial interaction driven by climate factors such as East Asian winter monsoon, temperature, and precipitation in river basins, dominantly influenced the provenance of fine-grained sediments from 7.0 to 2.6 ka. Anthropogenic impact on provenance increased after 2.6 ka. The chronology of the two cores showed extremely rapid sedimentation rate transitions at 5.2 ka and 1.5 ka, respectively, very likely attributed to anthropogenic-induced rapid progradation. Our study provides a model for better understanding the paleoenvironmental and paleogeographic evolution of a coastal area where multiple sources exist. • Anthropogenically high sedimentation rate in the South Bohai Coast in late Holocene. • Provenance discrimination of the fine-grained sediments in the South Bohai Coast since the mid-Holocene. • The major source of the fine-grained sediments in the South Bohai Coast changed episodically. [ABSTRACT FROM AUTHOR]

Coastal wetlands provide valuable ecosystem services and understanding their response to past climatic changes may help predict their possible future responses. In this paper, we obtained records of pollen, algae, sediment grain-size, and other environmental proxies, from a late Holocene sediment core (CFD-E) from the Caofeidian area, on the northwest coast of the Bay of Bohai, China. Our results indicate three major stages of environmental change. During Stage I (3500–2800 cal yr BP), arboreal pollen content was high (mostly >60%), especially for Pinus and Quercus , and the PCA sample scores on Axis 1 were negative indicating that regional vegetation was temperate broadleaved forest and the climate was wet. During Stage II (2800–2350 cal yr BP), the arboreal pollen content decreased substantially (mostly <40%), and the PCA Axis 1 sample scores were positive indicating a decrease in forest vegetation, grassland expansion, and a drier climate. During Stage III (2350–1400 cal yr BP), the arboreal pollen content increased again (mostly >40%), although it remained lower than during Stage I, indicating that forests expanded under a relatively humid climate while the wetland area decreased slightly. Our results also record the 2.8 ka and 2.4 ka events of monsoon weakening, which were characterized by increases in herbaceous pollen (indicating grassland expansion) and the drying of the regional climate. There are several differences in the regional expression of these two climatic events. During the 2.4 ka event, Chenopodiaceae pollen increased substantially (average of 42.0%), indicating the expansion of halophytes; whereas during the 2.8 ka event, an increase in Artemisia indicates the occurrence of a dry climate throughout the region. We suggest that the aridity during the 2.8 ka event was triggered by decreased solar activity and the resulting changes in the El Niño-Southern Oscillation, which weakened the East Asian summer monsoon. However, we suggest that the 2.4 ka event was driven by the weakening of the Atlantic Meridional Overturning Circulation. • Significant increase in halophytic vegetation during 3500–1400 cal yr BP • The 2.8 ka and 2.4 ka events were characterized by climate drying lasting ∼150 years. • During these two events the area of forest decreased and grassland expanded. [ABSTRACT FROM AUTHOR]

In this paper, we investigate Holocene precipitation changes in northern China to improve the understanding of the East Asian summer monsoon (EASM) and provide an environmental context for the development of Chinese civilisation. Our study is based on an analysis of 260 pollen samples from Holocene lacustrine sediments at Ningjinpo in northern China, and employs the biomisation method to reconstruct regional vegetation types and vegetation changes, and to decipher their driving factors, by incorporating regional climatic data and information on human activities. Results indicate that, in the early Holocene (10,000–8100 cal yr B.P.), regional climate was dry, with annual precipitation of 470 mm. In the middle Holocene (8100–3000 cal yr B.P.), a rapid increase was observed in precipitation, reaching 580 mm. During the late Holocene (2600–600 cal yr B.P.), climate became drier again, with annual precipitation decreasing to 480 mm. Between 10,000–600 cal yr B.P., vegetation exhibited distinct successional patterns dominantly influenced by climate, transitioning from meadow-steppe to forest, and then back to meadow-steppe. After 600 cal yr B.P., vegetation succession decoupled from climate change, with human activities emerging as the primary driving force, as indicated by the substantial increase in anthropogenic pollen and charcoal concentrations. In the future, under the combined influence of global warming and intensified human activity, the implementation of scientific environmental planning measures will become increasingly important for the restoration and sustainable development of regional vegetation ecosystems. • Unambiguous high-resolution precipitation record from the North China Plain. • Human activities variedly impact vegetation evolution since 2600 cal yr B.P. • A shift from natural to anthropogenic vegetation change happened at 600 cal yr B.P. [ABSTRACT FROM AUTHOR]

