Search Results (615)

Camera-trap images used in wildlife monitoring contain environmental information that is often underused. This study developed and evaluated a vision–language-model-based workflow for extracting structured visible habitat attributes from camera-trap photographs collected in a karst forest ecosystem in southern China. The workflow combined image preprocessing, schema-constrained prompting, structured JSON generation, programmatic parsing, logical-consistency validation, and automatic re-inference of invalid outputs. Seven attributes were evaluated: terrain, bare-rock visibility, vegetation layers, vegetation density, water visibility, water type, and visible human disturbance. Qwen3-VL-30B-A3B-Instruct was deployed locally, and its outputs were compared with expert-reference annotations for 102 camera-trap images. The evaluation used one model and one prompt/schema configuration and was designed to assess feasibility rather than cross-model or cross-ecosystem generalizability. All images ultimately produced valid structured records after the validation and retry procedure. Field-level exact agreement ranged from 90.20% to 99.02%. For water visibility, exact agreement was 96.08%, balanced accuracy was 97.56%, and macro-F1 was 94.20%; all 20 water-positive images were correctly identified. Water type achieved 95.10% exact agreement, with 19 of the 20 water-positive images matching the expert reference. Five experts separately verified all images using workbooks pre-populated with the reference labels while the model outputs were visible. In this non-blinded verification, Fleiss’ kappa ranged from 0.885 to 1.000 across the six estimable fields (0.974 for vegetation-layer sets treated as nominal categories); visible human disturbance had 100% observed agreement but no category variation, so kappa was not estimable. However, several reference distributions were strongly imbalanced: 96 of 102 images contained visible bare rock, 99 were assigned dense vegetation, and the validation subset contained no disturbance-positive images. The results therefore demonstrate preliminary feasibility under the evaluated conditions rather than broad generalizability. The proposed workflow provides a structured post-acquisition approach for deriving time-aligned visible habitat information from existing camera-trap imagery. Full article

Background and Aims: Karst ecosystems suffer from thin soil layers and severe nutrient limitation, while the interactive regulation of vegetation succession and restoration duration on soil C–N–P and microbial enzyme limitation remains unclear. This study aimed to disentangle individual and coupled effects of succession stage and 14-year restoration on soil stoichiometry and extracellular enzyme-based nutrient limitation in karst. Methods: We established five natural succession gradients (HS–MS) with fixed plots sampled in 2008 and 2022. Soil physicochemical properties and ecoenzyme stoichiometry (ecoenzyme stoichiometry, EEA; EEA ratios, vector length/angle) of eight soil enzymes (including hydrolases and oxidoreductases) were measured; two-way ANOVA, redundancy analysis (RDA) and correlation analysis were applied to quantify factor interactions. Results: N:P and available nitrogen:total nitrogen (AN:TN) decreased significantly over restoration; EEA stoichiometry remained stable across succession. Vector angle < 45° indicated the persistence of nitrogen limitation. The restoration duration of secondary succession masked the independent effects of community succession on most soil variables, with three coupling modes (masking, activation, synergism) identified for C, N, P and Ca²⁺:Mg²⁺. Conclusion: Long-term restoration reshaped karst soil nutrient pools and aggravated N limitation. Stage-targeted nitrogen activation and phosphorus mobilization strategies were proposed for differentiated karst ecological restoration. Full article

Forest-soil CO₂ efflux may respond to nutrient enrichment even when treatment effects on bulk soil pools are not detectable, but the separate and interactive effects of nitrogen (N) and phosphorus (P) remain unclear in karst ecosystems. We tested these effects in a 2 × 2 factorial field experiment with N addition (100 kg of N ha⁻¹ yr⁻¹), P addition (50 kg of P ha⁻¹ yr⁻¹), or both. Soil respiration (Rs) was monitored over an annual cycle, and plot-level temperature sensitivity was quantified as Q₁₀ from paired Rs–temperature observations. N addition significantly increased Rs, whereas neither the independent P effect nor the N × P interaction was statistically supported. The annual mean Rs was 9.2% higher under N and 19.9% higher under combined N and P than in the control. In contrast, Q₁₀ showed a significant P main effect (F_1,16 = 4.825, p = 0.043), while the N and N × P effects on Q₁₀ were not significant. No significant treatment effects were detected for the measured bulk soil properties or microbial biomass. Selected carbon-degrading gene abundances showed specific treatment contrasts. Short-term N enrichment therefore increased total soil CO₂ efflux, while P addition altered the apparent temperature sensitivity of Rs without significantly changing the annual mean Rs. Full article

