Intensive Disturbances Research Articles

Study of methods for predicting the stability of preparatory workings in the mines of Western Donbas

Purpose. Analysis of the effectiveness and feasibility of existing methods for predicting preparatory workings. Research methodology. The research was conducted using an analytical method (analysis, explanation, synthesis, comparison) and statistical data processing method. Research results. The conducted research allowed determining that the coal-bearing sedimentary massif of the Western Donbas, as a result of complex tectonic movements, is characterized by developed and intensive tectonic disturbances of a ruptural and plicative nature. The appearance of plicative disturbances in the hanging wall of the coal seam, accompanied by an increase in their thickness, leads to the concentration of stresses in the areas of disturbances caused by approaching the mining face. Regional plicative disturbances cause the formation of zones of anomalous activity in the intact mining massif. In addition to gravitational forces affecting the geological structure, tectonic stresses directed along the bedding plane are added to this phenomenon. Tectonic stresses are oriented in the direction of the main curvatures of the natural surface of rock deposition and depend on their magnitude. Geological deviations of various types are key indicators of anomalies in the tectonic environment and zones of reduced strength in an intact mining massif. These anomalies can result from the complex interaction of geological processes, including tectonic activity, water flow activity, and other natural factors. These deviations become fundamental factors contributing to the occurrence of gas-dynamic phenomena and rockfalls during the preparatory mining stage. Scientific novelty. The regularity of the interaction of geomechanical parameters of elements of the "layered massif – excavation support" system has been established. Practical significance. Studying methods for predicting the stability of preparatory workings allows for the development of effective excavation support systems according to geological conditions and prevents possible accidents and rockfalls in mining working areas.

Monitoring dynamic mangrove landscape patterns in China: Effects of natural and anthropogenic forcings during 1985–2020

Many mangrove forests located along estuaries and deltas worldwide are currently facing irreparable losses caused by natural factors and intensive anthropogenic disturbances. The limited capabilities of traditional remote sensing processing platforms tend to lead to poor image processing consistency in medium- and large-scale areas, resulting in lower ground object classification accuracy. Consequently, little information is available regarding the extent and causes of variation in large-scale mangrove forests. In this study, we used Google Earth Engine mangrove forest data from eight periods between 1985 and 2020, with total accuracy rates of 82.95–90.15%, and combined landscape metrics with a centroid transfer model to quantitatively analyze the landscape evolution of mangrove forests in China. Finally, we employed a geodetector based on optimized parameters to quantitatively determine the potential mechanisms driving mangrove landscape evolution. Overall, a slight increase followed by a sharp decrease in mangrove forest area in China during the past 40 years, with a turning point around 2000 and substantial shifts in mangrove spatial patterns in Guangdong and Guangxi Provinces, particularly in the Pearl River Estuary and Beibu Gulf. The landscape pattern of Chinese mangrove forests has become fragmented and isolated through rapid urbanization in recent decades. Mangrove forests shifted significantly (> 31 km) early in the study period, followed by smaller shifts later in the study period. The optimal spatial scale of mangrove landscape driver detection was 270 m × 270 m. The variation in mangrove forest area was caused by the interactions of multiple factors, particularly between mean annual precipitation and other potential influencing factors. Government policies guided the conservation and management of mangrove forests in China to varying degrees throughout the study period. Our findings on the dynamics of mangrove forests provide a reference for integrated coastal management, which will contribute to the ecological utilization and high-quality development of coasts during extensive urbanization along the southeastern coast of China and similar large estuary deltas worldwide.