The Zhe-Min Uplift (ZMU) has undergone tectonic subsidence, which has been associated with a notable transgression in the northern marginal seas of China since the middle Pleistocene. However, its uplift history during the late Quaternary is still inadequate. The Old Red Sand (ORS) is a late Pleistocene deposit that is widely distributed along the southeastern coast of China. The ORS consists of partially-cemented fine- to medium-grained sand. In this paper, we focus on mud-rich ORS deposits of the Liushui area, Pingtan Island, Fujian Province, and report optically stimulated luminescence (OSL) ages, and new datasets of grain size, mineralogy (detrital zircon, clay and detrital minerals) and organic carbon and nitrogen isotope profiles to improve understanding of chronology, provenance, palaeoenvironmental evolution and tectonic infuence. Based on the OSL data, we hypothesize that the development of the ORS was associated with lower sea levels, with most deposition occurring within MIS4. Based on comparison of detrital zircon U Pb ages, the coarse fraction of the Liushui ORS was mainly derived from the Minjiang River, with modest input from weathering of coastal granites. The East Asian Winter Monsoon contributed some materials from the East China Sea shelf during the last glacial period, as indicated by the fine-grained nature of the Liushui ORS, low K-feldspar/plagioclase ratios, high dolomite content and the frequency of Neoproterozoic and Palaeoproterozoic detrital zircons. The deposition of the ORS was influenced by both the East Asian Winter Monsoon and sea level changes. The clay minerals in the mud layers of the Liushui ORS were dominated by kaolinite and illite, with little chlorite and no smectite, indicating that they originated from the Minjiang River. The TOC/TN ratios of the mud layers, as well as their isotope characteristics, indicate the organic matter was derived from marine sources, presumably during the transgression event in MIS5. The average uplift rate of the ORS was about 0.03 mm/yr. The uplift of the ORS provided new insights into the geological records of the ZMU, which differed from the subsidence observed in the northern region of the Minjiang River during the late Pleistocene. • The formation of the ORS was association with lower sea level, and the MIS4 was primarily the deposition stage. • During the last glacial, the more sediments from the East China Sea shelf were transported to the ORS by EAWM. • The mud layer was the transgression records during MIS5. • The distribution of the ORS was influenced by tectonic activity. [ABSTRACT FROM AUTHOR]

The Carnian Pluvial Event (CPE) induced an intense carbon-cycle disturbance and biological crisis at a global scale. The eruption of the Wrangellia Large Igneous Province (W-LIP) is considered a possible triggering mechanism; however, this cannot fully explain the significant differences in environmental perturbations across different regions. In this paper, we present detailed records of petrography, mercury geochemistry, carbon and sulfur isotopes, trace elements, and provenance data for the Triassic lacustrine facies of the Ordos Basin in the North China Plate, which provide insights into the important effects of volcanic activities, other than the W-LIP, on palaeoenvironment during the CPE interval. Massive emissions of SO 2 , CO 2 , and pyroclastic deposits resulting from these volcanic activities triggered four humid episodes, each characterized by lake-level rise, negative δ13C org excursion, a transition from mudstones to organic-rich shales facies, as well as algal bloom within a time span of 180 kyrs. The establishment of an age framework in the Ordos Basin enables comparative analyses of environmental evolution during the Carnian age across the North China Plate, the western Tethys domain, and the South China Plate. During the period of global climate perturbation driven by the W-LIP eruption, we conclude that short-term localized volcanic activities may have further induced high frequentcy environmental perturbations, which influenced biological shifts and increase organic carbon burial. These short-term volcanic activities with different occurrence times and frequencies complicate local-scale palaeoenvironmental evolutions, which may be an important reason contributing to significant differences in environmental perturbations during the CPE interval across different regions of the globe. • Four humid episodes and sedimentary changes occurred within 0.18Ma in the Ordos Basin during Carnian age. • Environmental changes in the Ordos Basin was related to the local volcanisms in its nearby Qinling orogenic belts. • Short-term local volcanisms can complicate the environmental evolutions in different parts of globe during the CPE interval. • Local volcanic processes may cause inconsistent environment perturbation in different parts of globe during the CPE interval. [ABSTRACT FROM AUTHOR]

