Search Results (385)

Ecological stoichiometry, as a discipline investigating plant elemental coupling mechanisms, has become a research focus across various ecosystems. However, few studies have examined plant stoichiometric characteristics in the water–land ecotone of plateau karst lake wetlands. It remains unclear whether foliar nutrient contents and stoichiometric ratios in this transitional zone vary with flooding intensity. This study established three sampling gradients (near-water area, middle area, and far-water area) within the water–land ecotone of Caohai Lake wetland in Guizhou Plateau, measuring nutrient concentrations along with their stoichiometric ratios in leaves of three dominant plant species. The results revealed significant interspecific differences in leaf nitrogen (N), phosphorus (P), potassium (K), calcium (Ca) concentrations and N:P ratios among the three dominant species, while significant spatial variations were observed in N concentration and the C:N ratio across sampling locations. Correlation analysis demonstrated significant positive relationships among leaf N, P, and K concentrations, all showing negative correlations with C concentration. Phragmites australis exhibited significantly lower C:N and N:P ratios compared to Scirpus validus and Juncus effusus, suggesting its growth advantage through rapid nutrient acquisition. This species may serve as an efficient phytoremediator for N and P absorption from both soil and water. These findings provide valuable references for vegetation selection in constructed wetlands. Full article

Subterranean ecosystems represent some of the most unique and fragile habitats on Earth, yet they remain poorly understood and highly vulnerable to human-induced disturbances. Despite their ecological significance, these systems are rarely integrated into conservation planning, and surface-level protected areas alone are insufficient to safeguard their biodiversity. In southeastern Brazil, a karst landscape spanning approximately 1200 km², recognized as the region with the highest cave density in South America (approximately 2600 caves), is under increasing pressure from urban expansion, agriculture, and mining, all of which threaten the ecological integrity of subterranean habitats. This study sought to identify caves of high conservation priority by integrating species richness of non-troglobitic invertebrates, occurrence of troglobitic species, presence of endemic troglobitic taxa, and the degree of anthropogenic impacts, using spatial algebra and polygon-based mapping approaches. Agriculture and exotic forestry plantations (54%) and mining operations (15%) were identified as the most prevalent disturbances. A total of 32 troglobitic species were recorded, occurring in 63% of the 105 surveyed caves. Notably, seven caves alone harbor 25% of the region’s known cave invertebrate diversity and encompass 50% of its cave-restricted species. The findings highlight the global significance of this spot of subterranean biodiversity and reinforce the urgent need for targeted conservation measures. Without immediate action to mitigate unsustainable land use and resource exploitation, the persistence of these highly specialized communities is at imminent risk. Full article

Seasonally dry tropical forests (SDTFs) are shaped by strong climatic and edaphic constraints, including pronounced rainfall seasonality, extended dry periods, and shallow karst soils with limited water retention. Understanding how tree species respond to these pressures is crucial for predicting ecosystem resilience under climate change. In the Yucatán Peninsula, we characterized sixteen tree species along a spatial and seasonal precipitation gradient, quantifying wood density, predawn and midday water potential, saturated and relative water content, and specific leaf area. Across sites, diameter classes, and seasons, we measured ≈4 individuals per species (n = 319), ensuring replication despite natural heterogeneity. Using a principal component analysis (PCA) based on individual-level data collected during the dry season, we identified five functional groups spanning a continuum from conservative hard-wood species, with high hydraulic safety and access to deep water sources, to acquisitive light-wood species that rely on stem water storage and drought avoidance. Intermediate-density species diverged into subgroups that employed contrasting strategies such as anisohydric tolerance, high leaf area efficiency, or strict stomatal regulation to maintain performance during the dry season. Functional traits were strongly associated with precipitation regimes, with wood density emerging as a key predictor of water storage capacity and specific leaf area responding plastically to spatial and seasonal variability. These findings refine functional group classifications in heterogeneous karst landscapes and highlight the value of trait-based approaches for predicting drought resilience and informing restoration strategies under climate change. Full article

