Ji Shen

Chinese Academy of Sciences | CAS

Microbial communities are crucial for water quality and biogeochemical cycling in freshwaters. Microbes secrete extracellular enzymes to decompose organic matter for their needs of nutrients and scarce elements. Yet, there is a lack of knowledge on microbial metabolic limitations in freshwaters, especially in lake sediments. Here, we examined the c...

Strengthening aquatic resilience to prevent adverse shifts is critical for preserving global freshwater biodiversity and advancing Sustainable Development Goals. Nonetheless, understanding the long‐term trends and underlying causes of lake ecosystem resilience at a global scale remains elusive. Here, we employ an innovative framework, integrating s...

Understanding the transient dynamics of interlinked social–ecological systems (SES) is imperative for assessing sustainability in the Anthropocene. However, how to identify critical transitions in real-world SES remains a formidable challenge. In this study, we present an evolutionary framework to characterize these dynamics over an extended histor...

The remote forcing from land surface changes in the Sahara is hypothesized to play a pivotal role in modulating the intensity of the East Asian summer monsoon (EASM) through ocean-atmospheric teleconnections. This modulation has far-reaching consequences, particularly in facilitating societal shifts documented in northern China. Here, we present a...

Lakes on the Qinghai-Tibet Plateau (QTP) have been subject to multiple environmental pressures from rapid climate change and intensified human activity in recent decades. However, their ecological effects on the lake ecosystem remain largely unclear due to the lack of long-term monitoring data. This study presented the environmental and ecological...

A bs tract Climate change and anthropogenic activities mutually degraded global lake ecosystems during the Anthropocene. Nutrient mitigation via catchment management has been a constant priority for lake ecological restoration; however, the outcomes after mitigation remain uncertain. In particular, there is limited knowledge on the effects of large...

Harmful algal blooms (HABs) producing toxic metabolites are increasingly threatening environmental and human health worldwide. Unfortunately, long-term process and mechanism triggering HABs remain largely unclear due to the scarcity of temporal monitoring. Retrospective analysis of sedimentary biomarkers using up-to-date chromatography and mass spe...

Alpine lakes on the Tibetan Plateau are highly sensitive to global change and have been recognized as the sentinel of climate warming. However, anthropogenic impacts in populated area are migrating to these remote areas via transporting particulate nutrients by atmospheric deposition. Whether warming and nutrient deposition would impose additive or...

Contrasting moisture evolutions between westerlies‐dominated Central Asia and monsoonal Asia since the mid‐Holocene have been widely recognized. Yet, inconsistent hydrological records over the early Holocene from both regions hamper our understanding of hydroclimatic changes and associated mechanisms. Here we present isotopic and biomarker (alkenon...

The Holocene temperature discrepancy between paleoclimate reconstructions and climate model simulations—known as the Holocene temperature conundrum—calls for new high‐quality Holocene temperature records at high elevations. Here, we present a quantitative Holocene mean annual air temperature record based on a site‐specific branched glycerol dialkyl...

Plutonium (Pu) isotopes, neptunium-237 (²³⁷Np) and cesium-137 (¹³⁷Cs) in the environment have emerged as important tools for promoting geochemical studies. To elucidate their source terms, deposition process, and the geochemical behavior, as well as their response to catchment environmental changes in lacustrine environment, 239, 240Pu, ¹³⁷Cs and ²...

The evolution of the Indian Summer Monsoon (ISM) has been widely investigated owing to its significant climatic and socioeconomic influences. However, debates remain concerning the temporal variation during the Holocene and its driving mechanisms, particularly the potential contribution of sea-surface temperature (SST) in the tropical Indian Ocean...

A 150 cm long peat core was collected from a subalpine peatland (above sea level 1790 m) in Luoxiao Mountains，Hunan Province, China. Based on the analysis of AMS ¹⁴C dating, loss on ignition, total carbon, total nitrogen, grain size, humification, and pollen data, the environment change was reconstructed focusing on the intervals of the Younger Dry...

