Grassland is the largest terrestrial ecosystem, which possesses extremely important production and ecological functions. Long-term overutilization and climate change, however, have contributed to degradations of grassland ecosystems worldwide. The natural restoration of degraded grasslands takes long time, and manipulating practices could be indispensable to accelerate the restoration. Although grassland ecological restorations have been studied for several decades in China, the phenomenon of degradation-restoration-re-degradation-re-restoration is common, and grassland degradation has not been comprehensively improved due to the ecological functions have not been paid enough attention. Lately, ecological priority and green development are emphasized, and more attention has been paid to grassland protection and ecological restoration. Restoration of degraded grassland ecosystems is a major problem and daunting task to be solved urgently in China. To provide scientific references for the ecological restoration of degraded grasslands, we reviewed the researches of grassland ecological restoration, as well as the main practical and policy measures. Restoration effects, limiting factors and existing shortcomings of different practical measures (no-tillage sowing, rational grazing, artificial pasture establishment, fence enclosure, tillage and fertilization) were also assessed. On these bases, research directions and suggestions for the grassland ecological restoration in the future were put forth: (1) To establish a modern grass husbandry system and management pattern to fundamentally solve the contradiction between grass and livestock is the prime way to tackle the grassland degradation and ecological restoration; (2) To improve the grassland degradation classification and grading system to provide theoretical bases for ecological restoration; (3) To strengthen the development and utilization of native grass germplasms and soil microorganisms to provide material support for ecological restoration; (4) To break through the theoretical and technical bottlenecks to restore the grasslands full of poisonous weeds; (5) To build a region-classification-grade theoretical and technical system and evaluation system of ecological restoration. Grassland ecological restoration is a complicated, transdisciplinary and systematic engineering, and the key is to strengthen multi-field cooperation.

Net primary productivity (NPP) is the basis for characterizing the material and energy cycle of the ecosystem, which is one of the important components of regional and global carbon cycle. In order to reveal the spatiotemporal change characteristics and driving mechanism of NPP in China from 2001 to 2020, based on MOD17A3HGF data products, the spatiotemporal change and future development trend of NPP in China were analyzed by Sen trend analysis, Mann-Kendall significance test and Hurst index. The relative roles of climate change and human activities in the process of NPP change were quantitatively analyzed by using correlation and residual analysis methods. The results showed that (1) China’s NPP presented a spatial distribution pattern of high in the southeast and low in the northwest, showing a fluctuating upward trend in time, with an upward rate of 2.86 g·m^-2·a^-1. The spatial change remained unchanged. The area with a significant increase in NPP was significantly larger than the area with a significant decrease. In the future, 84.38% of China's regional NPP will continue to increase or change from a decreasing to an increasing trend. (2) NPP was positively correlated with precipitation and temperature as a whole, of which precipitation had a more significant impact on NPP. The areas with significant positive correlations between NPP and precipitation were mainly distributed in the north of the Yangtze River. The areas with significant positive correlations with temperature were mainly distributed in the central and north of the Qinghai Tibet Plateau, the southeast of the Yunnan Guizhou Plateau, the southeast coastal area and the south of Shandong. (3) Both climate change and human activities played an important role in the NPP improvement areas, but there were significant spatial differences in their relative roles in NPP improvement areas. The vegetation improvement areas dominated by climate change were mainly concentrated in the northeast, north China, Sichuan Basin and the middle and lower reaches of the Yangtze River plain, while the vegetation improvement areas dominated by human activities were mainly concentrated in central, southwest and northwest China. The impacts of climate change and human activities on vegetation degradation were relatively consistent in spatial distribution. The impacts of climate change on NPP degradation areas were slight, but human activities were the main factors causing NPP degradation.

Microplastics are widely detected in the environment, and microplastics entering the environment generally undergo slow and complex aging processes, affecting their interaction with other pollutants in the environment. In this paper, the aging methods, physical and chemical properties of aged microplastics, pollutant adsorption capacity and interaction mechanism were summarized. There are many aging methods for microplastics, mainly involving physical, chemical and biological methods, and different methods have their own characteristics and applicability. The microplastic surface would become rougher after aging, which results in the increase of the surface area. Meanwhile, ultraviolet and natural aging could increase the oxygen-containing functional groups on the surface and promote its adsorption to other pollutants by hydrophobic action, electrostatic action, complexation, hydrogen bond, van der Waals’ force, and π-π interaction. In view of the shortcomings of the aging of microplastics and their interaction with pollutants, some suggestions were proposed to provide support for microplastic aging and its environmental impacts research, such as microplastic aging under complex conditions and its influence on pollutants adsorption, adsorption mechanism of aged microplastic on heavy metal-organic composite pollution, aging of microplastics in living organisms and its biological toxicity, the release of plastics additives during the process of microplastics aging and its interaction with pollutants and that of aged microplastics with dissolved organic matter and minerals.