Long-term Earth observation has reliably documented vegetation greening, biomass increases, and the mitigation of rocky desertification across the South China karst. However, “greening” alone neither demonstrates an incremental effect of ecological restoration interventions nor substitutes for the verification of functional recovery in hydrology, soils, carbon, biodiversity, and ecosystem resilience. Based on structured searches completed on 10 August 2026 in the Web of Science Core Collection, Scopus, and China National Knowledge Infrastructure (CNKI), which yielded 837 records in total, this review is organized around three evidence chains: the identification of state changes, the attribution of intervention effects, and the verification of ecological functions. The available evidence indicates that (1) optical, microwave, LiDAR, thermal infrared, and UAV observations have clear advantages for monitoring vegetation cover, canopy structure, aboveground biomass, evapotranspiration, and landscape patterns; (2) key functional variables, including soil thickness, soil physicochemical properties, groundwater processes, soil and dissolved carbon, and species composition, can generally only be constrained indirectly and must be jointly validated using field plots, sensor observations, laboratory analyses, and process models; and (3) existing quasi-experimental studies in karst regions show that, where project boundaries, implementation timing, and comparable controls are available, methods such as difference-in-differences can strengthen the credibility of intervention-effect identification, although such evidence remains limited. Future research should prioritize function-oriented multi-source Earth observation products, independent validation across years and catchments, the explicit representation of uncertainty, and testable designs such as BACI and DID, thereby advancing remote sensing from merely documenting surface greening to providing verifiable evidence for judging ecosystem functional recovery. Full article

Land development inevitably causes disturbances to the ecosystem, leading to instability in ecological functions and abrupt changes in ecological resilience (ER). Previous studies mainly focused on the response of ER to land use but lacked simulations of nonlinear dynamics and quantitative analysis of the threshold effects, especially in mountainous cities with complex terrain. This study applied the boosted regression tree (BRT) model to explore nonlinear land-use effects and threshold features for ecological resilience (ER) across 16 topographic gradients in the Central Guizhou Urban Agglomeration. The gradients derive from four-level classification of elevation, slope, relief amplitude, and terrain position index. Results indicate that forestland shows consistent positive marginal associations with ER, with particularly strong relative contributions at mid-to-high topographic gradients. By contrast, cropland and construction land exert negative marginal effects that intensify under higher topographic constraints, and their suitable intervals narrow markedly in complex terrain. Model-derived empirical reference intervals show that forestland reaches 50–96% at high-elevation gradients; the upper limit for cropland is 7.07% on steep slopes; the suitable upper bound of construction land declines from approximately 50% in low-relief zones to 23% in high-relief zones. Such threshold disparities illustrate the moderating effect of topographic gradients on land-use-ecological resilience relationships, and these insights can offer conceptual references for differentiated territorial spatial governance of karst mountainous urban agglomerations. Full article

