Bacterial community and dissolved organic matter networks in urban river: The role of human influence.

Human activities have significantly altered the biogeochemical cycles of carbon, nitrogen, and sulfur in aquatic ecosystems, leading to ecological problems.This study utilized 16S rRNA gene high-throughput sequencing and excitation-emission matrix parallel factor analysis (EEM-PARAFAC) to evaluate the bacterial community composition and dissolved organic matter structure in the upstream (less impacted) and downstream (severely impacted) sections of the river, with a focus on the interactions between bacterial diversity and dissolved organic matter (DOM) characteristics.Results indicated significant spatial diversity in bacterial communities, with a higher α-diversity upstream compared to the more polluted downstream sections. Environmental parameters, particularly total phosphorus (TP) and dissolved oxygen (DO), were found to significantly influence the distribution and composition of bacterial phyla through redundancy analysis. The pattern of bacterial community assembly has shifted from predominantly deterministic to predominantly stochastic as a result of human activities. The analysis of DOM through EEM-PARAFAC identified three main fluorescent components, reflecting varied sources and interactions with bacterial communities. Upstream, microbial activities predominantly contributed to autochthonous DOM, while downstream, increased inputs of allochthonous DOM from human activities were evident. Furthermore, the study revealed that through the introduction of various organic pollutants and nutrient loads that shift microbial metabolic functions towards increased degradation and transformation of complex organic compounds downstream. Structural equation modeling (SEM) revealed that upstream human activities primarily affected bacterial communities indirectly by altering DOM properties. In contrast, downstream activities had both direct and indirect effects due to higher pollutant loads and more complex environmental conditions. These interactions underline the profound effect of anthropogenic factors on riverine ecosystems and emphasize the importance of managing human impacts to preserve microbial biodiversity and water quality.

Reshaping the spatiotemporal patterns of temporal stability of forage nutrition quality in alpine grasslands of the Qinghai-Tibet Plateau: Spatial homogeneity, overall decline and localized increases.

There is increasing evidence that forage nutrition quality is becoming more unstable over time due to climate change and/or human activities. However, there are limited numbers of studies at the regional scale exploring the spatiotemporal patterns and driving mechanisms of temporal stability of nutrition quality. Therefore, this study quantified the spatiotemporal patterns of temporal stability of forage nutrition quality in alpine grasslands of the Qinghai-Tibet Plateau under the singular or combined influences of climate change and human activities in 2000-2020. Temporal stability of forage nutrition quality displayed obvious spatiotemporal patterns, with human activities altering the impact of climate change on these spatiotemporal patterns. Under combined effects of climate change and human activities, spatial average values of temporal stability of crude protein (CP), ash (Ash), ether extract (EE), water-soluble carbohydrates (WSC), acid detergent fiber (ADF), and neutral detergent fiber (NDF) decreased by 13.54 %, 7.40 %, 9.02 %, 17.78 %, 9.20 %, and 7.28 % across the whole grasslands, respectively. However, 39.43 %, 45.72 %, 42.98 %, 37.82 %, 42.27 %, and 43.50 % areas showed increasing trends for the temporal stability of CP, Ash, EE, WSC, ADF and NDF, respectively. Climate change predominated 46.15 %, 44.46 %, 44.22 %, 47.32 %, 28.68 %, and 45.31 % of the relative change of temporal stability of CP, Ash, EE, WSC, ADF, and NDF, but human activities had higher influence for 53.82 %, 55.53 %, 55.77 %, 52.55 %, 71.30 %, and 54.68 % of grasslands, respectively. Therefore, the spatial patterns of temporal stability of forage nutrition quality were shifting towards homogeneity, with an overall decrease in temporal stability but localized increases in alpine grasslands of the Qinghai-Tibet Plateau. The effects of climate change and human activities on forage nutrition quality were not always synergistic. The trade-off between nutrition quality and its temporal stability did not always exist, but varied with geographic position.

Long-term alterations of nutrient dynamics and phytoplankton communities in Daya Bay, South China Sea.