Gas–liquid twin-fluid atomization from non-circular orifices

Passive control of twin-fluid atomization can be achieved by changing the orifice shape of the injector. In this study, the characteristics of twin-fluid atomization in the outside-in-liquid injector with circular, square, and rectangular orifices at various aspect ratios were investigated experimentally and computationally. The morphology of the spray was captured by shadowgraph, the diameter and velocity of the droplets were measured by the phase Doppler particle analyzer, and numerical simulations were performed for the central gaseous core. Comparing the sprays with square and circular orifices, droplets from the non-circular orifice are generally smaller with less disparities in droplet sizes due to the more intensive turbulent disturbances and corner effect. Furthermore, the non-circular orifice also results in better spatial distribution of the spray. The droplet diameters of the spray with a square orifice do not satisfy the log-normal distribution near the orifice along the centerline of the spray, which may be attributed to the different entrainment of spray droplets by the central gas flow for the sprays with circular and non-circular orifices. The twin-fluid sprays produced by the rectangular orifice also exhibit the same axial switching effect as in the high-pressure gaseous jet flow, in which the spray diffusion in the minor axis is more extensive than that in the major axis. Moreover, the droplets' Sauter mean diameter produced by the rectangular orifice is more sensitive to the size in the minor axis of the orifice and decreases as the aspect ratio of the orifice increases given the same cross-sectional area.

Distinct biogeographic patterns in Glomeromycotinian and Mucoromycotinian arbuscular mycorrhizal fungi across China: A meta-analysis

Fine root endophytes, recently reclassified as Mucoromycotinian arbuscular mycorrhizal fungi (M-AMF), are now recognized as functionally important as Glomeromycotinian AMF (G-AMF). However, little is known about the biogeography and ecology of M-AMF and G-AMF communities, particularly on a large scale, preventing a systematic assessment of ecosystem diversity and functioning. Here, we investigated the biogeographic assemblies and ecological diversity patterns of both G-AMF and M-AMF, using published 18S rDNA amplicon datasets and associated metadata from 575 soil samples in six ecosystems across China. Contrasting with G-AMF, putative M-AMF were rare in natural/semi-natural sites, where their communities were a subset of those in agricultural sites characterized by intensive disturbances, suggesting different ecological niches that they could occupy. Spatial and environmental factors (e.g., vegetation type) significantly influenced both fungal communities, with soil total‑nitrogen and mean-annual-precipitation being the strongest predictors for G-AMF and M-AMF richness, respectively. Both groups exhibited a strong spatial distance-decay relationship, shaped more by environmental filtering than spatial effects for M-AMF, and the opposite for G-AMF, presumably because stochasticity (e.g., drift) dominantly structured G-AMF communities; while the narrower niche breadth (at community-level) of M-AMF compared to G-AMF suggested its more susceptibility to environmental differences. Furthermore, co-occurrence network links between G-AMF and M-AMF were prevalent across ecosystems, and were predicted to play a key role in stabilizing overall communities harboring both fungi. Based on the macroecological spatial scale datasets, this study provides solid evidence that the two AMF groups have distinct ecological preferences at the continental scale in China, and also highlights the potential impacts of anthropogenic activities on distributions of AMF. These results advance our knowledge of the ecological differences between the two fungal groups in terrestrial ecosystems, suggesting the need for further field-based investigation that may lead to a more sophisticated understanding of ecosystem function and sustainable management.

The patterns of soil nitrogen stocks and C : N stoichiometry under impervious surfaces in China

Abstract. Accurate assessment of soil nitrogen (N) storage and carbon (C) : N stoichiometry under impervious surface areas (ISAs) is key to understanding the impact of urbanization on soil health and the N cycle. Based on 888 soil profiles from 148 sampling sites in 41 cities across China, we estimated the country's N stock (100 cm depth) in the ISA soil to be 98.74±59.13 Tg N with a mean N density (NISA) of 0.59±0.35 kg m−2, which was significantly lower (at all depths) than the soil N density (NPSA=0.83±0.46 kg m−2) under the reference permeable surface areas (PSAs). The NISA was also only about 53 %–69 % of the reported national mean soil N density, indicating that ISA expansion caused soil N loss. The C:N ratio of ISA (10.33±2.62) was 26 %–34 % higher than that of natural ecosystems (forests, grasslands, etc.) but close to the C:N of PSA. Moreover, there was a significant C–N correlation in ISA soil, showing no signs of C–N decoupling as suggested by the previous studies. The ISA had smaller variances in the C:N ratio than did the PSA at regional scale, indicating convergence of soil C:N stoichiometry due to ISA conversion. The eastern subregion of China had the highest NISA, although its natural soil N density was among the lowest in the country. Unlike the vertical pattern in natural permeable soils, whose N density declined faster in the upper soil layers than in the lower layers, NISA decreased linearly with depth. Similarly to natural soil N, NISA was negatively correlated with temperature; but unlike natural soil C:N which was positively correlated with temperature, the C:NISA was negatively correlated with temperature. NISA was not correlated with net primary productivity, but was significantly correlated with the soil N density of adjacent PSA and the urbanization rate. These findings indicate the ISA soil had a unique N distribution pattern, possibly as the result of intensive disturbances during land conversion. The dataset “Observations of soil nitrogen and soil organic carbon to soil nitrogen stoichiometry under the impervious surfaces areas (ISA) of China” is available from the National Cryosphere Desert Data Center (https://doi.org/10.12072/ncdc.socn.db2851.2023) (Ding et al., 2023).

