Search Results (43)

Despite extensive research on soil organic carbon in karst regions, the synergistic changes in multiple carbon fractions and their stabilization mechanisms across a complete rocky desertification gradient remain poorly understood. To clarify how soil carbon pools and their drivers change during karst rocky desertification, we selected Kaiyuan City, Yunnan Province, China, as the study area. Total carbon (TC), soil organic carbon (SOC), and their related fractions, including particulate organic carbon (POC), mineral-associated organic carbon (MAOC), iron-bound organic carbon (Fe-OC), calcium-bound organic carbon (Ca-OC), and soil carbon isotopic composition (δ¹³C), were analyzed under different degrees of rocky desertification. SOC and TC followed a nonlinear pattern: increasing from no to potential desertification, decreasing at light and moderate stages, and rising again at the severe stage, indicating a phased response rather than a monotonic decline. POC was lowest under no rocky desertification and increased significantly after desertification occurred, reaching its maximum at the severe stage. MAOC peaked at the potential stage. With increasing rocky desertification severity, POC/SOC increased from no to moderate stages and then slightly decreased, whereas MAOC/SOC generally decreased. Fe-OC and Ca-OC were lowest under no desertification and increased after desertification occurred, pointing to enhanced mineral protection. Soil δ¹³C values under moderate and severe desertification were higher than under no, potential, and light desertification, implying intensified decomposition and a relative increase in C₄ plants. Mean weight diameter (MWD) and geometric mean diameter (GMD) did not differ significantly among rocky desertification stages (p > 0.05). In contrast, fractal dimension (FD) differed significantly only between the light and moderate stages (p < 0.05). Correlation and redundancy analyses showed that soil water content, bulk density, and porosity were the key factors driving variation in SOC and its fractions. These findings provide both a theoretical basis and practical guidance for soil restoration and ecological management in karst faulted basins affected by rocky desertification. Full article

Karst rock desertification is an extreme form of land degradation that poses a serious threat to regional ecological security and sustainable development in Southwest China. Understanding the response patterns of plant communities and soil properties along desertification gradients is critical for developing effective ecological restoration strategies. This study focused on Qingzhen City, Guizhou Province, a representative karst desertification region. Using remote sensing to classify rock desertification intensity, together with systematic vegetation surveys and soil sampling, we investigated variation patterns in ecological parameters along the degradation gradient. The results revealed three key patterns. First, rock desertification was widespread across Qingzhen and exhibited pronounced spatial differentiation. Second, as desertification intensified, vegetation community structure became progressively simplified, transitioning from forests to shrublands. Biomass and vegetation cover declined from 77.25 kg/m² and 83% to 0.62 kg/m² and 15%, respectively. Notably, species diversity exhibited a bell-shaped relationship with desertification intensity, peaking at the potential desertification stage before declining under increasing environmental stress. Third, soil physicochemical properties showed complex nonlinear responses along the desertification gradient. Soil bulk density decreased, and pH increased with increasing desertification intensity, while volumetric water content fluctuated across stages. Soil total carbon and total nitrogen exhibited temporary enrichment during the light-to-moderate desertification stages, likely due to shifts in litter quality. Overall, these findings demonstrate that both plant communities and soil properties respond nonlinearly to rock desertification gradients. Together, the results enhance the understanding of the ecological processes underlying karst rock desertification and support the development of targeted regional restoration strategies. Full article