Dynamics of phytoplankton in coastal waters is a function of nutrient influx and the present study investigated the trend in nutrient dynamics and phytoplankton abundance of Daya Bay (DB), South China Sea, from 1986 to 2020. Dissolved inorganic nitrogen (DIN), Dissolved inorganic phosphate (DIP) and Silicates were measured. DIN concentration exhibited an increasing trend over the last decades, and it was above the threshold for the phytoplankton growth. DIP level showed a significant decreasing trend throughout the studied period, falling below the threshold for phytoplankton growth in the last decade, where harmful algal blooms were dominated by the dinoflagellates. Long-term anthropogenic influences severely change influx of DIN, DIP, and silicates which in turn shape the architecture of phytoplankton communities. Thus, the understanding of the complex interaction between nutrient influx, anthropogenic activities and dynamics of both water quality and biological elements are particularly important to decide criteria to manage coastal ecosystems.

Human-earth system dynamics in China's land use pattern transformation amidst climate fluctuations and human activities.

Amid rapid environmental changes, the interplay between climate change and human activity is reshaping land use, emphasizing the significance of human-earth system dynamics. This study, rooted in human-earth system theory, explores the complex relationships between land use patterns, climate change, and human activities across China from 1996 to 2022. Using a comprehensive analytical framework that combines Geographical Detector (GeoDetector), Random Forest (RF) model, Data Envelopment Analysis (DEA), Spearman's rank correlation, and k-means clustering, we analyzed data from national land surveys, climate records, and nighttime light observations. Our findings indicate a significant, though regionally varied, transformation in land use: arable land decreased by 1.67 %, driven by intense urbanization and policy shifts, particularly in rapidly urbanizing Jiangsu province where arable land diminished by 19.19 %. In contrast, construction land in the northern regions increased by 225.91 million hectares. Climatic influences are apparent, with rising temperatures positively correlating with arable land expansion in the Northeast and Northwest, and urban land in Jiangsu province increasing by 35.51 %. Variations in precipitation patterns were linked to changes in forested areas. This study highlights the dynamic and intricate interactions within the human-earth system, stressing the urgent need for sustainable land management and climate adaptation strategies that improve land use efficiency and resilience. Our research offers a solid foundation for informed policy-making in land management and climate adaptation, advocating a human-earth system science approach to address future environmental and societal challenges.

Human activities exacerbate river network degrading in the Qinhuai River basin.

Rivers are undergoing significant changes under the pressures of natural processes and human activities. However, characterizing and understanding these changes over the long term and from a spatial perspective have proven challenging. This paper presents a novel framework featuring twelve indicators that combine geometric and spatial structures for evaluating changes in river network patterns. Through global principal component analysis, these indicators were integrated into a comprehensive river network pattern index (RNP). Employing Pearson correlation analysis, geographically weighted regression, geographic detector models, and the Shapley Value, the study quantitatively analyzed various stressors' impacts and relative contributions on river network changes from the 1960s to 2015s. The results showed a clear trend of degradation over time, particularly with frequency and density declining by 57 % and 48 %, respectively. The changes across subbasins varied temporally and spatially, with the 1980s emerging as a significant temporal hotspot and six spatial hotspots identified among twenty subbasins. The analysis showed that agriculture was significantly negatively associated with RNP, while the relationship between urbanization and RNP was inverted N-shaped. To address the negative effects of human activities, a shift from uniform management approaches is crucial. In agricultural areas, adopting more intensive farming practices could help mitigate negative impacts on RNP. For highly urbanized regions, city planning should consider the interactions between urbanization and other factors affecting RNP. Overall, incorporating an understanding of RNP's spatial-temporal dynamics and driving factors into spatial planning is critical for creating effective and sustainable management strategies for human-river interactions.

A two-dimensional four-quadrant assessment method to explore the spatiotemporal coupling and coordination relationship of human activities and ecological environment.

