Search Results (129)

Coastal blue carbon ecosystems (traditional types such as mangroves, salt marshes, and seagrass meadows; emerging types such as tidal flats and mariculture) play pivotal roles in capturing and storing atmospheric carbon dioxide. Reliable assessment of the spatial and temporal variation and the carbon storage potential holds immense promise for mitigating climate change. Although previous field surveys and regional assessments have improved the understanding of individual habitats, most studies remain site-specific and short-term; comprehensive, multi-decadal assessments that integrate all major coastal blue carbon systems at the national scale are still scarce for China. In this study, we integrated 30 m Landsat imagery (1992–2022), processed on Google Earth Engine with a random forest classifier; province-specific, literature-derived carbon density data with quantified uncertainty (mean ± standard deviation); and the InVEST model to track coastal China’s mangroves, salt marshes, tidal flats, and mariculture to quantify their associated carbon stocks. Then the GeoDetector was applied to distinguish the natural and anthropogenic drivers of carbon stock change. Results showed rapid and divergent land use change over the past three decades, with mariculture expanded by 44%, becoming the dominant blue carbon land use; whereas tidal flats declined by 39%, mangroves and salt marshes exhibited fluctuating upward trends. National blue carbon stock rose markedly from 74 Mt C in 1992 to 194 Mt C in 2022, with Liaoning, Shandong, and Fujian holding the largest provincial stock; Jiangsu and Guangdong showed higher increasing trends. The Normalized Difference Vegetation Index (NDVI) was the primary driver of spatial variability in carbon stock change (q = 0.63), followed by precipitation and temperature. Synergistic interactions were also detected, e.g., NDVI and precipitation, enhancing the effects beyond those of single factors, which indicates that a wetter climate may boost NDVI’s carbon sequestration. These findings highlight the urgency of strengthening ecological red lines, scaling climate-smart restoration of mangroves and salt marshes, and promoting low-impact mariculture. Our workflow and driver diagnostics provide a transferable template for blue carbon monitoring and evidence-based coastal management frameworks. Full article

To clarify the ecological mechanisms underlying the succession of artificial grasslands to native alpine meadows and systematically reveal the patterns of ecological restoration in artificial grasslands in the Qinghai–Tibet Plateau, this study provides a theoretical basis for alpine meadow ecological restoration. In this study, artificial grassland and degraded grassland (CK) with different restoration years (20 years, 16 years, 14 years, and 2 years) in the Qinghai–Tibet Plateau were taken as research objects. We focused on the tillering characteristics, patch number, community structure evolution, and soil properties of the dominant species, C. alatauensis, and systematically explored the ecological restoration law by comparing and analyzing ecological indicators in different restoration years. The results showed the following: (1) With the extension of restoration years, the asexual reproduction ability of C. alatauensis was enhanced, the patches became large, and aboveground/underground biomass significantly accumulated. (2) Community structure optimization meant that the coverage and biomass of Cyperaceae plants increased with restoration age, while those of Poaceae plants decreased. The diversity of four species in 20A of restored grasslands showed significant increases (10.71–19.18%) compared to 2A of restored grasslands. (3) Soil improvement effect: The contents of soil organic carbon (SOC), total phosphorus (TP), nitrate nitrogen (NN), and available phosphorus (AP) increased significantly with the restoration years (in 20A, the SOC content in the 0–10 cm soil layer increased by 57.5% compared with CK), and the soil pH gradually approached neutrality. (4) In artificial grasslands with different restoration ages (20A, 16A, and 14A), significant or highly significant correlations existed between C. alatauensis tiller characteristics and community and soil properties. In conclusion, C. alatauensis in artificial grasslands drives population enhancement, community succession, and soil improvement through patch expansion. Full article