Microorganisms are sensitive indicators of aquatic environmental quality and ecosystem stability. Caohai Wetland, a typical subtropical plateau karst wetland suffering ecological degradation under combined natural-anthropogenic disturbances, is one of the three major plateau freshwater lakes in China and a critical wintering habitat for the Black-necked Crane (Grus nigricollis) along the East Asian–Australasian Flyway. Previous research has focused mainly on phytoplankton, aquatic plants, birds, and the water environment, while knowledge of its microbial community, especially the joint controls of multi-factor hydro-environmental conditions and aquatic plants across the whole lake, remains limited. To determine the diversity and seasonal dynamics of the microbial community and the key environmental factors driving it, water samples were collected from 17 sites in Caohai Lake across four seasons during 2022–2023 and analyzed by 16S rRNA gene sequencing, combined with measurements of hydro-physicochemical parameters and aquatic plant biomass and coverage. Among the 1370 ASVs obtained, the top five phyla in descending order of abundance were Pseudomonadota (45.04%), Bacillota (21.75%), Bacteroidota (11.82%), Actinomycetota (11.09%), and Verrucomicrobiota (3.65%). The microbial community exhibited significant seasonal variations, with richness, the Shannon-Wiener index, and Pielou’s evenness all significantly higher in autumn than in the other three seasons and lowest in spring. Correlation analysis indicated that water temperature was the primary driver of microbial community structure, while SD, EC, and COD also exerted significant influences; in addition, aquatic plant biomass and coverage were identified as key environmental factors shaping the microbial community composition in Caohai. This study provides fundamental monitoring data to support the assessment of the evolutionary trends of the Caohai wetland ecosystem and its conservation and management. Full article

The Upper Cretaceous and Jurassic karst aquifers of Sierra de Segura (southern Spain) represent an important groundwater resource within Sierras de Cazorla, Segura, and Las Villas Natural Park (the largest protected area in Spain). The two carbonate aquifer systems are separated by the low-permeability Utrillas Formation, composed mainly of sands, sandstones, and clay-rich sediments. Hydraulic connectivity between these aquifers remains poorly constrained in the literature. This study evaluated the hydrochemical and isotopic evidence of connectivity between the Upper Cretaceous and Jurassic aquifers using major ions (Na⁺, K⁺, Ca²⁺, Mg²⁺, Cl⁻, NO₃⁻, SO₄²⁻, and HCO₃⁻) and stable water isotopes (δ¹⁸O and δ²H) from 464 groundwater samples collected from 20 springs between May 2020 and October 2023. The hydrochemical results show a progressive increase in electrical conductivity and temperature from the Upper Cretaceous to the Jurassic aquifer, together with higher Mg²⁺, Na⁺, K⁺, Cl⁻, and SO₄²⁻ concentrations in the Jurassic system, indicating greater hydrochemical evolution. Principal Component Analysis (PCA) identified mineralization as the dominant controller of groundwater variability and revealed a hydrochemical gradient from relatively homogeneous Upper Cretaceous groundwater toward more mineralized Jurassic groundwater, with partial overlap between both groups. The convergence of hydrochemical, isotopic, multivariate, and temporal evidence is consistent with the hydraulic connectivity between the two aquifer systems. We propose the “SHOWER EFFECT” as a conceptual hypothesis involving potential groundwater transfer through the Utrillas Formation. However, alternative explanations cannot be excluded, and further tracer, groundwater age, and numerical modeling studies are required to test the proposed mechanism. Full article

Metal contamination in karst aquifers is a growing concern in rapidly urbanizing coastal regions. The Ruta de los Cenotes in Quintana Roo comprises groundwater-fed cenotes of high hydrogeological and ecological relevance. This study characterized the hydrogeochemical setting of five cenotes along a coastal–inland gradient, quantified metals in groundwater and sediments, and assessed ecological risk. Groundwater was sampled at 1, 15, and 25 m during dry and rainy seasons, and sediments at 30 m depth. Metals (Al, Ba, B, Cd, Cr, Cu, Fe, Li, Ni, Pb, and Zn) were determined by ICP-OES. Coastal and transitional cenotes showed calcium-sulfate waters and EC > 1200 µS/cm, whereas inland cenotes showed calcium-bicarbonate waters and EC < 1000 µS/cm. Multivariate analysis identified mineralization gradients during the dry season and site-specific variability during the rainy season. In groundwater, Al reached 0.487 mg/L in A-Ha, exceeding the NOM-127-SSA1-2021 limit of 0.20 mg/L. Al, Fe, Li, Cu and Zn were the main contributors to high ecological risk, with Al (RA = 3043.75) and Fe (RA = 74.15) showing the highest values during the rainy season. Overall, risk rankings differed seasonally, with Li > Cu > Zn > Fe > B > Ba in the dry season and Al > Fe > Zn > Cu > Cr in the rainy season. Sediment-associated ecological risk was highest at one coastal cenote (RI = 1868.66), driven mainly by Cd (2.17 mg/kg). These results provide quantitative information that can support future assessments and monitoring of metal-related vulnerability in karst ecosystems. Full article