Significant spatiotemporal variability of nitrous oxide emissions from a temperate reservoir experiencing intensive aquaculture disturbance

Freshwater reservoirs are known as important sources of atmospheric N2O; however, the patterns and controls of N2O emissions from these reservoirs remain poorly understood, particularly for reservoirs severely disturbed by aquaculture activities. This study aimed to bridge this knowledge gap by determining the spatiotemporal and magnitude variations of N2O concentrations, dynamics of the drivers of N2O concentration and diffusive flux, and N2O emission patterns from reservoirs severely affected by human activities. We measured N2O concentrations and estimated diffusive fluxes in a temperate reservoir—including the upstream river inflow zone—in northern China, which was experiencing acute aquaculture disturbance. A thin boundary layer equation was employed, and we analyzed the thermal and dissolved oxygen stratification conditions and other environmental auxiliary factors to identify crucial factors and underlying mechanisms that regulate N2O emissions. Our results showed that aquaculture activities led to the accumulation of high levels of organic matter and nutrients in sediments. The annual average water-dissolved N2O concentration and diffusive flux across the water–air interface in the reservoir were 24.97 ± 11.16 nmol L-1 and 0.43 ± 0.36 μmol m-2·h-1, respectively. The water-dissolved N2O concentrations exhibited supersaturation, indicating the reservoir as a net source of atmospheric N2O. Both N2O concentrations and diffusive fluxes exhibited strong spatiotemporal variability during the study period. The lacustrine area of the reservoir was the hotspot for N2O emissions. The statistical results indicated that nitrogen loading, temperature, and dissolved oxygen (DO) were the key drivers of N2O emissions. Moreover, dam construction and intensive aquaculture disturbances have altered aquatic conditions and significantly affected N2O emissions. Our results indicated that N2O emission estimates for the entire reservoir should cover different reservoir zones and sampling seasons. We suggest measures such as sediment dredging to reduce sediment organic matter and nutrient loading for mitigating N2O emissions from the reservoir.

Continual expansion of Spartina alterniflora in the temperate and subtropical coastal zones of China during 1985–2020

Biological invasions are considerably altering ecosystem structure and functions, especially in coastal ecosystems that are subject to intensive anthropogenic disturbances. Spartina alterniflora has been recognized as the most serious invasive species in coastal China, which has received considerable attention from the government and the public. There is urgent need to control this invasive species at regional and national scales, but such efforts were impeded by lack of time-series data of Spartina spread. Here, we assessed the pixel- and phenology-based algorithm for mapping Spartina saltmarshes, and applied this algorithm to generate annual Spartina saltmarsh maps (30-m spatial resolution) from 1985 to 2020 by using time series Landsat 5/7/8 images. The resulting maps suggest that Spartina has been expanding since 1990 in coastal China, with three noticeable phases (rapid, moderate, and rapid). Along the latitudinal gradient, Spartina exhibited a longer invasion history and more frequent changes at low latitudes. Although human interventions caused the decline of Spartina in certain areas, rapid natural spread was primarily responsible for its extensive and continual invasion. These results provide insights for efficiently managing this invasive species, enhancing the conservation of coastal wetlands, and promoting the sustainability of coastal wetlands.

PECULIARITIES OF FORMATION OF CARBOHYDRATE METABOLISM DISORDERS WITH COMORBID CHRONIC PANCREATITIS AND CHRONIC OBSTRUCTIVE PULMONARY DISEASE.

