Grassland Areas Research Articles

Ecosystem health assessment of the largest lake wetland in the Yellow River basin using an improved vigor-organization-resilience-services model

Wuliangsu Lake is the largest lake wetland in the Yellow River basin, it is the Northern Sand Belt of China, which is essential to maintaining ecological security in northern China and the areas downstream. With the increasing environmental problems, the basin has become a sensitive and complex geographical unit, and a better understanding of the level of ecosystem health in the basin is helpful for policymakers in developing measures for ecological restoration and eco-space management. In this study, we proposed an improved VORS model containing ecosystem vigor, organization, resilience and services to assess the ecosystem health in the Wuliangsu Lake Basin in 2000, 2011, and 2022. To improve spatial precision, the study area was partitioned into grids measuring 2 km × 2 km each. The results indicated that: (1) the ecosystem health showed a slight increase trend, which indicated by the increase level grids reached 94 % in 2000–2022 change. (2) The reduction in vegetation cover decreased the ecosystem vigor, which was indicated by the weak level increased from 22 % in 2000 to 73 % in 2022. Ecosystem structure becomes more complex enhanced the ecosystem organization, the value increased from 0.3 to 0.6 in 2000 to 0.6–0.8 in 2022. Ecosystem resilience slightly declined in 2011 and 2022, ecosystem services were relatively stable but were dominated by weak levels. (3) The majority land use type in the study area is farmland, and the ecosystem vigor decreases as the area of grassland decreases to farmland in these 22 years. The ecosystem’s structure was enhanced and the land use structure was progressively brought into balance. Changes in all four parameters of ecosystem health assessment are related to land use, and changes in ecosystem health are likewise related to land use changes. The improved VORS model constructed for the Wuliangsu Lake Basin objectively reflect the basin’s state of ecosystem health, and provide a reference for ecological restoration and basin regional planning.

Landscape patterns drive provision of nature's contributions to people by mobile species

Abstract Predicting how nature's contributions to people (NCP) vary spatially remains a challenge. For NCP provided by mobile species, it is unclear how predictions need to account for the influence of multiple habitat types that act as sources, sinks and potential distractors of the NCP‐providing species. Existing approaches that do not account for these effects may inaccurately predict outcomes in real landscapes. To move beyond these limitations, we transfer quantitative inference approaches from movement ecology to explore how spatial habitat patterns determine the negative NCP of the invasive common brushtail possum Trichosurus vulpecula in New Zealand. We used a Bayesian model to investigate how the size of, and distance from, grassland and indigenous and exotic forest patches together contribute to relative possum density (measured by capture probability across a trapping network) in a heterogeneous 11,000‐ha landscape. We found that indigenous and exotic forest area were the most important factors in determining possum density. Although capture probability declined with increasing grassland area, the addition of grassland did not improve the relative model fit above one with indigenous forest as the only habitat. We expected differences in predicted possum density at habitat boundaries, for example, due to preferential foraging at edges. We found that indigenous and exotic forests contributed to capture probability interactively, such that capture probability at the between‐habitat edge was lower than expected, given the habitat area. We also found that models allowing for non‐linear habitat effects of exotic forests or grasslands, but not indigenous forests, were significantly better at predicting possum density than simpler models. Synthesis and applications. Our novel approach for spatial prediction can be applied to any of nature's contributions to people (NCP), and extended to identify trade‐offs and synergies among multiple NCP. For example, the negative NCP of possum density trades off with multiple known positive NCP from indigenous forests, including culturally significant non‐material NCP, and material NCP produced by exotic forests. We recommend that landscape management plans to maximise these positive NCP in future scenarios also consider how the risk of possum density may dampen net NCP provision. To minimise this negative NCP, our results support trap deployment in both indigenous and exotic forest.