Various indices based on metal chemical data are used to evaluate pollution and ecological risk, but the consistency of the assessment results is usually unsatisfactory, and it is unclear if the ecological risk from sediment metals is accurately represented in in situ zoobenthos. Herein, the pollution and ecological risk associated with As, Cd, Cr,...

Microbes regulate the composition and turnover of organic matter. Here we developed a framework called Energy-Diversity-Trait integrative Analysis to quantify how dissolved organic matter and microbes interact along global change drivers of temperature and nutrient enrichment. Negative and positive interactions suggest decomposition and production...

Regime shifts of freshwater ecosystems driven by fast-changing multiple stressors are increasingly occurring. However, lake regime shifts across intensive agricultural landscapes are less explored, especially how different aquatic communities respond to multiple environmental forcings through time is poorly understood. Using a century scale paleoli...

The palaeo-shorelines around the lakes on the Tibetan Plateau can be used to reconstruct water level variations, which serve as sensitive indicators of hydroclimate change. Extensive studies have been carried out to constrain the Holocene lake level fluctuations by dating shorelines with a variety of methods (e.g., luminescence, ¹⁴C, ¹⁰Be and U–Th...

Mountains are pivotal to maintaining habitat heterogeneity, global biodiversity, ecosystem functions and services to humans. They have provided classic model natural systems for plant and animal diversity gradient studies for over 250 years. In the recent decade, the exploration of microorganisms on mountainsides has also achieved substantial progr...

Abrupt ecological shifts have become a pervasive feature of aquatic ecosystems with severe socio-ecological consequences. Yet, it remains uncertain whether these shifts happened synchronously or not among various lakes, and how multiple drivers interacted through time to drive these abrupt changes on a global scale. To address this knowledge gap, h...

The Tibetan Plateau (TP) is one of the most sensitive areas to global climate changes. Quantitative paleotemperature reconstructions on the TP since the Last Deglaciation provide a prominent opportunity not only for assessing the position, but also for better understanding the mechanism of recent warming. In this study, we first present a well-date...

Lake sediments are important archives of environmental changes and human activities, but the influences of human processes and lake spatial heterogeneity on the sedimentation of trace metals are still poorly understood. Based on 16 sediment cores from Lake Erhai (249 km²), trace metals (including As and Hg) contamination over the past century and t...

Lakes are recognized as critical zones for carbon transformation and storage, and lacustrine sediments sequestrate considerable amounts of organic carbon (OC). Understanding sedimentation processes and OC burial patterns is crucial to clarifying lakes’ role in global carbon cycling. However, OC sedimentation may be quite spatially heterogeneous wit...

One of the Holocene abrupt events around 4200 years ago, lasting for ∼200 years, is thought to have caused cultural disruptions, yet terrestrial climatic status right after the cold/dry event remains poorly defined and is often presumed that a generally cool condition prevailed during the Bronze Age (∼4000-2200 years ago). Here we report an alkenon...

Understanding long-term vegetation diversity patterns and their potential responses to climate and/or human driven processes are important for ecosystem modeling and conservation. Late-Holocene fossil pollen assemblage and associated vegetation diversity estimates provide an opportunity to explore the interactions among vegetation, climate, and hum...

Microbes play a critical role in regulating the size, composition, and turnover of dissolved organic matter (DOM), which is one of the largest pools of carbon in aquatic ecosystems. Global change may alter DOM-microbe associations with implications for biogeochemical cycles, although disentangling these complex interactions remains a major challeng...

Besides natural climate variations, human activities can also cause significant changes in regional vegetation composition, especially during the late Holocene period. Southwest China has experienced a long history of human activities in terms of deforestation and agricultural development. Here we present a continuous fossil pollen record covering...