The aim: To determine glycemic condition, regulation of carbohydrate metabolism, degree of insulin resistance in patients with chronic pancreatitis with its isolated course and with comorbid COPD and diabetes mellitus. Materials and methods: 110 patients with chronic pancreatitis were examined. The first group of patients included 38 individuals with an isolated course of chronic pancreatitis (1 group), 2nd group included 35 patients with chronic pancreatitis and COPD, 3rd group included 37 patients with chronic pancreatitis and COPD and type 3c diabetes mellitus. The control group (CCOPD) included 32 individuals with isolated COPD, the control group (CDM) includes 34 individuals with isolated type 2 diabetes mellitus. All the patients were examined for functional state of the pancreas and carbohydrate metabolism was assessed. Results: Patients suffering from chronic pancreatitis with COPD and diabetes mellitus developed 3.2 times increased glucose concentration on an empty stomach. Blood glucagon content in all patients was lower in comparison with that of practically healthy individuals which is indicative of an insufficient glucagon secretion by α-cells of the pancreas. Pancreatic polypeptide content in the blood was lower in patients with chronic pancreatitis and COPD and T3c diabetes mellitus in comparison with the reference value. Conclusions: A comorbid course of chronic pancreatitis with exacerbated COPD is associated with more intensive disturbances in carbohydrate metabolism regulation and glycaemia parameters in comparison with an isolated course of chronic pancreatitis. In case comorbidity includes a chronic pancreatitis, chronic obstructive pulmonary disease and diabetes mellitus, the most unfavorable glycemic profile is found which is indicative of carbohydrate metabolism decompensation.

Analysis of Structure, the Composition of Vegetation, and Diversity of Epiphytes and Their Hosts

The tourist area of Kali Bak Kampung Harapan Sentani Jayapura Regency is one of the buffer zones for the Cycloop Mountains nature reserve which has the function of a rainwater catchment area and supply of drinking water for the people of Jayapura Regency and City, but currently, the tourist spot is experiencing intensive disturbances and threats. This condition is the reason for this study to be carried out to analyze epiphytic plant vegetation and their hosts in the Kali Bak tourism area, Harapan Sentani Village, Jayapura Regency. The purpose of this study was conducted to determine the structure and composition of the vegetation as well as the diversity of epiphytes and their hosts at the Kali Bak tourist spot, Harapan Sentani Village, Jayapura Regency. Data collection was carried out using transect methods, documentation methods, and plot methods. There are 25 observation plots with a plot size of 20 x 20 meters which are placed on the right and left of the transect line. The results showed that 5 families of 8 species were Asplenium nidus L., Davallia trichomanoides BL., Dendrobium sp, Drynaria quercifolia (L). J.sm., Drynaria rigidula (Sw.).Bedd., Microsorum sp, Microsorum punctatum, and Nephrolepis falcata (Cav.) C. Chr. As for the host tree species, 6 families were obtained consisting of 6 species including Alstonia scholaris (L.) R. Br., Calophyllum inophyllum, Cycas rumphii Miq., Ficus virens Aiton., Gymnostoma papuana Miq., Intsia bijuga (Colebr.) OK. The overall diversity index for epiphytic plants, which is 1.98, is moderate. The overall diversity index for host trees is 1.26 which is moderate

Study on dynamic shear deformation behaviors and test methodology of sawtooth-shaped rock joints under impact load

Shear slip of rock joints under dynamic disturbance is a major factor causing disasters such as landslides and cavern instability. To explore the dynamic shear deformation behaviors of rock joints, an impact-induced direct shear test applicable for jointed rock specimen is conducted. A biaxial Hopkinson pressure bar (BHPB) equipment is employed, which can simulate intensive disturbances encountered during engineering construction in rock masses. Tangential and normal dynamic stresses on rock joint can be measured simultaneously through stress wave acquisition. Dynamic displacements are obtained based on a two-dimensional digital image correlation (2D-DIC) technique. Firstly, the feasibility of the experimental method is verified by trial tests on metallic specimens. The measurement technique for obtaining the dynamic stress and displacement of joint is proposed. Then, a series of dynamic shear experiments are carried out on jointed and intact granite specimens, respectively. The dynamic shear deformation of the specimens is obtained, and the effects and mechanisms of undulating angle and initial normal stress on the dynamic shear deformation are discussed. The test results show that, due to the variable input force and normal stress, the shear rate varies. The dynamic slip of the joint can be divided into three sub-stages: slip initiation, secondary stress accumulation, and post-slip. The shearing process of intact rock includes two stages: shear stress accumulation and post-peak damage. Deformation rebounding is also observed in the jointed and intact granite specimens. The maximum shear displacement is negatively correlated with the normal stress and the undulating angle. Based on the distribution and evolution of displacement field in rock specimen, the effects of undulating angle and normal stress on the shear strength and the maximum shear displacement are revealed. Finally, the damage modes of rock joint under different conditions are discussed.