In order to solve the hardness problem of Leguminosae seeds, two pioneer plants for mine ecological restoration, Crotalaria pallida Ait. and Cassia surattensis Burm. F. were chosen for experimental materials. The seeds were soaked in 200 mg·L-1 gibberellin and distilled water for 12, 24, and 36 h, respectively, to study the effects of gibberellin soaking on the germination of the tested seeds and seedling growth. The results showed that (1) with 200 mg·L^-1 Gibberellin soaking for 12 h, the germination rate of C. pallida was significantly higher than that in CK and distilled water seed soaking treatment. However, with more soaking time, the effects of promoting germination were not obvious, and Gibberellin soaking for 36 h could improve the seed vitality and other indices. (2) Both Gibberellin and distilled water soaking could promote seed germination rates of C. surattensis. The best seed soaking time of Gibberellin was 24 h, and the germination rate was significantly higher than that in CK and distilled water soaking treatment. The effects of germination promoting were decreased with soaking time. (3) The seed soaking with Gibberellin could not promote the biomass indices of C. pallida obviously, while the high concentration of Gibberellin should inhibit the seedling growth. (4) The seed soaking with Gibberellin could promote the biomass indices of C. surattensis, e.g., the seedling length and root length were improved under Gibberellin soaking for 24 h. In summary, the seed hardness of two test plants could be broken by Gibberellin soaking for an appropriate period of time. The reagent, concentration and soaking time should all be considered in terms of economic and time costs in ecological restoration of mining area.

Based on the cloud platform of Google Earth Engine (GEE), Landsat surface reflectance data of Loess Plateau from 1986 to 2021 were de-clouding and fused. The Normalized Difference Vegetation Index (NDVI) was calculated, and fractional vegetation coverage (FVC) was estimated using the pixel dichotomy model. On this basis, with the help of trend analysis, partial correlation analysis and residual analysis, the temporal and spatial variations of FVC and its influencing factors in the Loess Plateau in different time periods (1986-2021, 1986-1999 and 2000-2021) were analyzed. The results show that (1) in terms of time, FVC on the Loess Plateau increased significantly from 1986 to 2021 (Trend=0.0044 a^-1, P<0.01). In different time periods, the increasing trend from 2000 to 2021 (Trend=0.0058 a^-1, P<0.01) was faster than that from 1986 to 1999 (Trend=0.0038 a^-1, P<0.01). The FVC of all vegetation types on the Loess Plateau showed a significant increasing trend (P<0.01), among them, the grassland had the largest increasing trend (Trend=0.0066 a^-1, P<0.01). (2) Spatially, FVC decreased from southeast to northwest in the Loess Plateau. The FVC of the total area showed significant improvement in 1986-2021, 1986-1999 and 2000-2021 by 53.65%, 18.38% and 48.12%, respectively. (3) Elevation and Trend of topographic factors had significant effects on FVC. The value of FVC first decreased, then rose and finally decreased with the elevation, with the maximum value (0.7790) between 3000 m and 3500 m. FVC increased with the increase of Trend, with the maximum value (0.7025) appeared in the range of 25°-45°. The proportion of middle and high coverage and high coverage increased with the increase of Trend, in which the area proportion was the largest in the range of 15°-25° (73.93%). (4) The biased relationship between FVC and annual precipitation, annual mean temperature and solar radiation in the Loess Plateau from 1986 to 2021 were 0.239, 0.093 and -0.006, respectively. The proportions of pixels with significant positive correlations (P<0.05) accounted for 48.50%, 22.51% and 5.96% of the total area. The results of residual analysis showed that human activities was the main driving factor of vegetation dynamic change on the Loess Plateau, and the proportion of pixels that played a positive role was 73.20%.

The current status and spatial distribution characteristics of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb), and zinc (Zn) pollution in farmland soils of 93 cities in 30 administrative regions of China over the past 10 years were investigated by meta-analysis, based on literature data on heavy metals in Chinese farmland soils published in two databases, CNKI and Web of Science, from 2014 to 2023. The soil accumulation index and potential ecological risk index methods were used to evaluate the degree of pollution and potential ecological risk of the eight heavy metals in farmland soil, and principal component analysis was applied to elucidate the contributions of various activities to the risk of heavy metal pollution. The results showed that the heavy metal content in farmland soil in China generally exceeded the regional soil background value, and the proportion of eight heavy metals exceeding the standard in farmland soil in the study area was 38.2%-84.1%. In addition, the arithmetic mean value of Cd in the soil of the study area exceeded the risk screening value for Cd in the “Soil Environmental Quality Control Standard for Agricultural Land Soil Pollution” (GB 15618—2018). The results of the soil accumulation index showed that the degree of pollution of the eight heavy metals in farmland soil was Hg>Cd>Pb>Zn>Cu>Ni>Cr>As, from high to low. The pollution levels of Cd and Hg were high, and areas with mild or high pollution accounted for 69.33% and 65.9% of the study area, respectively. The calculation results of the potential ecological risk index (I_r) indicated that Cd and Hg in farmland soils in the study area were in the range of strong ecological risk. The proportions of Cd and Hg in the areas with I_r>300 were 41.9% and 45.2%, respectively. Principal component analysis revealed that the risk of heavy metal pollution in agricultural soils within the study area was primarily attributed to a combination of agricultural activities, industrial production, natural sources, and various other activities. These three principal components collectively accounted for 72.3% of the variance.

