Root exudates play an important role in soil carbon balance, acting as an important medium for material and energy exchange and information transfer between plant roots and soil, and also the crucial forms for plant response to environmental changes. Frequent extreme drought events accompanied with global climate change have imposed a profound impact on both above- and below-ground plant growth processes. However, significant limitation exists in understanding the responses of root exudates and their mediated rhizosphere priming effect to drought due to the complexity of root-soil interface interactions and the limitation in devices and methods for collecting root exudates. This paper reviews the effects of drought on the quantity and quality of plant root exudates, with emphasis on the rhizosphere priming effect mediated by root exudates under drought stress. The future research focuses on root exudates was also discussed. This study will provide suggestion for soil carbon sink assessment under the future climate change.

Aim: The important question of how riparian vegetation adapts to climatic and river hydrological changes is gaining global attention. Yet, the impact of snow and frequency of water level fluctuation on vegetation in the water level fluctuation zones remains underexplored. This study focuses on the response of the normalized difference vegetation index (NDVI) of riparian vegetation to climatic and hydrological changes in the basin of Yarlung Zangbo River, with an emphasis on understanding the impacts of snow and water level fluctuations in alpine fluctuation zones.

Method: This study employed Theil-Sen Median trend analysis and Mann-Kendall test to evaluate spatiotemporal vegetation trends utilizing NDVI as a key indicator from 1990 to 2022 in the Yarlung Zangbo River Basin, focusing on both the water level fluctuation zone and the adjacent 1-5 km buffer zones. A generalized linear model was used to quantify influencing factors including temperature, precipitation, snow water equivalent, and frequency of water level fluctuation.

Results: The spatial distribution of riparian vegetation’s NDVI demonstrated lower values in the northwest and higher in the southeast. Temporally, a notable fluctuating upward trend in NDVI was observed, reaching its peak in 2002 (0.16) and its bottom in 2022 (0.06). The annual NDVI progression revealed a consistent increase at mid-to-high altitudes, contrasting with the downstream areas’ sustained and irregular declines. Altitudinal analysis indicated that the decrease in NDVI varied in both the water level fluctuation and buffer zones, but was especially prominent between 1,500-3,000 m. The frequency of water level fluctuations stood out as the primary determinant for riparian NDVI, while temperature predominantly influenced the buffer zone’s NDVI. Additionally, the role of snow water equivalent in explaining NDVI became increasingly significant with elevation.

Conclusion: Vegetation in the water level fluctuation zone is influenced by various climatic and environmental factors, with water level fluctuations being pivotal. The importance of snow intensifies with increasing altitude, underscoring its significance in the spatial-temporal vegetation distribution.

Background & Aims: All biological organisms are constructed with a specific range and ratio of bioelements—namely the elementome. Organisms integrate multiple elements in optimal ratios to adapt to environmental heterogeneity. Biological elementome is assumed to be species-specific, which is determined by evolutionary history (phylogenetic distances) and controlled by inter-species competition and homeostasis. In community ecology, bioelemental composition and the variations in elementome provide an ideal indicator for quantifying the niche segregation of certain species in a community and predicting the possible responses of niche (displacement, expansion or concentration) to changes in environmental conditions. Biogeochemical niche (BN) quantifies species niches using the concept of elementome and n-dimensional hypervolume. On the basis of a brief summary of niche theory and ecological stoichiometry, we introduced the theoretical framework and the confirmatory studies of biogeochemical niche hypothesis (BNH) in this review. The prospects of its applications in different ecosystems were also discussed.

Review results: According to the BNH, the biogeochemical niche of certain species is defined as a function of phylogenetic distances (taxonomy), species sympatry (inter-species competitive pressure) and homeostasis/plasticity (the ability to maintain a stable elemental composition). This theory applies not only to plants, but also to animals and microbes. Using “biogeochemical niche(s)”, “metabolomic niche(s)”, “stoichiometric niche(s)” as key words, we conducted literature searches utilizing Web of Science (WoS) and CNKI, and manually picked out 84 relevant studies in November 2023. The studies mainly focused on C, N and P, and the most common keywords were “ecological stoichiometry” and “elemental composition”. In terms of taxa, the main taxa concerned in the studies were plants (54 articles), followed by animals (14 articles) and microorganisms (14 articles). We review the recent progress of BNH by taxa in this article.