Inland waterbodies play an important role in the global carbon cycle, acting both as carbon sources with organic carbon (OC) mineralization and as sinks with OC burial in sediments. Under recent impacts of global warming, anthropogenic land-use change and nutrient supply, however, there is a limited knowledge regarding OC dynamics in sediments of l...

Understanding the relationship between historical vegetation and bacteria is critical for disentangling spatiotemporal variations in microbial communities. However, the utility of historical vegetation as indicated by the reconstruction proxies like n-alkanes to explain microbial succession has been understudied, especially regarding aquatic microb...

Knowledge of climatic change during the past 2000 years in southwestern China is important for understanding the evolution of the Indian summer monsoon (ISM). For this study, we conducted systematic analysis of magnetic minerals in sediments from Lugu Lake in northwestern Yunnan Province. Magnetic measurements suggest that magnetite dominated the s...

Speleothem oxygen isotope (δ¹⁸Oc) records have been regarded as a critical reference to study past Asian monsoon variability. However, existing δ¹⁸Oc records in the Indian monsoon region are fragmented in time coverage and/or sampling resolution since the last deglaciation. Also, the climatic interpretation of δ¹⁸Oc is still obscure. Here, we repor...

Biodiversity loss is often an important driver of the deterioration of ecosystem functioning in freshwater ecosystems. However, it is far from clear how multiple ecosystem functions (i.e., ecosystem multifunctionality, EMF) relate to biodiversity across the benthic-pelagic habitats of entire ecosystems or how environmental stress such as eutrophica...

Anthropogenic and climatic stressors on freshwater ecosystems are of global concern. However, the interactions and effects of multiple stressors (e.g., nutrient enrichment, climate warming, altered wind and precipitation) acting over different spatial and temporal scales are often complex and remain controversial. Here, we reconstructed one‐century...

Over the Tibetan Plateau (TP), lakes as paleoenvironmental archives have been the most extensively investigated for their sensitivities to climate change on different timescales. Well-preserved shoreline and terrace remains surrounding these lakes provide critical geomorphological and sedimentary evidence that can be used to infer past lake levels...

High-quality paleoclimate reconstructions can provide crucial climate context to test the hypothesis of climatic impact on historical culture changes. Here we report high-resolution and quantitative temperature and precipitation records covering the entire “5000-year” Chinese history in northern China. Our temperature record shows a slight decrease...

Coastal deposits are ideal archives to decipher the history of terrestrial-marine interactions in response to sea-level changes. Over the last decades, numerous investigations have been implemented to uncover the stratigraphic framework and the paleoenvironment evolution of the Jiangsu coastal plain (JCP), China. However, there have been limited st...

Mountain ecosystems are sensitive to environmental changes and are affected by direct and indirect anthropogenic activities. This paper aims to understand the impacts of human occupation, environmental and climate change on the Great Hinggan Mountains (GHM) in northeastern China. The last 200 years of environmental changes are reconstructed by anal...

Plain Language Summary Reconstruction of Holocene climate change provides an important basis for understanding long‐term climate variability over the last 13.1 kyr and provides context for better projecting future climate change. The gradual Holocene cooling documented by many of the current proxy‐based temperature records obviously contradicts the...

Orbital-scale global climatic changes during the late Quaternary are dominated by high-latitude influenced ∼100,000-year global ice-age cycles and monsoon influenced ∼23,000-year low-latitude hydroclimate variations. However, the shortage of highly-resolved land temperature records remains a limiting factor for achieving a comprehensive understandi...

Human activities have greatly increased the influx of pollutants into global freshwater ecosystems. Understanding the pollution patterns at multi-decadal scales, and how the socio-economic development and public policy have shaped them, are crucial to assess the current status of environmental quality and develop sound strategies for watershed mana...

Climate change stands to have a tremendous impact on the world’s freshwater ecosystems. To understand how, researchers analyzed 15,289 functional genes related to nutrient cycling and stress processes gathered from biofilm microbes across mountainside streams in Norway, Spain, and China. With increasing elevation, microbial functional diversity ten...