Nitrogen (N) is a key nutrient for sustaining ecosystem productivity and agricultural sustainability; however, achieving high-precision monitoring in wetlands with highly heterogeneous surface types remains challenging. This study focuses on Caohai, a representative karst plateau wetland in China, and integrates Sentinel-2 multispectral and Zhuhai-1 hyperspectral remote sensing data to develop a soil nitrogen inversion model based on spectral indices, texture features, and their integrated combinations. A comparison of four machine learning models (RF, SVM, PLSR, and BPNN) demonstrates that the SVM model, incorporating Zhuhai-1 hyperspectral data with combined spectral and texture features, yields the highest inversion accuracy. Incorporating land-use type as an auxiliary variable further enhanced the stability and generalization capability of the model. The study reveals the spatial enrichment of soil nitrogen content along the wetland margins of Caohai, where remote sensing inversion results show significantly higher nitrogen levels compared to surrounding areas, highlighting the distinctive role of wetland ecosystems in nutrient accumulation. Using Caohai Wetland on the Chinese karst plateau as a case study, this research validates the applicability of integrating spectral and texture features in complex wetland environments and provides a valuable reference for soil nutrient monitoring in similar ecosystems. Full article

Karst landscapes, characterized by ecological constraints such as thin soil layers, severe rock desertification, and fragile habitats, require a clear understanding of the mechanisms regulating carbon storage and the impacts of ecological restoration measures. However, current research lacks detailed insights into the specific effects of ecological restoration measures. This study integrates multi-source remote sensing data and adjusts InVEST model parameters to systematically reveal the spatiotemporal evolution of carbon storage and its driving mechanisms in typical karst plateau regions of southwest China under ecological restoration measures. The results indicate: (1) From 2000 to 2020, the carbon stock in the study area increased by 6.09% overall. However, from 2020 to 2025, due to the rapid conversion of forest land into building land and grassland, the carbon stock decreased sharply by 7.69%. (2) Severe rock desertification constrains carbon stock, and afforestation provides significantly higher long-term carbon sink benefits. (3) The spatial heterogeneity of carbon storage is primarily influenced by the combined effects of natural factors (rock desertification, elevation, NDVI) and human factors (POP). Based on the research findings, it is recommended that measures to promote close forests be prioritized in karst regions to protect and restore forest ecosystems. At the same time, local habitat improvement and the establishment of ecological compensation mechanisms should be implemented, and the expansion of building land should be strictly controlled to enhance the stability of ecosystems and their carbon sink functions. These research findings provide a solid scientific basis for enhancing and precisely regulating the carbon sink capacity of fragile karst ecosystems, and are of great significance for formulating scientifically sound and reasonable ecological protection policies. Full article

This study investigated how moss species identity and coverage density influence soil organic carbon (OC), total nitrogen (TN), total phosphorus (TP), cation exchange capacity (CEC), and stoichiometric ratios (C/N, C/P, N/P ratios) across soil depths in karst ecosystems of northern Guangxi, China. Spectral responses to moss cover were concurrently analyzed. Soil properties under moss crusts and bare controls were quantified through chemical assays. Coverage effects were compared via bar charts (sparse) and point-line plots (dense) with fitted curves and 95% confidence intervals. Spectral reflectance (250–2500 nm) was measured to characterize surface optical properties. Statistical correlations between variables were established. Research has shown the following: (1) Moss coverage significantly enhanced OC, TN, and CEC versus bare soil (B. dichotomum showed the strongest improvement: dense crust increased OC/TN/TP by 6.37/1.73/0.45 g kg⁻¹ and doubled CEC). (2) All nutrients and CEC decreased with depth, most sharply for G. humillimum OC (22.38% reduction at 3–6 cm) and P. yokohamae CEC (9.97% reduction). (3) Stoichiometric ratios exhibited species-specific responses: B. dichotomum had the smallest inter-layer differences in C/N/P ratios, while G. humillimum increased C/N by 34.33% at 3–6 cm. Sparse coverage elevated N/P ratios up to 59.38% (G. humillimum, 0–3 cm). (4) Spectral analysis revealed the following: Sparse coverage boosted reflectance via edge scattering and soil background contributions. Dense coverage suppressed reflectance due to water absorption (1450/1900 nm) and limited scattering. Bare soil exhibited persistently low reflectance from hematite absorption (500–700 nm). Moss biocrusts—particularly dense B. dichotomum—optimize topsoil fertility and CEC in karst soils, though effects diminish sharply below 3 cm. Spectral signatures provide non-invasive indicators of coverage density and erosion resistance. These insights highlight the crucial role of species-specific moss selection in promoting sustainable restoration practices and long-term ecological recovery in rocky desertification regions. Full article