Remote sensing plays an important role in understanding the degradation and restoration processes of alpine grasslands. However, the extreme climatic conditions of the region pose difficulties in collecting field spectral data on which remote sensing is based. Thus, in-depth knowledge of the spectral characteristics of alpine grasslands and an accurate assessment of their restoration status are still lacking. In this study, we collected the canopy hyperspectral data of plant communities in the growing season from severely degraded grasslands and actively restored grasslands of different ages in 13 counties of the “Three-River Headwaters Region” and determined the absorption characteristics in the red-light region as well as the trends of red-light parameters. We generated a model for estimating the crude protein content of plant communities in different grasslands based on the screened spectral characteristic covariates. Our results revealed that (1) the raw reflectance parameters of the near-infrared band spectra can distinguish alpine Kobresia meadow from extremely degraded and actively restored grasslands; (2) the wavelength value red-edge position (REP), corresponding to the highest point of the first derivative (FD) spectral reflectance (680–750 nm), can identify the extremely degraded grassland invaded by Artemisia frigida; and (3) the red valley reflectance (Rrw) parameter of the continuum removal (CR) spectral curve (550–750 nm) can discriminate among actively restored grasslands of different ages. In comparison with the Kobresia meadow, the predictive model for the actively restored grassland was more accurate, reaching an accuracy of over 60%. In conclusion, the predictive modeling of forage crude protein content for actively restored grasslands is beneficial for grassland management and sustainable development policies. Full article

A systematic understanding of the spatial and temporal changes of grassland fractional vegetation cover (FVC) in Xinjiang and its drivers provide scientific reference for regional ecological restoration. In this study, we used MODIS EVI data from 2000 to 2023 and the Pixel binary model to estimate the grassland FVC value of Xinjiang; analyze its spatiotemporal dynamics with combination of trend and persistence detection methods; and explore its driving factors with ridge regression and residual analysis. The results show the following: (1) From 2000 to 2020, the grassland FVC in Xinjiang experienced an upward trend on the whole, yet a significant decrease after 2020. Spatially, the distribution characteristics are high in the northwest and low in the southeast, decreasing from mountains to basins. (2) Precipitation and soil moisture affected FVC positively, with contributions of 18.6% and 38.3%, respectively, while air temperature and solar radiation affected it negatively, with contributions of 22.9% and 20.2%, respectively. (3) The change in the grassland FVC in Xinjiang resulted from a combination of climatic factors and human activity, whose relative contribution rates were 57.2% and 42.8%, respectively; furthermore, the areas with positive effects on the FVC were smaller than those with negative effects. (4) While the FVCs of most grassland types in Xinjiang were dominantly influenced by both climatic factors and human activity, climatic conditions were the dominant drivers of the FVCs of temperate typical grasslands and temperate desert grasslands, whereas human activities had more influence on the FVC of temperate meadow grasslands. This study provides a scientific basis and guidance for optimizing the ecological barrier function and regulating vegetation coverage in arid areas by analyzing the spatiotemporal dynamics of grassland coverage in Xinjiang and quantifying the impact of different environmental factors on it. Full article

This study focuses on the alpine meadow ecosystem of the Qinghai–Tibet Plateau, which plays a vital role in carbon sequestration and water resource protection. However, mining activities have severely damaged the ecosystem, posing challenges for ecological restoration. The study selected the Jiangcang mining area and analyzed the physical, chemical, and carbon characteristics and heavy metal content of soil samples from the slag platforms and slopes (0–20 cm), which were restored in 2015 and 2020 to explore the effects of different soil reconstruction methods on soil function and ecological resilience. The results show that the minimum data set (MDS) can effectively replace the total data set (TDS) in assessing soil quality. The assessment indicates good restoration effects in 2020, with some areas rated high in soil quality. Although issues such as high bulk density, high electrical conductivity, low moisture content, nitrogen deficiency, and low organic matter limit ecological restoration, the carbon sequestration capacity of the restored soil is strong. This study provides scientific evidence for ecological restoration in cold mining areas, indicating that capping measures can enhance soil resistance to erosion, nutrient retention, and carbon sink functions. Full article