Stronger influences of grassland growth than grassland area on hydrological processes in the source region of the Yellow River

Concerns about regional hydrological responses to land use cover changes have arisen worldwide. However, the separation and quantification of the effects of changes in vegetation area and growth status on hydrological processes remains unclear. Here, we applied a distributed hydrology soil vegetation model (DHSVM) to analyze how the grassland growth state and surface area influence hydrological processes in the source region of the Yellow River (SRYR). The results showed that although the grassland surface area decreased slightly from 1981 to 2020, grassland growth (represented by the leaf area index) tended to increase from 2000. Grassland changes (including area and growth status) increased soil moisture storage and evapotranspiration to an overall extent of 2.03 % and 5.66 %, respectively; and most of the increase occurred after 2000 by 2.90 % and 9.40 %, respectively. These processes under grassland change led to an overall decrease in runoff of 2.41 %, with a much stronger decrease after 2000 of 4.3 %. Changes in grassland growth accounted for ∼95 % of the runoff variations caused by grassland changes in the SRYR during the 40-year study period, compared to changes in grassland surface area. Simulations assuming different extents of grassland degradation suggest that such degradation can reduce evapotranspiration and soil moisture storage, thereby increasing runoff, whereas grassland restoration has the opposite effect. Our results highlighted the sensitivity of hydrological processes in the SRYR to grassland growth and the need for appropriate interventions to maintain and restore grasslands.

Enhancing ecological connectivity in the Qilian Mountains: Integrating GCA and optimized MST models for ecological corridor construction

Amidst global climate change and increased anthropogenic activities, the Qilian Mountains face critical ecological and environmental challenges, including vegetation degradation and declining carbon stocks. Therefore, effective mitigation strategies are critical to building China’s ecological security and enhancing carbon storage. This study constructed and optimized an ecological corridor in the Qilian Mountains using models, such as minimum spanning tree and carbon stock calculation. It combined geographic meta cellular automata and other methods to model ecological recovery in the Qilian Mountains following corridor construction and investigated the areas of particular concern. The results show that: (1) the distribution of the 118 extracted ecological source sites (2020) exhibited a pattern of “dense in the east and sparse in the west.” Compared with the results of the 2010 extraction, the source site area had shrunk by 0.87 % and number of sites had increased by 45.68 %. This implies that the shrinkage and fragmentation of source sites are still increasing, underscoring the urgent need for ecological corridors. (2) Compared to the pre-optimization period, the network node connectivity of the corridor network formed by the optimized 114 primary corridors and 131 secondary corridors has increased by 110 % and the network connectivity has increased by 112 %, which enhances the connectivity of the corridors. (3) From 2000 to 2020, the carbon stock in the Qilian Mountains decreased and then increased; with the construction of a corridor mountain range, the carbon stock can be further increased by 1.4748 million tons. Additionally, the Geographic Cellular Automata (GCA) model simulated that in 2030, the area of forest land in the Qilian Mountains, area of grassland, and carbon stock will increase by 71.75 km2, 313.87 km2, and 6.663 million tons, respectively. These results confirm that ecological protection and corridor construction promote ecological restoration and enhance carbon stocks in the Qilian Mountains, providing a scientific basis for future ecological projects and carbon stock analysis in the region.

Calculation process and spatial heterogeneity characteristic of non-point source pollution caused by rainfall-runoff in Taizhou City

ABSTRACT With improved point source pollution management, the impacts of non-point source pollution on the ecosystem are increasingly evident. However, conventional techniques like output coefficient approaches fail to adequately capture its geographical and temporal variability. This study proposed a grid-based calculation technique to quantify non-point source pollution from rainfall-runoff in the Jinqing Watershed, Taizhou City, Zhejiang Province, based on the principles of the Soil Conservation Service-Curve Number (SCS-CN) model. The modified SCS-CN model effectively represented both temporal and geographical variations in rainfall-runoff pollution. Precipitation emerged as the primary determinant of non-point source pollutant load over time due to its strong positive association with rainfall. From January to April, there was a constant pollutant load; besides irregular rainfall patterns, land use types also influenced pollutant loads at a geographical scale. Building and cultivated areas exhibited positive correlations with nitrogen (r = 0.44, P = 0.05) and phosphorus (r = 0.54, P = 0.05), while forested and grassland areas showed negative correlations with nitrogen (r = −0.44, P = 0.05) and phosphorus pollutants (r = −044, P = 0.05). Pollution loads were also influenced by landscape patterns; concentrated dominant land use types resulted in higher contamination levels compared with scattered dominant land use types.

