Search Results (13,436)

Soil fungal communities play a central role in nutrient cycling and ecosystem functioning in tropical montane forests, yet the relative influence of topographic heterogeneity and soil depth on their assembly remains poorly understood. This study evaluated the composition, diversity, and functional structure of soil fungal communities associated with an experimental Podocarpus oleifolius plantation in the Colombian Andes. Using ITS2 rDNA sequencing, fungal assemblages were characterized from soil samples collected around ten trees distributed along a topographic gradient. For each tree, samples were collected at two soil depths (0–10 cm and 10–20 cm), yielding a total of 17 samples after quality control. Topographic variables derived from a digital elevation model were used to evaluate their influence on community structure. A total of 1875 Operational Taxonomic Units (OTUs) were detected, dominated by Ascomycota. No significant differences in alpha or beta diversity were observed between soil depths. In contrast, slope emerged as the strongest environmental driver of community composition. A high proportion of unassigned OTUs highlighted the presence of poorly characterized fungal diversity. These findings highlight the importance of incorporating fine-scale terrain heterogeneity into restoration strategies with native species and into future studies of soil microbial dynamics in tropical montane ecosystems. Full article

Reanalysis datasets provide gridded, high-frequency estimates of atmospheric variables that are essential for studying weather and climate, particularly in regions with sparse observational networks. Despite their widespread use, the quality of reanalysis products remains insufficiently validated in tropical regions, particularly in areas with complex terrain. In this study, we evaluate the performance of surface-level temperature and atmospheric pressure fields from ERA5 and ERA5-Land in the state of Alagoas, northeastern Brazil. The analysis is based on a 12-year comparison (2008–2019) with observational data from the National Institute of Meteorology (INMET). Prior to validation, altitude corrections were applied to minimize elevation-induced biases in the reanalysis fields. Performance was assessed using statistical metrics. Both reanalyses showed strong agreement with observations, with average correlations exceeding 0.91 for temperature and pressure. ERA5 temperature biases ranged from −0.2 °C to 0.3 °C, and those for ERA5-Land from −0.6 °C to −0.3 °C, with RMSE around 1.6 °C. Pressure biases were initially larger (−20 hPa to +6 hPa in ERA5), but were reduced to below 0.5 hPa at key reference stations after correction. Diurnal and seasonal cycle analyses confirmed the datasets’ ability to reproduce temporal variability, though both reanalyses tended to overestimate minimum temperatures and underestimate maximum temperatures. Further investigation is needed to identify the origin of anomalous temperature jumps in ERA5’s diurnal cycle, which seem unrelated to the assimilation cycles. Overall, the results highlight the robust performance of ERA5 and ERA5-Land in representing surface atmospheric conditions in tropical coastal regions, while also emphasizing the continued need for regional validation and preprocessing before application in high-resolution or short-term studies. Full article

Madagascar’s Central Highlands have experienced extensive deforestation and soil degradation, limiting the success of reforestation efforts. Poor soil fertility, particularly nitrogen limitation, constrains early seedling growth in degraded landscapes. This study evaluated the field performance of composted Black Soldier Fly frass (CBSFF) as a soil amendment for the native pioneer tree Dodonaea madagascariensis within the Ambohitantely Special Reserve. Four treatments were compared across four sites using a randomized complete block design: unfertilized control, cattle manure (4 g N), CBSFF one-fold (4 g N), and CBSFF two-fold (8 g N). The experiment was conducted on seedlings aged 16 months at the start of the study, and their growth was monitored over a six-month period. Growth responses were analyzed using generalized linear mixed-effects models with site included as a random factor. Seedling survival remained near 100% across all treatments, indicating no phytotoxic effects of composted frass under field conditions. Fertilization significantly enhanced both basal stem diameter and height growth. When standardized by nitrogen input, cattle manure and CBSFF produced comparable growth responses, indicating that nitrogen availability, rather than fertilizer identity, primarily drove early seedling performance. Height growth exhibited a clear dose-dependent response, with the double-dose CBSFF treatment producing the greatest increase. Planting method had a modest effect on height but did not alter the relative performance of fertilizer treatments. These findings demonstrate that composted BSF frass functions as an effective nitrogen source for early tree establishment in degraded tropical soils and performs comparably to traditional manure under field conditions. By validating insect-derived fertilizer within a restoration context, this study supports the integration of circular nutrient systems into sustainable reforestation strategies in biodiversity-rich yet resource-limited landscapes. Full article

