Zhen Li

Natural Resources Canada | NRCan · Geological Survey of Canada-Pacific

High resolution pollen records in the northern edge of subtropical China are crucial to understand the pattern of postglacial vegetation change and climate transition. Here we present vegetation succession and climate change during 9.2–8.0 cal kyr BP based on sub-decennial scale pollen data. Pollen spectra show that Quercus (evergreen) & Cyclobalan...

The taxonomy of the extant dinoflagellate genus Gonyaulax is challenging since its thecate morphology is rather conservative. In contrast, cysts of Gonyaulax are varied in morphology and have been related with the fossil‐based genera Spiniferites and Impagidinium. To better understand the systematics of Gonyaulax species, we performed germination e...

Significance Palaeoecological analysis reveals that the expansion of rice agriculture in southern China and Southeast Asia around 2,000 y ago caused widespread deforestation and biodiversity changes in tropical and subtropical forests. Tropical forests, with the highest level of plant diversity and concentration of endemic species, suffered greater...

The Holocene variability of Poaceae (grasses) and their response to climate changes has not yet been investigated , despite their prevalence and biodiversity in the Lower Yangtze Valley. In this study, we analysed phytolith assemblages in a high-resolution sediment core from the Lower Yangtze Valley to reconstruct the past vegetation and climate of...

Mangroves can not only provide multiple ecosystem service functions, but are also efficient carbon producers, capturers, and sinks. The estimation of the organic carbon accumulation rate (OCAR) in mangrove sediments is fundamental for elucidating the role of mangroves in the global carbon budget. In particular, understanding the past changes in the...

A high-resolution dinoflagellate cyst analysis on a sediment core GLW1D from the northern South China Sea (SCS) was performed to reconstruct paleoceanographic conditions over the last 12,500 years through qualitative, semi-quantitative, and quantitative methods. A modern dataset with 398 reference sites in the northern Pacific was assembled and use...

It is well known that modern resting cysts with morphologies matching those of species of the fossil genus Spiniferites germinate into motile cells of the genus Gonyaulax. Different Spiniferites species have been connected to a single Gonyaulax species, raising the question of whether they are over-classified. Through germination experiments of cys...

Mangroves, a blue carbon ecosystem between land and ocean in the (sub)tropics, are sensitive to changes in climate and the sea level. It is imperative to reconstruct the historical dynamics of their development to predict the fate of mangrove ecosystems in the backdrop of rapid global changes. This study analyzes records of the sources of organic m...

The grass subfamily Pooideae originated in a temperate niche during the late Cretaceous; it is the largest Poaceae subfamily, consisting of almost 4,000 species, which are distributed worldwide. Pooideae responses to climate changes at different time scales, and different ecological zones are thus important in understanding Poaceae evolutionary pro...

The responses of mangroves to future climate change can be reconstructed from past mangrove dynamics using proxies preserved in sediments. The contributions of mangrove-derived organic matter (MOM) can be calculated by using δ13Corg and molar C:N values. In order to verify the effectiveness of MOM for tracing mangrove development, four typical regi...

The Holocene evolution of the Krishna Delta was inferred using landform characteristics and 11 sediment cores with 59 Accelerator Mass Spectrometry ¹⁴C dates. The landform assemblages in a 5880 km² area of the Krishna Delta indicate an upper (landward) river-built fluvial plain and a lower (seaward) marine-built beach-ridge plain. Holocene sediment...

The geographical distribution of dinoflagellate cysts was investigated in palynologically treated surface sediments from the South China Sea (SCS) to understand the driving environmental factors associated with specific taxa. The western SCS generally has higher total cyst concentrations (>300 cysts g⁻¹) than the eastern region (<200 cysts g⁻¹). Th...

Mangroves, widely distributed along the coasts of tropical China, are influenced by Asia monsoon, relative sea level change and enhanced human activity. To predict the impacts of future climate change on mangrove ecosystems, it can be understood by reconstructing past mangrove dynamics using proxies preserved in coastal sediments. In this study, we...

Located in the intertidal zone of the tropical and subtropical coasts, mangrove forests are an important ecosystem in the global carbon cycle and serve as a protector of local seashores. Under the double impacts of climate change, especially sea-level rise, and human activity, mangrove forests around the world have faced degradation, against which...

