Fragile Ecological Environment Research Articles

Spatiotemporal changes and drivers of ecological security based on an improved ecological footprint model: the case of Hubei Province, China

The increasing contradiction between resource supply and demand has brought ecological security (ES) to the forefront. Research on the changes of ES pattern and their driving factors is crucial for coordinating the regional ecological and economic development. Hubei Province in China exhibits uneven distribution of resources and a fragile ecological environment. In this study, an improved ecological footprint (EF) model was employed to analyze the changes in the ES pattern of Hubei Province. And the logarithmic mean Divisia index model was introduced to analyze the corresponding driving factors. The results showed that (1) from 2000 to 2020, the EF per capita (ef), the ecological carrying capacity per capita (ecc), and the ecological deficit (ED) per capita (ed) of Hubei Province increased by 47.11%, 2.71%, and 51.72%, respectively. In 2020, the cities in the province were in a state of ED, and the spatial distribution was ‘high in the central part of the province and low in the east and west’. (2) Each ef type showed an increasing trend. The increase in ef mostly came from the increase in fisheries ef, fossil energy ef and cropland ef, with a contribution of 76.70%. The increase in ecc is mainly due to the increase in freshwater ecc, with a contribution of 274.87%. (3) The ecological pressure in the province continued to rise and has been in a state of being completely unsafe. The efficiency of ecological resource use has increased, and the ecological structure tends to be rationalized, but the ecological-economic coordination has weakened. (4) The overall EF growth in the province is mostly driven by economic, population and footprint structure factors, while footprint intensity suppresses EF growth. Therefore, it is advised to boost investment in eco-friendly tech, foster green economy growth, and prioritize renewable energy development. This study can provide a reference basis for policy formulation on environmental sustainability and ecosystem management.

The social-ecological benefits of grain for green program based on coupled coordination network: Taking the China’s Loess Plateau as an example

The Grain for Green Program (GFGP) is the world’s largest payment for ecosystem services (PES). In the past 20 years, the Chinese government has implemented three stages of GFGP, which have profoundly affected the social-ecological benefits (SEB) of China’s Loess Plateau (LP), one of the regions with the most severe soil erosion and the most fragile ecological environment in the world. Therefore, we explored the changes and coupling coordination relationships of LP’s SEB in the past three stages of GFGP, and examined the spatial correlation network relationships between various units and their roles of GFGP, which was particularly important for the rationality and implementation direction of LP’s GFGP in the future. We found that in different GFGP stages, changes in LP’s SEB showed stage differences and spatiotemporal differences. The comprehensive social benefits (CSB) changed slowly (1.342 dropped to 1.232), and there was an obvious “northwest-southeast” regional division in space. The changes in comprehensive ecological benefits (CEB) fluctuated more obviously (1.481, 1.638, 0.597). After experiencing significant improvements of CEB in two stages, it entered a bottleneck period in the third stage. For a long time, the LP’s SEB have been in a state of coupling coordination, but the coupling coordination degree dropped to 0.493 in the third stage. With climate change, the continuous increase in potential grain yield has led to increasing losses in CSB. It was difficult to promote further coordination of LP’s SEB by accelerating the improvement of CEB. The coupling coordination degree has gradually moved from overall coupling coordination to mild imbalance. At the same time, the overall density of the SEB coupling coordination space network correlation was 0.218, which has shown an obvious network structure, and formed four major sectors: main beneficiary sector, broker sector, net overflow sector, and bidirectional overflow sector in each stage of GFGP. The role of each county has undergone regional changes in the entire GFGP, and there were recurring power transmission mechanisms and complex network formation factors. Based on this, we proposed to promote the coupling coordination and positive network transmission of SEB in the next stage of LP’s GFGP through “low-carbonization of agricultural production”, “further improvement of the compensation mechanism”, and “fusion of power transmission mechanism and network formation factors”.