Per- and polyfluoroalkyl substances (PFASs) are a diverse group of emerging persistent organic pollutants (POPs) known for their versatile applications, complicated properties, and associated ecological and health risks through environmental pollution. While previous published reviews have summarized the sources and distribution of PFASs in soil and water ecosystems, this paper aims to fill the crucial gap by a systematic overview of their sources, spatial and temporal distribution, and human health risk assessment in the atmospheric environment. Sources of PFASs in atmosphere include the industrial production and application of fluoropolymers, product consumption, waste treatment, volatilization and sublimation from soil and water environments. The PFASs accumulate in atmospheric particulate matters, showing significant concentration variations across regions and seasons, influenced by the industrial activities, population density, and meteorological parameters. Typically, PFASs have a broader spatial distribution with low concentrations during warm seasons, while the pollution levels are higher and concentrated near emission sources in winter. Over the past decade, the concentration of atmospheric PFASs in China has decreased, but their types have significantly increased, mainly due to the impact of policy measures shifting towards the production of PFASs substitutes. Atmospheric PFASs can enter the human body and induce health risks through the exposure pathways of inhalation, skin uptake, and oral ingestion. Currently, inhalation exposure assessment models are mainly used to assess their health risks. Pollution prevention and control measures in developed regions, such as the United States and Europe, have achieved some reduction in PFAS emissions to environment, but they mostly targeted at single substance, and production is gradually moving towards substitutes with unclear risks. Looking ahead, future research on atmospheric PFASs should delve into the transport and transformation mechanisms, synergistic effects and toxicity risks with other pollutants (e.g., particulate matters), establishing long-term monitoring networks and quantitative source apportionment methods, revealing their health effect mechanisms in depth, and developing systematic and comprehensive human health risk assessment models.

Since land use change is an important representation of human-nature interactions, it is of great significance to study the spatial-temporal pattern and driving factors of land use change for the planning and implementation of the national strategy of ecological protection and high-quality development in the Yellow River Basin. With the data on land use of the Yellow River basin in 2000, 2010 and 2020, the characteristics and driving factors of land-use change were explored by means of the spatial analysis and mathematical statistics at the different scales. The results show that (1) the multi-year average proportions of grassland and farmland in the Yellow River basin were 47.9%±0.38% and 26.5%±0.69% respectively. Grassland was widely distributed in the middle and upper reaches, while farmland was concentrated in the lower reaches, indicating their responsibilities of ensuring national ecological security and food security in their corresponding regions. (2) The intensity of land use in 2010-2020 was much higher than that in 2000-2010 with the area of land use change and comprehensive land use dynamic degree increased by about 8 and 15 times, respectively. (3) Land use changes in the Yellow River Basin from 2000 to 2020 were characterized by the increase in urban land, grasslands and forests and decrease in farmland, that is, the urban land was expanded by 1.08×10⁴ km² with 58% of newly-increased area converted from farmland which was mainly occurred in the urban agglomerations in the middle and lower reaches of the Yellow River. Grasslands and forests were increased by 0.91×10⁴ km² with 75% of newly-increased area converted from farmland, which mainly occurred in the source area, as well as Qinghai and Gansu, the upstream areas of the Yellow River. The farmland was reduced by 1.30×10⁴ km² with 48% and 37% of them converted into urban land and grasslands, which mainly occurred in the plain areas of the middle and lower reaches of the Yellow River. (4) The land use changes in the Yellow River Basin were mainly driven by the factors, such as climate change, socio-economic development and policy implementation. Comprehensively driven by the warming and wetting climate, ecological protection and restoration policies and project implementation, the areas of forest and grass and watershed wetlands have increased and the quality of the ecosystem has also improved. However, under the background of increasing population scale and rapid economic development, the agricultural land has been seriously occupied for construction land. Therefore, the conflict between urbanization and ecological protection is becoming more prominent.