Dinoflagellates are a major component of the modern plankton. Of the 2192 species of marine free-living dinoflagellates presently described, an increasing number are being shown to produce resting cysts (probably hypnozygotes) within their life cycle. With rare exception, only the resting cysts fossilize, so they are of central importance in tracin...

The taxonomy of the dinoflagellate cyst-based genus Votadinium has been in need of revision. This was accomplished here by integrating morphology, LSU rDNA sequences, and cyst wall composition analyses through micro-Fourier transform infrared spectroscopy. Three new species, Votadinium pontifossatum, V. rhomboideum and V. reidii, were described as...

The South China Sea (SCS), influenced by the tropical East Asian Monsoon (EAM), experiences winter monsoon and summer monsoon shifts in near-surface wind, air temperature, sea-surface temperature, salinity, primary productivity, and other oceanographic conditions. To understand how monsoon seasons influence palynological dynamics and which palynolo...

To understand historical climate change in western Pacific coastal areas, a sediment core (SOJ-2) from the stable sedimentary environment of the Songjiho Lagoon on the east coast of South Korea was obtained for centennial-resolution palynological analysis. The ages of the SOJ-2 core is well controlled by carbon 14 dating with high-resolution accele...

We reconstructed the centennial climate changes for the period of 9–7 cal ka BP in the upper region of the Changjiang (Yangtze) River Delta plain. A general warming and wetting trend from 8560 to 7220 cal yr BP was indicated by the decrease in Quercus (deciduous) and increases in Quercus (evergreen), Pinus , and Polypodiaceae spores. However, there...

For the first time, palynological records of terrestrial palynomorphs and dinoflagellate cysts are investigated in a sediment core from the northern South China Sea (SCS) covering the last 12,500 years. Both terrestrial and marine palynomorph records show strong signals of the sea-level change during the studied interval. The highest herb pollen co...

Mangrove degradation must reduce carbon sequestration in recent years, thereby aggravating global warming. Thus, short-term impacts of human activity on mangrove ecosystems are cause for concern from local governments and scientists. Mangroves sediments can provide detailed records of mangrove species variation in the last one hundred years, based...

Using phytolith analysis from a well-dated and high-resolution sediment sequence in the apex of northern Yangtze Delta, we investigate environmental changes, the rise and decline of rice exploitation and possible impacts of environment on rice exploitation during the early mid-Holocene. The phytolith sequence documents a relatively warm and dry int...

Surface sediment samples were collected from upstream down to the subaqueous delta of the Red River in Vietnam to assess heavy metal pollution. Sediment Cr and V concentrations are strongly correlated with Al, Fe, Mn and total organic carbon concentrations, as well as particle size, suggesting that these two metals are derived primarily from natura...

The characteristic location of mangroves at the interface between marine and terrestrial habitats makes them vulnerable to regional environmental change. The monsoonal climate of tropical Asia, where mangrove forests are broadly distributed along the coastal zone, differs from that of the other tropical regions. Therefore, mangrove development in t...

Mangroves accumulate sedimentary sequences, where cores can provide historical records of mangrove evolution with past climate change and human activity. The study traced the history of mangrove evolution during the past one hundred years in a mangrove swamp of Maowei Sea, SW China. The sedimentation rates (0.38-0.95 cm yr−1) were calculated on the...

Mangrove forests, located at the interface between land and sea, have been impacted by an increase in intensive anthropogenic disturbance in developing countries or regions. In order to study the impact of human activity on mangrove forests, mangrove development was reconstructed over the last 130 yr, using the contribution of mangrove-derived orga...

We conducted a mineral magnetic study of river bank and subaqueous delta sediments from the Red River, Vietnam, in order to examine the role of sedimentary sorting on the variation of sedimentary magnetic properties from source to sink. The magnetic mineralogy mainly consists of magnetite and hematite. Bulk sediment particle-size variations have a...

The response of mangrove ecosystems to the Asian monsoon in the future global warming can be understood by reconstructing the development of mangrove forests during the Holocene climatic optimum (HCO), using proxies preserved in coastal sediments. The total organic matter in sediments of a segmented core, with calibrated age ranges between 5.6 and...

