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Simple Summary: In this study, we provide descriptions of three fossil species, Calamites cistii, Macrostachya sp., and Punctatisporites punctatus, discovered in the Cisuralian of the eastern Hexi Corridor, northwestern China. Our findings offer insights into the evolution of Calamitaceae strobili during the Late Paleozoic. Calamitaceae was the predominant arborescent element of the Late Paleozoic plant assemblages. However, there is currently controversy surrounding the evolutionary relationships of their four reproductive organs, and there is no unified understanding of the geographical distribution and species richness characteristics. This paper is based on the detailed description of the macro- and microstructures of Calamites and Macrostachya discovered in the Shanxi Formation of the Cisuralian in the eastern Hexi Corridor of northwestern China, and it discusses the evolutionary patterns of calamitean reproductive organs. The results indicate that the current specimens can be identified as the Calamites cistii and Macrostachya sp., and the in situ spores should exhibit distinct trilete marks, indicating that they belong to the Punctatisporites punctatus. The abundant fossil records suggest that the "Calamostachys" type should be considered as the ancestral type of strobili. Additionally, Calamitaceae was widely distributed in mid to low latitudes globally from the Pennsylvanian to the Cisuralian and coupled with paleogeographic distribution characteristics. [ABSTRACT FROM AUTHOR]

Microcharcoal morphology, which changes with biofuel type in the wildfire, can be used as an index for wildfire history and vegetation evolution. Here, five loess sites across the Chinese Loess Plateau were used to establish the biofuel history of the region during the Holocene based on microcharcoal morphological records. The results suggested that consistently increasing grass biofuel dominated the mid‐Holocene (∼7,500–3,000 yr BP), and the grassland or steppe expanded in the same interval. Since the climate conditions with simultaneous high precipitation and temperature of the mid‐Holocene are the most recent paleoclimate analog for future warming, we argue that the humid and warm conditions expected under future global warming on the Loess Plateau might lead to an increase in the grass rather than trees. Plain Language Summary: As the product of the incomplete combustion of plants, microcharcoal has been widely used as a wildfire indicator, though microcharcoal morphology has received little attention. Studies have recognized that microcharcoal morphology can indicate the biofuel type (grass or wood) burnt in wildfires and thus can be used as an ideal index in wildfire history and vegetation evolution research. Here, we shed new light on biofuel history based on this established relationship. We compiled 425 microcharcoal records from five sites across the Chinese Loess Plateau and combined the data with compiled pollen records to establish the vegetation history during the Holocene. The results suggest that grassland or steppe was prevalent during the mid‐Holocene, consistent with the synthesized herb pollen records, biome reconstruction, and high precipitation and temperature. Because the climate conditions of the mid‐Holocene are the most recent paleoclimate analog for future warming, we infer that the humid and warm conditions expected under future global warming may promote the expansion of grass vegetation on the Loess Plateau. The insights may reveal the vulnerability of the restoration achievements dominated by plantations today. In addition, we highlight the potential of the more easily preserved microcharcoal to explore vegetation history in future work. Key Points: Microcharcoal morphological history reveals that grassland or steppe dominated the mid‐Holocene on the Chinese Loess PlateauThe humid and warm conditions under future global warming on the Chinese Loess Plateau might lead to prevalent grass rather than treesEvidence suggests that more native grassland or steppe should be considered in future restoration programs on the Loess Plateau [ABSTRACT FROM AUTHOR]