Karst rivers are increasingly contaminated by both heavy metals and nanoplastics, yet their combined impact on riparian litter decomposition remains unresolved. We conducted a 90-day microcosm experiment using Miscanthus floridulus leaf litter collected from the Donghe River, Jishou, China, and exposed it to Pb (1 mg L⁻¹), polystyrene nanoplastics (10 and 100 µg L⁻¹), and their combinations. Pb alone modestly inhibited mass loss (61.0%) and respiration, while NP10 significantly accelerated decomposition (67.0%), and NP100 suppressed it (60.4%); co-exposure produced non-monotonic, concentration-dependent effects. Enzyme stoichiometry revealed that all treatments intensified nitrogen limitation but alleviated carbon limitation through reduced microbial activity. Bacterial communities, dominated by Pseudomonadota, exhibited remarkably stable phylum-level composition, high network complexity, and identical keystone taxa across all treatments, indicating strong functional redundancy and resilience. In contrast, fungal communities suffered severe declines in Basidiomycota abundance, collapsed network stability, and a single keystone taxon, underscoring their vulnerability. βNTI–RC_bray analyses demonstrated that stochastic processes (>50%) overwhelmingly governed both bacterial and fungal assembly, with only marginal deterministic shifts. Collectively, our findings highlight that bacteria—not fungi—serve as the primary decomposers under Pb–NP co-stress and that stochastic assembly, coupled with bacterial redundancy, buffers ecosystem function against emerging mixed pollutants in subtropical riverine systems. Full article

Forest parks are vital terrestrial ecosystems that provide multiple ecosystem services (ESs) to both society and nature, including carbon storage, water conservation, soil retention, and tourism-related cultural services. These services are essential for maintaining ecological security and supporting socio-economic development. However, little is known about how ESs vary across forest parks situated in different karst landforms, and integrated re-search on the combined effects of climate, vegetation, karst surface characteristics, and tourism remains limited. In this study, we examine forest parks in Guizhou Province, China, selecting four key ESs—water conservation, soil retention, carbon storage, and cultural services associated with tourism—and evaluate their levels through a comprehensive ecosystem services index (CES). We apply a structural equation model (PLS-SEM) to disentangle how climate, vegetation, karst surface features, and tourism activities drive spatial heterogeneity in CES. The results reveal significant differences among karst land-form units: carbon storage is relatively low in karst plateaus and gorges, whereas water conservation is highest in non-karst areas. Together, the four categories of driving factors explain 71.6–74.2% of the variance in CES, with climate emerging as the dominant contributor to spatial variation. For individual services, the principal drivers differ: normalized difference vegetation index (NDVI) and tourist numbers are jointly shaped by karst surface characteristics and climate, while multi-year average spring precipitation is the most influential factor across forest parks. This study provides new evidence of the socio-ecological mechanisms regulating ESs in karst mountain forestscapes and offers a scientific reference for enhancing and regeneratively managing ecosystem services in these fragile regions. Full article

The soil–water partition coefficient (Kd) of antibiotics is a critical indicator for assessing their migration potential in the environment. Currently, research on antibiotic Kd values in specific geological settings such as karst wetlands remains relatively limited. This study uniquely integrates partial least squares (PLS) regression with redundancy analysis (RDA), a hybrid approach that effectively handles complex environmental datasets prone to multicollinearity. The results identified Fe³⁺, NO₃⁻, and PO₄³⁻ in water, as well as clay content, organic matter, bulk density, and pH in sediments, as key factors influencing Kd through redundancy analysis. Using PLS, predictive models were developed for the logKd of four antibiotics: tetracycline (TC), doxycycline (DOX), chlortetracycline (CTC), and demeclocycline (DMC). The models demonstrated strong predictability with Q₂cum values of 0.96, 0.93, 0.99, and 0.83, respectively, indicating excellent model convergence. These findings provide important insights into how soil and water physicochemical properties influence the distribution of antibiotics, support the prediction of antibiotic transport and fate, and contribute to the exposure and risk assessment of these emerging contaminants in aquatic ecosystems. Full article