Extraction of grassland irrigation information in arid regions based on multi-source remote sensing data

Irrigation is a vital measure for maintaining grassland productivity in arid and semi-arid regions. Grasslands typically have characteristics such as unclear boundaries, complex vegetation types, and relatively small irrigation amounts, making it challenging to extract irrigation information. Currently, research on extracting grassland irrigation information is scarce. This study proposes a method for extracting grassland irrigation information using high spatiotemporal resolution (30 m, 1 day) downscaled surface soil moisture data, combined with Landsat 8/9 and Sentinel 1/2 data. This method was applied to extract the irrigation area, timing, and frequency of grasslands in the Delingha Piedmont, northwestern China. The results showed that the overall classification accuracy of irrigated grassland was 93.43 %, and the kappa coefficient was 0.91, indicating high extraction accuracy. The average values of recall, precision, and F-score for irrigation timing and frequency were 82.54 %, 72.25 %, and 77.03 %, respectively, with most irrigation events accurately identified, indicating commendable overall efficacy. The combined use of multi-source remote sensing data is crucial for the extraction of grassland irrigation information. Among these, The high spatiotemporal resolution downscaled surface soil moisture data, by providing detailed spatiotemporal surface soil moisture dynamics, demonstrate a potent capacity for capturing irrigation events, thus effectively enhancing the accuracy of grassland irrigation data extraction.

Natural Foraging Selection and Gut Microecology of Two Subterranean Rodents from the Eurasian Steppe in China.

As the most abundant group of mammals, rodents possess a very rich ecotype, which makes them ideal for studying the relationship between diet and host gut microecology. Zokors are specialized herbivorous rodents adapted to living underground. Unlike more generalized herbivorous rodents, they feed on the underground parts of grassland plants. There are two species of the genus Myospalax in the Eurasian steppes in China: one is Myospalax psilurus, which inhabits meadow grasslands and forest edge areas, and the other is M. aspalax, which inhabits typical grassland areas. How are the dietary choices of the two species adapted to long-term subterranean life, and what is the relationship of this diet with gut microbes? Are there unique indicator genera for their gut microbial communities? Relevant factors, such as the ability of both species to degrade cellulose, are not yet clear. In this study, we analyzed the gut bacterial communities and diet compositions of two species of zokors using 16S amplicon technology combined with macro-barcoding technology. We found that the diversity of gut microbial bacterial communities in M. psilurus was significantly higher than that in M. aspalax, and that the two species of zokors possessed different gut bacterial indicator genera. Differences in the feeding habits of the two species of zokors stem from food composition rather than diversity. Based on the results of Mantel analyses, the gut bacterial community of M. aspalax showed a significant positive correlation with the creeping-rooted type food, and there was a complementary relationship between the axis root-type-food- and the rhizome-type-food-dominated (containing bulb types and tuberous root types) food groups. Functional prediction based on KEGG found that M. psilurus possessed a stronger degradation ability in the same cellulose degradation pathway. Neutral modeling results show that the gut flora of the M. psilurus has a wider ecological niche compared to that of the M. aspalax. This provides a new perspective for understanding how rodents living underground in grassland areas respond to changes in food conditions.