Restoration Strategies in the Heidaigou Open-Pit Mine Dump Based on Water Sources and Plant Water Utilization

In this study, three typical plants capable of restoring in the Heidaigou open-pit mine dump, namely, Pinus sylvestris var. mongolica, Caragana korshinskii, and Medicago sativa, were taken as the research objects. The δ2H and δ18O values of atmospheric precipitation, soil water, stem water, and leaf water were measured using the stable isotope technique, and the distribution characteristics of the δ2H and δ18O values of different water sources were identified. The IsoSource model (version1.3.1) was used to calculate the contribution rate of different water sources to the plants, and the differences and dynamic changes in the water sources for P. sylvestris var. mongolica, C. korshinskii, and M. sativa during the rainy season were examined. Results showed that the water source of the three plants was found to be mainly soil water, and the utilization of each potential water source varied in different periods of the rainy season. In June, when SWC was sufficient, P. sylvestris var. mongolica and M. sativa primarily absorbed and utilized shallow and middle soil water, with relative utilization ratios of 55.5% and 59%, respectively, while C. korshinskii has a more balanced utilization ratio of soil water in each layer, with shallow soil water utilization at 33.7%, middle soil water at 34.2%, and deep soil water at 32.2%. In August, when SWC decreased, P. sylvestris var. mongolica, C. korshinskii, and M. sativa were all transferred to deep soil water, with utilization ratios of 75.8%, 78.8%, and 71.1%, respectively. The values showed that these three typical plants are capable of restoring can respond to external water changes through the plastic transformation of water absorption sources. Among them, C. korshinskii can flexibly use soil water in each layer, has stronger survival competitiveness in drought, and can better adapt to the fragile ecological environment of a mining dump.

The comprehensive effects of future multi‐scenario land use change and climate change on water conservation in Northwest China

AbstractWater conservation is an important ecosystem service, which is crucial to the fragile ecological environment and serious soil erosion in Northwest China. However, water conservation has been affected by climate change and human disturbance, and its future spatial and temporal changes are still unclear. This study employed the Integrated Valuation of Ecosystem Services and Trade‐offs (InVEST) model to assess the water conservation capacity of Northwest China between 1990 and 2020. Subsequently, the Patch‐generating Land Use Simulation (PLUS) model and the NASA Earth Exchange Global Daily Downscaled Projections (NEX‐GDDP‐CMIP6) were integrated to examine changes in water conservation from 2030 to 2050. The water conservation quantity in Northwest China had a fluctuating growth tendency between 1990 and 2020, with an average of 816.61 × 108 m3. The water conservation capacity's regional distribution pattern shows a steady increase from northwest to southeast. Northwest China's forest land had the greatest water conservation capacity between 1990 and 2020, at 66 mm, while the water land had the lowest, at 1.46 mm. The water conservation capacity in the 2030–2050 future scenario is less than that in 2020 when the regional distribution pattern is comparable to 2020. Natural development scenario (ND) in 2030 has the lowest water conservation capacity (13.41 mm) under ssp1‐2.6 precipitation scenario, whereas in 2050, the highest water conservation capacity (17.47 mm) is found in same scenario. The ecological protection scenario (EP) has the greatest water retention capacity (18.15 mm in 2040) and the lowest (14.38 mm in 2050) in the ssp5‐8.5 scenario. Our research can help restore and rebuild Northwest China's natural ecosystem and offer a theoretical foundation for the protection of ecological environment and the rational utilization of water resources in the region.

Atmospheric teleconnections responsible for the dominant patterns of interannual variability in summer drought over northern Asia

Abstract Summer drought over northern Asia (NA) seriously threatens the local fragile ecological environment and social economy development. In this study, using the standardized precipitation evapotranspiration index (SPEI), we firstly identify the dominant modes of interannual variability in summer drought condition over NA, and then explore the atmospheric patterns responsible for the formation of the modes. The results show that the first empirical orthogonal function mode (EOF1) of summer SPEI over NA exhibits a meridional dipole pattern, which is influenced primarily by the Polar–Eurasian teleconnection (POL) and Circumglobal teleconnection (CGT) patterns. Under the influence of negative POL and positive CGT patterns, there is an anomalous anticyclone (cyclone) over northwestern Siberia (Lake Baikal to Northeast China). Such atmospheric circulations lead to meridional dipole patterns in air temperature, moisture condition, vertical motion, and cloud cover over NA, favoring decreased (increased) precipitation and increased (decreased) potential evapotranspiration over northern (southern) NA, finally contributing to the formation of EOF1. The EOF2 shows an approximate zonal dipole pattern, which is influenced by the British-Baikal Corridor (BBC) and Scandinavia teleconnection (SCA) patterns. The positive BBC and SCA patterns can lead to an anomalous anticyclone over the Ural Mountains and cyclone over the Lake Baikal. Such atmospheric circulations result in a zonal dipole pattern in precipitation and potential evapotranspiration over NA through changing the local moisture condition, air temperature, and radiation, consequently favoring the formation of EOF2. Fitting analysis indicates that the aforementioned atmospheric factors can explain 76% (55%) of the interannual variability of EOF1 (EOF2).