As one of the most important reservoirs of water in arid regions, lakes experience a series of complicated changes. However, the natural driving mechanisms behind such changes remain unclear. In this study, we collected data from 1333 lakes in the arid region of Central East Asia (CEA) to investigate the underlying natural causes of lake changes over the past five decades. The lakes were located within three different geomorphological zones: (I) Tibetan Plateau zone; (II) high mountain—basin zone; and (III) low mountain zone. Our results show that lakes as a whole in CEA exhibit a unique change trend, with an overall lake area increase of 7099 km2 (41%) and with heterogeneous spatial variations over the past five decades. The lake area increase was 6236 km2 (47%), 935 km2 (31%) and decrease was 72 km2 (~1%) in zones I, II, and III, respectively. The different geomorphological zones have influencing factors. In zones I and II, increased precipitation (including cloud water) and temperature rise (causing glacier, frozen soil, and snow melt) contributed to approximately 66% of the change in lake area; in zone III, changes in precipitation contributed to approximately 87% of the lake changes. Increased atmospheric circulation of water vapor caused by warming of the ocean surface appears to be the main driving factor of these changes; this is supported by future projection scenarios. From 2006 to 2098, temperature and precipitation will increase by 4.0–7.8 °C and 1.07 to 1.29 mm per day, respectively, under both the RCP4.5 and RCP8.5 scenarios. Notably, although the climate appears to have become more optimum for lakes in CEA at the interdecadal timescale, short timescale climatic events such as lake expansion will bring more extreme climate events, such as extreme high-temperature heat waves, which should be considered as a potential threat to lake ecology in the future. [ABSTRACT FROM AUTHOR]

Understanding the evolution of river systems in southern Africa is fundamental to constrain the evolution of landscape and sediment dispersal patterns. It is widely considered that the upper Zambezi River was connected with the Limpopo River during the Cretaceous, forming what was then the largest river in Africa. Crustal flexure during the Paleogene severed the upper Zambezi drainage from the Limpopo, setting the framework of the modern Zambezi and Limpopo River systems. We present first evidence—based on heavy‐mineral assemblages from cores drilled offshore of the Limpopo River mouth and samples collected in different reaches of the modern Limpopo River, integrated with magnetic susceptibility, detrital‐zircon geochronology, and geomorphological analysis—suggesting that the current Limpopo River formed recently in the Plio‐Quaternary. Plio‐Quaternary climate change is envisaged to have controlled the recent dynamics of river drainage and consequent distribution of sediment loads, as observed in many other transcontinental rivers worldwide. Plain Language Summary: Landscape evolution, sediment dispersal patterns, and the accumulation of hydrocarbon and mineral resources in southern Africa, were largely determined by the evolution of the vast Zambezi‐Limpopo River system. It is widely believed that this river system attained its current configuration during the late Paleogene as a consequence of mantle‐driven dynamic uplift. Based on heavy‐mineral assemblages from river sediments and an International Ocean Discovery Program ocean core, we argue here instead for a Plio‐Pleistocene age for the formation of the modern characteristics of the Limpopo River (i.e., tens of millions of years younger than previously thought). This challenges the current paradigm on both formation modality and driving mechanisms of this vast river system. Plio‐Pleistocene climate change is envisaged to have controlled the dynamics of river drainage and consequent distribution of sediment loads, as observed in several other transcontinental rivers worldwide, underscoring the importance of these climate changes in driving river evolution world‐wide. Key Points: The modern Limpopo River of South Africa formed in the Plio‐PleistocenePlio‐Pleistocene drainage reorganization was driven by climate changeFormation age and driving mechanisms of South African rivers are revisited [ABSTRACT FROM AUTHOR]

The Oligocene-Miocene boundary Asian climatic reorganization linked to the northward migration of the East Asian monsoon into subtropical China is a potentially important but poorly constrained atmospheric CO2 consumption process. Here, we performed a first-order estimate of the CO2 consumption induced by silicate chemical weathering and organic carbon burial in subtropical China related to this climatic reorganization. Our results show that an increase in long-term CO2 consumption by silicate weathering varies from 0.06×1012 to 0.87×1012 mol yr−1 depending on erosion flux reconstructions, with an ~50% contribution of Mg-silicate weathering since the late Oligocene. The organic carbon burial flux is approximately 25% of the contemporary CO2 consumption by silicate weathering. The results highlight the significant role of weathering of the Mg-rich upper continental crust in East China, which would contribute to the rapid decline in atmospheric CO2 during the late Oligocene and the Neogene rise in the seawater Mg content. If this climatic reorganization was mainly induced by the Tibetan Plateau uplift, our study suggests that the growth of the Himalayan-Tibetan Plateau can lead to indirect modification of the global carbon and magnesium cycles by changing the regional hydrological cycle in areas of East Asia that are tectonically less active. [ABSTRACT FROM AUTHOR]