Identifying factors influencing reservoir eutrophication using interpretable machine learning combined with shoreline morphology and landscape hydrological features: A case study of Danjiangkou Reservoir, China

Reservoir nearshore areas are influenced by both terrestrial and aquatic ecosystems, making them sensitive regions to water quality changes. The analysis of basin landscape hydrological features provides limited insight into the spatial heterogeneity of eutrophication in these areas. The complex characteristics of shoreline morphology and their impact on eutrophication are often overlooked. To comprehensively analyze the complex relationships between shoreline morphology and landscape hydrological features, with eutrophication, this study uses Danjiangkou Reservoir as a case study. Utilizing Landsat 8 OLI remote sensing data from 2013 to 2022, combined with a semi-analytical approach, the spatial distribution of the Trophic State Index (TSI) during flood discharge periods (FDPs) and water storage periods (WSPs) was obtained. Using Extreme Gradient Boosting (XGBoost) and SHapley Additive exPlanations (SHAP), explained the relationships between landscape composition, landscape configuration, hydrological topography, shoreline morphology, and TSI, identified key factors at different spatial scales and validated their reliability. The results showed that: (1) There is significant spatial heterogeneity in the TSI distribution of Danjiangkou Reservoir. The eutrophication levels are significant in the shoreline and bay areas, with a tendency to extend inward only during the WSPs. (2) The importance of landscape composition, landscape configuration, hydrological topography, and shoreline morphology to TSI variations during the FDPs are 25.12 %, 29.6 %, 23.09 %, and 22.19 % respectively. Besides shoreline distance, the Landscape Shape Index (LSI) and Hypsometric Integral (HI) are the two most significant environmental variables overall during the FDPs. Forest and grassland areas become the most influential factors during the WSPs. The influence of landscape patterns and hydrological topography on TSI varies at different spatial scales. At the 200 m riparian buffer zone, the increase in cropland and impervious areas significantly elevates eutrophication levels. (3) Morphology complexity, shows a noticeable threshold effect on TSI, with complex shoreline morphology increasing the risk of eutrophication.

Prediction of Land Use and Habitat Quality in Harbin City Based on the PLUS- InVEST Model

Analyzing the spatiotemporal evolution of urban land use and habitat quality can reveal the correlation between land use and habitat quality, aiding in rational urban land policies and high-quality ecological environment development. This study was based on land use transition matrices and an Intensity-Migration （IM） model to analyze the changes in land use in Harbin from 2000 to 2020. It combined the PLUS model to explore the driving factors of land use expansion for various land types and predicted land use scenarios for 2030 under natural development, ecological protection, farmland protection, and urban development scenarios. Finally, the InVEST model was used to complete the habitat quality analysis. The results indicated： ① The dominant land use types in Harbin were cropland, forest land, and grassland. From 2000 to 2020, there was a significant tendency of conversion into grassland, cropland, forest land, and artificial surfaces, with noticeable changes in land use intensity. Water bodies, bare land, and wetland types showed less conversion and tended to be restrictive. ② Elevation was the primary factor influencing the expansion of grassland, cropland, forest land, bare land, wetland, and water bodies. Socioeconomic factors were the main factor affecting the expansion of artificial surfaces. ③ Simulation of land use types in Harbin for 2030 under the four scenarios showed an increase in forest land area and a decrease in grassland area, with insignificant changes in wetland, water bodies, and bare land areas. Except for in the ecological protection scenario, the area of artificial surfaces increased, whereas cropland decreased. ④ Overall, habitat quality in Harbin improved from 2000 to 2020. ⑤ In 2030, the spatial pattern of habitat quality in Harbin remained consistent across all scenarios, showing an overall improvement in habitat quality. Under the ecological protection scenario, areas with low and medium habitat quality decreased, whereas areas with higher habitat quality increased, indicating a relatively significant improvement in habitat quality. The research results provide a scientific basis and insights for the development of ecological civilization and urban planning and construction in Harbin.