Effects of land utilization transformation on ecosystem services in urban agglomeration on the northern slope of the Tianshan Mountains, China

Land utilization transformation (LUT) is a key factor affecting ecosystem services (ESs). The urban agglomeration on the Northern Slope of the Tianshan Mountains (UATM) is located in a typical arid region with extremely fragile ecological environment. However, the impact of LUT on the spatial pattern of ESs in the region over the past 20 years is not clear. This study aimed to explore LUT characteristics of the urban agglomeration on the UATM using a land transfer matrix, information entropy, land utilization intensity, and land utilization dynamic degree. Various ESs indexes were quantitatively measured using the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) model, and the effect of LUT on ESs was revealed through a geographic detector and spatial auto-correlation analyses. The results of this study led to the following conclusions: First, between 2000 and 2020, the primary land utilization types in UATM were arable land, grassland, and bare land, with significant cross-transformations occurring among these types. Meanwhile, LUT showed marked differences among different regions. LUT changed rapidly and significantly in the central region; in contrast, slower and slight changes were observed in the northern and southern regions. Second, during the research period, habitat maintenance, water yield and carbon sequestration decreased, and the soil retention function increased. The accelerated urban development in the second decade led to more rapid changes in ESs. Finally, both the structure and intensity of land utilization showed the strongest explanatory capability for changes in ESs. Different dimensions of LUT showed significant interactions with ESs. Therefore, it is advisable to guide LUT scientifically, promote vegetation restoration projects, alleviate the impacts of human activities and climate change on ESs, and enhance the ecological safety and environmental sustainability of UATM and even arid regions in Central Asia.

N limitation may inhibit the effectiveness of close-to-nature restoration measures for degraded alpine meadows on the northern Qinghai‒Tibet Plateau

As important terrestrial ecosystems on the Qinghai‒Tibet Plateau with important ecological and economic value, alpine meadows in some regions are in a degraded state due to climate change and unsustainable grazing. Due to the fragile ecological environment, exploring sustainable restoration models of degraded alpine meadows using close-to-nature restoration measures is the direction of ongoing efforts. Thus, in this study, three close-to-nature restoration measures, namely, manure application (M), Poa annua, Elymus dahuricus, and Puccinellia distans mixed with non-tillage reseeding (R), and the combined treatments (MR), were used to restore degraded alpine meadows from 2019 to 2021. The results showed that the M and MR treatments significantly enhanced plant biomass and reduced forbs dominance, thus improving community structure. Moreover, the M and MR treatments significantly affected plant and bacterial alpha diversity. However, the three restoration measures did not alter the correlation between the plant and bacterial communities. Furthermore, these three measures resulted in a significant increase in the plant carbon:nitrogen ratio and a significant decrease in the nitrogen:phosphorus ratio, while neither the plant carbon:phosphorus ratio nor the soil stoichiometric ratio changed significantly, indicating that nitrogen limitation was an important factor that limited the recovery process of the alpine meadows. The structural equation model indicated that the plant nitrogen:phosphorus ratio may regulate the response of plant and bacterial diversity to different restoration measures in alpine meadows. Our findings emphasize that the management of degraded alpine meadows using close-to-nature restoration measures should be a long-term effort, with more attention given to changes in the nitrogen content of meadow ecosystems.