Prospects & Suggestions: We suggest that the study of BNH be extended from C, N and P to more bioelements, to identify the species niche more accurately in higher dimensions. In different ecosystems, especially in stressful habitats, organisms should change their elementome to adapt to varied environments. More studies focusing on additional taxa (aquatic plants, plankton, fish, etc.) or certain habitats (freshwater or saline lake, river, high mountain, desert, etc.) are likely to help validate the universality of BNH. Furthermore, we propose to study the variations in biogeochemical niche at different life history stages of living beings, and bridge BN and population dynamics, to provide evidence for mechanism of species coexistence.

Aims Nei Mongol is an important ecological security barrier in northern China, and the study of changes in its vegetation productivity is of great significance to the ecological security of the northern region.

Methods Based on multi-source remote sensing data such as Eddy Covariance-Light Use Efficiency Gross Primary Productivity (EC-LUE GPP) in Nei Mongol from 1982 to 2017, this paper uses trend analysis and correlation analysis to analyze the temporal and spatial variation characteristics of vegetation gross primary production (GPP) in Nei Mongol and its correlation with air temperature, precipitation and soil moisture. On this basis, multiple linear regression and residual analysis methods were used to decompose and quantify GPP under the influence of climate changes and human activities, divide different time periods to carry out its impact on vegetation GPP, and explore the impact of different vegetation types on the driving factors response.

Important findings (1) Three meteorological elements showed good correlation with vegetation GPP, among which precipitation and soil moisture had higher correlations with GPP. (2) During the period 1982-1990, vegetation GPP showed an insignificant increasing trend with large fluctuations and the remaining three time periods (1991-2000, 2001-2010, 2011-2017) showed an insignificant downward trend. The areas with an overall downward trend accounted for 55% of the total area, and the other 45% showed a significant upward trend. (3) Except for the period from 2001 to 2010, climate changes played a decisive role in vegetation restoration in the other three time periods (1982-1990, 1991-2000, 2011-2017), explaining 20%, 16% and 13% of vegetation restoration, respectively. Human activities dominated vegetation degradation areas, explaining 13%, 19% and 20% of vegetation degradation, respectively. The research results can provide scientific reference for the implementation of ecological environmental protection and management policies and green and sustainable development in Nei Mongol.

Background & Aims: Seahorses (Hippocampus spp.) are well-known fishes from the family Syngnathidae, mainly due to their unique external morphology and reproductive strategy of male pregnancy. All Hippocampus species, listed in CITES Appendix II in 2002, are under trade regulations internationally. All Hippocampus species (wild populations only) inhabiting in China’s waters were listed as Category II of the National Key Protected Wild Animals in 2021. Through literature review, we (i) updated the species list of seahorses occurring in China’s waters, (ii) summarized their distribution regions, habitat and breeding features, and (iii) presented their threatened categories and threats. Our goal is to inform effective conservation measures for seahorse wild populations in China.

Review findings: In this paper, we reviewed and summarized seahorse species diversity, distributions, habitat uses, reproductive features, threatened categories, and threat factors from various reference sources, including online databases (Fishbase, The Fish Database of Taiwan, GBIF, WoRMS, IUCN), peer-reviewed papers, reports, theses, as well as informative Chinese ichthyographies. A total of 16 seahorse species were recorded in China’s waters, including 5 pygmy seahorses that are no more than 30 mm in body height. Among these, Japanese seahorses (H. mohnikei) were distributed most widely, across China’s all four seas. Crowned seahorses (H. coronatus) were only found in the Bo Hai, while Barbour’s seahorses (H. barbouri), Beibu Bay seahorses (H. casscsio, a new species found in 2016), and Tiger tail seahorses (H. comes) were only found in the South China Sea. Six species were only found in the coastal waters of Taiwan Province. Southern China, including Taiwan, Hainan, Guangdong, Fujian, and Guangxi, has high seahorse species diversity. The habitat uses of seahorses in China’s waters are very diverse, including coral and rocky reefs, seagrass and seaweed beds, muddy and sandy bottoms, gravels, and mangrove meadows. Some species have special requirements for their habitats. According to IUCN, 8 seahorse species were listed as Vulnerable (VU), 2 species were listed as Least Concern (LC), 5 species were listed as Data Deficient (DD), and 1 species was Not Evaluated (NE). The main threats to seahorses are bycatch and habitat destruction.