Reconstructing the environmental and hydrological response to millennial‐scale fluctuations of climate‐sensitive areas of mid‐latitudes is crucial to understanding the Late Pleistocene climate in terrestrial inland regions. We use sedimentological and geochemical proxies (e.g. lithology, gain size, loss‐on‐ignition, soluble salts, X‐ray fluorescence elements) from Balikun Lake in the eastern Tienshan Mountains, to elucidate variations in sedimentation, water chemistry and watershed weathering intensity of the Late Pleistocene interval (~20−60 ka). The record documents high‐frequency oscillations and alternating hydrological patterns on (multi‐) millennial timescales. Balikun Lake changes from nearly fresh to brackish and finally to hypersaline conditions during MIS3. The warm and wet climate during the early MIS3 facilitated regional vegetation and bioproductivity. Halite sedimentation took place from the middle to late MIS3, indicating a gradual drying trend. This reduced the lake area and vegetation cover, as well as weakened the chemical weathering rates of the watershed. These new interpretations challenge the idea of climate amelioration with the highest lake level and wettest conditions prevailing in the arid areas of north‐west China during the late MIS3, indicating a possible westerlies‐dominated Late Pleistocene climate in these areas. The evolution of the palaeohydrological regime and climate change in the Balikun Basin correlated well with the millennial‐scale high‐latitude Atlantic climate superimposed on the Northern Hemisphere summer insolation. Highlights: Evidence is presented for a warm and wet climate in arid western China during the early MIS3.The frequent occurrence of halite lithofacies in lake sediments indicates a gradual drying period from the middle to late MIS3.Evolution of the climate and paleohydrological regime in Balikun Basin follows millennial‐scale high‐latitude Atlantic climate cycles, superimposed on a climate that was largely driven by Northern Hemisphere summer insolation. [ABSTRACT FROM AUTHOR]

In the late Miocene, grasslands spread across the forested floodplains of the Himalayan foreland, but the causes of the ecological transition are still debated. Recent seafloor drilling by the International Ocean Discovery Program (IODP) provides an opportunity to study the transition across a larger region as archived in the Indus submarine fan. We present a multiproxy study of past vegetation change based on analyses of the carbon isotopic composition (δ13C) of bulk organic carbon, plant wax n‐alkanes and n‐alkanoic acids, and quantification of lignin phenols, charcoal, and pollen. We analyze the hydrogen isotopic composition (δD) of plant wax to reconstruct precipitation δD. We use the Branched and Isoprenoid Tetraether (BIT) index to diagnose shifts between terrestrial versus marine lipid inputs between turbidite and hemipelagic sediments. We reconstruct ocean temperatures using the TEX86 index only where marine lipids dominate. We find evidence for the late Miocene grassland expansion in both facies, confirming this was a regional ecosystem transformation. Turbidites contain dominantly terrestrial matter from the Indus catchment (D‐depleted plant wax), delivered via fluvial transport as shown by the presence of lignin. In contrast, hemipelagic sediments lack lignin and bear D‐enriched plant wax consistent with wind‐blown inputs from the Indian peninsula; these show a 7.4–7.2 Ma expansion of C4 grasslands on the Indian subcontinent. Within each facies, we find no clear change in δD values across the late Miocene C4 expansion, implying consistent distillation of rainfall by monsoon dynamics. Yet, a cooling in the Arabian Sea is coincident with the C4 expansion. Plain Language Summary: This project studied the mud and sand on the seafloor in the Indian Ocean, west of India and south of Pakistan. We drilled a core through the mud and focused on a section corresponding to 5.5 to 10 Ma. Much of the sand came from the Indus River, but when the river sediments went elsewhere, layers of chalky sediments formed from the shells of marine organisms. Those chalks contain the history of longer spans of time. In the sediments, we found molecular fossils from the waxy coating on plant leaves and the woody parts of plants as well as pollen and charcoal; these point to the types of plants that were growing on land whose remains were washed or blown out to sea. We also found molecular fossils of microbes that lived in the oceans, whose structures indicate ocean temperatures—although when soils washed out in large amounts, ocean temperature estimates are not available. The main finding is that grasses replaced forests across much of the Indian subcontinent and Indus catchment, accompanied by more grass fire and cooler ocean temperatures. Key Points: Multiproxy study of the Indus Fan organic matter reveals that terrestrial sources differ between turbidite and hemipelagic faciesCarbon isotopes, grass pollen, and charcoal indicate that C4 grasslands expanded between 7.4–7.2 Ma in hemipelagic faciesHydrogen isotopes in plant waxes differ between source regions but do not detect monsoon rainfall changes across the C4 grassland expansion [ABSTRACT FROM AUTHOR]

