Karst reservoirs with high dissolved inorganic carbon (DIC) concentration exhibit an efficient biological carbon pump (BCP) effects driven by phytoplankton photosynthesis; however, the biogeochemical interaction effect between DIC dynamics and phytoplankton community succession on the regulation of BCP remains to be elucidated. To address this issue, we conducted seasonal surveys across 11 karst reservoirs in the Wujiang River Basin and analyzed phytoplankton species composition, nutrients, DIC and its stable carbon isotopes (δ13CDIC). The results showed that reservoirs dominated by non-diatoms exhibited faster seasonal community succession rates, particularly those with algal bloom such as cyanobacteria or dinoflagellates. Random Forest regression and Mantel-tests identified non-diatoms as the primary predictor of community dissimilarity, with temperature, Chl-a, and CO₂(aq) depletion ranking as the most influential environmental filters. Non-diatoms exhibit enhanced dominance under CO2(aq)-limited conditions and increasing primary productivity and BCP efficiency, a process closely linked to dynamic shifts in DIC speciation (e.g., CO₂(aq) and HCO₃−). Furthermore, reservoirs with low hydraulic loads (Hydr-L) demonstrated pronounced seasonal vertical stratification that intensified CO2 limitation within the euphotic zone, which promoted non-diatom growth and resulted in a stronger BCP effect than reservoirs with high Hydr-L. Overall, our findings demonstrate that the phytoplankton community succession co-varies robustly with DIC dynamic speciation, with their synergistic interaction influencing the BCP efficiency in karst reservoirs. This framework enhances predictive understanding of carbon source–sink functioning in karst cave reservoirs under the context of biome community shifts driven by global warming and eutrophication.

Different responses of lake microbial assemblages to climate changes and human activities are not well understood due to the scarcity of long-term biodiversity records. In this study, an approach of paleolimnology and metagenomic sequencing of sedimentary ancient DNA was combinedly used to investigate environmental changes, lake primary productivity, and cyanobacterial community succession over the last similar to 500 years in Lake Daihai, northern China. The results show a different response of cyanobacterial communities to climate change and anthropogenic activities on different timescales. Lake primary productivity, biodiversity, and trophic status were in a generally natural state and were mainly controlled by temperature and precipitation before similar to 1850 CE, but were clearly affected by human activities thereafter. Overall microbial diversity values gradually increased after similar to 1850 CE, and ordination analysis further indicates that the present community is substantially dissimilar to that observed before similar to 1850 CE. The structure of cyanobacterial communities was relatively stable prior to similar to 1850 CE, followed by prominent decadal scale fluctuations that were broadly synchronous with the sedimentary organic matter molecular compositions. These molecular proxies reveal that anthropogenic forcing, rather than climate, may be the primary controls of cyanobacterial communities over the past one more century. Enhanced land-use change and cropland runoff, and increased discharges of industrial wastewater and human sewage are likely the main factors driving changes in lake primary productivity and cyanobacterial community composition. Our finding highlights the sensitive responses of lake ecosystem to anthropogenic disturbance in the monsoon marginal zone, and proper exogenous nutrient control (e.g., thresholds for agricultural runoff) is necessary to maintain the sustainability of the regional aquatic ecosystems.

The production of both methane (CH4) and refractory dissolved organic matter (RDOM) depends on microbial consortia in inland waters, and it is unclear yet the link of these two processes and the underlying microbial regulation mechanisms. Therefore, a large-scale survey was conducted in China's inland waters, with the measurement of CH4 concentrations, DOM chemical composition, microbial community composition, and relative environmental parameters mainly by chromatographic, optical, mass spectrometric, and high-throughput sequencing analyses, to clarify the abovementioned questions. Here, we found a synchronous production of CH4 and RDOM linked by microbial consortia in inland waters. The increasing microbial cooperation driven by the keystone taxa (mainly Fluviicola and Polynucleobacter) could promote the transformation of labile DOM into RDOM and meanwhile benefit methanogenic microbial communities to produce CH4. As such, CH4 and RDOM showed consistent spatial differences, which were mainly influenced by total nitrogen and dissolved oxygen concentrations. This finding deepened the understanding of microbial-driven carbon transformation and will help to more accurately evaluate the carbon source-sink relationship in inland waters.