Wetlands and meadows are two terrestrial ecosystems that are strikingly distinct in terms of hydrological conditions and biogeochemical characteristics. Wetlands generally feature saturated soils, high accumulation of organic matter, and hypoxic environments. They support unique microbial communities and play crucial roles as carbon sinks and nutrient retainers. In contrast, meadows are characterized by lower water supply, enhanced aeration, and accelerated turnover of organic matter. The transition from wetlands to meadows under global climate change and human activities has triggered severe ecological consequences in the Sanjiangyuan region, yet the mechanisms driving microbial network stability remain unclear. This study integrates microbial sequencing, soil physicochemical analyses, and structural equation modeling (SEM) to reveal systematic changes in microbial communities during wetland degradation. Key findings indicate: (1) critical soil parameter shifts (moisture: 48.5%→19.3%; SOM: −43.6%; salinity: +170%); (2) functional microbial restructuring with drought-tolerant Actinobacteria (+62.8%) and Ascomycota (+48.3%) replacing wetland specialists (Nitrospirota: −43.2%, Basidiomycota: −28.6%); (3) fundamental network reorganization from sparse wetland connections to hypercomplex meadow networks (bacterial nodes +344%, fungal edges +139.2%); (4) SEM identifies moisture (λ = 0.82), organic matter (λ = 0.68), and salinity (λ = −0.53) as primary drivers. Particularly, the collapse of methane-oxidizing archaea (−100%) and emergence of pathogenic fungi (+28.6%) highlight functional thresholds in degradation processes. These findings provide microbial regulation targets for wetland restoration, emphasizing hydrologic management and organic carbon conservation as priority interventions. Future research should assess whether similar microbial and network transitions occur in degraded wetlands across other alpine and temperate regions, to validate the broader applicability of these ecological thresholds. Restoration efforts should prioritize re-saturating soils, reducing salinity, and enhancing organic matter retention to stabilize microbial networks and restore essential ecosystem functions. Full article

Seagrass meadows play a critical role in biogeochemical cycling, especially in nitrogen and sulphur processes, driven by their associated microbiome. This study provides a novel functional analysis of microbial communities in seagrass (Zostera marina) rhizosphere and endosphere, comparing seedlings and mature plants. While nitrogen-fixing bacteria are more abundant in seedlings, mature plants exhibit greater microbial diversity and stability. Sediment samples show higher microbial diversity than roots, suggesting distinct niche environments in seagrass roots. Key microbial taxa (sulphur-oxidizing and nitrogen-cycling bacteria) were observed across developmental stages, with rapid establishment in seedlings aiding survival in sulphide-rich, anoxic sediments. Chromatiales, which oxidize sulphur, are hypothesized to support juvenile plant growth by mitigating sulphide toxicity, a key stressor in early development. Additionally, sulfate-reducing bacteria (SRB), though potentially harmful due to H₂S production, may also aid in nitrogen fixation by producing ammonium. The study underscores the dynamic relationship between seagrass and its microbiome, especially the differences in microbial community structure and function between juvenile and mature plants. The study emphasizes the need for a deeper understanding of microbial roles within the seagrass holobiont to aid with Blue Carbon stores and to improve restoration success, particularly for juvenile plants struggling to establish effective microbiomes. Full article

The responses of soil nitrogen component dynamics and enzyme activities to vegetation degradation in wet meadows ecosystems remain unclear. This study employed a combination of field surveys and laboratory experiments to investigate soil nitrogen components and nitrogen cycling enzyme activities under different intensities of vegetation degradation and during the vegetation growth season in a wet meadow on the Qinghai–Tibetan Plateau. The aim was to explore the responses of soil nitrogen components and nitrogen cycling enzyme activities to vegetation degradation and their interrelationships. The results showed that vegetation degradation significantly reduced TN, NH₄⁺-N, MBN, PRO, and NiR, and increased NO₃⁻-N, URE, and NR. Soil nitrogen components and enzyme activities exhibited seasonal fluctuations across different degradation levels during the growing season. The Pearson correlation analysis revealed a significant positive correlation between temperature, moisture, nitrogen fractions, and nitrogen cycle-related enzyme activities, as well as between the nitrogen fractions and the enzyme activities themselves. Partial Least Squares Path Modeling (PLS-PM) elucidated the relationships between soil properties and nitrogen components under different degradation levels, explaining 78% of the variance in nitrogen components. Degradation level, growth season, and soil physical properties had indirect associations with nitrogen components, whereas soil enzyme activities exerted a direct positive influence on nitrogen components. Our research revealed the universal impact mechanism of environmental factors, soil characteristics, and vegetation degradation on nitrogen cycling in a wet meadow, thereby making a significant contribution to the restoration and maintenance of functional integrity in alpine wetland ecosystems. Full article