Weed interference during early growth stages is a major constraint on sugarcane productivity, yet effective tools for species-specific detection remain limited in tropical agricultural systems. This study evaluated the spectral separability between Sugarcane (Saccharum officinarum) and a dominant weed species, Rottboellia cochinchinensis, to develop an accessible framework for early-stage weed mapping. Multispectral data acquired from an Unmanned Aerial Vehicle (UAV) and hyperspectral data obtained from a field spectrometer were utilized. Hyperspectral data were synthesized to reconstruct multispectral bands (UAV image bands) using a regularized linear synthesis model, thereby generating spectral signatures. Spectral separability between sugarcane and Rottboellia cochinchinensis was assessed visually and statistically (Jeffries–Matusita distance). Blue and Green bands provided the strongest differentiation between species, while RedEdge enhanced separability when paired with pigment-sensitive wavelengths. When using vegetation indices based on the near-infrared (NIR) band, the visual appearance of class separation was poor due to the NIR band’s sensitivity to variation in leaf internal structure, canopy architecture, water content, and spectral mixing with the soil background at the early stage of sugarcane. These results were used to differentiate weed coverage from sugarcane. Object-based image analysis (OBIA) outperformed the pixel-based method, achieving higher overall accuracy (0.9038) and a more spatially coherent weed delineation (Kappa = 0.8499). These findings suggest that synthesized spectral signatures of Rottboellia cochinchinensis and sugarcane, combined with targeted spectral indices and OBIA techniques, offer a practical and transferable approach for early detection of Rottboellia cochinchinensis at the farm level. Full article

Rapid urbanization in South Asian coastal cities is systematically dismantling natural cooling infrastructure, driving unprecedented urban heat island (UHI) intensification with severe consequences for human health, energy systems, and urban livability. Despite growing research attention, comprehensive frameworks that simultaneously capture temporal UHI dynamics, machine learning-based thermal projections, and community-grounded validation remain scarce, particularly for secondary coastal cities in tropical developing regions. This study addresses these gaps by investigating UHI dynamics in Chattogram City Corporation (CCC), Bangladesh, through three integrated methodological pillars: (1) multi-temporal remote sensing analysis using Landsat 5 and 8 imagery spanning 2005–2025; (2) comparative evaluation of five machine learning algorithms (LightGBM, Random Forest, XGBoost, SVM, and MLP) for land use/land cover (LULC) classification and land surface temperature (LST) regression, with iterative scenario projections for 2029, 2033, and 2037; and (3) a structured public perception survey of 384 residents validated through participatory mapping and focus group discussions. Landsat analysis revealed dramatic LULC transformations: built-up areas expanded 88% (12,649 to 23,719 acres), while waterbodies declined 53.1% and vegetation decreased 21.9%. Mean LST increased by 9.09 °C (from 30.94 °C to 40.03 °C), with mean UHI intensity rising from 19.59 to 33.88 standardized units over two decades. LightGBM achieved optimal LULC classification (F1-weighted: 0.765) while Random Forest best predicted LST (RMSE: 1.51, R²: 0.809). Projections indicate continued thermal escalation, with mean LST reaching 43.64 °C and UHI intensity exceeding 37.41 standardized units by 2037. Persistent thermal hotspots were identified in the southwestern coastal corridor, western industrial belt, and central business district. Community survey data corroborated satellite-derived patterns, with 73.44% of respondents observing environmental degradation, yet only 22% aware of formal heat mitigation policies, and 87% supporting vegetation-based cooling interventions. This integrated framework advances urban thermal monitoring in tropical coastal cities and provides spatially targeted, community-endorsed evidence for climate-responsive urban planning. Full article