The production of refractory dissolved organic matter (RDOM) is complex and closely related to microbial consortia in aquatic ecosystems; however, it is still unclear how microorganisms regulate the production of RDOM and its molecular composition in inland waters. Therefore, we conducted a large-scale survey of inland waters and analyzed the optical and mass spectrometric characteristics of DOM, the microbial community and functional genes, as well as related environmental parameters, to understand the abovementioned issues. Here, the RDOM production was found mainly regulated by microbial (e.g., phylogeny and community assembly) rather than other environmental factors in inland waters. Biostatistical analyses and carbon isotopic evidence indicated that the successive microbial processing from labile DOM to RDOM (i.e., carboxyl-rich alicyclic molecules, CRAMs) was widely present in inland waters, involving the microbially mediated carbon skeleton turnover and heteroatom conversion. There was a significant empirical relationship between CRAMs and the ratio of Proteobacteria to Actinobacteria, highlighting the intraspecific interaction of bacteria more important than other microbial groups (i.e., archaea, eukaryotes, and fungi) for the RDOM production. This study demonstrated a fundamental role of microbial regulation in RDOM production within the inland waters, thereby facilitating future estimation of carbon sequestration potential in inland aquatic ecosystems.

The microbial "unseen majority" as drivers of carbon cycle represent a significant source of uncertain climate change. To comprehend the resilience of life forms on Earth to climate change, it is crucial to incorporate knowledge of intricate microbial interactions and their impact to carbon transformation. Combined with carbon stable isotope analysis and high-throughput sequencing technology, the underlying mechanism of microbial interactions for organic carbon degradation has been elucidated. Niche differentiation enabled archaea to coexist with bacteria mainly in a cooperative manner. Bacteria composed of specialists preferred to degrade lighter carbon, while archaea were capable of utilizing heavier carbon. Microbial resource-dependent interactions drove stepwise degradation of organic matter. Bacterial cooperation directly facilitated the degradation of algae-dominated particulate organic carbon, while competitive feeding of archaea caused by resource scarcity significantly promoted the mineralization of heavier particulate organic carbon and then the release of dissolved inorganic carbon. Meanwhile, archaea functioned as a primary decomposer and collaborated with bacteria in the gradual degradation of dissolved organic carbon. This study emphasized microbial interactions driving carbon cycle and provided new perspectives for incorporating microorganisms into carbon biogeochemical models.

Background Planktonic bacteria and archaea play a key role in river nutrient biogeochemical cycling; however, their respective community assembly and how to maintain their diversity are not well known in dammed rivers. Therefore, a seasonal survey of planktonic bacterial and archaeal community compositions and related environmental factors was conducted in 16 cascade reservoirs and corresponding river waters on the Wujiang River and the Pearl River in southwest China to understand the above mechanisms. Results Deterministic processes dominated bacterial and archaeal community assembly. The structural equation models showed that water temperature can directly or indirectly affect the microbial diversity. Interestingly, planktonic bacterial diversity increased with increasing water temperature, while archaea showed the opposite trend; the overall diversity of bacteria and archaea was no significant changes with changeable water temperature. Abundant microbes had a stronger distance–decay relationship than middle and rare ones, and the relationship was stronger in winter and spring than in summer and autumn. Conclusions Planktonic bacteria and archaea in dammed rivers had different biogeographic distributions, and water temperature was a key controlling factor. The different responses of planktonic bacterial and archaeal diversity to water temperature could be due to their different phylogenetic diversity. This ultimately maintained the stability of total microbial community diversity. This study reveals the different responses of planktonic bacteria and archaea to water temperature and perfects the theoretical framework for planktonic microbial biogeography in dammed rivers.