Background: The adaptability of leguminous plant–rhizobia symbionts enables enhanced plant stress tolerance in environmentally stressed areas. However, how rock desertification (RD) severity affects the endophytic and nitrogen-fixing bacterial communities in Pisum sativum root nodules remains unclear. Methods: We systematically surveyed the microbial communities of P. sativum nodules across a gradient of four RD areas. We sequenced 16S rRNA and nifH amplicons, determined soil physicochemical properties, and performed bioinformatic analyses to relate nodule microbiome diversity to soil variables. Results: The dominant endophytic genera across all sites were Allorhizobium–Neorhizobium–Pararhizobium–Rhizobium and Pseudomonas, with Rhizobium identified as the primary nitrogen-fixing taxon. Soil pH and total phosphorus (TP) showed significant correlations with the overall endophytic bacterial community, whereas total nitrogen (TN), TP, and soil water content (SWC) were associated with nitrogen-fixing taxa. Notably, P. sativum nodules from areas of slight rocky desertification (SRD) harbored higher endophytic bacterial diversity and enhanced carbohydrate metabolism compared to those from moderately rocky desertified (MRD) sites. Conclusions: This study sheds light on how bacterial communities within legume root nodules respond to RD stress, deepening our understanding of plant–microbe co-adaptation and informing microbial-assisted restoration strategies in karst desertification areas. Full article

Karst desertification (KD) severely constrains regional ecological security and sustainable development. As an important ecological restoration measure, soil and water conservation agroforestry (SWCAF) systems have unclear mechanisms for soil microbial responses. This study investigated the effects of potential–light (PL), light–moderate (LM), and moderate–high (MH) KD on soil physicochemical properties and microbial communities in Karst SWCAF (KSWCAF) systems. It explored the drivers of microbial community changes. The results showed that (1) Soil physicochemical properties exhibited nonlinear changes along the KD gradient. Key soil-fertility indicators including silt, clay, total porosity (TP), total phosphorus (Total_P), total nitrogen (Total_N), soil organic carbon (SOC), and carbon nitrogen ratio (C_N) showed significant unimodal patterns, peaking at the LM stage with optimal overall soil quality; (2) The dominant bacterial phyla were Pseudomonadota, Acidobacteriota, Actinomycetota, and Planctomycetota, while the dominant fungal phyla were Ascomycota, Basidiomycota, and Mortierellomycota. The overall abundance of these dominant phyla increased with intensifying KD, except that the relative abundance of Pseudomonadota was lowest in the QZ study area, while Acidobacteriota was highest in the QZ area. The dominant fungal phylum Ascomycota increased with KD intensification; (3) KD significantly influenced microbial community structure and beta diversity. Fungi showed stronger responses to the KD gradient than bacteria. Bacterial alpha diversity was significantly higher in the LM stage compared to the PL and MH stages (p < 0.05), while fungal alpha diversity was significantly lowest in the MH stage (p < 0.05); (4) Bacterial networks exhibited highest complexity but reduced stability at the LM stage, whereas fungal networks enhanced stability at the MH stage by increasing modularization and positive correlation proportions; (5) RDA revealed that soil physicochemical factors explained 66.89% and 98.82% of bacterial and fungal community variation, respectively, with pH, moisture, and C_N as key drivers. Overall, KD regulates microbial community structure and functional allocation by reshaping the soil environmental gradient, with the LM stage potentially representing a “transitional optimization window” for KSWCAF ecosystem structure and function. This study provides a theoretical basis for microbial regulation strategies in KD control and soil and water conservation (SWC) processes. Full article

Establishing shrub plantations on mobile sand dunes is an effective strategy to combat desertification in semi-arid regions. Herbaceous communities developing beneath these plantations enhance ecosystem stability and improve revegetation outcomes. This study investigated the structural responses of soil bacterial communities, key functional genes (nifH, amoA, and phoD), and plant–soil–microbe interactions across a herbaceous vegetation succession gradient (initiation, early, middle, and stable stages) under Caragana microphylla sand-fixation plantations in the sandy Horqin Grassland. The results revealed that plant species richness, diversity, and biomass increased progressively with succession. Concurrent improvements in soil nutrients (organic matter, nitrogen, phosphorus, and potassium) and enzymatic activities (urease, protease, phosphatase, glucosidase, polyphenol oxidase, and dehydrogenase) were observed. The abundances of nifH, amoA, and phoD genes rose progressively with vegetation succession, contributing to enhanced soil nutrient levels. All dominant bacterial phyla and genera detected constituted shared taxa across successional stages, but their relative abundances shifted dynamically. Herbaceous succession facilitated rapid restoration of bacterial diversity, though structural recovery lagged, depending on the quantitative fluctuations of the dominant taxa. Soil pH, organic matter, electrical conductivity, total N, total P, available P, and available K all significantly influenced the soil bacterial community, with pH and organic matter being the most influential factors. These findings highlight plant–soil–microbe interactions as intrinsic drivers of vegetation succession in desertified ecosystems. Full article