Nitrate contamination threatens surface water and groundwater quality in karst regions, posing risks to drinking water safety and aquatic ecosystems. Strong surface water–groundwater connectivity in karst recharge areas can accelerate contaminant transport through fractures and conduits. In this study, 166 samples, comprising 100 groundwater samples and 66 surface-water samples, were collected under wet-season, normal-flow, and dry-season conditions from a typical karst recharge area in Fengshan Township, Dafang County, Guizhou Province, China. Hydrochemical analyses, dual nitrate isotope analysis, and isotope-based mixing models were integrated to evaluate potential nitrate source contributions and examine the hydrochemical factors associated with nitrate variability. Groundwater was dominated by Ca–HCO₃ and mixed hydrochemical facies and exhibited relatively stable ionic compositions, whereas surface water showed more diverse facies and greater variability in total dissolved solids, SO₄²⁻, Na⁺, K⁺, and Cl⁻, reflecting a stronger response to external inputs and short-term hydrological processes. NO₃⁻ concentrations ranged from 0.02 to 16.24 mg/L in groundwater and from 0.00 to 41.20 mg/L in surface water, with mean concentrations of 3.07 and 4.38 mg/L, respectively. Mixing-model estimates identified manure and sewage (47%) and soil nitrogen (30%) as the leading potential contributors to groundwater nitrate, whereas manure and sewage had the largest estimated contribution to surface-water nitrate (68%). Given the overlap among the isotopic signatures of potential sources, these percentages represent probable source combinations rather than exact apportionments. The absence of consistent covariation between NO₃⁻ and Cl⁻ indicated that nitrate transport was not controlled solely by conservative mixing but was jointly regulated by source-input intensity, rapid surface-runoff responses, conduit transport, subsurface mixing, dilution, and water–rock interactions. Statistical modeling further showed that groundwater NO₃⁻ variability was associated with the major-ion composition, whereas surface-water NO₃⁻ variability was partly explained by a multiple regression model incorporating SO₄²⁻ and Cl⁻. Together, these findings support a conceptual source-to-transport framework involving external inputs, rapid surface-water responses, karst conduit transport, subsurface mixing, and water–rock interaction. This study provides insight into contrasting potential nitrate sources and transport processes in connected karst surface water-groundwater systems and supports pollution-source tracing, recharge-area management, and drinking-water source protection. Full article

Soil microbial biogeography on nearshore islands remains less well understood than that on remote archipelagos, particularly when bacterial and fungal diversity, community composition, and co-occurrence associations are evaluated together. We characterized bacterial 16S rRNA gene and fungal ITS communities in 36 topsoil samples collected from five nearshore islands in the northern South China Sea and examined their associations with plant diversity, soil physicochemical properties, and climatic and geographic conditions. Bacterial Shannon diversity, ACE richness, and Simpson diversity differed significantly among islands, as did fungal ACE richness, whereas fungal Shannon and Simpson diversity showed no significant differences. Bray–Curtis-based analyses revealed island-associated differentiation in bacterial community composition and fungal community composition, although multivariate dispersion also differed among islands. Sample-level subnetworks derived from an integrated co-occurrence network showed that the number of bacteria–bacteria edges differed significantly among islands, whereas the numbers of bacteria–fungi and fungi–fungi edges did not. Exploratory Spearman correlation analyses and variation partitioning indicated that microbial properties were more broadly associated with soil physicochemical properties and climatic–geographic conditions than with plant diversity. By evaluating both microbial kingdoms within the same field campaign, this study identifies partly distinct bacterial and fungal biogeographic and co-occurrence patterns and provides a baseline for future microbial biodiversity monitoring on nearshore islands. Full article