Southwestern China, a biodiversity hotspot, underwent dramatic climate change following the Last Glacial Maximum and intensive human activity also exerted a major impact since the late Holocene. In this paper, we report a pollen record from Yilong Lake in Yunnan Province, southwestern China, to understand vegetation response to long-term climatic variation and human activities at a regional-level over the last 27,000 years. Findings show that temperate and coniferous taxa were dominant before 18 cal kyr BP reflecting the glacial climate. Between 18 and 14 cal kyr BP, thermophilic taxa increased in response to global deglaciation. A notable shift from deciduous to evergreen forests occurred at approximately 14 cal kyr BP, after which pollen concentration increased but pollen diversity decreased. Pollen assemblages indicated dense forests, primarily composed of evergreen oaks developed under warm and strong summer monsoon conditions from 13 to 8 cal kyr BP. High rates of vegetation change occurred during the middle Holocene before vegetation diversity gradually increased during the Holocene Thermal Optimum, with high variability of precipitation in the Yilong Lake region. Anthropogenic forcing progressively became the main factor affecting vegetation composition and vegetation change rates over the past three millennia. • We reported a pollen record from Yilong Lake in Yunnan province, China. • Cold-tolerant taxa dominated before 18 cal kaBP after which thermal-like taxa increased. • Evergreen forests replaced deciduous forests around 14 cal kaBP. • Vegetation change rates peaked in mid-Holocene with mega-thermal but frequent droughts. • Departure of vegetation and potential climax occurred in late-Holocene due to human activities. [ABSTRACT FROM AUTHOR]

The Heinrich Stadial 2 (HS2) event is poorly defined in the Greenland δ18O ice core record; however, it can be identified in stalagmite records from China. In this paper, we reconstruct an absolutely-dated and high-resolution calcite δ18O record from Shima Cave, central China, covering the interval from 26.0 to 23.9 ka BP, with a temporal resolution of ~16 years. By integrating our newly reported record with all available δ18O records of Marine Isotope Stage 2 from China, which are securely 230Th/U-dated, we calculate the timing of the onset, termination and duration of HS2. The statistical results show that the prominent HS2a phase started at ~24.4 ± 0.1 ka BP and ended at ~23.6 ± 0.1 ka BP, lasting approximately 0.8 ± 0.3 ka. If the onset of the Dansgaard-Oeschger 2 event in the Greenland δ18O record is synchronous with the termination of HS2a, then the GICC05 chronology should be adjusted by +230 years to align it with stalagmite results. Further investigation of HS2 shows that Chinese cave records exhibit a distinct two-fold structure, corresponding to HS2a and HS2b, as observed in marine sediment cores, particularly those recovered around the Atlantic Ocean. These records show comparable changes in relative amplitudes during the HS2a and HS2b phases, which could possibly be related to different weakening episodes in the Atlantic Meridional Overturning Circulation. • An ~16-year-resolution East Asian summer monsoon (EASM) history covering the onset of Heinrich Stadial 2 event. • Statistical analyses of timing for Heinrich Stadial 2. • Globally pervasive twofold structure during Heinrich Stadial 2. [ABSTRACT FROM AUTHOR]