Atmospheric aerosols strongly regulate surface solar irradiance in tropical coastal environments through scattering and absorption. This study examines aerosol–irradiance interactions over Penang, Malaysia, using Aerosol Robotic Network (AERONET) observations of aerosol optical depth (AOD), single scattering albedo (SSA), and extinction Ångström exponent (AE); NASA’s Prediction of Worldwide Energy Resource (POWER) irradiance data; and Modern-Era Retrospective analysis for Research and Applications Version 2 (MERRA-2) reanalysis for aerosol compositional context. Bottom-of-atmosphere radiative forcing efficiency (BOA RFE) was quantified for global, direct and diffuse irradiance (GHI, DNI and DHI) under clear- and all-sky conditions during 2014–2018. Results show persistent aerosol-induced attenuation of surface radiation, with GHI and DNI RFE predominantly negative, while DHI RFE remains consistently positive, indicating redistribution of solar energy from direct to diffuse components. Time resolved analysis reveals daily GHI RFE typically ranging from approximately −0.5 to −3.5 W m⁻² per unit AOD, with episodic excursions below −4 W m⁻² per AOD during high-aerosol events, whereas DNI RFE frequently reaches values below −0.8 W m⁻² per AOD, confirming its greater sensitivity to aerosol extinction. In contrast, DHI RFE commonly exceeds +5 W m⁻² per AOD and intermittently surpasses +10 W m⁻² per AOD, reflecting enhanced scattering and multiple-scattering effects. AOD-stratified analysis demonstrates a nonlinear weakening of forcing efficiency with increasing aerosol burden, with mean GHI RFE decreasing from approximately −1.6 to −0.4 W m⁻² per AOD between low- and high-AOD regimes, accompanied by corresponding reductions in DNI (−0.35 to −0.1 W m⁻² per AOD) and DHI (+3.3 to +0.8 W m⁻² per AOD). Overall, aerosol loading is identified as the dominant control on BOA radiative forcing efficiency in this tropical coastal environment, while SSA and AE act as secondary modulators. Full article

Ormosia macrocalyx grows in tropical forests and is endangered in Mexico. The species has ecological and economic importance. To evaluate the relationship between fruit length and seed number, Pearson correlation and principal component analysis were used. A linear mixed-effects model was also applied. Pearson correlation, principal components analysis (PCA) and a Linear Mixed-Effects Model (LMM) were performed on an exploratory basis. In addition, seed coat and cotyledon anatomy were examined, and histochemical tests for secondary metabolites were carried out. Two high correlations and two components were obtained from the PCA, and the LMM showed that fruit length influenced the number of seeds per fruit. In the seed coats, differentiated layers of macrosclereids and osteosclereids were identified, where the hilar region presented macrosclereids and a pyriform bar of tracheids, the reserved cotyledons showed double-walled cells and simple plasmodesmata, the histochemical analyses demonstrated the presence of cellulose, condensed tannins, lipids, alkaloids, and proteins, and no starch was present. This study provides the first description of seed coat and cotyledon anatomy in O. macrocalyx, as well as the first report of secondary metabolites in storage cotyledons. These results could be useful for further studies of this species. Full article