Although many studies had been conducted on soil microbial communities in forest ecosystems before this one, how the diversity and network complexity of soil microbial communities evolved throughout the succession of karst forests remained unclear. We collected soil samples from three vegetation successional stages (grassland stage, shrub stage and arbor stage) in Maolan National Nature Reserve, Guizhou Province, China, and applied high-throughput sequencing technology to explore soil microbial diversity, community composition, co-occurrence network characteristics and their internal correlations. The results showed that the succession process significantly affected soil microbial diversity (p < 0.05). Bacterial diversity increased by 12.33% as succession proceeded, whereas fungal diversity declined by 37.50%. The dominant microbial communities exhibited obvious stage-specific characteristics. For bacteria, Bacillaceae served as a universally dominant taxon. Paenibacillaceae and Thermoactinomycetaceae were enriched in the grassland (CD) stage, and the relative abundance of Streptosporangiaceae reached its maximum in the arbor (QM) stage. For fungi, Trimorphomycetaceae and Hypocreaceae were ubiquitous dominant groups. Aspergillaceae possessed the highest relative abundance in the CD stage, while Clavicipitaceae peaked in relative abundance in the QM stage. The complexity of bacterial co-occurrence networks rose with succession, whereas fungal network complexity decreased. Both positive and negative linkages in bacterial networks increased over succession, while both types of connections in fungal networks declined. Soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP) and N/P ratio exerted the strongest influences on bacterial communities and bulk density; SOC and TN were the key drivers structuring fungal assemblages. Micromonosporaceae and Xanthobacteraceae showed significant positive correlations with TP and N/P ratio (p < 0.05), whereas Thermoactinomycetaceae and Oscillospiraceae presented significant negative correlations with these two indicators (p < 0.01). Clavicipitaceae had strong positive correlations with SOC and TN (p < 0.01), and Herpotrichiellaceae together with Aspergillaceae displayed significant negative correlations with SOC and TN (p < 0.05). This study clarified the regulatory effects of karst forest secondary succession on soil microbial communities and provided theoretical evidence for the ecological restoration of karst regions. Full article

Soil microbial carbon use efficiency (CUE) is an essential metric for assessing soil carbon cycling efficiency. In contemporary biogeochemical models, microbial CUE is often treated as a constant, but it is intricately regulated by biotic and abiotic factors, especially in heterogeneous karst rocky desertification (KRD) ecosystems. In the Guizhou Huajiang KRD area, this study used ecological stoichiometry, high-throughput sequencing, analysis of variance, and partial least squares regression to evaluate CUE across three restoration types, Zanthoxylum bungeanum (ZB), Selenicereus undatus (SU), and Pennisetum × sinese (PS), with Zea mays (ZM) as control. Results showed that restoration types affected CUE. Soil bulk density (SBD), total potassium (TK), and available phosphorus (AP) were key predictors of CUE, significantly correlating with generalist communities such as Planctomycetota, Gemmatimonadota, unclassified_Gemmatimonadaceae, unclassified_Roseiflexaceae, and unclassified_Trichomeriaceae. Inconsistent variations in α- and β- diversity across types indicated CUE regulation was driven by integrated structural and functional responses. These findings highlight the importance of soil physical properties, potassium cycling, low-phosphorus adaptation, and generalist communities for species selection. Future studies must isolate vegetation and management effects, extending observations from winter to the full growing season to clarify seasonal plant-soil-microbial feedbacks. Full article