Factors driving the assembly of prokaryotic communities in bulk soil and rhizosphere of Torreya grandis along a 900-year age gradient.

Excessive nutrient inputs imperil the stability of forest ecosystems via modifying the interactions among soil properties, microbes, and plants, particularly in forests composed of cash crops that are under intensive disturbances of agricultural activities, such as Torreya grandis. Understanding the potential drivers of soil microbial community helps scientists develop effective strategies for balancing the protection and productivity of the ancient Torreya forest. Here, we assayed the link between plant and soil parameters and prokaryote communities in bulk soil and T. grandis rhizosphere in 900-year-old stands by detecting plant and soil properties in two independent sites in southeastern China. Our results showed no apparent influence of stand age on the compositions of prokaryote communities in bulk soil and T. grandis rhizosphere. In contrast, soil abiotic factors (i.e., soil pH) overwhelm plant characteristics (i.e., height, plant tissue carbon, nitrogen, and phosphorus content) and contribute most to the shift in prokaryote communities in bulk soil and T. grandis rhizosphere. Soil pH leads to an increase in microbiota alpha diversity in both compartments. With the help of a random forest, we found a critical transition point of pH (pH = 4.9) for the dominance of acidic and near-neutral bacterial groups. Co-occurrence network analysis further revealed a substantially simplified network in plots with a pH of <4.9 versus samples with a pH of ≥4.9, indicating that soil acidification induces biodiversity loss and disrupts potential interactions among soil microbes. Our findings provide empirical evidence that soil abiotic properties nearly completely offset the roles of host plants in the assembly and potential interactions of rhizosphere microorganisms. Hence, reduction in inorganic fertilization and proper liming protocols should be seriously considered by local farmers to protect ancient Torreya forests.

Features of Winter Stratosphere Small-Scale Disturbance during Sudden Stratospheric Warmings

We analyzed the characteristics of small-scale wave disturbances emerging during the evolution and transformation of the jet stream (JS) in the winter stratosphere and the lower mesosphere of the northern hemisphere, including the periods of sudden stratospheric warming (SSW) events. Continuous generation of small-scale wave disturbances is shown to occur over quiet geomagnetic winter periods in the region of a steady jet stream in the strato–mesosphere. We studied spatial spectra for the vertical velocity variations, determined by the parameters of emerging wave disturbances. The greatest intensities of disturbances are recorded in the regions corresponding to the high velocities of the JS (from 100 m/s and higher). In the northern hemisphere, those latitudes encompass ~40–60° N. When a steady jet stream forms, the horizontal length and periods of the most intensive wavelike disturbances are shown to vary within 300–1000 km and 50–150 min correspondingly (which match the characteristic scales of internal gravity waves, or IGWs). During the SSW prewarming stage, the JS transforms substantially. Over the same periods, a disturbance intensification is recorded, as well as the emergence of larger-scale disturbances with 3000–5000-km horizontal wavelengths, and even higher. After the SSW peak and during the stratosphere circulation recovery, the velocity in the JS substantially decreases and an essential reduction in wave-disturbance generation occurs. There are decreases in the average amplitude values (by factors of 1.8–6.7). The strongest amplitude drop was observed for short waves (zonal wavelength λU = 300 km). The maximum attenuation for all wavelengths was observed for the strongest 2008/2009 winter SSW. For the analyzed events, such attenuation was observed for up to about a month after the SSW peak. Thus, JS disruption during major SSWs leads to deactivating the source for generating small-scale wave disturbances in the stratosphere. This may affect disturbances in higher atmospheric layers. The results obtained are the experimental evidence that JS itself is the primary source for the generation of IGWs in the stratosphere–lower mesosphere.