The accurate detection of mowing events is important in many applications, including in agricultural contexts such as yield and fodder production, as well as biodiversity assessments, habitat modeling, and protected area monitoring. This work presents the first free and open dataset of mowing events covering the entire Austrian territory for the year 2023 at a spatial resolution of 10 × 10 m. We use the Sentinel-2 time series of the Normalized Difference Vegetation Index (NDVI) to detect mowing events, and additionally, we use the mean of the two ShortWave InfraRed (SWIR) bands to exclude misclassification caused by remaining cloud artifacts and shadows. The validation procedure builds on a visual interpretation of the Panomax webcam archive complemented by a selection of field observations. The final validation dataset consists of 211 mowing events recorded in 85 different locations across Austria. In total, 77.73% of these mowing events were detected with a mean time delay of 4 days. The detection delay in summer was smaller than the values recorded in spring and fall. The pixel-based approach exhibited superior efficacy, especially for meadows with three or more mowing events, compared to the polygon-based approach. The results of our study are consistent with those of previous works demonstrating the capacity to produce high-quality mowing event data for various grassland areas in a fully automated manner, independent from training datasets. The results could be used in research on biodiversity or in practical applications such as agricultural policy support and control, fodder supply evaluation, or impact assessment in nature restoration efforts. Full article

Alpine meadows on the Qinghai–Tibetan Plateau are experiencing rapid degradation due to climate change and anthropogenic disturbances, leading to severe ecological consequences. In this study, we investigated the response of soil microbial communities and their metabolic functions across a degradation gradient using metagenomic sequencing and comprehensive soil physicochemical analysis in the city of Lhasa, China. Results showed that soil pH increased with degradation, while most nutrients, including different forms of nitrogen, phosphorus, and potassium, declined. pH, ammonium nitrogen, and organic matter were identified as key factors driving degradation dynamics. Microbial community composition shifted markedly, with distinct biomarker taxa emerging at different degradation levels. Network analysis revealed a progressive loss of microbial connectivity, with Actinobacteria dominance increasing in heavily degraded soils, while cross-phylum interactions weakened. Functional analysis of biogeochemical cycling genes showed that carbon, nitrogen, and phosphorus cycling were all disrupted by degradation, but each exhibited unique response patterns. These findings will extend our understanding of microbial-mediated soil processes under degradation and provide a scientific foundation for ecosystem management, conservation, and targeted restoration strategies in alpine meadows. Full article

Soil aggregate stability and carbon–nitrogen content are critical indicators for assessing the vegetation restoration effects. Salix cupularis plays a vital role in rehabilitating desertified alpine meadows on the eastern Qinghai–Tibet Plateau. However, research remains limited about how afforestation influences the soil aggregate stability and associated carbon and nitrogen dynamics. In this study, sandy land (0 years) served as the control, and the spatial time replacement method was used to examine changes in the soil water-stable aggregate composition, stability, organic carbon (OC) and total nitrogen (TN) contents, and density at a 0–60 cm depth after 5 and 10 years of afforestation restoration (Salix cupularis). Ecological restoration significantly enhanced the proportion of macroaggregates (>0.25 mm) in the topsoil (0–20 cm), and improved aggregate stability. After 10 years of restoration, macroaggregates increased by 45.04% and 51.32%, respectively. The average weight diameter and geometric mean diameter of the aggregates increased by 51.32% and 59.53%, respectively. Following restoration, there was a gradual increase in the OC and TN contents in the soil, with the highest increase observed in the 0–10 cm layer (266.67% and 391.67%). The OC and TN of the aggregates also displayed a similar trend. Correlation analysis results indicated a significant positive relationship between the soil OC and TN contents and density, OC content in aggregates of various diameters, and the stability of these aggregates. The Pearson’s correlation coefficient for OC in aggregates > 1 mm was the highest. Compared with 5 years, 10 years of recovery were more conducive to the formation of macroaggregates, enhancement in aggregate stability, and the accumulation of OC and TN. Therefore, vegetation restoration on the Zoige Plateau can significantly enhance the soil water-stable aggregate composition and stability and can also increase the soil and OC and TN contents and density, thereby enhancing the soil ecological quality. This study provides fundamental data and theoretical support for rehabilitating desertified grasslands on the eastern Qinghai–Tibet Plateau. Full article