The dry area in northwest China (ARNC), with its tough climate, serious soil erosion, and poor soil quality, is one of China’s most fragile ecosystems. Studying changes in plant growth cycles here is very important for improving environmental monitoring and making plans to adapt to climate change. While vegetation growing season parameters (Start/End of Season: SOS/EOS) serve as vital indicators of ecosystem dynamics, comprehensive understanding has been constrained by limited long-term phenological datasets and insufficient exploration of multi-factor interactions. This study used PLS-SEM to analyze 27-year (1990–2016) vegetation index data, systematically quantifying spatiotemporal variations in growing season phenology and disentangling climate–terrain driving mechanisms. The results revealed the following key findings. (1) Spatial heterogeneity in phenological patterns, with the annual average Start of Season (SOS) and End of Season (EOS) being 114.7 Day and 301.7 Day, respectively, exhibiting a northwest–high to southeast–low gradient. The findings indicate a prolongation of the vegetation growing season, with significant spatial variability. (2) Interannual fluctuations showed the SOS and EOS coefficient of variation (CV) values of 0.230 and 0.234, respectively, with southeastern regions displaying higher instability than northwestern counterparts. (3) The spatial variation in SOS/EOS is primarily influenced by meteorological and geographical factors, with an explanatory power exceeding 30%. This research advances mechanistic understandings of arid ecosystem responses to environmental stressors, providing a scientific foundation for targeted ecological restoration, desertification mitigation, and sustainable land management in climate-sensitive drylands. Full article

The C-X-C motif chemokine ligand 10 (CXCL10) is implicated in the progression of osteosarcoma (OS), the most aggressive pediatric bone malignancy. However, its role often presents a profound clinical paradox: although high circulating levels are strongly linked to poor prognosis, its canonical function is to recruit anti-tumor immune cells. This review unravels these contrasting roles by proposing a novel spatiotemporal model. We argue that in the early stages, immune-evading OS cells initiate the formation of a pre-metastatic niche (PMN) in the lungs, creating a localized inflammatory environment that becomes the primary source of elevated circulating CXCL10. As the disease progresses, elevated systemic levels of CXCL10 overwhelm the localized chemokine gradient at the primary tumor site, creating a potent immune decoy that diverts anti-tumor CXCR3+ T cells away from the tumor. The resulting immune desertification permits unchecked tumor growth and an increased metastatic burden. We also discuss the therapeutic implications of this model, proposing that disrupting the chemokine axis offers a roadmap for developing rational, stage-specific therapies to effectively combat metastatic OS. Full article

Rocky desertification severely restricts socio-economic development in the karst regions. However, assessments linking karst rocky desertification and NPP changes over the long term and at high resolution are limited. This study aims to reveal the spatiotemporal patterns and driving mechanisms of NPP changes in Wenshan Prefecture, addressing the scientific gap in quantitative process research and mechanism identification in karst desertification areas. We estimated vegetation NPP from 2000 to 2020 using remote sensing data and the CASA model. The Theil–Sen trend analysis and Mann–Kendall test were applied to assess temporal variation, while a Geographical Detector identified the dominant natural and human factors and their interactions shaping NPP spatial patterns. Our results showed that NPP increased overall by 4.07 gC m⁻² a⁻¹, alongside a general decline in rocky desertification. The most significant improvement occurred between 2010 and 2015, when rocky desertification shrank by 2224 km² and the dynamic rate reached 1.42%. Mean NPP reached 1057 gC m⁻² a⁻¹, with a “northwest high–southeast low” spatial pattern, and 77% of the region showed significant increases. Rocky desertification was most severe at elevations between 1000 and 2000 m. In the karst region, NPP is mainly controlled by natural factors, with soil depth and slope being the strongest influences. Human activity had the largest negative impact, and most factors interacted synergistically, where hydrothermal gradients and human disturbances more strongly suppressed NPP on steep, thin slopes than individually expected. These findings provide robust scientific evidence and practical decision-making support for ecological restoration, rocky desertification control and long-term sustainable development in Wenshan and other karst regions, highlighting the importance of continuous monitoring and adaptive management strategies to consolidate restoration achievements and guide future land-use planning and regional ecological policy. Full article