Recommendations: Seahorses are a special taxonomic group of fishes with high vulnerability, and we propose five recommendations for urgent conservations of seahorses in China. First, the significance of seahorses as flagship species in marine biodiversity conservation should be realized and we need to use them to raise marine-conservation awareness of the general public. Establishing marine protected areas for seahorses and their habitats, and applying other effective area-based conservation measures (OECMs) might also be taken into account. Second, it is known that non-selective fishing gears such as bottom trawling have high seahorse bycatch volume, and the dredge net operations can damage seaweed beds where seahorses inhabit. Therefore, any solution for reducing bycatch, increasing survival rates of seahorses after releasing, protecting habitats and innovating fishing gears are welcome. Third, identifying the key habitats of different seahorse species in China’s waters is very important for establishing protected areas and fisheries spatial management. Currently, such data are very limited. Some key areas we synthesized in this study require national-wide surveys to validate before planning for marine reserves and OECMs of seahorses in China. Fourth, seahorse trade regulation and enforcement should be strengthened, and the management of seahorse utilization should be regulated properly. To this end, techniques to distinguishing wild populations from farmed seahorses should be established as soon as possible before the expansion of seahorse aquaculture.

Background & Aims: There are 1,591 fish species in China’s inland waters, which accounts for 10% of the inland water fish species in the world. However, the development of the fish diversity monitoring in China’s inland water has still lagged and the long-term continuous and comprehensive monitoring networks and platforms has been scared. The China inland water fish biodiversity observation network (CIWF-BON) is the first nationwide network built for monitoring fish diversity of the inland waters in China. The purpose of this paper is to give a thorough overview of the achievement and to highlight the operations and duties of CIWF-BON.

Progress: The network has established the first national database of the inland water fish biodiversity and collects and preserves more than ten thousand fish specimens and the fish diversity data from important river basins, including the data sets of fish species diversity, early resources, genetic diversity, and biology of important fish species, and so on. The network also has established technical specifications for monitoring fish diversity in inland waters in China based on the synthesis of the conventional and novel monitoring methods to promote the standardization of collecting fish diversity data and enhance the possibility of analyzing large-scale data. The Chishui River Rare and Endemic Fish Conservation and Aquatic Biodiversity Observation and Research Station of the Chinese Academy of Sciences has been built to further monitor the fish diversity of the Chishui River and undertake the research on the protection and restoration of fish resources in the upper reaches of the Yangtze River basin.

Findings: Based on the long-term monitoring data, the network has systematically researched the distribution pattern, change, and the impact factors of the fish communities in the important rivers, the characteristics of reproductive biology and reproductive impact mechanisms of the endangered fish Chinese sturgeon (Acipenser sinensis), the environmental conditions of the four major Chinese carps reproduction in the middle reaches of the Yangtze River, as well as the biological characteristics of the endemic fish. The results show that the human activities, such as overfishing, dams, and invasive species, have caused significant changes in fish community structure of the important river basins. Large water conservancy and hydropower projects in the mainstream of the Yangtze River have caused the sharp decline in the population of Chinese sturgeon and seriously influence the breeding activities, making the wild population critically endangered. After the impoundment of the Three Gorges Reservoir, the eggs and larval of the four major Chinese carps (FMCC) are significantly decreased from 1997 to 2012 in the middle Yangtze River. The first spawning dates of FMCC in the Yichang reach delayed by about 21 days and the number of the eggs is changed with first decreasing and then increasing. The results lay the data foundation and provide the scientific evidence for the important national missions and policies, such as assessing the ecological impact of the Three Gorges Project, the ten-year fishing closure on the Yangtze River, the ecological and environmental protection of the Chishui River, and the conservation of the Chinese sturgeon, and so on.

Suggestions: To advancing the construction of the national observation network, we suggest to increase investment and establish observation stations, to promote data sharing and regional cooperation, and to conduct research and application of novel technologies and methods.

Aims: As the main component of ecosystem, macrofungi have important ecological functions and economic values. In this study, we aim to understand the species diversity, compositions, and resources of macrofungi in Beijing by performing comprehensive investigations, identifications, and analyses.

Methods: The macrofungal investigations were carried out in 2020-2022 by using line transect and random sampling methods. Specimens were identified by using morphological and molecular methods, and the complete list of macrofungi in Beijing was obtained based on both identification results and literature surveys. Species composition analyses, floristic geographical component analyses and resource evaluations were carried out based on the list by using statistical methods and literature surveying.

Results: A total of 5,448 specimens were collected, and 608 species were identified. The complete list of macrofungi in Beijing containing 619 species belong to 277 genera, 93 families, 22 orders, 6 classes, 2 phyla. Among all the species, 24 belong to Ascomycota, 595 belong to Basidiomycota, five were records new to China, 120 were new to Beijing. There were 19 dominant families with more than 10 species, accounting for 59.61% of the total species, including Agaricaceae, Polyporaceae, Psathyrellaceae, Russulaceae, Tricholomataceae, and so on. There were 33 dominant genera with more than 5 species, accounting for 38.13% of the total species, including Cortinarius, Gymnopus, Inocybe, Leucoagaricus, Russula, and so on. Cosmopolitan, north temperate, and pantropical genera accounted for 61.37%, 31.05%, and 5.42%, respectively. There were 71 edible, 43 medicinal, 22 poisonous, 45 both edible and medicinal fungi.