Urbanization, together with shifts in rainfall patterns, has become an increasingly important driver of hydrological extremes in many rapidly developing tropical regions. In the Cimanceuri River Basin, Tangerang Regency, Indonesia, these processes have intensified over the last decade, raising concerns regarding flood risk. This study examines the combined influence of urban expansion and rainfall variability on flood dynamics over 2013–2025. Multi temporal land use classification based on Landsat imagery indicates a pronounced growth of impervious surfaces, primarily driven by rapid urban development and the conversion of agricultural land. To assess the hydrological consequences of these changes, rainfall–runoff processes and flood inundation were simulated using the Soil Conservation Service Curve Number (SCS–CN) method within a coupled HEC-HMS and HEC-RAS 2D modelling framework. Simulations were performed for multiple temporal conditions and design rainfall scenarios. Model calibration relied on observed flood events recorded in March 2025 in the Mustika Residential Area, Tangerang. The results suggest that urbanization has contributed to measurable increases in both peak discharge and inundation extent. Between 2013 and 2025, impervious surface coverage expanded by approximately 67%, accompanied by a rise in the composite Curve Number from 85.86 to 86.63 and an estimated 5.2% increase in flood extent. Also, the design rainfall increased from 85.01 to 90.95 with an average increase of 7.34%. Comparison between simulated inundation patterns and aerial imagery shows satisfactory agreement, with an average deviation of less than 10%, indicating acceptable model performance. Hydrologic analyses generated two discharge scenarios, consisting of event-based flow from the 5 March 2025 rainfall data and return-period flows derived from design rainfall under different rainfall-shift periods. The rainfall-shift analysis quantified changes in design rainfall and corresponding discharge using progressively updated rainfall records. Together, the results emphasize the combined effects of urban expansion and shifting rainfall patterns on flood dynamics, underscoring the need for adaptive land-use planning and climate-responsive water management in rapidly urbanizing catchments. Full article

Carbon is an essential component in the regulation of climate systems through the global biogeochemical cycle. However, changes in land use/land cover (LULC) have reduced the capacity of terrestrial ecosystems like watershed to store carbon. This shows the need for a policy framework that balances conservative objectives with agricultural demands, as watersheds are required to support carbon storage and food production. Previous studies have generally assessed carbon dynamics or LULC change separately, with limited integration of policy-driven scenarios. Therefore, this study aimed to conduct multi-scenario carbon storage modeling to evaluate LULC protection strategies in the Cimanuk Watershed, Indonesia, an area experiencing significant LULC pressures. The method used consisted of Support Vector Machine (SVM)–Markov, the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST), Geodetector, and Getis-Ord Gi*. A total of four scenarios were used to project LULC and carbon storage in 2042, which included Business as Usual (BAU), Paddy Field Protection (PFP), Forest Protection (FOP), and Paddy Field and Forest Protection (PFFOP). The results showed that forest area declined by 39,400 ha between 2015 and 2025, thereby reducing carbon storage. The PFFOP scenario was identified as the most viable, combining the protection of paddy fields and forests to balance agricultural production and carbon sequestration. Among the factors analyzed, slope exerted the greatest influence on carbon storage. Spatial cluster analysis showed that carbon hotspots were predominantly located in the upper Cimanuk sub-watershed. These results offered valuable insights into scenario-based sustainable watershed management to optimize carbon storage and maintain agricultural function. Furthermore, the proposed framework showed promising potential for application in other tropical watersheds, serving as a reference for decision-makers in sustainable watershed management. Full article

Thailand preserves one of the most extensive records of Mesozoic vertebrate tracks in Tropical Asia, yet these ichnological data have never been comprehensively synthesized. This review compiles and reassesses all known Triassic to Cretaceous vertebrate tracksites in Thailand to clarify their stratigraphic distribution, taxonomic diversity, and palaeobiogeographical significance. Published records, new field observations, and updated stratigraphic correlations are integrated to evaluate trackmaker attributions and temporal patterns. The Thai record documents diverse assemblages including chirotheriids, early theropods, sauropodomorphs, ornithopods, sauropods, and crocodilians. Late Triassic–Early Jurassic assemblages capture a major faunal transition, revealing the co-occurrence of non-dinosaurian archosaurs and some of the earliest dinosaurs in the region, whereas Lower Cretaceous sites are dominated by theropods, sauropods and diverse ornithopods. Comparison with other Asian ichnofaunas indicates faunal continuity across eastern Asia and supports early dinosaur dispersal into equatorial low latitudes. This synthesis also evaluates site conservation, highlighting the vulnerability of several Triassic localities and a positive trend of community-led discoveries since 2009, underscoring the need for proactive management and standardized digital documentation. Overall, the Thai ichnological succession represents the most complete Mesozoic track record presently known from Tropical Asia and provides key insights into vertebrate evolution, palaeoecology, and regional biogeography. Full article