Total nitrogen (TN) in the surface water is an important factor affecting water ecological environment. The increase of TN concentration will lead to eutrophication, red tide, and other phenomena, which are harmful for aquatic organisms and even human health. In order to analyze the temporal and spatial variation characteristics of TN concentration in the surface water in China in recent years and provide basis and support for the decision making and deployment of TN pollution control of surface water, the temporal variation trend and spatial distribution characteristics of TN concentration in surface water in China during 2016-2020 were systematically analyzed based on the monitoring results of national environmental quality monitoring network of surface water, using Surface Water Environmental Quality Standard and Evaluation Method of Surface Water Environmental Quality (Trial) as the evaluation basis, combined with Pearson correlation coefficient method. From 2016 to 2020, TN concentrations in the surface water, rivers, and lakes were in the range of 2.54-3.00 mg∙L^-1, 2.72-3.23 mg∙L^-1 and 1.19-1.31 mg∙L^-1 respectively. TN concentration in rivers was much higher than that in lakes and reservoirs. In terms of time variation, the interannual variation of TN concentration in the surface water in China showed a trend of rising first and then falling. The monthly variation of TN concentration showed seasonal characteristics of higher in spring and winter and relatively lower in summer and autumn. In terms of the watershed distribution, the order of TN concentrations of each watershed ranked from high to low was: Haihe River>Yellow River>Liaohe River>Huaihe River>Pearl River>Zhejiang and Fujian area River>Yangtze River>Songhua River>Northwest River>Southwest River. The order of TN concentrations of each lake area from high to low was: Yunnan and Guizhou>Eastern Plain>Mongolia and Xinjiang>Northeast> Qinghai Tibet Plateau. TN concentrations in Haihe River, Liaohe River, Yellow River and Huaihe River basin were generally higher, all over 3.00 mg∙L^-1, while TN concentrations in Northwest River and Southwest River basin were much lower, which were 1.39 mg∙L^-1 and 1.23 mg∙L^-1 respectively. In addition, the into-lake rivers had a strong correlation with the TN concentration of the corresponding lakes and reservoirs. TN concentrations of into-lake rivers and into-ocean rivers reached or exceeded 4.00 mg∙L^-1 and 2.00 mg∙L^-1 respectively higher than those of the corresponding lakes and ocean regions, showing a great influence on lakes and ocean regions. It's important to take nitrogen control measures for into-lake rivers and into-ocean rivers to control or alleviate nitrogen loads and prevent the eutrophication of lakes and ocean regions.

The quantitative assessment of net ecosystem productivity (NEP) and its influencing factors is helpful to further understand the regional carbon cycle and its driving mechanism. As one of the sensitive regions to climate change, the study on temporal and spatial variation characteristics of NEP in the Yellow River Basin and its climate driving factors is of great significance for clarifying the characteristics of terrestrial carbon sink pattern in northern China. Therefore, based on estimation model of NEP, the spatiotemporal evolution characteristics of NEP in the Yellow River Basin and its driving mechanisms from 2000 to 2020 were analyzed by trend analysis, correlation analysis, cluster analysis and other methods in this study. Results were shown as follows: (1) the annual average NEP in the Yellow River Basin was 92.7 g·m^-2, showing carbon sink as a whole. For the spatial distribution, the NEP in the Yellow River Basin showed an increasing trend from the west to the east. There was an obvious spatial aggregation effect on NEP in the Yellow River Basin, in which the high-value and low-value aggregation areas accounted for 32.6% and 41.7% of the basin area, respectively. (2) The NEP in the Yellow River Basin had generally increased since 2000, with an average annual increase of 4.7 g·m^-2. In particular, 62.4% of the regions had a significant increase in NEP, and the carbon sequestration capacity of vegetation had been significantly improved. In different regions, the increase rate of NEP in the middle reaches of the Yellow River was the largest, with an average annual increase of 7.8 g·m^-2. For different vegetation types, the NEP of evergreen forest increased most significantly, and the proportion of area with a significant increasing trend was the highest, reaching 82.8%. (3) From the perspective of future trends, the average Hurst index of NEP in the Yellow River Basin was 0.74, which was characterized as strong sustainability. The NEP showed a significant increase trend, and the proportion of the area that would maintain strong sustainability in the future would reach 56.2%, indicating that the carbon sequestration capacity in most areas of the Yellow River Basin would continue to increase in the future. (4) From the climate correlation analysis, NEP in the Yellow River Basin was positively correlated with precipitation and negatively correlated with sunshine hours. However, the impact of temperature on NEP was not significant. In terms of the influence range of key climatic factors, the precipitation had the largest influence area (70%), followed by sunshine (19.3%), and temperature (10.7%). Therefore, the precipitation was considered to be the dominant climatic factor determining the spatial distribution of NEP in the Yellow River Basin.