Quantitative comparison and evaluation between aerial and underground parts of Gentiana straminea through simultaneous determination of five major compounds by RP-HPLC

Herbal Gentiana straminea Maxim. (Family Gentianaceae), “Ma Hua Jiao” in Chinese, is a commonly used Chinese medicine. Secoiridoids and flavonoids have been identified as the major active components of herbal medicines used in the treatment of hepatitis, rheumatism and many other diseases. It is the overharvesting of the roots of this plant for medicinal purposes that has led to a drastic decline in its population. In the present study, the above and below ground parts of Gentian Bitter Glycine were quantitatively compared and evaluated for the determination of the major active constituents. Five major compounds, loganic acid, swertiamarin, gentiopicroside, sweorside and isoorientin, were extracted by solvent extraction technique and analyzed by Reversed-phase High Performance Liquid Chromatography (RP-HPLC). By analysing the principal components and calculating the composite scores, the results show that the aboveground component in different areas ranked higher compared to the underground component, with the former being able to substitute to some extent for the latter's underground component. Finally, based on hierarchical cluster analysis, we identified the ideal natural growing region for aerial parts of G. straminea distributed on the Qinghai-Tibetan Plateau. The significance of this work is that we can balance the demand for herbs with environmental preservation by selectively picking the aerial parts, which can regrow next year, instead of removing the whole plant. It protects the fragile ecological environment of the Tibetan Plateau and is important for sustainable development.

Geochemical indicators to constrain weathering, provenance and tectonic setting of the Pisha Sandstone (Early–Middle Triassic) in Northeast Ordos Basin, China

The Pisha Sandstone is widely exposed in the northeastern margin of the Ordos basin. Since the Mesozoic the basin was subjected to uneven uplift several times, strong weathering and erosion have been occurring and a large amount of sediments derived from these erosional strata are input into the lower Yellow River, posing a fragile ecological environment along the river. However, the geochemical characteristics of the Pisha Sandstone have remained poorly understood. In this study, we focus on the Pisha Sandstone from Early–Middle Triassic Liujiagou, Heshanggou and Ermaying Formation, present a very first petrographic and geochemical data together with detailed field geological characteristics, aiming to place geochemical indicators on weathering, provenance and tectonic setting of the Pisha Sandstone. The results show that sandstones in Pisha Sandstone are classified as arkose, litharenite and wacke. The geochemical proxies including Chemical Index of Alteration (CIA = 67.2), Chemical Index of Weathering (CIW = 80.1), Plagioclase Index of Alteration (PIA = 75.6) and Index of Compositional Variability (ICV = 1.6) indicate Pisha Sandstone experienced first–cycle deposit and moderate to strong chemical weathering. Trace element and rare earth element concentrations together with their ratios (La/Sc, La/Co, Th/Sc, Th/Co, Cr/Th) reveal a felsic provenance, and source rock compositions are predominantly granodiorite and granite from the north margin of the Inner Mongolia Paleo–Uplift (IMPU), with a small amount of mafic or intermediate components. The geochemical signatures and tectonic discrimination diagrams display a collision setting for the Pisha Sandstone and further reveal the sediments had been deposited in a continental island arc setting. The results of this work may provide new theoretical basis for environmental protection in the Pisha Sandstone area.

Unraveling soil filling and transport in fissures on karst slopes using multiple tracers

The fragile ecological environment and unique surface–subsurface geological duality of karst regions have led to complex processes and rates of underground soil loss, which is subject to much controversy. However, to ensure the ecological sustainability of karst areas, it is imperative to address this issue systematically using innovative study methods. With focuses on ten fissures and fivecross-sections in a typical karst area in southwestern China, this study applied unmanned aerial vehicles for field surveys and indoor modeling techniques to investigate the distribution density of fissures in typical karst areas, which is crucial for calculating underground soil loss. By measuring magnetic susceptibility, organic carbon content, and particle size of fissure soils, the primary sources of soil in the fissures were identified. Additionally, the rate of soil loss passing through karst fissure was calculated using 137Cs tracing and 14C dating techniques. Results indicate that (1) the proportion of fissure area per square kilometer of land is 1.59 %; (2) the soil in the fissures is mainly filled with the topsoil outside the fissures, and (3) the average rate of soil filling into the fissures is 16.13 t km−2 yr−1, account for only 5.8 % of the total soil erosion modulus. The study shows that soil filling into fissures is the main process of underground soil loss on karst slopes, and the rate of soil loss through fissures is very small. This study offers valuable insights into soil movement processes and quantification of soil erosion in karst regions, thus aiding in the preservation and sustainable management of these unique ecosystems.