Copy number variations (CNVs) are a major source of structural genomic diversity that influence adaptation, reproduction, and production traits in livestock. The Black Bengal goat, an economically important Indian breed known for its high fecundity, superior skin quality, and resilience to humid tropical climates, was studied to uncover its structural genomic landscape. We performed whole-genome CNV analysis using high-depth (10×) sequencing data from eight individuals. A total of 31,816 copy number variants (CNVs) were identified, predominantly duplications, with an average length of approximately 45 kb. These CNVs were combined into 8910 copy number variation regions (CNVRs) covering approximately 0.15 Gb (about 5.3% of the autosomal genome). CNVR hotspots were mainly located on chromosomes 1. Gene annotation showed that regions overlapping with CNVs and CNVRs contained over 1987 protein-coding genes that are involved in pathways related to immunity, reproduction, metabolism, and extracellular matrix (ECM) organization. The presence of copy number variations involving genes such as GDF9 and BMPR1B on chromosome 7 & 6, respectively, are important because it indicates that the breed has a high reproductive capacity due to dosage-sensitive duplications. Changes in the extracellular matrix and increased dermal strength have been linked to duplications of genes such as COL6A1, LAMC2, LAMB3, FMN1, and CLDN1. This helps explain the superior hide quality of the breed. This research offers a comprehensive map of CNVs and CNVRs within the genome of the Black Bengal goat. It demonstrates how these duplications lead to structural changes that enhance both reproductive performance and skin resilience. These findings provide a valuable genomic resource for future marker-assisted selection, comparative genomics, and conservation breeding programs aimed at preserving indigenous goat populations. Full article

This study examined the relationships among seminal bacterial composition, oxidative status, and semen quality in Thai native, crossbred, and commercial roosters. Fresh ejaculates (n = 10 per group) were evaluated for semen quality parameters—mass motility, total motility, progressive motility, sperm concentration, and viability and for malondialdehyde (MDA) levels, a marker of lipid peroxidation, as well as total bacterial load. Bacterial profiles were characterized using long-read 16S rRNA gene sequencing. Compared with commercial roosters, Thai native roosters exhibited significantly higher sperm motility and viability, along with markedly lower MDA concentrations (p < 0.05). Crossbred roosters showed intermediate values for most semen traits and oxidative indicators. Bacterial profiling revealed clear differences among rooster types in bacterial composition: commercial and crossbred roosters had higher bacterial richness and a greater prevalence of Gram-negative taxa, whereas Thai native roosters harbored lower bacterial diversity and load. Correlation analyses demonstrated that bacterial load was positively correlated with MDA concentration and negatively correlated with sperm motility and viability. These findings suggest that variation in seminal bacterial profiles, oxidative status, and semen quality is associated with differences among rooster types. The lower bacterial burden and lipid peroxidation observed in Thai native roosters may reflect greater reproductive resilience under tropical conditions, with potential implications for breeding and semen management strategies. Full article

Climate-related extremes such as floods and droughts have been the main causes of natural disasters in southern Africa in recent years, with noticeable trends in climate extremes being observed. The Limpopo Province in South Africa has been especially prone to these extremes. The extreme precipitation in Limpopo is mainly caused by a mix of intense tropical weather systems and La Niña conditions, both exacerbated by climate change. Climate change exacerbates current water challenges across the province by affecting precipitation patterns, distribution, timing and intensity, leading to extreme climate events such as floods and drought. The historical and future trends of precipitation and relevant extreme indices using observed data from the South African Weather Service and CORDEX ensemble model simulations under the RCP4.5 and RCP8.5 scenarios were examined. An analysis of all precipitation data suitable for the study of long-term variability and trends indicates that most areas underwent drying to various degrees over the last century, especially the central and western parts. Drier conditions over the eastern parts have become more prevalent over the last 50 years. Also, more extremes on a sub-seasonal basis were experienced. Regarding future scenarios, three projected time periods compared to the baseline period (1976–2005) were examined: Current climatology (2006–2035), near-future (2036–2065), and far-future (2066–2095). Most areas will experience a further decrease in precipitation under both emission scenarios, especially in the south-east, central and extreme northern parts. In addition, these areas are expected to experience a decrease in the frequency of heavy precipitation days for all periods under both RCP scenarios, mainly due to drying. Consecutive dry days are expected to increase significantly. Transitioning to renewable energy and enhancing natural carbon sinks can reduce emissions, while prioritizing resilience through renewable energy, water management, and climate-smart agriculture will help address climate change challenges in the province. Full article