Climate change is altering global temperature and precipitation patterns, with particularly strong effects expected in Mediterranean regions, where reduced groundwater recharge and increased evapotranspiration may affect groundwater-dependent ecosystems. This study provides a preliminary, indicator-based assessment of the potential sensitivity of the Cabecera del Bornova Groundwater Body (Guadalajara, Spain), which sustains the Somolinos karst wetland, under natural conditions and protected as a Natural Groundwater Reserve and Natural Lacustrine Reserve. Empirical correlations were established between accumulated deviations of historical precipitation and observed piezometric levels in two monitoring piezometers using second-degree polynomial functions. The most informative relationships were obtained for piezometer ZE01, particularly at the daily scale, whereas the second piezometer showed weaker relationships. These functions were applied to regionalized climate projections generated with the FICLIMA methodology from ten CMIP6 models under SSP1-2.6, SSP2-4.5, SSP3-7.0 and SSP5-8.5 scenarios from the IPCC Sixth Assessment Report. The results indicate a general decreasing tendency in empirical piezometric-level indicators throughout the 21st century, although the magnitude of the response is highly sensitive to the selected rainfall station, temporal resolution, climate model and scenario. Extreme projected declines are interpreted as extrapolation-sensitive outputs rather than deterministic predictions of aquifer drawdown or groundwater-reserve depletion. Direct impacts on lagoon level, spring discharge or wetland extent cannot be quantified with the dataset. The results highlight the need to expand piezometric monitoring, instrument the Manadero del Bornova spring, monitor lagoon water levels and develop physically based recharge and groundwater-flow models. Full article

Alpine karst lakes in Jiuzhaigou exhibit spatial variations in optical properties associated with differences in water depth, underwater substrates, and travertine distribution. Conventional satellite observations may not provide sufficient spatial resolution to resolve the small-scale optical variations present in these shallow and heterogeneous lakes. In this study, UAV-based hyperspectral imagery was used to quantify spatial optical variations among three representative cascade lakes located in the “Y-shaped” valley network of Jiuzhaigou, China. Hyperspectral reflectance data were transformed into the CIE L*a*b* color space to quantify perceptual color variability, while the Euclidean color difference metric (ΔE) was used to assess relative spatial heterogeneity. In addition, seven empirical optical proxies were developed to describe spatial variations in apparent optical properties without attempting absolute retrieval of water constituents. A tiered unsupervised K-means clustering approach was applied to resolve optical heterogeneity across multiple spatial scales. Global-scale clustering separated the major optical differences among lakes, whereas lake-specific clustering revealed distinct intra-lake optical zones, including areas with stronger benthic influence, transitional optical conditions, and zones dominated by water-column signals. Non-parametric Kruskal–Wallis H tests showed significant differences among optical zones, indicating that the selected proxies can distinguish spatial optical variability. The results show that UAV hyperspectral observations combined with color metrics and empirical optical proxies can effectively describe fine-scale spatial optical variations in alpine karst lakes. Rather than retrieving absolute biogeochemical or bathymetric parameters, this approach provides a reference description of relative optical variability that may assist future repeated observations and spatial monitoring of protected aquatic ecosystems. Full article

The carbon budget of maize croplands has been widely studied across the Chinese Maize Belt. However, the effects of drought on ecosystem-scale carbon fluxes in rain-fed maize croplands remain poorly understood in Southwest China. To address this gap, we conducted long-term, continuous eddy covariance measurements of carbon fluxes at a rain-fed maize field in Guizhou Province from 2022 to 2025. During the maize growing season, the mean net ecosystem exchange (NEE) was −310 ± 21 g C m⁻², with over 50% of the total seasonal NEE occurring in July. Interannual variability in the NEE was primarily driven by prolonged dry spells during the reproductive stage. Maize cropland without straw return acted as a net C source when harvest removals were considered. We therefore recommend promoting straw return practices in the region to strengthen soil carbon sequestration capacity and enhance agroecosystem resilience to drought. And further research is needed to evaluate the role of straw return practices on the carbon budget in the area. Full article