Located at the interface between terrigenous and marine ecosystems, mangroves are particularly sensitive to environmentalchange. They provide a sedimentary sink for organic carbon, whereby cores can provide detailed records of mangrove species.We aimed to trace the history of mangrove development over the past 150 yr in Yingluo Bay, SW China. Sedim...

Middle Holocene vegetation and mangrove successions are clearly evident in the palynological records of two cores from the upper Mekong River delta in Cambodia. Spanning from ~ 9.4 to 6.3 cal ka BP, the cores mainly record a transgressive sequence from floodplain freshwater marsh to tidal flat, which was overlain by man-grove. Corresponding to the...

Palynological records in cores C4 and B106 from the Gulf of Tonkin reveal signals of paleo-monsoon and paleoenvironmental change during the late Pleistocene and Holocene. Before ∼ 13.4 cal kyr BP, the Gulf of Tonkin was exposed to the atmosphere and covered by grassland. Starting at ∼ 11.7 cal kyr BP, the Gulf of Tonkin was inundated by brackish wa...

The Changjiang delta, in eastern China, is one of the largest tidal-dominated deltas in the world. In order to get the information on the initial delta, we obtained a 53-m-long sediment core at Jiangdou City in the upper part of the delta in 2008. Based on sediment composition, grain size, texture, and faunal content, we divided the core sediments...

Fire has played an essential role in the development of human civilization. Most previous research suggests that frequent-fire regimes in the late Holocene were associated with intensification of human activities, especially agriculture development. Here, we analyze fire regimes recorded in the Song Hong delta area of Vietnam over the past 5,000 ye...

Pollen analysis was carried out on samples of surface sediments from various plant communities of mangrove systems in Yingluo Bay, Guangxi to examine the relationships between vegetation and present-day pollen. High percentages of mangrove types can be indicators of the mangrove vegetation in general, although some terrestrial pollen occur. The exa...

The palynological sequence from core ND-1 on the Song Hong delta in the northern Vietnam reveals the climate change during the last deglaciation. The identified pollen in the core is dominated by Castanopsis (Lithocarpus), Elaeocarpus, Ficus, Piperaceae and Quercus. High percentages of temperate taxa including the conifers Dacrydium, Podocarpus, Pi...

On the basis of the results of palynological research on two cores from the Song Hong (Red River) delta in the sub-tropical zone of Asia, centennial- to millennial-scale climate changes and human impacts during the Holocene were clarified. Three cycles of cooling and warming were identified during the last 5000 yr: a cool and wet climate during 453...

Microfossil assemblage and pollen zone characteristics in Core B10 recorded the history of environmental changes in the southern Yellow Sea since Würm Subinterglaciation. Environmental variations reflected by these glacial and interglacial sediments coincide with general characteristics of paleoenvironmental and sedimentary changes in the Yellow Se...

Eight sporopollen zones have been divided based on the results of high-resolution sporopollen analysis of Core B10 in the southern Yellow Sea. Based on the results along with14C datings and the subbottom profiling data, climatic and environmental changes since the last stage of late Pleistocene are discussed. The main conclusions are drawn as follo...

Planktonic foraminiferal δ18O record for core DGKS9603 from the Okinawa Trough shows a series of climatic fluctuations and sudden cooling events in short time scale during 50 kaBP, which appear to correlate closely to the Younger Dryas and Heinrich events H1–5 recorded in Chinese loess, the South China Sea, the North Atlantic cores and the Greenlan...

The analysis of carbon isotope in phytoliths from modern plants and surface soils in China shows that the values of carbon isotope are consistent with those from C3 and C4 plants, and the processes of photosynthesis of the original plants can be clearly identified by carbon isotope in phytoliths. The value of carbon isotope varied from −23.8‰ to −2...

Based on the analyses of foraminifer and accelerator mass spectrometer radiocarbon dating in DGKS9603 core from mid-Okinawa Trough close to bottom, oscillation curve, which expressed the relation between the surface water temperature and the depth, has been obtained by using foraminifer analysis and calculation of FP-12E transfer function. The whol...