Conclusion: The species diversity of macrofungi in Beijing is high, and the economic resources are rich. The geographical composition of the flora reflects typical north temperate distribution characteristics. The species number of macrofungi in Beijing could be increased in the future since some large genera of mushrooms, such as, Cortinarius, Entoloma, Inocybe, Russula have not been sufficiently studied.

Background & Aim: As a significant nitrogen source in many natural terrestrial ecosystems where nitrogen is limited, associations formed by bryophytes and nitrogen-fixing cyanobacteria play an essential role in the global nitrogen cycle. Species composition and habitat of bryophyte-cyanobacteria associations result in contrasting nitrogen fixation capacities in different ecosystems. However, the current studies on bryophyte-cyanobacteria associations are predominately conducted in high-latitude ecosystems of the Northern Hemisphere, with few and scattered reports in other ecosystems. Therefore, we summarized the distribution, species composition, cyanobacterial colonization rate, cyanobacterial abundance, and nitrogen fixation potential of reported bryophyte-cyanobacteria associations worldwide, aiming to provide a reference for further study on the diversity and nitrogen fixation capacity of bryophyte- cyanobacteria associations in various ecosystems globally.
Progress: According to our analysis and summarization, a total of 110 bryophyte species from 58 genera in 41 families and more than 26 cyanobacteria species from 17 genera in 9 families, were identified to be involved in bryophyte-cyanobacteria symbiotic associations. The associated bryophyte species varied among diverse ecosystems. For example, Pleurozium schreberi-cyanobacteria associations are dominate in the understory of boreal forests, while Sphagnum spp.-cyanobacteria associations dominate wetland ecosystems. Nostoc species are the dominant cyanobacteria in most ecosystems due to their unique physiological characteristics and strong ecological adaptability. Among different ecosystems the colonization rate, abundance, and nitrogen fixation capacity of cyanobacteria on bryophytes differed significantly. Nitrogen fixation was highest in Arctic tundra ecosystems (1.3-24.6 kg N·ha^-1·yr^-1), followed by boreal forests (0.04-11.53 kg N·ha^-1·yr^-1), and was the lowest in temperate grasslands (0.008-0.124 kg N·ha^-1·yr^-1).
Perspective: We emphasized that the research on species composition and the capacity for nitrogen fixation was quite inadequate. We also highlighted four research perspectives: (1) Employing techniques such as metagenomics and establishing observation and research stations to explore and study the colonization characteristics and nitrogen fixation ability of cyanobacteria associated with bryophytes. (2) Conducting further and systematic research on bryophyte-cyanobacteria associations in all types of ecosystems. (3) Unifying the measurement and estimation methods of nitrogen fixation rate in different ecosystems. (4) Determining the key influencing factors and regulatory pathways of the diversity, distribution, colonization rate, cyanobacteria abundance, and nitrogen fixation rate of bryophyte- cyanobacteria associations.

Aims In recent years, the aquatic ecosystem of Caohai Lake, in Guizhou Province in southwest China, has shown a trend of phase shift from macrophyte- to phytoplankton-dominated states, which indicates the weakening ecological functioning of the lake. The chlorophyll a (Chl a) concentration is an important indicator of phytoplankton biomass. It is of great significance to clarify the variation of Chl a concentration in comprehensively understanding the ecological status and developing feasible restoration measures for the Lake.

Methods Surface water samples were collected from the Lake in summers and autumns of 2020-2021 to analyze the variation of Chl a concentration. The generalized additive model (GAM) was applied to explore the relationship between each environmental factor and Chl a concentration.

Important findings The results showed that, the Chl a concentration in surface water of Caohai Lake increased during phase shift, with an average up to (17.96 ± 10.62) μg·L^-1(during the monitoring period in 2021), which was 2.5 times greater than that before the phase shift (during monitoring period in 2020). The comprehensive trophic state of the Lake changed from mesotrophic state to eutrophic state, and the water quality presented an obvious trend of deterioration. Results from the single-factor GAM analysis showed that permanganate index (COD_Mn), total nitrogen (TN) concentration and water temperature (WT) had significant effects on Chl a concentration, which among all investigated environmental factors, account for 26.70%-33.30% of the concentration variation of Chl a, with WT, COD_Mn, TN concentration exhibiting the largest, intermediate, and smallest impact respectively. Based on the present study, it is concluded that COD_Mnand TN concentration were important factors driving the variation of Chl a concentration in Caohai Lake, and WT was an inducing factor. The massive extinction of submerged macrophyte and the significant increase of Chl a concentration indicated that the Lake is in phase shift from macrophyte- to phytoplankton-dominated state. Feasible measures should be developed timely to promote the restoration of submerged macrophyte, and further studies on phase shift mechanisms and restoration measures for the Lake should be carried out.