Dissolved organic matter (DOM) is crucial for the carbon biogeochemical cycle and has a close link with microbiome in aquatic ecosystems; however, the causal relationship between DOM and microbial diversity in inland waters is not very clear so far. Therefore, a national survey of China's inland waters was conducted, and the DOM chemical composition and microbial community composition were determined by Fourier transform ion cyclotron resonance mass spectrometry and high-throughput sequencing to clarify the abovementioned question. Here, we found that DOM chemodiversity was governed by microbial community assembly in inland waters, not vice versa. Under the control of microbial biogeography, DOM chemodiversity showed a clear geographical distribution difference. Water DOM chemodiversity was mainly constrained by bacterial and archaeal community composition, whereas sediment DOM chemodiversity was mainly controlled by eukaryotic and fungal community composition. In addition, the sediment DOM chemical composition was also affected by the interaction of different microbial groups between waters and sediments. The study is the first to clarify the causal relationship and proposes a microbial regulatory mechanism on the geographical distribution pattern of DOM chemodiversity, thus further deepening the understanding of the DOM biogeochemical cycle.

Phytoplankton cell size is well known as an essential functional trait, but its control factors are still unclear. Considering light provides the necessary energy for phytoplankton survival, we hypothesized that photosynthetic light energy utilization could influence phytoplankton cell size control. Several scenarios were conducted to understand the relationship between Fv/Fm and cell size for phytoplankton interspecies, and metatranscriptome in the field and transcriptome in the laboratory were used to understand relevant molecular mechanisms. The results indicated that there was a universal significant positive relationship between Fv/Fm and cell volume in general. The molecular evidence demonstrated that light utilization by phytoplankton regulates their cell size by harmonizing the generation and allocation of chemical energy and fixed carbon in the cell. Phytoplankton cell size would cease to enlarge once the increased light energy conversion and subsequent fixed carbon could no longer satisfy the increasing demand of size enlargement. This unity of energy and matter in shaping phytoplankton size results in cell size being an important functional trait. This study is the first to discover the above molecular mechanisms and is helpful to deepen the understanding on the cell size control of phytoplankton.

Microbial diversity, together with carbon function, plays a key role in driving the wetland carbon cycle; however, the composition, driving factors of carbon-functional genes and the relationship with microbial community have not been well characterized in coastal wetlands. To understand these concerns, microbes, carbon-functional genes, and related environmental factors were investigated in twenty wetlands along China's coast. The results indicate that carbon-functional gene composition is dominated by archaeal rather than bacterial community and that Nanoarchaeaeota is the dominant archaeal phylum associated with carbon cycling in anoxic sediments. Compared with microbes, carbon-functional composition was more stable because they showed the highest Shannon diversity and archaeal functional redundancy. Deterministic processes dominated microbial community, and stochastic processes were more important for carbon-functional genes. Labile Fe governed archaeal and carbon-functional composition by coupling with nitrogen and carbon biogeochemical cycles, while bacterial community was affected by NH4-N and SOC/SON. This study highlights the predominant contributions of archaea to carbon-functional genes and to the stability of carbon-functional composition, thus providing new insights into the microbial dominance of the carbon cycle and the evaluation of carbon function in coastal wetlands.

Japanese larch (Larix kaempferi), a non-native tree species, has been widely planted in the Qinling Mountains since the last century, but it does not meet the habitat needs of giant pandas (Ailuropoda melanoleuca), mainly because of food, further causing habitat degradation and fragmentation. However, how soil microorganisms, considered as predictors of the soil environment, respond to Japanese larch remains poorly explored, especially compared with native forests. Here, we collected 40 soil samples from plantation, bamboo, and natural (excluding bamboo) forests in the Changqing Nature Reserve and Foping Nature Reserve in Qinling to compare soil bacterial community composition and diversity using high-throughput sequencing of bacterial 16S rRNA genes. The soil chemical properties and bacterial communities differed noticeably under forest-type classification patterns. The soil of the Japanese larch planted forests underwent substantial degradation, with higher acidity, lower alpha diversity, and more significant enrichment in the oligotrophic bacteria Acidobacteria and Verrucomicrobia, in contrast to the other two primary forests with elevated soil nutrient levels. The application of PICRUSt2 indicated the down-regulation of amino acid-related metabolism in planted forests. Moreover, pH was the primary factor determining the whole bacterial community structures. To avoid the uncertainty of a single sampling region, we chose different sampling sites that could be considered as geographical factors, possibly due to environmental heterogeneity or dispersal limitations, which also explained the specific community patterns of microorganisms. Overall, this paper may help provide a scientific basis for future revegetation in giant panda habitats, highlighting the urgent need for ecological restoration and sustainable forestry management.