Herbaceous plant species form the plant synusia of desert ecosystems and play crucial roles in wind-breaking, sand-fixing, and the maintenance of oasis ecosystem stability. This study focused on the leguminous species Medicago sativa and Astragalus laxmannii and the gramineous species Elymus dahuricus, Agropyron desertorum, Agropyron mongolicum and Agropyron cristatum. These are the plants commonly used for ecological restoration in the desertification regions of northwestern China. We conducted a pot experiment with six soil moisture gradients (15% [ck], 12%, 10%, 8%, 6%, and 4%) to simulate drought conditions. We studied how varying degrees of drought stress influenced growth, functional traits and drought resistance, aiming to elucidate the mechanisms by which plants respond to drought. The study indicated that: (1) Drought stress directly and indirectly reduced both the seedling emergence rate and plant height. As soil water content decreased, the seedling emergence rate and plant height declined across all species. (2) The leaves and roots of the plants adopted different strategies to cope with drought stress. As soil water content decreased, leaf water content, leaf succulence, and leaf tissue density increased, while specific leaf area and leaf biomass decreased. Additionally, the root-shoot ratio increased, whereas root biomass, total root length, root surface area, and root volume all decreased. (3) Root system adaptation is the key factor influencing the drought resistance of plants. Drought resistance varied among the six species. Medicago sativa, Elymus dahuricus, and Agropyron cristatum exhibited stronger water retention and more stable growth under drought stress, making them better suited for ecological restoration in arid regions. Our study elucidates differentiation strategies for coping with drought stress and offers essential parameters and theoretical support for species selection and rational assemblage in the ecological restoration of arid regions. Full article

The effects of climate change are now evident on all scales, both global and local. Extreme events linked to climate change, such as heat islands and water bombs, are occurring with increasing frequency, causing significant harm to humans. Furthermore, rising temperatures also cause significant drought and desertification, which must be carefully assessed and analyzed. For this reason, with a view to evaluating environmentally sustainable development, the following research focuses on the variables that contribute to the reduction in local water availability in the province of Reggio Calabria, considering air temperature, evapotranspiration, precipitation, and available water resources. The Mann–Kendall test revealed a statistically significant increasing trend in air temperature (Z = +2.5, p < 0.01) and a decreasing tendency in precipitation, while the NDWI analysis indicated a reduction of about 34% in surface water resources between 2019 and 2023. The Spearman test showed strong negative correlations between temperature and water availability (ρ = −0.68) and between evapotranspiration and water availability (ρ = −0.66). Lastly, four artificial intelligence (AI) classifiers were compared: Random Forest, XGBoost, Gradient Boosting Decision Tree, and Logistic Regression. Random Forest performed the best, with 93% accuracy and 90% precision. The results confirm the strong negative dependence of temperature and evapotranspiration on water resources and identify Random Forest as the most reliable model for determining the area’s most at risk of drought. Full article