For regional ecological protection and vegetation restoration, it is of great importance to study the spatio-temporal pattern of vegetation cover and its responding mechanism to natural and anthropogenic factors. Taking the Pearl River basin as an example, this study showed the spatio-temporal variation characteristics of NDVI using Theil-Sen Median analysis and Mann-Kendall significance test. The study revealed the relationship between NDVI and climate factors and anthropogenic factors through correlation analysis, and explored the key factors contributing to the spatial differentiation of NDVI using geographic detectors model. The results showed that the NDVI of the Pearl River basin was on the rise from 2000 to 2020. 2000-2004, 2005-2009, and 2014-2018 were three periods of rapid growth. Overall, NDVI in the four sub-basins of Pearl River basin increased in the studied period. However, there were differences in the spatial distribution and growth rate of NDVI among the four sub-basins. Specifically, Dongjiang River basin had the highest mean NDVI, Beijiang River basin had the highest rising rate of NDVI, while Pearl River Delta basin had the lowest mean NDVI and lowest growth rate. (2) During the study period, the area of forest in the Pearl River basin decreased, while the area of construction land increased significantly. In the areas transformed from other land cover types to forest, grassland and cropland, the proportions of NDVI on the rise were 95.37%, 85.31% and 90.75%, respectively. In the areas transformed from other land cover types to construction land, NDVI was mainly in a downward trend. Thus, the land cover change had different impacts on NDVI. (3) NDVI was mainly positively correlated with temperature and precipitation, indicating that the influence of climate factors on NDVI in the Pearl River basin was positive. In most regions, NDVI increased with increasing nighttime light intensity, but decreased with increasing population density. The areas with significant negative correlation between NDVI and anthropogenic factors were mainly distributed in Pearl River Delta urban agglomeration and big cities, while the areas with positive correlation were mainly distributed in the periphery of these regions. (4) The land cover type, population density and nighttime light intensity contributed most to spatial variation of NDVI. The interaction of the two influencing factors showed mutual and non-linear enhancement. In all sub-basins, the interaction between land cover type and nighttime light intensity, and the interaction between land cover type and population density showed higher explanatory powers. The research results can provide a basis for formulating comprehensive vegetation resource management in the Pearl River basin.

Improving regional carbon sink capacity is a key strategic initiative for China's ecological civilization construction, which is an important measure to promote the green transformation of economic and social development. The Taihang Mountains are the significant ecological barrier in North China, and their ecosystems have efficient carbon sink capacity. It is of great significance to study the spatiotemporal differentiation characteristics of carbon storage in the ecosystem of the Taihang Mountains and the driving mechanism of influencing factors to implement the national “dual carbon” project construction in North China, strengthen the regional oxygen release and carbon sequestration capacity, and even comprehensively improve the quality of the regional ecological environment. In this study, based on the land cover and carbon intensity data of the Taihang Mountains in 2005, 2010, 2015 and 2020, the spatial distribution of carbon storage area was estimated with the InVEST model. On this basis, the main driving factors affecting its spatial differentiation were explored by using geographic detectors, and this paper analyzed its driving mechanism. The results showed that: (1) from 2005 to 2020, the land use types in the Taihang Mountains had been changed significantly. The land use area of forest and construction land increased, and the land use area of farmland and grassland decreased. Farmland and grassland were mainly converted to construction land, while some were converted to forests. (2) The total carbon storage in the Taihang Mountains ranged from 1.48×10⁹-1.50×10⁹ t, with an overall gradual increase. From the perspective of land type, the descending order of the proportion of carbon storage showed that forest>farmland>grassland>construction land>water>unused land. The increases of forest and construction land were the main reasons for the increase in carbon storage. (3) The spatial differentiation of carbon storage in the Taihang Mountains was affected by topographic, environmental and soil factors. Based on Geodetector, the influences of NDVI (0.214-0.280) and soil type (0.151-0.160) on the spatial differentiation of carbon storage were significantly greater than those of other factors. The interaction between the driving factors was stronger than that of a single factor, and the strongest synergistic effect was the DEM synergistic NDVI type (0.368-0.406), which indicated that the role of drivers on the spatial variation of ecosystem carbon stocks needs to be considered in the construction of “double carbon”. This study used Geodetector approach to explore the mechanisms of the driving factors of spatial differentiation in ecosystem carbon storage, and provides a new way for research in the field of ecosystem carbon storage.