Dissolved organic matter (DOM) plays an important role in wetland carbon cycle; however, the geographical pattern of DOM chemodiversity and controlling factors are not very clear for coastal wetland sediments, especially at large spatial scale. To this end, twenty China's coastal wetlands were surveyed on a national scale for their sediment DOM and related environmental parameters, and the DOM molecular compositions were resolved by Fourier transform ion cyclotron resonance mass spectrometry and relevant bioinformatics. The chemodiversity of a total of 14, 343 DOM molecular formulas showed a clear geographical pattern: a decrease with an increase in latitude. The moisture and organic matter contents of sediments were key factors controlling DOM chemodiversity and decreased with the increasing latitude. In addition, the sediment with higher DOM molecular chemodiversity contained more unsaturated compounds, and lignin-like and tannins increased with the decreasing latitude. This study highlights the molecular characteristics of sediment DOM in China's coastal wetlands and helps to deepen the geographical knowledge of coastal wetland DOM.

River damming alters biogeochemical cycles in river continuum. Yet, its effect on the biogeochemical behavior of riverine strontium (Sr) is still unclear. Here, we measured riverine 87Sr/86Sr in both dissolved and particulate phases and relevant parameters in karst cascade reservoirs of Southwest China, and simulated 87Sr/86Sr fractionation during biological processes through experimental incubation of model phytoplankton. The results showed that the dissolved 87Sr/86Sr was rather homogeneous across the water body and nearly identical to inorganic particulate-bound 87Sr/86Sr, and reservoir Sr mainly sourced from carbonate weathering. However, the dissolved Sr concentrations were stratified and increased with depths of the reservoir water columns. This stratification was likely caused by phytoplankton and the precipitation and dissolution of calcite, with the stratified strength controlled by reservoir hydraulic loads. A long-term loads along cascade reservoirs thus could result in a significant increase in dissolved Sr concentrations rather than 87Sr/86Sr. The culture experiment indicated that the dissolved Sr was massively captured by the phytoplankton during which insignificant 87Sr/86Sr fractionation occurred. Thus, the 87Sr/86Sr of reservoir phytoplankton would conserve the dissolved 87Sr/86Sr. The distinctly lower 87Sr/86Sr of phytoplankton than terrestrial organic particulates highlights its potential to distinguish autochthonous and allochthonous sources of reservoir particulate matter. This study demonstrated that damming largely alters the elemental and isotopic distribution of riverine Sr and would deepen the understanding of Sr biogeochemistry in dammed rivers.

生境适宜性评价对野生动物的保护与管理具有重要意义.为了解陕西秦岭地区斑羚(Naemorhedus griseus)的生境状况,利用2011-2013年间在秦岭地区采集的斑羚分布点数据,通过MaxEnt模型对陕西秦岭地区的斑羚生境进行适宜性评价.结果表明,陕西秦岭地区的斑羚适宜生境面积约为9800 km2,占秦岭山地面积的17％,主要位于秦岭中西部区域;次适宜生境面积约为6940 km2,占秦岭面积的12％,主要位于适宜生境的周边区域.海拔、月均昼夜温差和年降雨量是影响陕西秦岭地区斑羚生境适宜性的主要环境变量,而人类干扰对生境适宜性的影响较小.陕西秦岭地区的斑羚偏好于选择1800-3000 m的中高海拔区间、年降水量为750-850 mm、月均昼夜温差8℃左右的环境.明确了斑羚适宜生境在秦岭的分布状况及关键环境影响因子,可为下一步制定濒危动物保护和生境管理提供理论依据.