The evolution of the Indian Summer Monsoon (ISM) has been widely investigated and traditionally interpreted as consequences of orbital forcing change and the migration of the Intertropical Convergent Zone (ITCZ). The potential influence of sea-surface temperature (SST) on ISM variation at millennial time scales has been progressively proposed in re...

Stream bacterial communities are shaped by a combination of local and regional processes, such as environmental filtering, biotic interactions and dispersal, but biotic interactions have received comparatively less attention. Here, we investigated stream bacterial alpha and beta diversity within taxonomic and phylogenetic contexts around Qiandao La...

The environmental history of the source region of the Yellow River (SRYR) is vital for understanding its hydrological response to climate processes in the alpine northeastern Tibetan Plateau (TP). In this study, we present the first sediment core record from Lake Gyaring, one of the largest fresh lakes in SRYR, using proxies of total organic carbon...

Luminescence dating technology has been used for chronological constraints on lacustrine sediments due to the ubiquitous materials (e.g., quartz and feldspar) as dosimeters, and a relatively long dating range, compared with the commonly used radiocarbon dating method. However, quartz dating on the Tibetan Plateau may suffer from dim and unstable lu...

Background: Understanding the large-scale patterns of microbial functional diversity is essential for anticipating climate change impacts on ecosystems worldwide. However, studies of functional biogeography remain scarce for microorganisms, especially in freshwater ecosystems. Here we study 15,289 functional genes of stream biofilm microbes along...

Dating of sediments in the tidal-dominated Yangtze River delta remains a challenge because of extremely complicated processes during sediment transport and deposition in such a fluvial-marine transition zone. To better understand the late Quaternary sedimentary history of the Yangtze River delta, we explore the applicability of K-feldspar luminesce...

Community variation (i.e., beta diversity) along geographical gradients is a well-known ecological pattern, but the corresponding variation in beta diversity components (e.g., species turnover and nestedness) and underlying drivers remain poorly understood. Based on two alternative approaches (that is, the beta diversity partitioning proposed by Ba...

Over the past decades, paleoenvironmental studies in the Indian summer monsoon region have mainly focused on precipitation change, with few published terrestrial temperature records from the region. We analysed the distribution of isoprenoid glycerol dialkyl glycerol tetraethers (isoGDGTs) in the sediments of Lake Chenghai in southwest China across...

High-resolution pollen and charcoal records from Dianchi in central Yunnan Province, southwestern China are presented in this study and reveal variations in vegetation, fire, lake environments, and climate over the last 20,000 years (20 ka). The results show that the climate during the period 20.0–18.0 ka was relatively cold, and rainfall in winter...

A multi-proxy record of Holocene and late-Pleistocene aeolian mineral dust is reconstructed using a combination of geochemical (trace elements), mineralogical and grain-size analyses on cores from the Hani peatland in north-eastern (NE) China. The dust record displays a sharp increase in dust deposition during the late Holocene in comparison to the...

Numerous paleoclimate records on reconstructed monsoon precipitation isotopes (δDp and δ18Op) have been published to infer past hydroclimate changes in Asian monsoon region. However, there are still debates on whether or not these reconstructed δDp or δ18Op can represent changes of monsoon precipitation. In this study, we report a ~ 5000 year recor...

Human activity and climate change have driven complex physical and ecological changes in China’s inland waterbodies. Many lakes are facing serious problems with degraded ecosystem functions and services, driven by multiple factors. Knowledge of how lakes change and respond to these drivers is crucial for sustainable lake management. Paleolimnologic...

Elevated concentrations of polycyclic aromatic hydrocarbons (PAHs) have been observed with rapid agricultural and industrial development in the Songnen Plain, Northeast China, but the prospective sources have not been yet apportioned. The concentration of PAHs was measured in 31 sediment samples from 11 Songnen Plain lakes in 2015. The background f...