Karst rocky desertification on the Qinghai–Tibet Plateau poses a severe threat to the region’s fragile ecosystem. Accordingly, the rapid and accurate delineation of plateau karst landforms is essential for monitoring ecological degradation and guiding restoration strategies. However, automatic recognition of these landforms in remote sensing imagery is hindered by challenges such as blurred boundaries, fragmented targets, and poor intra-region consistency. To address these issues, we propose the Region Affinity Propagation Network (RAP-Net). This framework enhances intra-region consistency, edge sensitivity, and multi-scale context fusion through its core modules: Region Affinity Propagation (RAP), High-Frequency Multi-Scale Attention (HFMSA), and Global–Local Cross Attention (GLCA). In addition, we constructed the Plateau Karst Landform Dataset (PKLD), a high-resolution remote sensing dataset specifically tailored for this task, which provides a standardized benchmark for future studies. On the PKLD, RAP-Net surpasses eight state-of-the-art methods, achieving 3.69–10.31% higher IoU and 3.88–14.28% higher Recall, thereby demonstrating significant improvements in boundary delineation and structural completeness. Moreover, in a cross-regional generalization test on the Mount Genyen area, RAP-Net—trained solely on PKLD without fine-tuning—achieved 2.38% and 1.94% higher IoU and F1-scores, respectively, than the Swin Transformer, confirming its robustness and generalizability in complex, unseen environments. Full article

The aim of this study was to elucidate the reproductive strategy of Camellia luteoflora, an endangered evergreen endemic to karst ecosystems. We observed and recorded its flowering phenology and flower-visiting insects, observed pollen morphology, determined pollen viability, and assessed stigma receptivity. The results showed that the flowering period of C. luteoflora started from early September to late December, with the average flowering period of individual flowers being 10–12 days. The pollen morphology of C. luteoflora was subprolate and prolate, with three germinal apertures and the fossulate exine ornamentation. Pollen viability was the highest at the initial opening stage (80.30%). In the process of pollen in vitro, the order of influence on the germination rate and pollen tube length was temperature > sucrose > calcium chloride (CaCl₂) > boric acid (H₃BO₃). The best combination for the germination rate was 24 °C, 75 g/L sucrose, 0.2 g/L CaCl₂, 0.15 g/L H₃BO₃, while that for the pollen tube length was 24 °C, 100 g/L sucrose, 0.2 g/L CaCl₂, 0.25 g/L H₃BO₃. Stigma receptivity was the strongest at the full blooming stage. The pollen/ovule ratio (P/O) was 2240, suggesting a facultative outcrossing breeding system. The outcrossing index (OCI) was 4, suggesting that the exogamous breeding system is the cross-pollination type, partially self-compatible and insect pollinator-dependent. The flower-visiting insects included bees, weevils, and ants. In summary, C. luteoflora exhibits an extended flowering period, with a prolonged overlap of stable pollen viability and stigma receptivity, suggesting a potential strategy to cope with pollination uncertainty. However, field observations recorded only a few species of potential pollinators, while the occurrence frequency of non-pollinating insects was relatively high. It is thus hypothesized that this apparent lack of effective pollinators may act as a potential barrier to successful fertilization and natural regeneration, which might also be one of the factors contributing to its endangered status. Future studies, particularly pollinator exclusion and hand-pollination experiments, are critically needed to verify whether pollinator limitation is indeed a key factor. Full article

The karst region is highly ecologically fragile due to its unique geology and poor water and nutrient retention. Despite long-term restoration, vegetation often remains in the secondary shrubland stage. Soil microorganisms play a vital role in maintaining ecosystem functions, but how microbial communities respond to combined water and nitrogen-phosphorus nutrient changes in karst shrubland remains poorly understood. This knowledge gap hinders effective restoration strategies in karst shrublands. Here, the effects of water, nitrogen, and phosphorous additions and their interactions on soil physico-chemical properties, soil microbial abundance, diversity, community composition, and the co-occurrence network were explored. A full factorial experiment (water × nitrogen × phosphorous, each at two levels) was conducted in a karst shrubland with over 20 years of vegetation restoration, with treatments including control, water (+120 mm yr⁻¹), nitrogen (+20 g N m⁻² yr⁻¹), phosphorus (+16 g P m⁻² yr⁻¹), and their four combinations. Our results suggested that water addition significantly increased soil water content and soil microbial abundance but reduced fungal diversity. Nitrogen addition significantly increased soil nitrate nitrogen content and fungal diversity, and fungal diversity showed an increasing trend under phosphorous addition. The addition of nitrogen and phosphorous did not significantly alter the soil microbial community composition, while water addition showed a tendency to change the soil fungal community composition. Network topological properties, robustness, and vulnerability analyses indicated that individual nitrogen or phosphorous additions, as well as their interactions, reduced network complexity and stability. In contrast, water addition alone or in combination with nitrogen and/or phosphorous alleviated these negative effects, and the water and phosphorous interaction exhibited the highest levels of network complexity and stability. Further analysis showed that the soil pH, available phosphorous, ratio of carbon to phosphorous, and ammonium nitrogen were explanatory variables contributing significantly to soil microbial abundance, diversity, community composition, and network complexity. Overall, these findings highlighted the pivotal role of water availability in enhancing soil microbial stability under nutrient enrichment, offering valuable insights into ecological restoration in karst ecosystems. Full article