Phytoplankton carbon (C) and nitrogen (N) stoichiometric homeostasis plays an important role in aquatic ecosystems. Their C:N ratio is a result of cellular metabolic balance, and the relevant regulatory strategy for its plasticity is still unclear. Therefore, a field survey of seven reservoirs in Tianjin, North China, was conducted to understand variations in phytoplankton C:N ratios, and a laboratory culture of Chlamydomonas reinhardtii was performed to understand the relevant regulation strategy for cellular C-N stoichiometric homeostasis under different C and N availability by using transcriptome sequencing and Nano SIMS and C stable isotope analyses. The results indicated that CO2 limitation had no significant effect on the phytoplankton C:N ratio in either scene, whereas limitation of dissolved inorganic N induced a 35% higher ratio in the field and a 138% higher ratio in the laboratory. Under CO2 limitation, algal CO2-concentrating mechanisms were operated to ensure a C supply, and coupled C-N molecular regulation remained the cellular C:N ratio stable. Under nitrate limitation, differentially expressed gene-regulated intensities increase enormously, and their increasing proportion was comparable to that of the algal C:N ratio; cellular metabolism was reorganized to form a "subhealthy" C-N stoichiometric state with high C:N ratios. In addition, the N transport system had a specific role under CO2 and nitrate limitations. Our study implies that algal stoichiometric homeostasis depends on the involved limitation element and will help to deepen the understanding of C-N stoichiometric homeostasis in freshwater phytoplankton.

Planktonic microorganisms play an important role in maintaining the ecological functions in aquatic ecosystems, but how their structure and function interrelate and respond to environmental changes is still not very clear. Damming interrupts the river continuum and alters river nutrient biogeochemical cycling and biological succession. Considering that river damming decreases the irregular hydrological fluctuation, we hypothesized that it can enhance the ecological functional stability (EFS) of planktonic microorganisms. Therefore, the community composition of planktonic bacteria and archaea, functional genes related to carbon, nitrogen, sulfur, and phosphorus cycling, and relevant environmental factors of four cascade reservoirs in the Pearl River, Southern China, were investigated to understand the impact of damming on microbial community structure and function and verify the above hypothesis. Here, the ratio of function to taxa (F:T) based on Euclidean distance matrix analysis was first proposed to characterize the microbial EFS; the smaller the ratio, the more stable the ecological functions. The results showed that the reservoirs created by river damming had seasonal thermal and chemical stratifications with an increasing hydraulic retention time, which significantly changed the microbial structure and function. The river microbial F:T was significantly higher than that of the reservoirs, indicating that river damming enhances the EFS of the planktonic microorganisms. Structural equation modeling demonstrated that water temperature was an important factor influencing the relationship between the microbial structure and function and thus affected their EFS. In addition, reservoir hydraulic load was found a main factor regulating the seasonal difference in microbial EFS among the reservoirs. This study will help to deepen the understanding of the relationship between microbial structure and function and provide a theoretical basis of assessing the ecological function change after the construction of river damming.

Hydropower plays an important role in the supply of renewable energy, but it also exerts a great influence on the river continuum. Understanding nutrient cycling and microbial community succession in hydropower reservoirs is key to weighing hydroelectric pros and cons. However, the underlying control mechanisms are still not well known, especially with respect to the impacts of hydrological conditions. Based on a comprehensive survey of hydropower reservoirs along the Wujiang River in SW China and an integration of published data, we found that reservoir physicochemical and biological stratifications and planktonic microbial community assembly were synergistically evolving, and reservoir hydraulic load (i.e., mean water depth per unit retention time) was a key factor controlling the strength of stratifications, CO2 and N2O fluxes, nutrient retention efficiency, and bacterioplankton diversity. Hydraulic loads are artificially designed for hydropower reservoirs, and nutrient cycling and biological succession in reservoirs are thus governed by anthropogenic regulation. This study provides a theoretical basis to mitigate the environmental impacts of hydropower dams by regulating reservoir hydraulic load.