Aim Community variation (i.e. beta diversity) along geographical gradients is of substantial interest in ecology and biodiversity reserves in the face of global changes. However, the generality in beta diversity patterns and underlying processes remains less studied across trophic levels and geographical regions. We documented beta diversity patter...

Environment quality of suburban and urban lakes receives special attention due to their great impacted by human perturbations and important roles in ecosystem services. Herein, the spatio-temporal variations of 10 metal and metalloid elements in 13 sediment cores from a large suburban lake (Dianchi) were studied to explore the changes in sedimentar...

A 328.58 m drill core (XK12) was recovered from lacustrine–alluvial sediments in the Xingkai Basin, northeast China, with the aim of obtaining a high-resolution pollen record of East Asian winter monsoon (EAWM) evolution since 3.6 Ma. An index based on the pollen record of thermophilous trees and terrestrial herbs is used as an indicator of winter...

Over the past few decades, paleoenvironmental studies in the Indian Summer Monsoon (ISM) region have mainly focused on precipitation change, with few published terrestrial temperature records from the region. We analyzed the distribution of isoprenoid glycerol dialkyl glycerol tetraethers (isoGDGTs) in the sediments of Lake Chenghai in southwest Ch...

Identifying variability and the mechanisms driving variability in the Indian summer monsoon (ISM) since the last deglaciation is critical for understanding past hydroclimatic change. In this study, we present an accelerator mass spectrometry radiocarbon dated record of δ¹⁸O variations in authigenic carbonates derived from Lake Chenghai in southwest...

Lake biodiversity is an incomplete indicator of exogenous forcing insofar as it ignores underlying deformations of community structure. Here we seek a proxy for deformation in a network of diatom assemblages comprising 452 species in 273 lakes across China. We test predictions from network theory that nodes of similar type will tend to self-organis...

Studying the response of vegetation to past climate changes may help better predict the potential impacts of future climate changes on the terrestrial ecosystems. Here we present a pollen record that covers the second half of the Holocene from the Nanling Mountains, southern China. Our record reveals six cooling events occurring during 5600−4800, 4...

Water-depth biodiversity gradient, one of the typical biogeographical patterns on Earth, is understudied for bacteria in freshwater ecosystems, and thus left the underlying mechanisms poorly understood especially for benthic bacteria. Here, we investigated the water-depth distribution of surface sediment bacterial phyla and their driving factors in...

Organic carbon mineralization and storage in the inland water bodies is an important component of global carbon cycling. However, the mechanisms influencing carbon cycling in the inland water bodies remain uncertain. In this study, n-alkane data from a sediment core spanning the last glacial-interglacial cycle from Lake Xingkai in northeast China,...

Analysis of lake sediment geochemistry is valuable for understanding past hydroclimatic changes via the reconstruction of changes in catchment erosion, chemical weathering, redox processes and the intensity of evaporation. In this study, we analyzed the geochemical composition, magnetic susceptibility and carbonate content of the Holocene sediments...

Understanding biodiversity patterns and the role of biotic attributes in governing these patterns remains one of the most important challenges in ecology. Here, taking water depth in Lake Lugu as a typical geographical gradient, we studied how these different taxa, that is bacteria, diatoms and chironomids, respond to the water depth and environmen...

Documenting climate change over the past 2000 years, or the Common Era, is critical to understand how the climate system evolved from one controlled by natural forcings alone to one influenced by anthropogenic greenhouse gas forcing. However, global and regional temperature changes during this interval are still poorly understood, largely due to th...

We present a sub-centennial resolution summer temperature record from the SE Tibetan Plateau (Tiancai Lake, SW China, 3900 m a.s.l.) derived from a chironomid stratigraphy covering the last c.19.5 ka. The record highlights the interaction between tropical and high-latitude climate forcing through the changes in atmospheric circulation during the la...