Aims: In recent years, wind power generation has been developing rapidly in China, and studies have found that wind power projects have varifying degrees of impact on bird diversity. However, previous studies primarily adopted traditional survey methods of birds in the region, without conducting long-term systematic monitoring of birds killed by wind turbines. Little is known about the possible causes of wind turbine mortality. Thus, it is difficult to propose targeted mitigation measures based on the actual causes of birds being killed by wind turbines.

Methods: In this paper, our study area was the wind turbines factory in the coastal area of Yancheng, Jiangsu Province. The carcass search method was applied to investigate the wind turbine mortality of birds in the study area. We conducted a total of 22 consecutive surveys from October 2020 to September 2021 to explored bird mortality from wind turbines.

Results: (1) There were 12 species in 8 orders and 10 families that were found dead under the wind turbines. The dead birds were primarily native birds or species that breed in the region, accounting for 66.7% of the dead bird species. (2) A total of 41 dead birds were found under the wind turbines. The most common were ring-necked pheasants (Phasianus colchicus) at 19 individuals, which were generally found in farmland or agricultural protection forest. Dead night herons (Nycticorax nycticorax) and egrets (Egretta garzetta) were also common, with 6 and 5 individuals found, respectively, and were generally found in near fishponds. (3) Based on the injuries of the dead birds, it was concluded that the bases of the wind turbines caused more collisions resulting in death than the fan blades.

Conclusion: According to our study, we proposed the following suggestions to mitigate the impact of wind turbines on birds. These suggestions include continuous bird monitoring, controlling habitats under wind turbines, and strengthening the research and development of bird-related repellent technology and equipment. We hope this study can provide a reference for the coordinated development between wind power and ecological environmental protection in China.

Aims Exploring the spatial distribution patterns and interactions of populations can help elucidate the underlying driving factors in population structure construction and the maintenance mechanism of spatial distribution. It guides the allocation, and management of different populations in the forest ecosystems, and also provides a scientific basis for local ecological environment protection and regional resource development.

Methods In this study, Picea crassifolia was selected as the research object. Three repeated plots with an area of 1 hm² were set up in the Pailugou Watershed of the Qilian Mountains, and all individual trees with a diameter at breast height (DBH) ≥1 cm were measured and recorded. The spatial patterns and intraspecific interactions of Picea crassifolia were analyzed by using a pair-correlation function (univariate and bivariate pair-correlation function) and mark correlation function (marked correlation function, marked variogram function, and Schlather’s I(r) function).

Important findings (1) The diameter class distribution of P. crassifolia population was continuous, with an inverted “J” type structure. (2) Picea crassifolia as a whole, saplings, and young trees showed a small-scale aggregation distribution, and gradually tended to random distribution with the increase of spatial scale. Medium trees showed a random distribution pattern on the whole observation scale, while large trees showed a regular distribution on the small scale and random distribution on the large scale. (3) Large trees of P. crassifolia showed small-scale negative correlations with other size class individuals and middle-scale positive correlations. There were strong positive correlations between medium and young trees, and between sapling and young trees at a small to medium scale, and they gradually changed to no correlation with the increase of spatial scale. (4) Individual characteristics of P. crassifolia showed high correlations, strong inhibitions, and significant symmetry competitions on a small to medium scale.