Evaluation of water ecological health of Yanhe River based on benthic fauna integrity index.

Yanhe River Basin is located in the hilly gully area of the Loess Plateau with serious soil erosion. Strong human activities in the middle and lower reaches lead to fragile ecological environment. Soil erosion status varies among different geomorphic units within the watershed (loess liang hilly and gully region, loess mao hilly and gully region, and broken platform region). In this study, we surveyed the benthic community from the Yanhe River Basin in April (spring) and October (autumn) of 2021. To evaluate the water ecological health status of the watershed and investigate the effects of different geomorphic units on the benthic integrity of the benthos, we constructed the benthic-index of biotical integrity (B-IBI) based on the biological data. We identified a total of 113 species of 73 genera in 4 phyla of benthic fauna, with aquatic insects as the dominant taxa in both seasons. Through screening 26 candidate indicators, we found that the spring B-IBI consisted of three indicators: relative abundance of individuals of dominant taxonomic units, family biotic index (FBI), and relative abundance of predator individuals, and that autumn B-IBI was composed of the number of taxonomic units of Ephemeroptera, FBI value, and the relative abundance of predator individuals. Results of the B-IBI evaluation showed that 83.3% of the sampling sites in the upper mainstem and tributaries were at a healthy condition, while only 28.6% sampling sites in the middle and lower mainstem and tributaries were at a healthy condition. In addition, the health status of the watershed was better in spring than in autumn. The Kruskal-Wallis nonparametric tests showed that benthic density, species number, and B-IBI percentile scores in the fragmented loess area were significantly higher in spring than in autumn, and significantly lower in autumn than in the loess liang hilly and gully region and loess mao hilly and gully region, being mainly caused by the increasing erosion due to the concentrated rainfall in wet season. Results of the redundancy analysis showed that key environmental factors affecting benthic community structure in spring were boulder substrate, chlorophyll-a, oxidation reduction potential, turbidity, conductivity, and dissolved oxygen, and were nitrate-nitrogen, oxidation reduction potential, and pH in autumn.

Impacts of Climate Change and Human Activity on Lakes around the Depression of Great Lakes in Mongolia

The western region of Mongolia is characterized by an arid climate and a fragile ecological environment. It is a sensitive zone in response to global climate change and one of the major sources of dust globally. This region is home to numerous lakes, and their dynamic changes not only reflect global climate variations but also have implications for the global ecological environment quality. In this study, Landsat images were used as the data source, and Google Earth Engine (GEE) was employed to extract lakes with an area larger than 1 km2 from 1992 to 2021. The spatiotemporal characteristics of lake water area (LWA) changes were analyzed, and a structural equation model was applied to attribute the lake changes. The results indicate an overall trend of increasing lake area followed by a decrease in the study area. Specifically, lakes in the provinces of Khovd and Gobi-Altai exhibited a decreasing trend followed by an increasing trend, while lakes in the provinces of Uvs and Zavkhan showed an increasing trend followed by a decreasing trend. Three typical types of lakes, namely, alpine lakes, throughflow lakes, and terminal lakes, all exhibited a trend of increasing area followed by a decrease. The analysis of driving forces behind lake area changes reveals that climate change and human activities primarily exert indirect influences on the lake area changes in each province. Specifically, climate change and human activities lead to changes in soil moisture, which have a significant explanatory power for lake area changes. Regarding the typical types of lakes, climate change serves as the primary driving force for alpine lakes, while human activities are the main driving forces for throughflow lakes and terminal lakes.

Automatic and Efficient Detection of Loess Landslides Based on Deep Learning

Frequent landslide disasters on the Loess Plateau in northwestern China have had a serious impact on the lives and production of the people in the region due to the fragile ecological environment and severe soil erosion. The effective monitoring and management of landslide hazards is hindered by the wide range of landslide features and scales in remotely sensed imagery, coupled with the shortage of local information and technology. To address this issue, we constructed a loess landslide dataset of 11,010 images and established a landslide detection network model. Coordinate Attention (CA) is integrated into the backbone with the aid of the YOLO model to capture precise location information and remote spatial interaction data from landslide images. Furthermore, the neck includes the Convolutional Block Attention Module (CBAM), which prompts the model to prioritize focusing on legitimate landslide objectives while also filtering out background noise to extract valid feature information. To efficiently extract classification and location details from landslide images, we introduce the lightweight Decoupled Head. This enhances detection accuracy for landslide objectives without excessively increasing model parameters. Furthermore, the utilization of the SIoU loss function improves angle perception for landslide detection algorithms and reduces the deviation between the predicted box and the ground truth box. The improved model achieves landslide object detection at multiple scales with a mAP of 92.28%, an improvement of 4.01% compared to the unimproved model.