This study investigated the effects of plateau pika (Ochotona curzoniae) disturbances and altitude on soil organic carbon (SOC) storage characteristics, including SOC content and SOC density (SOCD). In this study, plateau pika outbreak areas and non-outbreak areas at different altitudes were compared in terms of vegetation biomass, soil physicochemical properties, SOC content and SOCD to establish the relationship between vegetation and soil characteristics (including SOC content and SOCD). The results showed that SOC and SOCD decreased significantly (p < 0.01) in plateau pika outbreak areas, but SOCD increased first and then decreased with elevation in non-outbreak areas. Soil total nitrogen (TN) content decreased significantly (p < 0.01) with elevation in both plateau pika outbreak and non-outbreak areas. There were significant differences (p < 0.05) in total phosphorus (TP) at low elevations and nitrate nitrogen (NO₃⁻-N) at high elevations between outbreak and non-outbreak areas, but other nutrients did not differ hugely between outbreak and non-outbreak areas at the same elevation. Correlation analysis revealed that belowground biomass (BGB) in the plateau pika outbreak area was significantly and positively correlated with SOC (p < 0.01); structural equation modeling (SEM) analysis revealed that altitude had a direct effect on SOC (path coefficient = −0.882, p < 0.001) in the plateau pika outbreak area, but only a reduced influence on SOC and SOCD in the non-outbreak area; nitrate nitrogen in the plateau pika outbreak area and TN were the key influencing factors, which exerted a strong direct influence on SOC and SOCD (path coefficient = −0.666 and 0.639 (p < 0.001), respectively). Therefore, increasing vegetation biomass and nitrogen nutrient content through reseeding pasture and fertilization can facilitate the accumulation and recovery of SOC and SOCD in the ecological restoration of degraded alpine meadows, and it is especially important to quickly enrich soil nitrogen content in the outbreak area of plateau pika populations at high altitudes. Full article

Mountain grassland ecosystems around the globe are highly sensitive to seasonal extreme climate events, which thus highlights the critical importance of understanding how such events have affected vegetation dynamics over recent decades. However, research on the time-lag of the effects of seasonal extreme climate events on vegetation has been sparse. This study focuses on Tajikistan, which is characterized by a typical alpine meadow–steppe ecosystem, as the research area. The net primary productivity (NPP) values of Tajikistan’s grasslands from 2001 to 2022 were estimated using the Carnegie–Ames–Stanford Approach (CASA) model. In addition, 20 extreme climate indices (including 11 extreme temperature indices and 9 extreme precipitation indices) were calculated. The spatiotemporal distribution characteristics of the grassland NPP and these extreme climate indices were further analyzed. Using geographic detector methods, the impact factors of extreme climate indices on grassland NPP were identified along a gradient of different altitudinal bands in Tajikistan. Additionally, a time-lag analysis was conducted to reveal the lag time of the effects of extreme climate indices on grassland NPP across different elevation levels. The results revealed that grassland NPP in Tajikistan exhibited a slight upward trend of 0.01 gC/(m²·a) from 2001 to 2022. During this period, extreme temperature indices generally showed an increasing trend, while extreme precipitation indices displayed a declining trend. Notably, extreme precipitation indices had a significant impact on grassland NPP, with the interaction between Precipitation anomaly (PA) and Max Tmax (TXx) exerting the most pronounced influence on the spatial variation of grassland NPP (q = 0.53). Additionally, it was found that the effect of extreme climate events on grassland NPP had no time-lag at altitudes below 500 m. In contrast, in mid-altitude regions (1000–3000 m), the effect of PA on grassland NPP had a significant time-lag of two months (p < 0.05). Knowing the lag times until the effects of seasonal extreme climate events on grassland NPP will appear in Tajikistan provides valuable insight for those developing adaptive management and restoration strategies under current seasonal extreme climate conditions. Full article