Red-bed desertification represents a critical form of land degradation in subtropical regions, yet the coupled soil–vegetation processes remain poorly understood. This study integrates Sentinel-2 vegetation indices with soil fertility gradients to assess vegetation–soil interactions in the Nanxiong Basin of South China. By combining Normalized Difference Vegetation Index (NDVI)-based vegetation classification with comprehensive soil property analyses, we aim to uncover the spatial patterns and driving mechanisms of degradation. The results revealed a clear gradient from intact forests to exposed red-bed bare land (RBBL). NDVI classification achieved an overall accuracy of 77.8% (κ = 0.723), with mixed forests being identified most reliably (97.1%), while Red-Bed Bare Land (RBBL) exhibited the highest omission rate. Along this gradient, soil organic matter, available nitrogen, and phosphorus declined sharply, while pH shifted from near-neutral in forests to strongly acidic in bare lands. Principal component analysis (PCA) identified a dominant fertility axis (PC1, explaining 56.7% of the variance), which clustered forested sites in nutrient-rich zones and isolated RBBL as the most degraded state. The observed vegetation–soil pattern aligns with a “weathering–transport–exposure” sequence, whereby physical disintegration and selective erosion during monsoonal rainfall drive organic matter depletion, soil thinning, and acidification, with human disturbance further accelerating these processes. To our knowledge, this study is the first to directly couple PCA-derived soil fertility gradients with vegetation patterns in red-bed regions. By integrating vegetation indices with soil fertility gradients, this study establishes a process-based framework for interpreting red-bed desertification. These findings underscore the utility of remote sensing, especially NDVI classification, as a powerful tool for identifying degradation stages and linking vegetation patterns with soil processes, providing a scientific foundation for monitoring and managing land degradation in monsoonal and semi-arid regions. Full article

Plant functional traits serve as vital tools for understanding vegetation adaptation mechanisms in changing environments. As the primary organs for nutrient acquisition from soil, fine roots are highly sensitive to environmental variations. However, current research on fine-root adaptation strategies predominantly focuses on tropical, subtropical, and temperate forests, leaving a significant gap in comprehensive knowledge regarding fine-root responses in rocky-desertification habitats. This study investigates the fine roots of Pseudotsuga sinensis across varying degrees of rocky desertification (mild, moderate, severe, and extremely severe). By analyzing fine-root morphological and nutrient traits, we aim to elucidate the trait differences and correlations under different desertification intensities. The results indicate that root dry matter content increases significantly with escalating desertification severity. Fine roots in mild and extremely severe desertification exhibit notably higher root C, K, and Mg concentrations compared to those in moderate and severe desertification, while root Ca concentration shows an inverse trend. Our correlation analyses reveal a highly significant positive relationship between specific root length and specific root area, whereas root dry matter content demonstrates a significant negative correlation with elemental concentrations. The principal component analysis (PCA) further indicates that the trait associations adopted by the forest in mild- and extremely severe-desertification environments are different from those in moderate- and severe-desertification environments. This study did not account for soil nutrient dynamics, microbial diversity, or enzymatic activity—key factors influencing fine-root adaptation. Future research should integrate root traits with soil properties to holistically assess resource strategies in rocky-desertification ecosystems. This study can serve as a theoretical reference for research on root characteristics and adaptation strategies of plants in rocky-desertification habitats. Full article

Image analysis is a valuable approach in a wide array of environmental applications. Mapping land cover categories depicted from satellite images enables the monitoring of landscape dynamics. Such a technique plays a key role for land management and predictive ecosystem modelling. Satellite-based mapping of environmental dynamics enables us to define factors that trigger these processes and are crucial for our understanding of Earth system processes. In this study, a reclassification scheme of image analysis was developed for mapping the adjusted categorisation of land cover types using multispectral remote sensing datasets and Geographic Resources Analysis Support System (GRASS) Geographic Information System (GIS) software. The data included four Landsat 8–9 satellite images on 2015, 2019, 2021 and 2023. The sequence of time series was used to determine land cover dynamics. The classification scheme consisting of 17 initial land cover classes was employed by logical workflow to extract 10 key land cover types of the coastal areas of Bab-el-Mandeb Strait, southern Red Sea. Special attention is placed to identify changes in the land categories regarding the thermal saline lake, Lake Assal, with fluctuating salinity and water levels. The methodology included the use of machine learning (ML) image analysis GRASS GIS modules ‘r.reclass’ for the reclassification of a raster map based on category values. Other modules included ‘r.random’, ‘r.learn.train’ and ‘r.learn.predict’ for gradient boosting ML classifier and ‘i.cluster’ and ‘i.maxlik’ for clustering and maximum-likelihood discriminant analysis. To reveal changes in the land cover categories around the Lake of Assal, this study uses ML and reclassification methods for image analysis. Auxiliary modules included ‘i.group’, ‘r.import’ and other GRASS GIS scripting techniques applied to Landsat image processing and for the identification of land cover variables. The results of image processing demonstrated annual fluctuations in the landscapes around the saline lake and changes in semi-arid and desert land cover types over Djibouti. The increase in the extent of semi-desert areas and the decrease in natural vegetation proved the processes of desertification of the arid environment in Djibouti caused by climate effects. The developed land cover maps provided information for assessing spatial–temporal changes in Djibouti. The proposed ML-based methodology using GRASS GIS can be employed for integrating techniques of image analysis for land management in other arid regions of Africa. Full article