Potential impacts of coal mining activities on nitrate sources and transport in a karst river basin in southwest China.

Typical sources of nitrate pollution in the fragile ecological environment of karst areas, such as agricultural production activities and domestic sewage, have long attracted serious concern. However, coal development can play an equally significant role in releasing the nitrogen fixed in coal into surface watersheds in the form of nitrate, nitrite, or ammonia, consequently threatening the water quality of surface water systems in mining areas. In this study, a typical karst surface watershed system affected by coal mining activities was selected for an in-depth investigation with the aim of realistically assessing the potential contribution of coal mining to nitrogen pollution. The results reveal increasingly concerning nitrate pollution from August 2020 to November 2021 in the Huatan River watershed under the influence of anthropogenic activities, especially mining development and agricultural production. Given that the nitrogen and oxygen isotope compositions of nitrate do not support the presence of denitrification, the variation in the NO3-/Cl- ratio and the relatively stable Cl- concentration may be a reflection of nitrification. Although the leaching of atmospheric precipitation on the strata in the basin promoted the release of nitrogen associated with coal mining, the higher rate of nitrogen cycling in the oligotrophic mine water environment limited the contribution of coal mining to nitrogen pollution in the surface watershed. Specifically, the contribution of coal mining activities to nitrogen pollution in surface karst river is mainly NH4+-N, which contributes 10% or less to the nitrate input to the waters of the Huatan River. The findings thus highlight the necessity of further uncovering the geochemical cycling process of nitrogen during the transport of mine water in the coal mining environment.

Land Use/Cover-Related Ecosystem Service Value in Fragile Ecological Environments: A Case Study in Hexi Region, China

The monetary value assigned to ecosystems and their essential goods and services is known as ecosystem service value (ESV). Fragile ecological environments, susceptible to climate change and human disturbances, require significant ecological protection. This protection is vital not only for stabilizing socio-economic conditions but also for fostering a positive feedback loop within natural systems. Looking ahead, identifying priority conservation areas and regions of particular concern in fragile environments based on ESV changes is a proactive approach. Until now, current studies on ESV in fragile ecological environments have been insufficient, falling short of adequately serving the purpose of ecological protection in such areas. The Hexi region (HXR), situated in the interlaced area of the Qilian Mountains and the Alxa Plateau in northwest China, possesses a fragile ecological environment. Due to the intricate interactions between humans and the environment, it stands out as a crucial area for studying ecosystem services in fragile habitats. Hence, this study aims to systematically analyze the ESV in the HXR over the past 30 years. Here, the values of 11 ecosystem service categories in HXR during 1990–2020 were calculated, clarifying their spatiotemporal difference and dynamic changes based on land use/cover (LULC) products for years 1990, 1995, 2000, 2005, 2010, 2015, and 2020, using an improved equivalent factors method. The findings revealed that the unit standard equivalent factor is 1.51 × 105 CNY·km−2·a−1, and the total ESV value has grown from CNY 182.50 to 185.48 billion from 1990 to 2020. Hydrologic regulation, climate regulation, and soil conservation service values are the principal single ESV categories across HXR. Over the past three decades, ESV changes in HXR have been primarily driven by water area, grassland, and wetland, with the sensitivity of ESV to LULC generally increasing (0.15~9.10%). Natural forcing and anthropogenic perturbations have combined to cause changes in LULC in HXR, influencing ESV fluctuations. Future ecosystem protection activities in HXR should prioritize the maintenance of grasslands, water regions, and wetlands to ensure the preservation of ESV. This study clarifies the impacts of LULC change on ESV in fragile natural environments and highlights the significance of focusing on ESV changes for the health promotion of natural-social systems. The findings provide a foundation for constructing a sustainable development model that is in harmony with both people and the environment.