Atmospheric dust emission is closely related to conditions in the source area. Typically, loess deposits represent the accumulation of locally derived dust, providing the opportunity to reconstruct past variations in dust emission and hence insights into dust‐climate linkages and the underlying mechanisms of dust mobilization, transport, and deposition. As yet, however, information on patterns of dust emission in Central Asia is sparse. Here we present the last glacial sedimentological data of a loess section from the Ili Basin, northwest China. Our results show that the variations in sand‐sized fraction can indicate frequencies of occurring strong winds, which was likely driven by the Eurasian ice sheets during Marine Isotope Stage Stage 2 (MIS2) and MIS4 and by the boreal summer insolation during MIS3. The mass accumulation rate (MAR) reflects an integration of sediment availability in the provenance, vegetation cover in the deposition area, and wind regime. The differences of driving factors potentially explain the observed mismatches between variations in grain size and MAR. Comparison of dust fluxes observed in Greenland ice core and the North Pacific deep‐sea sediment with the Central/East Asian MAR records supports the idea that the high flux of long‐distance export of Asian dust is closely associated with the Siberian High and also influenced by changes in the atmospheric transport efficiency and likely by the source strength. Key Points: Eurasian ice volume was crucial for the eolian processes in the Ili BasinMismatches between the grain size and MAR variations lie in differences in their governing factorsClimate of source regions and transport efficiency modulated dustiness in the Ili Basin and dust flux in distant paleoarchives [ABSTRACT FROM AUTHOR]

Dramatic warming in the late Oligocene occurred after 8 Ma, characterized by ocean warming and a collapse of the Antarctic ice sheet (the late Oligocene warming event [LOWE]); however, few terrestrial records have yet been employed to verify the LOWE and investigate its associated driving forces. The Nima Basin, located in the central Tibetan Plateau contains thick Oligocene sediments, allowing its ecological record to be used as verification of the LOWE. Here we used the reconstructed vegetation record from the Nima Basin in the 1,100‐m‐thick DZC section, aided with zircon U‐Pb dating of the interbedded tuffite layers. Two tuffite layers yielded ages of about 23.4 and 24.8 Ma; thus, the sedimentary age of the whole section is predicted to be 27.5–22.4 Ma. Sporopollen analysis revealed that the dominant taxa throughout the whole section were conifers (over 85%), including Piceapollis, Pinuspollenites, and Abietpollenites. One notable feature is that the broad‐leaved trees (e.g., Quercoidites and Meliaceoidites) increased obviously (averaging from 0.9% to 6.6%, max 41.2%) after 25.6 Ma. This change could be interpreted as a response to late Oligocene global warming, which changed the forest line and corresponding plant species composition. The mean average precipitation of 400–850 and 800–1,000 mm, respectively, inferred from the above vegetation types in the Nima Basin, both exceed the present 150 mm. This indicates that the south Asian monsoon had already developed in the Oligocene and that the LOW event accompanied the global warming. Key Points: The U‐Pb dating shows the DZC section; Nima Basin was deposited mainly in the late OligoceneThe sporopollen results of the DZC section show conifers were dominant but angiosperms increased after 25.58 MaThe changed vegetation was a response to the LOWE and suggested the south Asian monsoon enhanced at that time [ABSTRACT FROM AUTHOR]

Abstract: Tectonic uplift and climate change play a key role in the evolution of sedimentary systems in terrestrial basins. The Qaidam Basin in the northeastern Tibetan Plateau is well suited for studying these processes because of its location and its thick, continuous sequence of Cenozoic sediments. Unfortunately, however, there is a lack of continuous, well‐dated sedimentary records from the region. In the present study, we combined grain‐size analyses of sediment cores and outcrop samples with structural analysis of seismostratigraphic data from the western Qaidam Basin. The results reveal dramatic shifts in the depositional environment at ~11.5–10 Ma, coeval with the topographic development of the area. Together with paleoclimatic analysis and a conceptual model, we conclude that tectonic movements, rather than climatic changes, were the dominant forcing factor. [ABSTRACT FROM AUTHOR]