Spatio-temporal Pattern of Ecosystem Service Value Evolution in the Yihe River Basin in the Context of Land Use Change

In this study, the modified equivalent factor method was applied to account for the long time series ecosystem service value （ESV） of the Yihe River Basin from 1975 to 2020 in the context of land use change, and the cold hot spot analysis and topographic position analysis methods were introduced to explore the characteristics of its spatial pattern. The results showed that： ① From 1975 to 2020, the land use type of the Yihe River Basin was dominated by arable land, and the land use changes were characterized by the rapid decrease of arable land and the continuous expansion of construction land, a slight increase in the area of forest land and grassland, a contraction of the water body area, and little change in the area of unused land. ② The modified equivalent factor method was more suitable for accounting for the ESV in the basin. From 1975 to 2020, the overall ESV of the basin showed an upward spiral trend （33.369-33.816 billion CNY）, dominated by the regulating services. The ESV of arable land was the highest with a decreasing trend, whereas the ESV of unused land was the lowest. ③ In the horizontal spatial pattern, the hot spot of ESV was near mountains and reservoirs, and the cold spot of ESV was near urban areas. In terms of vertical spatial patterns, with growing topographic gradient, vertical changes in ESV for all land use types showed an increasing trend followed by a decreasing trend. The results of the study revealed the spatial and temporal patterns of ecosystem service values in the Yihe River Basin in the context of land use change and provide a scientific basis for optimizing the land use structure and spatial pattern and enhancing ecosystem services.

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.

Evolution of riparian vegetation in response to anthropogenic effects: The Taleqan River, Iran

AbstractDuring the last decades, human interventions, such as dam construction and land‐use change, have caused changes in geomorphic patterns and riparian zones in many rivers in Iran. This study aimed to assess the spatio‐temporal evolution of riparian vegetation and the spatial area of biogeomorphic feedback windows (BFWs) located in the riparian Salicaceae vegetation patches and their traits responding to human interventions in the Taleqan River during 1990–2022. The river was divided into five reaches using the geomorphic unit system (GUS) method, and the river sensitivity index (SI), location of BFWs, vegetation typology and main cover typology were investigated in the reaches using aerial photographs and satellite images from 1990 to 2022. For this purpose, the main cover typology was classified into grassland, woody vegetation, bank‐attached bars, islands, vegetated islands, river channels and urban areas. The stem diameter and density, degradation level and longitudinal/latitudinal alluvial bars in each of the BFWs were investigated using the field survey. Based on the findings, the lowest values of the SI (braiding index [BI], channel activity [CA] and channel width [CW]) and the highest expansion of BFWs were observed in the upstream reaches of the Taleqan River. Human disturbances in these reaches were less than in the reaches downstream, allowing the expansion of vegetation habitats. The vegetation patches were unstable and scattered in the midstream and downstream, and the width decrease of the river channel was created by land‐use change and channelization. A significant direct relationship was observed between BFW establishment, stem diameter and density, and vegetation height. The BFWs create an opportunity for engineer vegetation to prevent erosion and expand new habitats by creating biogeomorphic accumulation landforms and trapping alluvial bars on the lee side of engineer woody vegetation. This study highlights the interactions between riparian areas and hydrogeomorphic processes within riparian corridors exposed to human disturbances to help better define a comprehensive plan for river management.

Improving the identification of pollution source areas with catchment-resolution sensitivity analysis

The significant impacts of total nitrogen (TN) and total phosphorus (TP) on riverine ecosystems underscores the critical need to identify the primary nutrient source areas in watersheds. This study aims to unravel the influences of terrain and land use types on mean monthly TN (TNM) and mean monthly TP (TPM) export across varying catchment resolutions in the Qiantang River Watershed of China. The findings of this study illuminated the critical role of topography in understanding nutrient dynamics, wielding a profound influence over water flow patterns and nutrient dispersion. Both land slope and Stream Power Index (SPI) displayed substantial negative correlations (r < −0.6) with TNM and TPM concentrations, whereas the Topographic Wetness Index (TWI) showed positive correlations with the nutrient indexes. In addition to terrain characteristics, impervious land surfaces had a positive correlation with nutrient concentrations, while grassland and forest areas exhibited negative correlations. Results further underscored the substantial influence of catchment resolution on correlations between watershed properties and riverine nutrient concentrations. It was imperative to choose an effective catchment resolution in watershed delineation – not too coarse, nor too fine – to accurately capture the topographic and land use impacts on nutrient dynamics. With the most appropriate catchment size (Catchment 700 km2), the critical pollution source areas for TN and TP pollution were identified, and thus could be used to guide future pollution reduction efforts. The study not only highlights the importance of identifying an appropriate catchment size for water pollution, but also emphasizes the necessity of effectively extracting critical pollution source areas to mitigate water nutrient pollution and increase the ecological integrity of the Qiantang River Watershed.