Aims The study of the spatial distribution pattern of soil nutrient stoichiometry along the altitude gradient is helpful to clarify the status of nutrient limitation in the mountainous ecosystems, to reveal the potential influencing factors to nutrient limitation, and to provide a scientific basis for regional ecological protection and vegetation restoration.
Methods The sampling plots were established along an altitude gradient from 3 100 m to 3 700 m in Pailugou watershed of the Qilian Mountains. Soil samples from 0-10 and 10-20 cm layers were collected separately to analyze the distribution of soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP) contents, and stoichiometric characteristics among different altitude and soil layers. Correlations between these nutrient characteristics and climatic factors, aboveground biomass, and soil pH were analyzed.
Important findings Results showed that: (1) Soil nutrients were concentrated on the soil surface and decreased with soil depth. The SOC and TN contents increased initially and then decreased as altitude increased. Soil TP content increased with increasing altitude. (2) Soil N:P increased from 3 100 m to 3 400 m, reached the maximum value at 3 400 m, and then decreased with increasing altitude and soil N:P was less than 14, suggesting an increase in N limitation along the altitude gradient. The C:P in soil was lower at high altitude than that at medium or low altitude, while C:N decreased with increasing altitude. (3) SOC content was positively correlated with TN content and negatively correlated with TP content. TN and TP content had no significant correlation. (4) Mean air temperature and total precipitation in the growing season showed positive correlation with SOC content and C:N:P, negative correlation with TP content, and no correlation with TN content. SOC and TN content had positive correlations with the aboveground biomass of shrublands. Soil pH was negatively correlated with TP content, but did not affect SOC and TN content significantly. Our results indicate that the productivity of alpine shrublands in the watershed was mainly limited by N and an appropriate amount of N application could alleviate the limitation.

Aims The purpose of this study was to understand the effects of the second generation wild boar grazing on species diversity and soil physicochemical properties of coniferous-broad-leaved mixed forest in the Jiajin Mountain, and to provide reference for the maintenance of ecological stability and scientific grazing of the mixed coniferous and broad-leaved forest in this area.

Methods On the basis of comprehensive investigation, according to the number, area, behavior characteristics and activity range of wild boar, four grazing disturbance intensity (from strong to weak was followed by I, II, III, IV) were divided, and no disturbance state was set as control (CK) to explore species diversity and soil physicochemical properties under different grazing disturbance intensity.

Important findings (1) 172 species of vascular plants, belonging to 55 families and 117 genera, were recorded, with the families, genera and species of trees, shrubs and herbs reaching the highest under slight disturbance intensity (IV). (2) The responses of tree, shrub and herb diversity index to the disturbance gradient were basically the same, but the richness index (S), Shannon diversity index (H') and Simpson dominance index (D) reached the maximum under the IV level disturbance intensity, which were higher than those in CK. The diversity level tended to decline with the increase of disturbance intensity (IV-I). In addition, for Pielou evenness index (E), there was no significant difference among different disturbance intensity levels. (3) Compared with CK, soil water content, maximum water content and total nitrogen content decreased under wild boar grazing. The greater the grazing pressure, the greater the proportion of decline. The content of soil total porosity, total phosphorus, available phosphorus and organic matter content increased in the IV level of interference, and decreased significantly under the I-III level interference; the soil density increased with the increase of disturbance intensity. (4) Redundancy analysis showed that soil organic matter content, available phosphorus content, soil density, soil water content, soil porosity, total phosphorus content, total nitrogen content and diversity index were significantly correlated. The light disturbance intensity is beneficial to the richness of community species diversity, the improvement of soil fertility and soil structure, which is a positive factor for the maintenance of ecological stability of the mixed coniferous and broad-leaved forest in the Jiajin Mountain. The study provides a reference for the forest ecological environment protection and sustainable development in this area under the background of increasingly expanding grazing and animal husbandry and increasingly frequent disturbance of human activities.

Aims Because of the connotation and extension of biosafety, the fuzziness of basic elements, the diversity of evaluation indexes and evaluation methods, China has not yet formed a comprehensive and effective biosafety evaluation index system. The purpose of this paper is to construct the biological safety evaluation system and to study the current situation of biological safety.
Methods Firstly, we analyze the characteristics and shortcomings of the concept of “biosafety” in Biosafety Act by using normative analysis method. From the point of view of national security, biosafety refers to the ability and state of the country to effectively prevent and deal with the threat of dangerous biological factors and related factors, and to maintain and safeguard its own security and interests. Clearly the extension of biosafety, that is, only the interests of national security, public health, ecological and environmental protection threats to biological risk, is the object of biosafety regulation. Secondly, the basic elements of biosafety include natural biosafety and socio-economic biosafety. Natural biological safety mainly refers to people’s health and ecological environment protection, including individual biological safety and biodiversity safety. Socio-economic biosafety focuses on national security interests, that is, social stability and national economic interests, including biotechnology safety, biological laboratory safety. Thirdly, taking the basic elements of biosafety as the Yardstick of management, taking national security interests, public health and ecological environment protection as the evaluation subject, taking the concept of biological rule of law as the idea, using the model construction method, based on the DPSEEA (driving force-pressure-state-exposure-effect-action) model, a biosafety evaluation index system with the characteristics of biological rule of law is constructed by combining qualitative index and quantitative index.
Result A set of biological safety evaluation index system with the characteristics of biological rule by law is constructed, including the level of biosafety laws and regulations system, the degree of cracking down on biosafety related crimes, the establishment and perfection of the coordination mechanism among biosafety departments, the number and percentage of biosafety laboratories meeting the prescribed standards, the number and density of biosafety talents, the total amount of official assistance to the biological industry and the basic health sector and other investments, the proportion of target population covered by vaccines, the popularization rate of biosafety publicity and education, and a total of 32 biosafety evaluation indicators.
Conclusion Based on the field investigation and data statistical analysis, the evaluation system was validated by the biological safety work in Shenzhen in 2019 and 2020. The results show that the biological safety work in Shenzhen has achieved remarkable achievements in agricultural biological safety, animal and plant epidemic prevention, and prevention of alien species invasion. However, there are still some deficiencies in laws and regulations system, cultivation of biosafety personnel, investment of funds and biosafety popularization rate. In view of the above problems, this paper puts forward some suggestions, such as perfecting the legal system of biosafety and paying attention to the coordination of laws, realizing the multi-coordinated biocontrol of “One health”, strengthening the talent training and capital investment, and strengthening the propaganda and education of biosafety.