Modelling soil organic carbon stock distribution across different land-uses in South Africa: A remote sensing and deep learning approach

Soil organic carbon (SOC) is a critical measure for ecosystem health and offers opportunities to understand carbon fluxes and associated implications. However, SOC can be significantly influenced by anthropogenic land use change, with intensive and extensive disturbances resulting in considerable SOC loss. Consequently, understanding the spatial distribution of SOC across different land uses, particularly at national level characterised by different biomes, is vital for integrated land-use planning and climate change mitigation. Remote sensing and deep learning (DL) offer a reliable largescale mapping of SOC by leveraging on their big data provision and powerful analytical prowess, respectively. This study modelled SOC stocks across South Africa’s major land uses using Deep Neural Networks (DNN) and Sentinel-3 satellite data. Based on 1936 soil samples and 31 spectral predictors, results show a relatively high accuracy with an R2 and RMSE value of 0.685 and 10.15 t/h (26% of the mean), respectively. From the seven land uses evaluated, grasslands (31.36%) contributed the most to the overall SOC stocks while urban vegetation (0.04%) contributed the least. Moreover, although SOC stock was found to be relatively proportional to land coverage, commercial (46.06 t/h) and natural (44.34 t/h) forests showed a higher carbon sequestration capacity. These findings provide an important guideline to managing SOC stocks in South Africa, useful in climate change mitigation through sustainable land-use practices. Whereas landscape restoration, and other relevant interventions are encouraged to improve SOC storage, care must be taken within land-use decision making to maintain an appropriate balance between carbon sequestration, biodiversity, and general ecosystem functions.

Merging control strategies of connected and autonomous vehicles at freeway on-ramps: a comprehensive review

Purpose On-ramp merging areas are typical bottlenecks in the freeway network since merging on-ramp vehicles may cause intensive disturbances on the mainline traffic flow and lead to various negative impacts on traffic efficiency and safety. The connected and autonomous vehicles (CAVs), with their capabilities of real-time communication and precise motion control, hold a great potential to facilitate ramp merging operation through enhanced coordination strategies. This paper aims to present a comprehensive review of the existing ramp merging strategies leveraging CAVs, focusing on the latest trends and developments in the research field. Design/methodology/approach The review comprehensively covers 44 papers recently published in leading transportation journals. Based on the application context, control strategies are categorized into three categories: merging into sing-lane freeways with total CAVs, merging into sing-lane freeways with mixed traffic flows and merging into multilane freeways. Findings Relevant literature is reviewed regarding the required technologies, control decision level, applied methods and impacts on traffic performance. More importantly, the authors identify the existing research gaps and provide insightful discussions on the potential and promising directions for future research based on the review, which facilitates further advancement in this research topic. Originality/value Many strategies based on the communication and automation capabilities of CAVs have been developed over the past decades, devoted to facilitating the merging/lane-changing maneuvers at freeway on-ramps. Despite the significant progress made, an up-to-date review covering these latest developments is missing to the authors’ best knowledge. This paper conducts a thorough review of the cooperation/coordination strategies that facilitate freeway on-ramp merging using CAVs, focusing on the latest developments in this field. Based on the review, the authors identify the existing research gaps in CAV ramp merging and discuss the potential and promising future research directions to address the gaps.

Flow-level coordination of connected and autonomous vehicles in multilane freeway ramp merging areas

On-ramp merging areas are deemed to be typical bottlenecks for freeway networks due to the intensive disturbances induced by the frequent merging, weaving, and lane-changing behaviors. The Connected and Autonomous Vehicles (CAVs), benefited from their capabilities of real-time communication and precise motion control, hold an opportunity to promote ramp merging operation through enhanced cooperation. The existing CAV cooperation strategies are mainly designed for single-lane freeways, although multilane configurations are more prevailing in the real-world. In this paper, we present a flow-level CAV coordination strategy to facilitate merging operation in multilane freeways. The coordination integrates lane-change rules between mainstream lanes, proactive creation of large merging gaps, and platooning of ramp vehicles for enhanced benefits in traffic flow stability and efficiency. The strategy is formulated under an optimization framework, where the optimal control plan is determined based on real-time traffic conditions. The impacts of tunable model parameters on the produced control plan are discussed in detail. The efficiency of the proposed multilane strategy is demonstrated in a micro-simulation environment. The results show that the coordination can substantially improve the overall ramp merging efficiency and prevent recurrent traffic congestions, especially under high traffic volume conditions.