Monitoring of vegetation changes based on RS monitoring in Changbai Mountain Nature Reserve

High vegetation cover helps maintain the ecosystem's stability and reduces the risk of soil erosion and natural disasters. Vegetation restoration is essential for the ecological value of Changbai Mountain Nature Reserve. In this study, the interannual changes in vegetation cover in Changbai Mountain Nature Reserve, China, from 2013 to 2022 were studied in depth based on Landsat remote sensing data and land use transfer matrix. The study includes interannual dynamic changes in vegetation types, quantitative analysis of interannual changes in surface vegetation types, and the land use transfer matrix analysis. In addition, the drivers of dynamic changes in vegetation types were analysed. The research indicates a notable advancement in ecological restoration within Changbai Mountain Nature Reserve between 2013 and 2022. There was a substantial reduction in the extent of barren land, which predominantly transitioned into grass and woodland areas. In particular, the year 2022 exhibited a significant increase in grassland area when compared to 2013, with a remarkable expansion of 27.18 square kilometers, primarily concentrated in the central-eastern sector of the study area. The findings of this investigation serve as a valuable scientific foundation for guiding ecological preservation and management decisions within Changbai Mountain Nature Reserve, contributing to a deeper comprehension of the evolving patterns in vegetation cover.

Simulation and evaluation of ecosystem service value along the Yellow River in Henan Province, China

The unprecedented growth in population and swift industrial advancements exert considerable strains on the ecosystem, particularly within medium-sized and large urban landscapes. The critical investigation into the intricate links between current and prospective land utilization, as well as the ecosystem service value (ESV), holds considerable empirical relevance for the calibration of land usage frameworks, thereby contributing to the sustainable evolution of extensive urban zones. Utilizing GlobeLand 30 data, the present research probes into the pattern of land transformation and the spatial-temporal dispersal of ESV in Henan’s Yellow River vicinity over a span from 2000 to 2020. For the enhancement of land usage alignment, a Markov-PLUS fusion model was devised to gauge three disparate ESV transition scenarios slated for 2030, namely, natural development scenario (NDS), cropland protection scenario (CPS), and ecological protection scenario (EPS). The principal determinants of land transformation within the 2000–2020 period were recognized as elevation, populace concentration, and atmospheric temperature. Amid the rapid accretion of construction land engulfing substantial cropland and grassland areas, there was an ESV diminution to the tune of 1.432 billion RMB between 2000 and 2020. The ESV’s high-value regions were discerned within relatively undisturbed ecosystem zones, with the lower-value sections identified in cropland and constructed areas, where human interventions exerted pronounced effects on the ecosystem. In accordance with the 2030 land usage simulations and analyses, in contrast to alternative scenarios, the EPS exhibited the least fluctuation in land type alterations in 2030, demonstrated the most pronounced escalation in cold spot concentration, and reached a peak agglomeration level. This underscores that the EPS not only offers a refinement in land utilization configuration but also mediates the equilibrium between economic and ecological considerations. The insights derived from this investigation afford innovative evaluative methods for spatial planning, ecological recompense, and sustainable land exploitation within large- and medium-scale urban domains.