The investigation of the peristome of vapour-wind dispersal type mosses were found sensitive to humidity. The structure of peristome changed at different humidity， which played an important role in the release of spores. The Polytrichum commune Hedw.var.commune of Karst plateau， Guizhou Province was selected as the research object， and the difference of the structure of peristome and the release rule of spore under the change of humidity were observed. In order to reveal the influence and function of the hygroscopic movement on the spore release. The results showed that： ①When the humidity was increased， the sizes of peristome structure and epiphragm were increased significantly， then recovered when the humidity dried again. The space between peristome increased significantly from 8.33 to 11.53 μm， and the area of epiphragm was increased by 20%. ②In the experiment of continuous wind blowing， the quantity of spores released during the initial period of the hygroscopic movement was increased significantly， then decreased with the recovery of the peristome structure， and kept at a very low quantity at last. As the humidity was increased， the percentage of cluster spores in the released spores was increased， and increased with the decrease of the released spores， and reached significant difference when the peristome structure recovered. ③The wind experiments were carried out at the dry stage， the initial stage of the hygroscopic movement and the peristome structure in the recovery stage respectively， the quantity of spores released at the initial stage of the hygroscopic movement was significantly higher than that at the dry and re-recovery stages of the peristome structure， however， when the structure of peristome was restored， the released quantity of spores was still higher than that of dry spores due to the increase of the percentage of cluster spores. Thus， the structure of P.commune Hedw.var.commune peristome changed during the hygroscopic movement， and when the structure of peristome was restored， the ability of releasing spores was still higher than that of drying， with positive significance to the spread and reproduction of this species.

In a large dam-regulated reservoir with regular hydrological pattern and strong flooding gradients across shore elevations, plants inhabiting in different shore elevations have to confront long-lasting flooding of differential intensities every year. Such persistent stress may lead to intraspecific differentiation of flooding tolerance in seeds. Echinochloa crusgalli var. zelayensis is a dominant annual plant in the shores of the Three Gorges Reservoir (TGR), which plays an important role in the shore vegetation. The objective of this study is to check whether intraspecific differentiation of seed flooding tolerance has occurred among E. crusgalli var. zelayensis populations in the TGR shores and whether such differentiation is associated with weak seed dispersal.

We collected seeds of E. crusgalli var. zelayensis from different populations in the TGR shores, and then placed them at four elevations in the shores flooded by reservoir impoundment. Parameters reflecting seed flooding tolerance including post-flooding percentage of intact seeds, seed germinability and seedling emergence rate were investigated for the seeds from different populations and undergoing flooding of different intensities. Floating time of seeds and speed of water level rise during impoundment were examined, and used to quantify dispersal potential of seeds in the shores of the TGR when flooded.

Both intact seed percentage and final seedling emergence rate after flooding significantly declined with increasing shore elevations where the seeds were collected, indicating that intraspecific differentiation in seed flooding tolerance has occurred among E. crusgalli var. zelayensis populations in the TGR shores after 7-year operation of the reservoir. The distance of seeds transported by rising water during reservoir impoundment was limited due to short-floating time of the seeds and relatively low speed of water level rise in the reservoir. This would be favourable to the development of intraspecific differentiation in seed flooding tolerance.