Spatiotemporal patterns and evolutionary trends of eco-environmental quality in arid regions of Northwest China.

The arid regions of northwest China suffer from water shortages, low land quality, and a fragile ecological environment, while social and economic development has increased the ecological and environmental load. The spatiotemporal pattern and evolutionary trend of ecological environmental quality were investigated by constructing a remote sensing-based ecological environmental index (EQI) evaluation model incorporating four indicators: drought index (DI), soil erosion index (SEI), greenness index (GI), and carbon exchange index (CEI). The study found that between 2001 and 2020, the DI, the SEI, and the CEI in the northwest arid region exhibited a downward trend with reduction rates of - 3e-05, -0.0006, and -0.0018, respectively. However, the GI demonstrated an upward trend, with a growth rate of 0.002. The average EQI in 2020 was 0.315, indicating a fair grade, with only 11.56% falling above the medium level. A general increasing trend was observed throughout the study period in EQI, with an incremental rate of 0.0002. Areas with future improvements in EQI accounted for 57.547% and were principally located in the eastern part of Inner Mongolia, Qinghai, and the northern and southern portions of Xinjiang. Notably, land use was significantly correlated with EQI (p < 0.01), with a hierarchy of effects that ran: forest land (0.678) > cultivated land (0.422) > grassland (0.382) > wasteland (0.138). The highly robust findings presented here offer innovative methods for ecological and environmental monitoring in the arid region of the northwest, with potential implications at an international scale.

Evaluation and optimization of ecological spatial resilience of Yanhe River Basin based on complex network theory

The loess hilly and gully areas have broken terrain, vertical and horizontal ravines and fragile ecological environments. Improving the resilience of the regional ecological space is conducive to improving the quality of the local ecological environment. With the ecological space of the Yanhe River Basin selected as the research object, this paper constructs a research framework of "network identification topology-resilience evaluation-spatial optimization" and uses morphological spatial pattern analysis (MSPA) and the minimum cumulative resistance model (MCR) to identify ecological spatial networks. Based on circuit theory, the ecological pinch point is identified, the ecological spatial network is optimized, and scenario simulation is performed. Through complex network theory and related indicators, the ecological spatial resilience of the basin is evaluated, and the hierarchical optimization strategy of the ecological space is confirmed. According to the ecological function of the source area and the results of the resilience evaluation, the boundaries of the protected control area, guidance development area, remediation area, and maintenance and improvement area of the basin are delineated. The importance of ecological source and corridor protection is classified, and corresponding protection strategies are proposed. The research results can provide theoretical support and practical guidance for the territorial spatial planning and ecological space construction of the Yanhe River Basin and provide a reference for the ecological restoration, resource development and environmental governance of the Yanhe River Basin.

Geochemical characteristics of shale gas hydraulic fracturing flowback/produced water in Zheng’an block, northern Guizhou Province, China

Guizhou Province of China is rich in shale gas resources. In recent years, important progress has been made in the exploration and development of shale gas in the Upper Ordovician Wufeng Formation-Lower Silurian Longmaxi Formation in Zheng'an block in northern Guizhou, adjacent to Sichuan Basin. Due to the complex geological conditions and fragile ecological environment in the shale gas distribution area, serious environmental pollution risks may exist in shale gas exploitation. Therefore, this paper conducted element, hydrogen and oxygen isotope analyses for shale gas fracturing flowback/produced water of Well AY7-4 in Zheng'an block. The results showed that the contents of K, Na, Ca, Mg and NH4+ in the flowback/produced water of Well AY7-4 were very high, with an average of 118 mg/L, 7616 mg/L, 266 mg/L, 47 mg/L and 76 mg/L, respectively. The content of Na, Ca and Mg is similar to that of shale gas flowback/produced water in Weiyuan, but lower than that in Changning and Fuling. NH4+ content was similar to that in Changning, but much higher than that in Weiyuan. The average Cl content was 11605 mg/L, which was similar to that in Weiyuan, but lower than that in Changning and Fuling. The average Br content is 48 mg/L, slightly lower than that of Weiyuan, and about half of that of Changning and Fuling. Correspondingly, the Br/Cl value of Well AY7-4 is the lowest, reflecting its relatively low Br content. The average content of Li, B and Sr is 17 mg/L, 10 mg/L and 45 mg/L, respectively, which is similar to that of the Weiyuan, Changning and Fuling shale gas fields. The distribution model of Li and Sr is similar to that of Cl, Br and Na, but the B content and B/Cl value of Well AY7-4 are the lowest. The linear relationship between Br and Cl contents and between δD and δ18O of flowback/produced water of Well AY7-4, freshwater used for hydraulic fracturing and hydraulic fracturing injected fluid indicates that flowback/produced water of Well AY7-4 is mainly the mixed product between low salinity injected fracturing fluid and high salinity brine retained in shale formation. The hydrogen and oxygen isotopic compositions gradually become heavier over time, indicating that the proportion of high salt end formation brine in flowback/produced water is increasing. The contents of Cl, Br, Na and NH4+ in the flowback/produced water of Well AY7-4 are far higher than the allowable discharge value, which is a potential environmental pollution risk and cannot be discharged directly.