Human activities that involve diverse behaviors and feature a variety of participations and collaborations usually lead to varying and dynamic impacts on the ecological environment. Quantitative analysis of the dynamic changes and complex relationships between human activities and the ecological environment (eco-environment) can provide crucial insights for ecological protecting and balance maintaining. We proposed a two-dimensional four-quadrant assessment method based on the dynamic changes in Human Activity Index (HAI) - Environmental Ecological Condition Index (EECI) to analyze the dynamic trends and coupling coordination degree (CCD) between HAI and EECI. This approach was applied in an empirical study of Hainan Province. A comprehensive HAI at a resolution of 1 km × 1 km is established to measure human activities, while an EECI is developed to evaluate ecological environment quality. The eco-environment showed continuous improvement, with the HAI initially rising and then declining. Analysis of coupling coordination revealed a ratio of 6:1 between coordinated development regions and conflict regions, indicating a gradual improvement in overall coupling coordination. The interaction between the HAI and EECI is strengthening, though variations exist across different locations. Using the geodetector method, we identified Net Primary Productivity (NPP), Land use and land cover (LULC), and Particulate Matter (PM) as the primary factors influencing changes in coupling coordination between HAI and EECI. These factors indirectly affect the stability and carrying capacity of the ecological environment. This method facilitates a quantitative examination of the dynamic relationship between HAI and EECI in different regions, offering insights into ecosystem functionality, biodiversity maintenance, and the effect of HAI on the region.

Unveiling the spatiotemporal dynamics and influencing factors of carbon stocks in the yangtze river basin over the past two decades.

Terrestrial ecosystems are critical to the global carbon cycle and climate change mitigation. Over the past two decades, the Yangtze River Basin (YRB) has implemented various ecological restoration projects and active management measures, significantly impacting carbon stock patterns. This study employed random forest models to analyze the spatial and temporal patterns of carbon stocks in the YRB from 2001 to 2021. In 2021, carbon density in the YRB ranged from 8.5 to 177.4 MgC/ha, with a total carbon stock of 18.05 PgC. Over 20 years, the YRB sequestered 1.26 billion tons of carbon, accounting for 11.28 % of the region's fossil fuel carbon emissions. Notably, forests exhibited the highest carbon density, averaging 98.01 ± 25.01 MgC/ha (2021) with a carbon stock growth rate of 51.6 TgC/yr. Piecewise structural equation model was used to assess the effects of climate and human activities on carbon density, revealing regional variability, with unique patterns observed in the source region. Human activities primarily influence carbon density indirectly through vegetation alterations., while climate change directly impacts ecosystem biophysical processes. These findings offer critical insights for climate mitigation and adaptation strategies, enhancing the understanding of carbon dynamics for sustainable development and global carbon management.

Record of microplastic deposition revealed by ornithogenic soil and sediment profiles from Ross Island, Antarctica.

Microplastics (MPs) are a global concern as an emerging pollutant, and the investigation on MPs in Antarctic aids in informing their global pollution assessments. Therefore, there are urgent scientific concerns regarding the environmental behavior, origins, influencing factors, and potential hazards of MPs in Antarctica. This study presents the characteristics of MPs from one ornithogenic sediment profile (coded CC) and two ornithogenic soil profiles (coded MR1 and MR2) from ice-free areas on Ross Island, Antarctica. We explored the potential sources of MPs and the main influencing factors for deposition based on their distribution with depth in the profiles. Through laser-infrared imaging spectroscopy (LDIR), a total of 30 polymer types were identified in all samples, with polyethylene terephthalate (PET) and polyvinyl chloride (PVC) as the dominant types, accounting for more than 70% of the total. The abundance of MPs in the CC sediment profile ranged from 2.83 to 394.18 items/g, while in MR1 and MR2 soil profiles, the abundance ranged from 2.25 to 1690.11 and 8.24 to 168.27 items/g, respectively. The size of MPs was mainly concentrated in the range of 20-50 µm, and possible downward movement of certain polymer types was revealed. From the perspective of temporal variation, we suggest that MPs were heavily influenced by local human activities including scientific research, fishing, and tourism, balanced by protective regulations, while no solid evidence was obtained to support strong influence from biological transport through penguins. This research enhances our understanding on the environmental behavior of MPs in the terrestrial systems of remote polar regions.

Fiddler crabs (Tubuca arcuata) as bioindicators of microplastic pollution in mangrove sediments.