Extensive use of agricultural plastic film as greenhouse and ground cover with low recycling rates results in a significant increase of plastic fragments and microplastics in the soil, consequently affecting the sustainable utilization of agricultural land. This paper focuses on the growth scale, spatial-temporal distribution, and regional differences of agricultural plastic film based on statistical yearbooks.The generation pathways, distribution of microplastics from agricultural film and potential risks of microplastic to farmland in China are analyzed and summarized.Statistical data shows that there is a continuous increase of plastic film usage in China with an annual growth rate of approximately 6.51% during 1994 to 2020. Among them, there is a peak value of usage of agricultural plastic film observed at 2015, in which ground cover film accounted for over 50.0%. Ground cover film is a dominate source of microplastics in farmland soil, especially in the northwest arid oasis regions, reaching up to 38.0 kg∙hm⁻², Microplastics from agricultural film is generally generated through natural, agricultural, and biological pathway depending on microbial activity, plastic types, and environmental conditions. Overall, the long-term planting areas in the northwest and the intensive farming areas in North China, East China, and Southwest China face serious microplastic pollution with levels reaching up to 4.83×10⁴ ind∙kg⁻¹. The porous characteristic of soil allow microplastic particles to migrate through gravity settlement and rainwater infiltration, leading to the microplastic contamination of soil, migration of other pollutants carried by them and subsequent risks to soil structure, soil flora and fauna, microbial communities, and human health. Finally, both the technical development such as raising the lower limit of thickness of polyethylene agricultural film and drawing biodegradation standards, “plastic ban/restriction” policies provide a basis for upgrading the industrial structure of agricultural plastic film, favoring plastic pollution control in China. Source prevention, development of alternative techniques, and close-loop management of agricultural plastic film are effective methods to address current agricultural film pollution, while technological upgrading will be comprehensive solution to improve agricultural plastic pollution control in the future.

Forest soil microorganisms determine the energy flow and material cycle of forest ecosystems, and their community structure and influencing factors are significant to maintain ecosystem stability and respond to global climate change. Phospholipid fatty acids (PLFAs) can be used as biomarkers to directly reflect the biomass and community structure of different microbial communities in soil because they only exist in living microorganisms. This study focuses on soil microorganisms and uses the PLFA method to analyze the community structure, biomass, and physicochemical properties of microorganisms in natural forest soils from all six climate types in China. The main factors affecting the microbial community structure were analyzed using correlation analysis and redundancy analysis methods. The analysis results indicate that there are significant differences in soil density, soil pH, soil litter carbon content, soil organic carbon content, soil total nitrogen content, soil carbon nitrogen ratio, and soil total phosphorus content among the six climate types. There are significant differences in fungal community biomass among the six climate types, with a trend of first increasing and then decreasing as the climate types change from cold zone to temperate zone to tropical zone. The ratio of fungi to bacteria in warm temperate soil is the highest (0.7), significantly higher than that in subtropical and tropical soils (0.4-0.5). The ratio of Gram positive to negative bacteria in tropical and alpine soils is significantly higher than that in other climate types (1.3-1.5), with the lowest in subtropical soils (0.7). The climate (annual average temperature, annual precipitation) and soil physicochemical properties (soil pH, soil density, soil total nitrogen content and soil organic carbon content) are significantly correlated with the soil microbial biomass and community structure represented by PLFAs content (P<0.01). This study summarizes that there is no significant difference in the overall microbial biomass represented by total PLFAs among six climate types, but there are significant differences in soil physicochemical properties and microbial community structure. The main influencing factors of forest soil microbial community structure are annual mean temperature, annual mean precipitation and soil pH value. This study reveals the characteristics of forest soil microbial communities in China as a whole, and providing a basis for us to reveal the response of soil microbial communities to climate change in space.

Microplastic pollution, as a new type of ecological and environmental problem, is becoming a big challenge faced by the world. The threat and potential risk of microplastic pollution to ecosystem is becoming a hot research topic in the current environmental field. The microplastic-based compound pollution with various pollutants in the environment is more serious than the microplastics pollution alone, so research on the internal mechanism of microplastic composite pollution and the relevant prevention and control strategies taken are more complex than those for microplastic pollution. In this paper, we divided the microplastic-based compound pollution with other pollutants in soil environment into two categories based on the pollution sources, including endogenous pollution (e.g., toxic additive released from microplastic) and exogenous pollution (e.g., heavy metals, persistent organic pollutants, antibiotics). Three main paths of microplastic-based compound pollution in soil were summarized as follows: The first one was microplastics adsorbing common major pollutants, such as heavy metals, persistent organic pollutants, and antibiotics in soil environment; the second one was microplastics forming biofilms with soil microorganisms; the third one was microplastics releasing toxic additives and causing joint pollution. We also analyzed the interaction processes of microplastic pollution with the above-mentioned pollutants and itself-released additives and the relevant influencing factors, as well as their combined ecotoxic effects. Finally, some future research development trends in soil microplastic-based compound pollution areas were presented. This paper aims to provide some references for further understanding of microplastic-based compound pollution in soil and exploring its interaction mechanisms, conducting risk assessments and identifying control strategies.