Assessing the ecosystem service value (ESV) of grasslands is crucial for sustainable resource management and environmental conservation. This study evaluates the spatiotemporal changes in grassland ecosystem services in the Bosten Lake Basin using long-term land use data (2000–2022). Employing the Patch-generating Land Use Simulation (PLUS) model, we develop three future scenarios—natural development, ecological protection, and economic priority—to predict grassland utilization trends. The findings reveal a continuous decline in grassland area and ecosystem service values, driven by climate change and human activities. Compared with 2022, all three scenarios indicate further degradation, but ecological protection measures significantly mitigate ESV loss. This study provides scientific insights for sustainable land management and policy-making, contributing to ecological restoration strategies under climate change impacts. The findings reveal the following: (1) Over the 22-year period, the grassland area in the Bosten Lake Basin has experienced an overall decline. Notably, the area of plain desert steppe grassland expanded from 626,179.41 ha to 1,223,506.62 ha, whereas plain meadow grassland reduced from 556,784.64 ha to 118,948.23 ha. (2) The total ecosystem service value of grasslands in the basin exhibited a marginally insignificant decrease, amounting to a reduction of 5.73422 billion CNY. The values for mountain desert, mountain desert steppe, mountain typical steppe, and mountain meadow grasslands were relatively low and showed minimal change. (3) In comparison to 2022, the projected areas of grassland under the three scenarios for 2000 show a substantial reduction, particularly in plain desert and hilly desert grasslands. The ecosystem service values across all scenarios are expected to decline in tandem with varying degrees of grassland degradation. This research underscores the impact of global warming and human activities on the shrinking grassland area and the diminishing ecosystem service values in the Bosten Lake Basin. The current state of grassland resources in the study area is under threat, highlighting the urgent need for strategic planning and conservation efforts to ensure sustainable development and ecological integrity. Full article

The Ruoergai Wetland is the highest and largest plateau peat swamp wetland in the world, providing more than 30% of the water for the upper reaches of the Yellow River. It performs vital regulatory functions in maintaining the quality and stability of the regional ecosystem of the Yellow River Basin. It is of great significance to study the spatial and temporal variability of water conservation services as well as ecological restoration and enhancement strategies at multiple scales. Based on field research, using the InVEST model, this study quantitatively assessed water conservation for a long period at the Ruoergai Wetland, proposing a strategy to improve water conservation capacity. The results showed that both grassland (mainly alpine meadow with Kobresia Willd and Cyperus papyrus) and wetland in the study area exhibited degradation. The proportions of significantly decreased, moderately decreased, slightly decreased areas were 50.64%, 16.81%, 11.64%, respectively. There were also significant changes in water conservation capacity from 2020 to 2023, with strong spatial heterogeneity. Average water conservation per unit area ranged from 52.70 to 211.99 mm/m², with a decreasing trend. However, in the past 10 years, the area of soil erosion decreased by about 4735 km². Although the soil erosion situation has improved to a large extent, there is still increasing soil erosion in some areas. Based on the field investigation, the intrinsic mechanisms of water conservation in alpine wetlands were elaborated, the driving forces behind the changes in water conservation functions were described, and further ecological restoration strategies were proposed from the perspectives of engineering measures, spatial zoning, and industrial structure. Full article