Compiled pollen records derived from four cores (ZK004, ZK005, SZ03, and SZ04, respectively) were established to reveal the last 800 thousand years (ka) climate change and its driving forces in the Yangtze River Delta, East China. The percentages of the herbaceous taxa (Poaceae, Artemisia, Asteraceae, Chenopodiaceae, Cyperaceae, Typhaceae, and others), arbors and ferns (Fagaceae, Pinaceae, Ulmaceae, Betulaceae, Juglandaceae in arbors; Polypodiaceae and other Monoletespores and Triletespores in ferns), and the natural logarithmic ratios of these values yield reliable records representing distinct climate stages and periodic cycles. During 800-480 ka, the Yangtze River Delta experienced a relatively stable East Asian summer monsoon (EASM) and East Asian winter monsoon (EAWM), but after that time, both the EASM and EAWM intensified. Within these stages, distinct periodic cycles (including 100-, 41-, and 23-kyr cycles) each indicate orbital control. Such climate stages and cycles are well correlated with palaeoclimate records on the Loess Plateau, implicating the same EASM and EAWM association across the East Asian landmass. Linear interpolation of the absolute age is less robust but can be useful for the last 800 ka when there is no alternative dating method. [ABSTRACT FROM AUTHOR]

The history of climate change and related driving mechanisms of the Gonghe Basin, northeastern Qinghai-Tibetan Plateau, China, was reconstructed in the Holocene epoch, based on the comprehensive analysis of multi-proxies consisting of magnetic susceptibility, grain size, and geochemical elements from eolian and peat deposits at different altitudes. The results indicate that Holocene climate change at different altitudes is both consistent and different: a synchronous record of an increased warm-humid phase (10.0-8.5 ka) and a cold phase around 8.2 ka in the Early Holocene; an optimal warm-humid condition in marginal mountains of the Gonghe Basin in the Mid-Holocene; and a gradual decline in temperature and humidity in the Late Holocene. The Gonghe Basin interior in the Mid-Holocene was relatively arid, with increased moisture in the Late Holocene. On this basis, we compared our results to the paleoclimatic record in the low-latitude Asian monsoonal region, which indicates that, in addition to the Asian summer monsoonal strength having influenced regional climate change, the upward and subsidence motion of airflow over the Qinghai-Tibetan Plateau induced by topographic conditions, evaporation, and the feedback effect by the substrate was also influential. The latter was especially important for spatial-temporal differences in Middle and Late Holocene climatic changes at different altitudes. [ABSTRACT FROM AUTHOR]

It is desirable to know the distribution of phosphorus (P) fractions in soil so that plants may use P efficiently. Here we report the dynamics of inorganic and organic P in P-deficient black and rice soil cropped by soybean, white lupin, and maize supplied with nitrogen (N) inputs by N fixation and urea fertilizer. Inorganic P fractions of the three cropped soils could be ranked as O-P (organic phosphorus) > Al-P (aluminum phosphorus) > Fe-P (iron phosphorus) > Ca10-P (calcium-10 phosphorus) > Ca8-P (calcium-8 phosphorus) > Ca2-P (calcium-2 phosphorus), irrespective of soil type. The potential of various inorganic P fractions to plant nutrition differed between soybean and white lupin. The percentage of total P present as inorganic P was affected by crop, soil type, and N source. In black soil, the change of organic P fraction induced by N fixation was larger than by urea application. The moderately labile organic P (MLOP) concentration was not affected significantly by soil type and crop species, and it was probably the main P source to the inorganic P fraction because the correlation between the two pools was high (r = 0.945; P < 0.05). Crop species differed in their uptake of inorganic and organic P from soil. Though P fraction concentrations varied between black soil and rice soil, their response to crop species and N source was similar. The amounts of P removed from soil were affected by N source. The right choice of crop species and the application a suitable N source may increase crop yield and P uptake by plant in P-deficient soils. [ABSTRACT FROM PUBLISHER]