Planting pattern is the key factor affecting the carbon sink and economic benefits of farmland ecosystem. To optimize reginal cropping systems, develop low-carbon green agriculture, and ensure sustainable agriculture development, it is of great importance to clarify the carbon sink characteristics and economic benefits under different planting patterns. In this study, a field experiment was conducted from 2020 to 2021 in southern Anhui, China, including four planting patterns: single-cropping rice, tobacco-rice rotation, rice-wheat rotation, and ratoon rice. Life cycle assessment was used to evaluate the net carbon sink and economic benefits. In addition, the carbon footprint compositions and influencing factors of different cropping patterns and crops were investigated. The results showed that, (1) the economic net income followed the order of tobacco-rice rotation>ratoon rice>rice-wheat rotation> single-cropping rice. The high output value of tobacco contributed to the high income of tobacco-rice rotation. The highest rice yield was found in the ratoon rice cultivation, in which the total grain yield of the first and regeneration seasons was 12921.5 kg∙hm^-2. (2) The net carbon sink followed the order of rice-wheat rotation>ratoon rice>single-cropping rice>tobacco-rice rotation. Compared with the rice-wheat rotation, N₂O emission and total carbon emission were significantly decreased by 37.2% and 9.2%, respectively, in ratoon rice. The CH₄ and N₂O emission accounted for 54.5% and 18.0% of carbon footprint in ratoon rice. (3) CH₄ emission was reduced through controlling farmland water, increasing fertilizer use efficiency, and leaving piles appropriately for ratoon rice, which is vital to control carbon emissions. The carbon footprint of flue-cured tobacco (Nicotiana tabacum L.) was mainly consisted of N₂O, chemical fertilizer, and agricultural film, and each of them accounted for more than 20% of the total emissions. In addition, the proportion of labor force (accounted for 11.7%) and fuel oil (accounted for 12.7%) in flue-cured tobacco planting were much higher than those in rice and wheat. (4) The tobacco-rice rotation obtained higher economic benefits and the high harvest of both tobacco leaves and grain yield. However, the carbon sink was negative in tobacco-rice rotation. It is necessary to study how to mechanization production and energy saving and consumption reduction of tobacco leaf baking. The ratoon rice obtained high grain yield in rice, and was low in input cost and carbon emissions, consistent with the national carbon peak and neutrality goals. In conclusion, this study quantitatively evaluated the carbon sink and economic benefits of different planting patterns, and provided a technical model and theoretical basis for energy saving, emission reduction and low-carbon green agriculture.

Vegetation provides important linkages within the atmosphere, pedosphere, hydrosphere and biosphere. It is of great significance to investigate the characteristics of spatial-temporal variations of fractional vegetation cover (FVC) and its driving factors in the study of regional ecological environment changes. Based on the MODIS NDVI data and 12 driving factors in the same period, the temporal and spatial variations in FVC of Ningxia from 2000 to 2020, and its driving factors as well as the interaction of different factors were analyzed using trend analysis method and geographical detector. The results showed that (1) FVC in Ningxia had presented an increasing trend over the past 21 years, as the proportion of areas with the increased FVC accounted for 81.79% of the total. Vegetation conditions had been significantly improved, with areas in the low, lower-middle FVC decreased and areas in the middle, medium-high and high FVC significantly increased. (2) The spatial distribution of FVC was high in the north and south and low in the middle. Geographical detector analysis indicated that the spatial distribution of FVC in Ningxia was mainly affected by climate, topography and human activities, among which annual precipitation, average temperature and precipitation in the growing season and altitude had strong explanatory power. (3) In the interannual change, the influence of climatic factors on FVC showed increasing importance, but the topography and the human activity factors showed less influence. The cross-detection demonstrated that the influences of all factors on FVC were mutually enhanced and showed nonlinear enhancement relationships. The explanatory power of landforms and human activities generally improved after interacting with climate factors, and interaction between land use and average temperature in the growing season had the strongest explanatory power on the spatial distribution of FVC, with q of 0.635. This study provides further understanding of the vegetation coverage in Ningxia, especially the influencing mechanism of vegetation spatial distribution.

Quantitative assessment of the impact of climate change and human activities on terrestrial ecosystem carbon cycle is of great significance for understanding of vegetation change driving mechanism, ecological construction and protection. Based on the actual net primary productivity (NPP) calculated by the model Biome-BGC from 2000 to 2019 and the potential net primary productivity calculated by the climate model, this paper quantitatively analyzed the impact of climate change and human activities on vegetation ecosystem in Shaanxi Province. The results showed that the change of vegetation NPP in Shaanxi Province was mainly driven by climate, accounting for 11.96% of the total area. Climate superimposed with the influence of human activities which played a more important role, accounting for 86.93% of the total area. The increase of vegetation NPP in Shaanxi Province accounted for 98.06% of the total area. Among this, 11.93% of the total area was driven by climate factors, which mainly distributed in the agricultural areas of Guanzhong area and Hanzhong Basin. 86.13% of the total area was driven by human activities, which mainly distributed in northern and southern Shaanxi. These results indicated that the ecological construction projects such as returning farmland to forest and natural forest protection have made remarkable achievements in the two regions. The reduced area accounts for 0.83% of the total area. Among this, 0.03% of the total area was driven by climate factors and distributed throughout the province, while 0.8% of the total area caused by human activities distributed in the surrounding areas of cities and towns and was mainly attributed to urban construction. There was no change in NPP in 1.11% of the total area. In conclusion, the changes of vegetation NPP in Shaanxi Province were mainly affected by climate and human activities, with the latter being the main driving force.