In recent years, microplastics (MPs) have been widely found in the environment and pose potential risks to ecosystems, which attracted people's attention. Using bioindicators has been a great approach to understanding the pollution levels, bioavailability, and ecological risks of pollutants. However, only few studies have investigated MPs in mangrove ecosystems, with few bioindicators of MPs. Herein, the distribution of MPs in mangrove sediments and fiddler crabs (Tubuca arcuata) in mangroves was investigated. Results showed that the abundance values of MPs are 1160‒12,120 items/kg and 11-100 items/ind. in mangrove sediments and fiddler crabs, respectively. The dominant shape of MPs detected in mangrove sediments and fiddler crabs was fragments with sizes of 20‒1000 µm, larger MPs of 50-1000 µm were found in abundance. Polypropylene (PP), which is one of the most commonly used plastic materials, was the main polymer type. The distribution of MPs in fiddler crabs closely resembled that in surface mangrove sediments with a strong linear correlation (R2 > 0.8 and p < 0.05) between their abundance. Therefore, the MP contamination level in mangrove sediments can be determined by studying MP pollution in fiddler crabs. Moreover, the results of the target group index (TGI) indicated that fiddler crabs prefer feeding specific MPs in mangrove sediments. Our findings demonstrate the suitability of fiddler crabs as bioindicators for assessing MP pollution in mangrove sediments.

[Changes in Soil Organic Carbon Density and Its Response to Climate Change and Human Activities Before and After the Grain for Green Project on the Loess Plateau].

Accurately assessing the changes in soil organic carbon storage （SOCS） before and after the Grain for Green Project （GFG） in the Loess Plateau （LP） and exploring the relationship between its spatial and temporal distribution and the influencing factors were important references for the development of regional recycling as well as the formulation of ecological protection policies. Based on the data of climate, human activities, and SOCD in the surface （0-20 cm） and deep （0-100 cm） soil before and after GFG in the LP from 2001 to 2020, we investigated the changes in SOCD at different spatial and temporal scales by using the methods of trend analysis, the kriging method, and variance partitioning analysis. The results showed that： ① Before and after the GFG, the surface SOCS of the whole region increased by 8 338.7×104 t； the deep SOCS increased by 1 160.02×104 t. ② In each bioclimatic subregion, the whole-region average SOCD of Ⅰ （Semi-Humid Forest Region）, Ⅱ （Semi-Humid Semi-Arid Forest and Grassland Region）, and Ⅲ （Semi-Arid Typical Grassland Region） showed a significant increasing trend, with a decreasing trend in Ⅳ （arid semi-arid desert grassland area） and Ⅴ （arid desert area）. ③ The average surface SOCS increase in different ecosystems was ranked as follows： cropland > grassland > woodland > shrubs > bare land and sparse vegetation. The deep soil increase was ranked as follows： grassland > cropland > woodland > shrubs > bare land and sparse vegetation. ④ Climate factors were the most important driving factors for changes in SOCD； the annual average temperature and precipitation were significantly positively correlated with changes in SOCD. The results of the study could provide data support for regional ecological management and land use policy formulation to promote high quality development of the ecological environment in the LP.

[Spatiotemporal Variation Characteristics and Driving Factors of Vegetation NPP in the Ulansuhai Nur Basin from 2001 to 2020].