Soil active nitrogen (N) fractions are essential for plant growth and nutrient cycling in terrestrial ecosystems. While previous studies have primarily focused on the impact of vegetation restoration on soil active nitrogen in karst ecosystems, the role of microclimate variation in rocky desertification areas has not been well explored. This study investigates soil active nitrogen fractions and key biotic and abiotic factors across four grades of rocky desertification—non-rocky desertification (NRD), light rocky desertification (LRD), moderate rocky desertification (MRD), and intense rocky desertification (IRD)—within two distinct microclimates: a dry-hot valley and a humid monsoon zone in the karst region of Guizhou Province, China. We evaluate soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), soil nitrate nitrogen (NO₃⁻-N), ammonium nitrogen (NH₄⁺-N), microbial biomass nitrogen (MBN), soluble organic nitrogen (SON), and plant diversity. Results showed that SOC, TN, and TP were significantly higher in IRD areas. Soil NO₃⁻-N, MBN, and SON initially decreased before increasing, with consistent MBN growth in the dry-hot valley. NH₄⁺-N did not differ significantly under NRD but was higher in the dry-hot valley under LRD, MRD, and IRD. The dry-hot valley had higher MBN and SON across most desertification grades. Microclimate significantly influenced soil active N, with higher levels in the dry-hot valley under LRD and MRD conditions. Plant diversity and regeneration varied markedly between the microclimates. In the dry-hot valley, Artemisia dominated herbaceous regeneration, especially in MRD areas. Conversely, the humid monsoon zone showed more diverse regeneration, with Artemisia and Bidens prevalent in MRD and NRD grades. Despite declining plant diversity with desertification, the humid monsoon zone displayed greater resilience. These findings highlight the role of microclimate in influencing soil nitrogen dynamics and plant regeneration across rocky desertification gradients, offering insights for restoration strategies in karst ecosystems. Full article

Grassland ecosystems provide a range of services in semi-arid and arid regions. However, they have significantly declined due to overgrazing and desertification. In the current study, we employed Landsat time series data (TM, OLI, OLI-2) spanning from 1990 to 2024, combined with vegetation indices such as NDVI and SAVI, along with NDWI and digital elevation models (DEMs), to analyze land cover dynamics in the Ugii Lake watershed area, Mongolia. By integrating multisource remote sensing data into the advanced XGBoost (extreme gradient boosting) machine learning algorithm, we achieved high classification accuracy, with overall accuracies exceeding 94% and Kappa coefficients greater than 0.92. The results revealed a decline in montane grasslands (−6.2%) and an increase in other grassland types, suggesting ecosystem redistribution influenced by climatic and anthropogenic factors. Cropland exhibited resilience, recovering from a significant decline in the 1990s to moderate growth by 2024. Our findings highlight the stability of barren land and underscore pressures from ecological degradation and human activities. This study provides up-to-date statistical data to support decision-making in the conservation and sustainable management of grassland ecosystems in Mongolia under changing climatic conditions. Full article