In order to enrich the understanding of the growth environment of Sphagnum， explore its possible impact on the formation of erosional karst tiankeng， and find more suitable growth conditions for it， we used gradient method， with S.palustre of different canopy density environments in the edge of the Tuntianjing sinkhole in Bijie City， to definite the chlorophyll fluorescence parameters and water storage capacity. Results showed： ①The initial fluorescence（F_o） and maximum fluorescence（F_m） of S.palustre increased significantly with increasing canopy density（F_o：224.67-264； F_m：716-785.33）. The maximum photochemical efficiency（F_v/F_m） of PSⅡ decreased firstly and then became constant； photochemical quenching coefficient（qP） and photosynthetic electron transport rate（ETR） increased significantly（qP：0.17 -0.46； ETR：5.72-9.68） with increasing canopy density； non-photochemical quenching coefficient（NPQ） decreased significantly from 1.57-0.8. ②With canopy density increased， the rate of water absorption and water storage capacity of S.palustre were significantly increased， the natural water absorption and the saturated water absorption increased from 14.36-26.37 and from 21.7-27.01， respectively； the natural water storage increased from 3 032.97-12 816.01， and the saturated water storage increased from 4 576.34-13 175.97. ③Although S.palustre has a good sunproof， they are more suitable for living in the low light conditions. As canopy density increased， it was beneficial to accumulate chlorophyll， promote photosynthesis and increase the accumulation of biomass， leading to a stronger water storage capacity. Competition can inhibit the growth of S.palustre， share soil moisture， and a certain moisture was very important for the growth of S.palustre. ④The good water-holding properties and water absorption of S.palustre have an important role in slowing surface runoff that slowing down in geological processes. The difference in water holding capacity of S.palustre under different canopy densities can affect the distribution of water flow to a certain extent， thus affecting the formation of erosion-type sinkholes.

Aims In the context of global change, vegetation changes in arid areas in the context of global change are both affected by climate change and human activities. Quantifying the vegetation dynamics and their driving mechanism are essential for monitoring the ecological environment change in arid areas and for promoting the sustainable development. Because of the complexity of human activities, most researches are limited to the response of normalized differential vegetation index (NDVI) to climate change, while the impacts of human activities have not yet been comprehensively considered.
Methods Firstly, we proposed a quantification method to quantify the main human activities related to land use. Then, the contribution of climate change and human activities to the NDVI in the middle part of the northern slope of the north Tianshan Mountains was analyzed using the multiple linear regression model and random forest model.
Important findings We found that an overall upward trend was evident in NDVI variations from 2000 to 2015. The fitting accuracy of NDVI based on the random forest model was significantly better than the multiple linear regression model with an improved R² of about 24%. The contribution of human activities related to arable land to NDVI change in the study area showed an increasing trend which was greater than climatic factors from 2000 to 2015. This study provides new insight into the effects of climate change and human activities on vegetation and a scientific basis for the protection and restoration of the ecological environment in the arid areas.

The microenvironment of Karst Tiankeng has a significant effect on the characteristicsof plant structure.In order to provide reference for the structural adaptation of the peristome of moss in the microenvironment, the submicrostructure of the peristome of the Hypopterygium in the karst Tiankeng was studied by scanning electron microscope (SEM).From the submicroscopic morphology of peristome, two species of Hypopterygium, named H.flavo-limbatum C.Muell and H.japonicum Mitt, have obvious differences in the shapeof their dentium, tropism of dentium, dorsal ridges of the exstomium, ventral lateral stripes of the processus and whether they have ganglioma or not.It belongs to the characteristic of stability and can be used as the basis of system classification. On the other hand, the length and width of dentium, number of plates, transverse raphe and middle raphe are variable characteristics, which should be screened when the peristome of mosses are used as the basis of systematic classification.Illuminance, air temperature, air humidity and altitude are the main environmental factors affecting the development and growth of peristome morphological and structural of H.flavo-limbatum in Tiankeng. Air humidity, illuminance and artificial interference are the main environmental factors affecting the development and growth of peristome morphological and structural of H.japonicum in Tiankeng. Both of the peristome structures of two species of Hypopterygium are most affected by humidity, andtheir habitats are mostly humid and rich in soil moisture.

Establishing a systematic, standardized and efficient national park system with Chinese characteristics is an important strategic measure for the system construction of China’s ecological civilization. It is of great significance and far-reaching influences to strengthen the construction and management of nature reserves, protect biodiversity and build a beautiful China. On the basis of combing the achievements of national park system pilot work, especially obvious progress since 2018, this paper puts forward some strategies and suggestions to accelerate its development. It can provide some references for future research and development of national park system.