为分离新疆野苹果(Malus sieversii(Ledeb.)Rome)BAG家族候选成员以及探究BAG7在逆境胁迫中的生理功能,采用转录组测序及转基因技术对新疆野苹果进行研究.结果显示,新疆野苹果中有7个MsBAG家族成员,其中MsBAG7可以受干旱、低温及DTT的诱导表达,而且MsBAG7在拟南芥中的过量表达可以改善植物的抗旱、耐寒及抗DTT能力.

Particulate inorganic carbon (PIC) is one of the most important components of carbon cycle in hydropower reservoirs. However, the processes of production, migration, and transformation of PIC in hydropower reservoirs are still unclear. As such, we investigated the concentration and carbon isotope composition of PIC and dissolved inorganic carbon and related environmental parameters of hydropower reservoirs on the Wujiang River, Southwest China, to understand these processes. The observed δ 13 C datasets demonstrated that the river PIC is derived from exogenous carbonate weathering and endogenous carbonate precipitation, whereas the reservoir PIC is dominated by authigenic PIC driven by phytoplankton. The reservoir PIC concentration and δ 13 C PIC showed seasonal stratification in the water profile, the extent of which depends on surface photosynthesis and bottom respiration. The influence of phytoplankton on the production and transformation of PIC was different among the reservoirs with different ages and trophic levels, and the δ 13 C technique can reveal these processes very well. This study improves the comprehensive understanding of carbon cycling in hydropower reservoirs and environmental effects of river damming.

Planktonic bacteria and archaea play a key role in maintaining ecological functions in aquatic ecosystems; however, their biogeographic patterns and underlying mechanisms have not been well known in coastal wetlands including multiple types and at a large space scale. Therefore, planktonic bacteria and archaea and related environmental factors were investigated in twenty-one wetlands along China's coast to understand the above concerns. The results indicated that planktonic bacteria had different biogeographic pattern from planktonic archaea, and both patterns were not dependent on the wetland's types. Deterministic selection shapes the former's community structure, whereas stochastic processes regulate the latter's, being consistent with the fact that planktonic archaea have a larger niche breadth than planktonic bacteria. Planktonic bacteria and archaea co-occur, and their co-occurrence rather than salinity is more important in shaping their community structure although salinity is found to be a main environmental deterministic factor in the coastal wetland waters. This study highlights the role of planktonic bacteria-archaea co-occurrence on their biogeographic patterns, and thus provides a new insight into studying underlying mechanisms of microbial biogeography in coastal wetlands.

Cypripedium japonicum is an endangered terrestrial orchid species with high ornamental and medicinal value. As global warming continues to intensify, the survival of C. japonicum will be further challenged. Understanding the impact of climate change on its potential distribution is of great significance to conserve this species. In this study, we established an ensemble species distribution model based on occurrence records of C. japonicum and 13 environmental variables to predict its potential distribution under current and future climatic conditions. The results show that the true skill statistic (TSS), Cohen’s kappa statistic (Kappa), and the area under the receiver operating characteristic curve (AUC) values of the ensemble model were 0.968, 0.906, and 0.995, respectively, providing more robust predictions. The key environmental variables affecting the distribution of C. japonicum were the precipitation in the warmest quarter (Bio18) and the mean temperature in the driest quarter (Bio9). Under future climatic conditions, the total suitable habitat of C. japonicum will increase slightly and tend to migrate northwestward, but the highly suitable areas will be severely lost. By 2070, the loss of its highly suitable habitat area will reach 57.69–72.24% under representative concentration pathway (RCP) 4.5 and 8.5 respectively, and the highly suitable habitats in Zhejiang and Anhui will almost disappear. It is noteworthy that the highly suitable habitat of C. japonicum has never crossed the Qinba mountainous area during the migration process of the suitable habitat to the northwest. Meanwhile, as the best-preserved area of highly suitable habitat for C. japonicum in the future, the Qinba mountainous area is of great significance to protect the wild germplasm resources of C. japonicum. In addition, we found that most of the changes predicted for 2070 will already be seen in 2050; the problem of climate change may be more urgent than it is believed.