The Xining Basin on the northeastern Tibetan Plateau holds the longest continuous Cenozoic stratigraphic record in China. The sequence record contains considerable information on the history of Tibetan uplift and associated climatic change. In particular, high resolution n-alkane biomarker proxy and pollen records have been obtained from the Paleogene sediments of the Xiejia section of the basin. A combination of the n-alkane and palynological records reveals that the paleoclimate in the Xining Basin experienced a long-term cooling trend from 50.2 to 28.2 Ma with a distinctive ecological event spanning 37.5 to 32.7 Ma. Since this ecological event, a vertical zonation of vegetation from lowland arid grasses, to middle-elevation subtropical broad-leaf plants, to high-elevation coniferous trees was established. We interpret that these changes in climate and vegetation were probably responses to a combination of long term global cooling since the Eocene climatic optimum and uplift of the surrounding mountains on the northern Tibetan Plateau in the early Cenozoic. [ABSTRACT FROM AUTHOR]

The red clay eolian sequence on the Chinese Loess Plateau (CLP) is an important archive for paleoclimate change from the late Miocene to Pliocene, and can provide significant information for the controversial problems of East Asian monsoon evolution and its forcing mechanism. In this study, we present a pollen record from Baode, northern CLP. The record shows four stages of paleoecological evolution. From 5.6-4.4 Ma, a forest steppe ecosystem developed under an extremely warm period with high seasonal precipitation. Since 4.4 Ma, a drier episode occurred, which prompted parkland landscapes to develop. During 3.5-3.05 Ma, the environment changed to a rather open steppe ecosystem with a much cooler and drier climate. After 3.05 Ma, the vegetation evolved to forest steppe. Using the percentages of arboreal plants to mirror precipitation, and comparing with other published pollen data from the CLP, we find the existence of S-N directionality of the precipitation change and high percentage of arboreal plants in the entire CLP during the Early Pliocene, which suggest the CLP was characterized by a strong East Asian summer monsoon. The strong summer monsoon corresponds well to the low global ice volume, which may illuminate global climate mechanism for the summer monsoon evolution in the early Pliocene. [ABSTRACT FROM AUTHOR]

Two lacustrine sporopollen records obtained from the Qaidam Basin (in the non-monsoonal region) and the Linxia Basin (in the monsoonal transition zone) indicate that during the early Pleistocene open forest-steppe/steppe vegetation developed in the Qaidam Basin, while in the Linxia Basin an open cypress forest-steppe shifted to a conifer/conifer-steppe and then to open forest-steppe vegetation. Existing sporopollen records from the Chinese Loess Plateau (CLP) (in the monsoonal region) indicate that around the Sanmen Paleolake open forest-steppe shifted to pine/conifer-broadleaved mixed forest. The conifer cover then changed to a subtropical evergreen broadleaved forest distributed around the Nihewan Paleolake. These changes suggest that wetter conditions progressed from western China to the east, and the climate became more humid than that of today indicating a stronger Asian summer monsoon during the early Pleistocene. [ABSTRACT FROM AUTHOR]

The Eocene palaeovegetation landscape and palaeoclimate reconstructed from the pollen records in the Jiuquan Basin, northwest China provide some important information on the early uplift of the Tibetan Plateau and the origin and evolution of the aridification in northwest China. The records show the arid-semiarid scrubs with open forest palynofloras controlled by the subtropical high existed in northwest China during the 40.2–33.4 Ma. Four pollen assemblages are found: Nitrariadites-Cheno-podipollis-Pinaceae assemblage (40.2–37.9 Ma) is followed by Chenopodipollis-Nitrariadites assemblage (37.9–34.6 Ma), Pinuspollenites & Abietineaepollenites-Chenopodipollis assemblage (34.6–33.9 Ma), and Chenopodipollis-Nitrariadites assemblage (33.9–33.4 Ma). The percentage of thermophilic types is in anti-correlation with that of the dry types, which means the palaeoclimate is relatively warm-wet or cold-dry during most of that time. Such aridity may be related to the water vapor reduction and the planetary wind system movement northward in response to the cooling caused by small-ephemeral ice-sheets. [ABSTRACT FROM AUTHOR]