Farmland use transition (FUT) not only reshapes agricultural production systems but also significantly impacts cross-regional carbon sink transfers in the grain trade. However, comprehensive studies exploring connections between FUT and grain carbon sink transfer (GCST) are limited. We constructed an indicator system and transformation framework for FUT by considering dominant and recessive dimensions. Moreover, we estimate GCST based on grain supply–demand balance and fixed carbon coefficients. Fixed effects and threshold models are employed to identify both linear and nonlinear relationships between FUT and GCST. Results show that FUT significantly reshapes carbon sink flows. In terms of dominant FUT indicators, cultivation land rate (CLR) and grain planting area proportion (GPAP) positively drive GCST by expanding the carbon sink supply and exporting ecological services. Regarding recessive FUT indicators, both grain yield per unit area (GYield) and pesticide-fertilizer intensity (PFI) promote GCST, highlighting the role of efficiency and inputs, while rural per capita disposable income (RPCDI) suppresses GCST due to agricultural marginalization. A grain yield threshold of 2.092 t/ha is identified. Below this value, FUT exerts substantial positive effects on GCST. Above it, the effects weaken. This study explains the relationship between FUT and ecosystem carbon sinks, providing a scientific basis for advancing green agriculture in karst mountainous areas. Full article

Climate change has intensified the frequency and severity of forest disturbances globally, including windthrow, which poses substantial risks for both forest productivity and ecosystem stability. Rapid and precise assessment of wind-induced tree damage is essential for effective management, yet many injuries remain visually undetectable in the early stages. This study employed drone-based multispectral imaging and a simulated wind stress experiment (static pulling) on Norway spruce (Picea abies (L.) Karst.) to investigate the detectability of physiological and structural changes over four years. Multispectral data were collected at multiple time points (2023–2024), and a suite of vegetation indices (the Normalised Difference Vegetation Index (NDVI), the Structure Insensitive Pigment Index (SIPI), the Difference Vegetation Index (DVI), and Red Edge-based indices) were calculated and analysed using mixed-effects models. Our results demonstrate that trees subjected to mechanical bending (“Bent”) exhibit substantial reductions in the near-infrared (NIR)-based indices, while healthy trees maintain higher and more stable index values. Structure- and pigment-sensitive indices (e.g., the Modified Chlorophyll Absorption Ratio Index (MCARI 2), the Transformed Chlorophyll Absorption in Reflectance Index/Optimised Soil-Adjusted Vegetation Index (TCARI/OSAVI), and RDVI) showed the highest diagnostic value for differentiating between damaged and healthy trees. We found the clear identification of group- and season-specific patterns, revealing that the most pronounced physiological decline in Bent trees emerged only several seasons after the disturbance. Full article

This study investigates the microclimate characteristics and temporal variations in carbon and water fluxes in the naturally restored plots in Puding County, Anshun City, Guizhou Province. Continuous monitoring and collection of environmental factors through the eddy covariance system reveals the dynamic change patterns of the microclimate environment in the early stages of returning farmland to forest and the dynamic characteristics of carbon and water fluxes in the ecosystem. The results show that the study area exhibits a pronounced carbon sink capacity at the annual scale. The net ecosystem exchange (NEE) gradually increased with the extension of the recovery time, and the carbon sink intensity reached its peak during the growing season (June–August). The water use efficiency (WUE) was significantly higher in the growing season compared to the non-growing season, indicating that the WUE and carbon sequestration capacity increased simultaneously. Structural equation model (SEM) analysis revealed that latent heat flux has the most significant regulatory effect on carbon sink function. Furthermore, temperature, relative humidity, and latent heat flux have a significant positive regulatory effect on NEE (p < 0.001), while rain and soil heat flux affect carbon sink function through an indirect path. By constructing a complex meteorological carbon flux relationship network, the main regulatory mechanism of the ecosystem carbon sink in the Puding area was revealed. These findings confirm that the implementation of returning farmland to forest has effectively enhanced the carbon sequestration capacity of karst ecosystems. Full article