Vegetation net primary productivity （NPP） represents the ability of plants to fix ecosystem carbon, which is a key indicator to determine the health status and sustainable development of ecosystems. Its spatial and temporal changes and driving factors play an important role in revealing the status of vegetation restoration and guiding ecological restoration. Based on MODIS17A3 NPP data, land use, and meteorological data from 2001 to 2020, the temporal and spatial variation characteristics and driving factors of vegetation NPP in the Ulansuhai Nur Basin of Inner Mongolia were explored by using the methods of coefficient of variation, Theil-Sen Median trend analysis, Mann-Kendall significance test, Hurst index, and Geodetector. The results showed that： ① From 2001 to 2020, the vegetation NPP in the Ulansuhai Nur Basin showed a fluctuating upward trend, with an average value （in terms of C） of 141.03 g·ï¼ˆm2·a）-1 and an average increase rate of 2.33 g·ï¼ˆm2·a）-1. The vegetation NPP had obvious spatial differentiation, which was characterized by high in the southwest and low in the northeast and high in Hetao Plain and low in sandy land and mountainous areas. ② NPP mainly showed an increasing trend, and the area proportions of increasing, decreasing, and unchanged areas were approximately 80%, 3%, and 17%, respectively. The average coefficient of variation of vegetation NPP was 0.149, which mainly showed low fluctuation change, and the area accounted for approximately 51%. The future change trend of NPP was mainly characterized by anti-persistence, with an area ratio of approximately 75%. ③ Land use, altitude, maximum temperature, and slope were the dominant driving factors of variation NPP change in the Ulansuhai Nur Basin, and the q values were all above 0.200. The interaction between altitude and relative humidity had the greatest explanatory power for the spatial differentiation of vegetation NPP in the Ulansuhai Nur Basin. There were significant differences in the explanatory power of land use and all factors except nighttime light to the spatial differentiation of vegetation NPP in the Ulansuhai Nur Basin. According to the research results, in the future, we should strengthen the ecosystem management of the Ulansuhai Nur Basin； continue to implement strict ecological protection and restoration policies； and comprehensively consider factors such as climate, topography, and human activities to carry out comprehensive ecological management according to local conditions to improve the quality of ecosystem services.

Vulnerability and driving mechanism of four typical grasslands in China under the coupled impacts of climate change and human activities.

Understanding of how different grasslands types respond to climate change and human activities across different spatial and temporal dimensions is crucial for devising effective strategies to prevent grasslands degradation. In this study, we developed a novel vulnerability assessment model for grasslands that intricately evaluates the combined impact of climate change and human activities. We then applied this model to analyze the vulnerability and driving mechanism of four representative Chinese grasslands to climate change and human activities. Our findings indicate that the vulnerability of the four grasslands would show a pattern of higher in the west and lower in the east under the influence of climate change alone. However, when human activities are factored in, the vulnerability across the four grasslands tends to homogenize, with human activities notably reducing the vulnerability of alpine grasslands in the west and, conversely, increasing the vulnerability of grasslands in the east. Furthermore, our study reveals distinct major environmental drivers of grasslands vulnerability across different regions. The two western alpine grasslands exhibit higher vulnerability to annual mean temperature and isothermality compared to the eastern temperate grasslands, while their vulnerability to precipitation of the coldest quarter is lower than that of the eastern temperate grasslands. These findings are helpful for understanding the multifaceted causes and mechanisms of grasslands degradation, providing a scientific foundation for the sustainable management and conservation of grassland resources.

Exploring the evolution of ecosystem health and sustainable zoning: A perspective based on the contributions of climate change and human activities.

Maintaining ecosystem health (EH) in watersheds is crucial for building a national pattern of ecological security. However, a comprehensive diagnosis of watershed EH and an exploration of its driving mechanisms are still lacking. This study proposed an EH assessment model from a vitality-organization-resilience-service-environment (VORSE) perspective. Taking the Yellow River Basin of Shaanxi Province (YRBS), China, as a research object, the spatiotemporal evolution trend of EH from 2000 to 2020 was quantified. At the same time, we also quantified the respective contributions of climate change (CC) and human activities (HA) to the EH dynamics based on residual analysis. The results showed that EH in the YRBS increased by 11.80 % from 2000 to 2020, and the spatial distribution of the EH was higher in the southern region than in the northern part. At the pixel scale, areas with improving trends accounted for 90.57 % of the YRBS, while 9.43 % deteriorated, with the improving areas mainly in northern Shaanxi and the deteriorating areas in the Guanzhong region. The correlation between the EH and precipitation was primarily positive, while the correlation between the EH and temperature was mainly negative. The residual analysis showed that the contribution rate of CC to EH changes was 78.54 %, while that of HA was 21.46 %, indicating that CC was the dominant driver of EH changes in the YRBS. Specifically, 82.64 % of the improvement in EH was attributed to CC and 17.36 % to HA. Conversely, 65.30 % of the deterioration in EH was attributed to CC and 34.70 % to HA. Furthermore, CC, HA, and CC&HA dominated EH changes in 26.85 %, 3.77 %, and 69.38 % of the YRBS area, respectively. In addition, the Hurst exponent analysis identified six types of future EH development scenarios, each requiring different restoration strategies. This study provides valuable insights for future EH diagnosis, EH restoration efforts, and the formulation of sustainable development goals in other watersheds.