Conversion of farmland to forest or grassland improves soil carbon, nitrogen, and ecosystem multi-functionality in a subtropical karst region of southwest China

The conversion of farmland to forest in China has been recognized for its positive impact on above-ground vegetation and carbon sequestration. However, the impact on soil quality during land conversion, particularly in vulnerable karst areas, has received less attention. In this study conducted in a karst area of southwest China, eight different farmland conversion strategies were investigated to assess improvements in surface soil carbon, nitrogen, and ecosystem multi-functionality (EMF). Our results showed that farmland converted to afforestation areas or farmland that was abandoned contained higher amounts of carbon (total, organic, active) and ammonium nitrogen (NH4+-N) in the soil compared to farmland converted to grassland or maize crop. Soluble organic carbon levels were higher in afforestation and grassland areas compared to maize crop controls. By contrast, soil from grassland and abandoned land exhibited higher levels of nitrate nitrogen (NO3--N) compared to afforestation land or maize crop controls. There were no differences in NH4+-N content between any condition, except for afforestation land that specifically contained the Zenia insignis plant species. Afforestation land consistently exhibited higher EMF values than grassland. Pearson correlation analysis revealed positive relationships between soil indices and EMF scores, except for NO3--N.Random forest analysis explained 95% of the variation in soil EMF and identified specific soil factors: total carbon, organic carbon, active labile organic carbon, total nitrogen, and ammonium nitrogen, as the main drivers of soil multi-functionality. Our studies show how various reforestation strategies can enhance soil nutrient sequestration and improve soil multi-functionality of farmland in the karst areas.These findings provide insight into sustainable soil management practices for converting farmland into natural areas.

Assessment and Driving Factors of Wetland Ecosystem Service Function in Northeast China Based on InVEST-PLUS Model

Wetland ecosystem service function provides and maintains the Earth’s life system, which supports human and social development. However, in recent years, with the intensification of human social activities, the wetland area in northeast China has been reduced, and wetland ecosystem service function has been damaged. This paper evaluates the ecosystem service function of wetlands in northeast China based on the InVEST model, taking 40 prefecture-level cities as the evaluation unit, calculating the carbon stock, soil retention, and habitat quality of the wetlands in the study area and analyzing the drivers of changes in ecosystem service function using the PLUS model. The following results were obtained: temporally, the wetland carbon stock decreased from 754 Tg in 2000 to 688 Tg in 2020; the wetland soil retention increased from 24,424 Tg in 2000 to 33,160 Tg in 2010, and then decreased to 28,765 Tg in 2020; and the quality of wetland habitats was roughly unchanged. The wetland habitats in the study area were categorized into 5 types, classified as I, II, III, IV, or V, and the spatial changes in the 40 prefecture-level cities in northeast China were analyzed. The driving factors affecting the change in the wetland ecosystem service function were further analyzed, mainly focusing on changes in the wetland area itself. The influence of other land-use types and the influence of related policies were analyzed in three aspects, among which the GDP and spatial density of the population are social factors, and the elevation and slope are natural factors that provide larger contributions to the change in wetland area. The reduction in forest and grassland areas and the increase in cultivated land and construction land areas have a negative effect on the ecosystem service function of wetlands, and the implementation of relevant wetland protection policies promotes the ecosystem service function of wetlands. According to the problems faced by wetlands in different regions, the government formulates strategies that are in line with local development, with a view to implementing wetland ecological development in the northeast region in the new context, which will help to realize intensive land use and stimulate the vitality of the region.