Spatiotemporal Variation and Influence Factors of Habitat Quality in Loess Hilly and Gully Area of Yellow River Basin: A Case Study of Liulin County, China

China has set up ecological protection and high-quality development of the Yellow River Basin as its national strategy. However, the fragile natural ecosystem and intensive human disturbances pose challenges to it. This study evaluates habitat quality change and analyzes its drivers in a representative county of this region, aiming to provide scientific basis for ecological protection and sustainable development. We took Liulin, a representative county of middle Yellow River Basin as the study area and evaluated the spatiotemporal variation of habitat quality from 2000 to 2020 with the InVEST model. Further, the influencing factors of habitat quality pattern were explored using GeoDetector, and their gradient ranges dominating the habitat quality change were determined by gradient analysis. The results showed that: (1) Areas of low and medium-low habitat quality grades were distributed interactively in the whole county; medium grade areas were scattered in the northeast and southwest parts of the county; and medium-high and high grades area were distributed sporadically along the Yellow River and its branches. (2) Habitat quality of the county almost unchanged from 2000 to 2010. However, from 2010 to 2020, with the rapid expansion of construction land (increased by 9.62 times), the area proportion of medium, medium-high, and high habitat quality grades decreased from 7.01% to 5.31%, while that of low and medium-low habitat quality grades increased from 92.99% to 94.69%. (3) The habitat quality was influenced by multiple natural-human factors. The main influencing factor was land use, followed by elevation. (4) Most changes of habitat quality occurred in areas with lower elevation, gentler slope, and higher vegetation coverage, which were affected by intensive human activities. These results suggest that in future land use policy making and the construction land expansion in Liulin County should be restricted, and differentiated ecological protection and restoration strategies should be implemented in areas with different habitat quality.

Significance of the local anthropogenic effects in the dynamics of wild geese wintering on the Ramsar Site Lakes by Tata (Wetland City Tata)

Abstract The Old Lake of Tata, an important wild goose roosting site in Central Europe, is unique in its location being in the middle of a city with a population of 24,000. Consequently, the site is subject to intensive human disturbances. Goose migration and wintering on the lake was studied for over 37 years (1984–2021). In addition to weather, hydrological, and feeding conditions, particular attention was focused on human influences (which were deemed generally disruptive, but also beneficial in some cases) that can induce significant changes in the population dynamics of the 30,000–50,000 wild geese from 13 species wintering here. Almost without exception, the largest observed changes in the abundance of wild geese roosting overnight on the Old Lake are due to anthropogenic effects. In the majority of cases, the most significant population changes are due to impacts associated with the operation and upkeep of the lake and the New Year’s Eve fireworks. As a result, the winter operation of the Old Lake has been regulated by the Wild Goose Preference Mode since 2011, and the City of Tata has banned the use of fireworks during the winter period since 2018. Consequently, the conditions for wild goose migration have improved significantly. However, the situation of the Old Lake is still quite fragile and more conservation measures are needed to protect it further.