Enhanced human activities since 20th century in pearl river delta, southern China: Evidence from high-resolution sedimentary records of polycyclic aromatic hydrocarbons and synthetic musks.

To understand the environmental impact of anthropogenic activities, the high-resolution temporal and compositional variations of polycyclic aromatic hydrocarbons (PAHs), oxygenated PAHs, and synthetic musks, related to human activities were investigated in a sediment core taken from the Pearl River Estuary, southern China. The temporal trend of the target compounds was evidence of the considerable impact of anthropogenic activities in the Pearl River Delta. Two significant increases of the target compounds levels in the sediment core were aligned with two nodes of key periods of economic development in China, namely, the foundation of People's Republic of China (1950s) and China's accession to the World Trade Organization (2000s). Subsequently, the significant decline of the target compounds in sediments from the 2010s indicated the successful regulation of pollutant discharges and pollution control measures. The increase in the contribution of higher molecular weight PAHs suggested a potential transition from agricultural activities to industrial activities.

Effects of environment and human activities on rice planting suitability based on MaxEnt model.

Rice is one of the major food crops, and the study of suitable planting areas for rice plays an important role in improving rice yield and optimizing the production layout. This study used Maximum Entropy (MaxEnt) model to simulate and predict the distribution of suitable rice planting areas in China from 1981 to 2020 by combining the climate, soil, and human activities, analyzed the spatial and temporal changes of suitable rice planting areas in China, and determined the main factors affecting rice planting suitability. The results indicated that the main factors influencing the distribution of suitable planting areas for rice in China were gross domestic product (GDP), population density (Pop), and annual sunshine duration (Sun), with human activities playing a dominant role. The high suitable planting areas of rice were mainly distributed in Hubei, Hunan, Jiangxi, Anhui, Guangdong, southeastern Sichuan and western Guizhou. The total suitable planting areas for rice were 346.00 × 104 km2, 345.66 × 104 km2, 347.01 × 104 km2, and 355.57 × 104 km2 from 1981 to 1990, 1991 to 2000, 2001 to 2010 and 2011 to 2020, respectively. With the passage of time, the area of unsuitable areas for rice gradually decreased, and the area of medium suitable areas increased, with large changes in the area of high- and low-suitable areas. Moreover, due to the transfer of a large number of rural laborers to the cities in recent years, the tension between people and land caused by the population explosion has led to the increasing impact of Pop on rice suitable areas and the relatively weakening of the impact of GDP on rice production interventions. The results can be used to provide scientific evidence for the management of rice cultivation and food production safety, with a view to reducing the impacts of climate change on agricultural production in the context of global climate change.

Global distribution pattern of soil phosphorus-cycling microbes under the influence of human activities.

Human activities have profoundly altered the Earth's phosphorus (P) cycling process and its associated microbial communities, yet their global distribution pattern and response to human influences remain unclear. Here, we estimated the abundances of P-cycling genes from 3321 global soil metagenomic samples and mapped the global distribution of five key P-cycling processes, that is, organic phosphoester hydrolysis, inorganic phosphorus solubilization, two-component system, phosphotransferase system, and transporters. Structural equation modeling and random forest analysis were employed to assess the impact of anthropogenic and environmental factors on the abundance of P-cycling genes. Our findings suggest that although less significant than the climate and soil profile, human-related factors, such as economic activities and population, are important drivers for the variations in P-cycling gene abundance. Notably, the gene abundances were increased parallel to the extent of human intervention, but generally at low and moderate levels of human activities. Furthermore, we identified critical genera, such as Pseudomonas and Lysobacter, which were sensitive to the changes in human activities. This study provides insights into the responses of P-cycling microbes to human activities at a global scale, enhancing our understanding of soil microbial P cycling and underscoring the importance of sustainable human activities in the Earth's biogeochemical cycle.