Spatiotemporal characteristics and driving mechanisms of land-use transitions and landscape patterns in response to ecological restoration projects: A case study of mountainous areas in Guizhou, Southwest China

With the acceleration of urbanization and industrialization, the land-use mode in mountainous areas has changed significantly, causing serious ecological destruction. Therefore, improving the efficiency of land-resource use in mountainous areas and enhancing ecological protection are important issues. This study focuses on typical mountainous areas in Guizhou Province to explore their significance not only for ecological restoration but also for sustainable socioeconomic development. In this study, we integrated the framework of the interaction between land-use transitions and landscape patterns and employed Spearman's rank correlation coefficient and a spatial bivariate model to reveal the spatiotemporal heterogeneity of landscape patterns and land-use transitions. The results showed that for 1990–2020, the cultivated, forest, and grassland areas decreased by −1353.66, −749.98 and − 541.72 km2 respectively, whereas the water area, urban, and other construction land increased by 799.69, 542.62, and 1230.90 km2, respectively. Moreover, the cultivated land areas converted into urban and other construction land were 358.03 and 661.77 km2 respectively, and the grassland areas converted into forest and other construction land were 3550.08 and 277.32 km2, respectively. Different land-use transitions presented rapid expansion and contraction characteristics, resulting in an increase in overall patch fragmentation, a decrease in uniformity, and an increase in irregular patches, which enhanced the spatial heterogeneity of diversity and complexity. Finally, the land-use transition effects on landscape patterns were primarily elevation, slope, and primary road facility factors. In-depth research on land-use transitional evolution and its impact on landscape patterns has important theoretical and practical value for formulating land-management policies and promoting sustainable development in mountainous areas.

Threshold responses and relationships between waterbird distribution and habitat factors at Shengjin Lake, China

The wintering period is an essential part of the annual life history of waterbirds. The environmental conditions of habitats in winter directly affect the abundance and physical condition of waterbirds. Therefore, it is important to study the relationship between waterbird abundance and habitat factors. In this study, we conducted significance and threshold analyses between habitat factors and the waterbird community at Shengjin Lake, a Ramsar Site in China, using Redundancy Analysis (RDA), Spearman Correlation Analysis, and Threshold Indicator Taxa Analysis (TITAN). The results indicate that seven environmental variables significantly affected the abundance of waterbird communities, that is, fractional vegetation cover, degree of receding water, grassland area, mudflat area, shallow water area, deep water area, and distance to reeds. Waterbird communities exhibited significant threshold responses to all seven factors. The number of species significantly responding to different habitat factors varied among waterbird communities, with the highest number of species (15) responding to distance to reeds. Except for the deep water area and distance to reeds, waterbirds showed higher positive than negative thresholds for the remaining five factors. Different groups of waterbirds influenced the threshold responses of waterbird communities to habitat factors, and there were variations in how each waterbird group responded to these factors. The results of this study highlight the importance of habitat type, water recession degree, and shelter conditions in waterbird habitat selection. Minor differences in habitat structure can influence waterbird habitat preferences. Therefore, wetland management at Shengjin Lake should consider the specific habitat needs of different waterbird species.

Forecasting Land Use Dynamics in Talas District, Kazakhstan, Using Landsat Data and the Google Earth Engine (GEE) Platform

This study employs the robust capabilities of Google Earth Engine (GEE) to analyze and forecast land cover and land use changes in the Talas District, situated within the Zhambyl region of Kazakhstan, for a period spanning from 2000 to 2030. The methodology involves thorough image selection, data filtering, and classification using a Random Forest algorithm based on Landsat imagery. This study identifies significant shifts in land cover classes such as herbaceous wetlands, bare vegetation, shrublands, solonchak, water bodies, and grasslands. A detailed accuracy assessment validates the classification model. The forecast for 2030 reveals dynamic trends, including the decline of herbaceous wetlands, a reversal in bare vegetation, and concerns over water bodies. The 2030 forecast shows dynamic trends, including a projected 334.023 km2 of herbaceous wetlands, 2271.41 km2 of bare vegetation, and a notable reduction in water bodies to 24.0129 km2. In quantifying overall trends, this study observes a decline in herbaceous wetlands, bare vegetation, and approximately 67% fewer water bodies from 2000 to 2030, alongside a rise in grassland areas, highlighting dynamic land cover changes. This research underscores the need for continuous monitoring and research to guide sustainable land use planning and conservation in the Talas District and similar areas.