Analysis of land surface temperature variation based on MODIS data a case study of the agricultural pastural ecotone of northern China

The agricultural pastural ecotone of northern China (APENC), as one of the world’s four agro-pastural ecotones, is a typical fragile ecological zone and sensitive zone responding to global climate change. The thermal environment pattern of APENC has been dramatically changed due to intensive human disturbances, especially the land use/land cover change induced by a series of ecological restoration projects implementation after 1999. Few studies focused on land surface temperature (LST) variation in this region due to the lack of long time series remote sensing data. The spatial, temporal and trend characteristics of LST were quantitatively analyzed at different timescales based on a long-term sequence of MODIS data in APENC (2003–2020). Results showed that (i) the thermal pattern of APENC was dominated by high LST areas and very high LST areas at an annual and seasonal timescale. These regions mainly distributed in Yellow River Basin, southeast boundary and vast plains in the northeast. The high value of absolute variability (AV) mainly occurred in the western of Yinshan-Greater Khingan Mountains and northeast of APENC. Meanwhile, the AV was largest in winter and then decreased from spring to fall. The fluctuation degree of AV was largest in summer while the slightest in fall. (ii) The LST exhibited insignificantly and rapidly warming during 2003–2007 and 2012–2014, respectively. Whereas the significant cooling trend occurred during 2007–2012 and 2014–2020. (iii) The LST showed a warming trend at an annual, spring and winter timescale since the increasing trend in nighttime was faster than the decreasing trend of LST in daytime. The cooling trend occurred in fall and summer because the decreasing range of LST in daytime was greater than the increasing nighttime trend. These results will provide an important regional demonstration for climate change study of arid and semi-arid region and a reference for agricultural and livestock production for APENC.

Four-decades of bed elevation changes in the heavily regulated upper Atchafalaya River, Louisiana, USA

Previous studies have established that under natural conditions, alluvial river confluence zones experience channel scour followed by mid-channel bar development. Less attention is given to bed evolution downstream of large alluvial river confluences under engineered conditions, such as discharge regulation and levee confinement. Here we present four decades of morphologic changes along the 69-km uppermost Atchafalaya River, a downstream distributary of the confluence of the Mississippi River Outflow channel and the Red River. We aim to find the answer to one critical question: how does the channel bed downstream of an engineering-controlled confluence respond to regulated flow? We utilize single-beam bathymetry data collected in 1967, 1977, 1989, 1998, and 2006 to quantify riverbed deformation of the reach after the flow regulation began in 1963. Suspended sediment load and stream power during the four decadal periods are calculated. Results show that between 1967 and 2006, extensive bed degradation occurred and the average bed elevation reduced by 3.8 m. A total volume of 105 ± 26 × 106 m3 sediment was scoured from the uppermost Atchafalaya riverbed over this 40-year period, implying that channel erosion in this river reach has contributed to downstream coarse sediment delivery and associated deltaic growth in the Atchafalaya Bay. Bed aggradation only occurred during 1989–1998 in response to excess sediment input from the Mississippi River, likely attributable to the 1993 long-lasting Mississippi River flood. But the same amount of riverbed deposit eroded in the following eight years, demonstrating how quickly a large regulated river can diminish a perturbation owing to excess sediment input. These findings not only reveal the complexity of morphologic adjustments of a river channel in response to intensive engineering disturbances but also provide useful information for future modeling studies and management plans for the Atchafalaya and other large, engineered alluvial river confluences.

Quiet Ionospheric D-Region (QIonDR) Model Based on VLF/LF Observations

The ionospheric D-region affects propagation of electromagnetic waves including ground-based signals and satellite signals during its intensive disturbances. Consequently, the modeling of electromagnetic propagation in the D-region is important in many technological domains. One of sources of uncertainty in the modeling of the disturbed D-region is the poor knowledge of its parameters in the quiet state at the considered location and time period. We present the Quiet Ionospheric D-Region (QIonDR) model based on data collected in the ionospheric D-region remote sensing by very low/low frequency (VLF/LF) signals and the Long-Wave Propagation Capability (LWPC) numerical model. The QIonDR model provides both Wait’s parameters and the electron density in the D-region area of interest at a given daytime interval. The proposed model consists of two steps. In the first step, Wait’s parameters are modeled during the quiet midday periods as a function of the daily sunspot number, related to the long-term variations during solar cycle, and the seasonal parameter, providing the seasonal variations. In the second step, the output of the first step is used to model Wait’s parameters during the whole daytime. The proposed model is applied to VLF data acquired in Serbia and related to the DHO and ICV signals emitted in Germany and Italy, respectively. As a result, the proposed methodology provides a numerical tool to model the daytime Wait’s parameters over the middle and low latitudes and an analytical expression valid over a part of Europe for midday parameters.