Long-term trends in human-induced water storage changes for China detected from GRACE data.

Terrestrial Water Storage (TWS) plays a pivotal role in water resource management by providing a comprehensive measure of both surface water and groundwater availability. This study investigates changes in TWS driven by human activities from 2003 to 2023, and forecasts future TWS trends under various climate change and development scenarios. Our findings reveal a continuous decline in China's TWS since 2003, with an average annual decrease of approximately 1.36 mm. This reduction is primarily attributed to the combined effects of climate change and human activities, including irrigation, industrial water use, and domestic water consumption. Notably, TWS exhibits significant seasonal and annual fluctuations, with variations ranging ±10 mm. For the future period (2024-2030), we project greater disparities between water resource supply and demand in specific years for the Songliao, Southwest, and Yangtze basins. Consequently, future water resource management must prioritize water conservation during wet seasons, particularly in years when supply-demand conflicts for limited water resources intensify. This study is valuable for effective planning and sustainable utilization of water resources.

Assessing the possible influence of human activities on sediment transport in the Saskatchewan River and its delta.

Sediment transport is a complex, multi-dimensional process. With the advancement in computing power and sophistication of computer applications over recent decades, it has become possible to conduct detailed analysis and simulations of soil erosion and sediment transport. The primary objective of this study was to examine and predict the potential influence of human activities on sediment transport. This was achieved by analyzing sediment transport in the Saskatchewan River beneath the E.B. Campbell Dam and in the Saskatchewan River Delta. The Hydrologic Engineering Center's-River Analysis System (HEC-RAS) was deployed to ascertain the sediment transport capacity and estimate erosion, sedimentation, and riverbed changes. Cross-sectional data, flow data, and sediment data were used in conjunction with HEC-RAS. The simulation results reveal that sediment transport below the E.B. Campbell Dam is limited, leading to notable sediment erosion. The selected study area has witnessed significant erosion during high-flow periods, particularly in the event of floods. Between 2012 and 2019, the riverbed elevation at the selected survey site decreased by approximately 0.45 m. The study findings corroborate that the Saskatchewan River and its delta have been impacted by human activities. Potential erosion and deposition below the E.B. Campbell Dam have been simulated for the selected site. The aim is to provide decision-makers or related stakeholders with insight into how dam operations can be adjusted to decrease erosion while sustaining hydrological, ecological, and environmental outcomes from human activities.

Facilitating giant panda crossings of national highway in Wolong area of Giant Panda National Park amid human activities.

As human activities continue to expand, wildlife persistence faces escalating threats from roads. In Wolong area of Giant Panda National Park, the local giant pandas (Ailuropoda melanoleuca) are divided into two population groups along the National Highway G350 (NHG). Therefore, selecting suitable areas to help those giant pandas communicate across the NHG is necessary. In this research, we evaluated the presence of human activities and simulated their absence to analyze how they affect the giant panda's habitat in Wolong. Subsequently, based on the kernel density estimation (KDE) for giant pandas and the main human distribution locations, we selected suitable areas for the population link between the two road sections on the NHG. We simulated the absence of human activities on the two road sections to compare changes in the habitat suitability index (HSI) and connectivity value (CV) relative to their presence. We aimed to carefully select the area for future giant panda corridor plans and simulate whether eliminating human activities will significantly improve the HSI and CV of the area. Our results show that: (1) Human activities presence has led to subtle changes in the landscape pattern of suitable habitats and a decrease in Wolong by 78.76 km2 compared to their absence. (2) Human activities presence significantly reduced HSI and CV in the 1000 m buffer along the NHG compared to their absence. (3) The HSI and CV of the 1000 m buffer in the simulated absence of human activities for the two road sections were significantly higher than their presence. This research identified the optimal road section for crossing the NHG to link giant panda population groups and habitats in Wolong. These insights are significant for formulating conservation decisions and corridor plans and for promoting wildlife conservation in reserves amid high levels of human activity.