贵州普定土壤酶活性和氮循环功能基因数据集

The karst ecosystem in southwest China is the most fragile ecological environment in China. To protect the ecological environment, the project of "Grain to Green Program" was initiated in the late 1990s for the vegetation restoration in this region. Changes in soil microbial abundance, community composition and functional activity are closely linked to soil nutrient supply and turnover, which are the critical factors influencing vegetation restoration processes. Soils were sampled from five different vegetation types at Chenqi catchment and Tianlong Mountain, and rhizosphere soils were sampled from the typical tree species at Tianlong Mountain. Through rigorous data quality control processes (including survey sampling, sample analysis, and data accuracy checks), we obtained a dataset of soil microbial enzyme activities and nitrogen cycling functional genes in different vegetation types from the karst ecosystem. This dataset consisted of one excel file with eight different sheets, which contains the data on soil microbial enzyme activities, nitrogen cycling functional gene abundance and nitrogen transformation rate, microbial living biomass, microbial residue carbon, and soil physicochemical properties along soil profile ranging from the surface to bedrock layer in various vegetation types of 2016. Furthermore, the dataset also includes the enzyme activity and physicochemical properties of the rhizosphere soils from typical tree species in the primary forest in 2018. The dataset serves as valuable reference data for better understanding the microbial regulation mechanism of soil nutrient cycling in karst areas, and it is also of great practical significance for soil nutrient management in ecologically fragile regions under the background of "Grain to Green Program" policy.

Spatio-temporal evolutionary analysis of surface ecological quality in Pingshuo open-cast mine area, China.

The open-pit mining area is highly affected by human activities, which aggravate soil erosion and disturb surface ecology, bringing many problems and challenges to its environmental management and restoration, which has received widespread attention. The establishment of an objective, timely and quantitative remote sensing monitoring, and evaluation system for the spatio-temporal evolution of the surface ecological environment in the open-pit mining area is of great significance for its environmental protection, management decisions, and sustainable social development. Based on the Google Earth Engine (GEE) platform, this paper uses Landsat images to construct and calculate the remote sensing ecological index (RSEI) of the Pingshuo open-cast mine area (POMA) from 1990 to 2020 and monitor and evaluate its surface ecological environment. Combined with the Theil-Sen median, Mann-Kendall test, and Hurst index, the spatio-temporal process was analyzed. The results showed that the ecological environmental quality of the mining area first decreased and then increased from 1990 to 2020. 1990-2000 was a period of serious ecological degradation, followed by improvement. The overall improvement area reached 87.03%, and the degradation was concentrated in the coal mining area. Between 1990 and 2020, the Hurst index of the mining area was 0.452, indicating that the region has a fragile ecological environment and has difficult maintaining its stability. The global Moran's I mean value of the RSEI of the study area is 0.92, which combined with Moran's scatter plot to indicate that there is a strong positive spatial correlation rather than a random distribution of its ecological environment. During the study period, the impact on the climate of the ecological environmental change of POMA was weak, and human factors such as coal mining, land reclamation, and social construction were the main driving forces for the change in ecological quality. The results of this study reveal the changing trend of surface ecology in the mining area over the past 30 years, which is helpful for understanding its impact mechanism on ecological quality and provides support for the management of the region.