The state-owned forest regions are the key regions to implement carbon neutralization in China. Accurate estimations of carbon storage and carbon sequestration potential of forest vegetation are of great significance for making strategies to cope with climate change and for coordinating regional eco-economy-social development. Based on the data of forest resource survey type II, the carbon storage and density of forest vegetation in the key state-owned forest region of Daxing’ anling, Heilongjiang Province were estimated by using the volume-biomass method on the basis of tree species (groups) and age groups. Based on the space-time substitution method, the carbon sequestration potential of forest vegetation was evaluated according to the ecological regionalization of forest vegetation and the type of zonality climax community. The results showed that (1) the total carbon storage and average carbon density of forest vegetation were 2.7246×10⁸ Mg and 39.46 Mg∙hm^-2, respectively. The proportion of carbon storage in arbor forest was 99.93%, and its average carbon density was 4.00 times of that in shrub wood and 3.72 times of that in open forest. (2) The carbon storage and carbon density of forest vegetation varied greatly in different regions. The regions of Xinlin Forestry Bureau (3.4497×10⁷ Mg) and Panzhong National Nature Reserve (1.0936×10⁶ Mg) had the highest and lowest carbon storage, respectively. The regions with the highest and lowest carbon densities were Shuanghe National Nature Reserve (59.68 Mg∙hm^-2) and Pan National Nature Reserve (22.11 Mg∙hm^-2). The establishment of nature reserves and reasonable and ordered human intervention both played positive roles in improving the carbon sequestration capacity of forest vegetation. (3) The proportion of carbon storage in Larix gmelini forest was nearly half of the total carbon storage in the research area, and the average carbon density of Pinus sylvestris var. mongolica forest was much higher than that of other forest types. (4) In general, forests for timber and for seed production had the largest carbon storage and average carbon density. (5) The half-mature forest is the age group with the largest carbon storage, and the average carbon density rose with the increase of age. (6) The carbon sequestration potential in total was 1.9367×10⁸ Mg, mainly owing to the growth of existing forest vegetation. To sum up, it is recommended to strengthen the theoretical research and technological research on the protection and restoration of natural secondary forests, to improve the quality and stability of forest ecosystems, to enhance their capacity to sequester carbon and increase sink, and to innovate the management of forest vegetation carbon sink, as well as to broaden the value realization path of ecological products in the forest carbon sink.

Rapid development of urbanization and increase of human activity have led to great changes in land use as well as a series of ecological environment and climate problems. As carbon peaking and carbon neutrality strategies are taken in China, new and higher requirements for the quantitative structure and spatial distribution of future land use were raised. Under the carbon neutrality strategy, predicting future land use changes and carbon emission characteristics by simulating land use structure and spatial optimization based on multi-objective scenarios is of great significance for the land dimension of carbon neutrality. Combined with future climate, historical and policy scenarios of SSPs, this paper simulated land use changes in Chengdu-Chongqing economic circle during 2010-2030 based on PLUS model, including quantity and spatial structure characteristics. Based on four objective function constraints of economic benefit, carbon emission, carbon storage, and ecosystem service value, it conducted spatial optimization on land use structures of Chengdu-Chongqing economic circle in 2030 under different scenarios, and deeply analyzed carbon emission characteristics of land use changes in 2030. As shown by the results, (1) from 2010 to 2020, there was the decreased area of cultivated land and grassland, but increased area of construction land, forest land, water area and unused land in Chengdu-Chongqing economic circle. (2) The predicted land use changes in the Chengdu-Chongqing economic circle in 2030 based on five future scenarios were different. Besides, the overall change pattern in the SSP126 and SSP245 scenarios was similar to that in the historical scenario, but the forest expansion was faster in the SSP126 scenario. Under the SSP585 scenario, the construction land and forest land rapidly expanded to the cultivated land. Apart from that, the policy scenario took into account the development of construction land and ecological land, so the cultivated land decreased the most, but the cultivated land area remained above the red line of cultivated land. (3) The land use carbon emission of the Chengdu-Chongqing economic circle in 2030 predicted by the five scenarios was all lower than that of 2020, with the carbon emission under the SSP126 scenario being the lowest and that under the policy scenario being the biggest. The research results verify that the realization of carbon peaking and carbon neutrality goals of the Chengdu-Chongqing economic circle is dependent on the clean transformation of energy structure, the low-carbon adjustment of the industrial structure, the consolidation and improvement of the ecological carbon sink of plants, etc. In the mid-and-long term, the future land resources planning of Chengdu-Chongqing economic circle should be inclined to follow SSP245 scenarios or fall somewhere between SSP245 and SSP126 scenarios, in order to better bridge the carbon neutrality strategies.