Jicama (Pachyrhizus erosus L.) is a tropical tuber crop that has potential not only as a food source but also as a natural active ingredient in the cosmetics industry. This study aims to evaluate the phenology of tuber development and the content of primary and secondary metabolites of two jicama accessions (Bogor and Kebumen) at three tuber ages (3, 4, and 5 months). The parameters observed included tuber weight, starch yield, total soluble solids (TSS), total titratable acidity (TTA), vitamin C, total phenols, total flavonoids, and antioxidant activity (% inhibition). For data analysis, we used the T-test to compare differences between accessions. The results showed that tuber weight and starch yield increased significantly up to 5 months of age, while secondary metabolite content (phenols, flavonoids, antioxidant activity) was higher in young tubers (3–4 months). This study shows a trade-off between productivity (starch and vitamin C) and bioactive metabolite content (phenols, flavonoids, antioxidants) as the tubers age. The Bogor accession has a more stable vitamin C content, phenol levels, and antioxidant activity, while the Kebumen accession shows higher flavonoid levels in young tubers. The optimal tuber age and accession recommended to obtain a balance between productivity and secondary metabolite content is the Bogor accession at 4 months of age. This supports the potential use of jicama in the cosmetics industry as a brightening agent (vitamin C), humectant (sugar), anti-aging agent (phenols, flavonoids), and base ingredient for natural starch-based formulations. This study provides the first integrated evaluation of tuber phenology, primary metabolites, and secondary metabolite dynamics of two Indonesian jicama accessions in relation to cosmetic functionality. The results highlight a clear trade-off between productivity and bioactive compound accumulation, offering a scientific basis for selecting optimal harvest age and accession for cosmetic raw materials This study provides the first integrated evaluation of tuber phenology, primary metabolites, and secondary metabolite dynamics of two Indonesian jicama accessions in relation to cosmetic functionality. The results highlight a clear trade-off between productivity and bioactive compound accumulation, offering a scientific basis for selecting the optimal harvest age and accession for cosmetic raw materials. Full article

Bougainvillea (Bougainvillea glabra) is a perennial woody species belonging to the Nyctaginaceae family, native to South America. It is widely recognized for its brightly colored bracts and strong adaptability, and is widely cultivated as a major ornamental plant in tropical and subtropical regions. However, QTL mapping studies on morphological traits remain limited in the genus Bougainvillea, and the genetic basis underlying its key ornamental traits is still largely unclear. In this study, an F₁ segregating population was constructed using the cultivars ‘Mrs Eva White’ and ‘Formosa’ as parents, and was used for high-density genetic map construction and quantitative trait locus analysis. Fourteen leaf and thorn-related traits were investigated, with coefficients of variation ranging from 8.16% to 64.54%. Based on specific-locus amplified fragment sequencing (SLAF-seq), a total of 1,133,206 SLAF markers were developed, among which 479,488 were polymorphic. Using the inclusive composite interval mapping (ICIM) algorithm in the GACD 1.2 software, a high-density genetic linkage map was constructed for B. glabra, consisting of 17 linkage groups and 3256 markers. The genetic map spanned 1797.64 cM, with an average marker interval of 0.55 cM. A total of 22 QTLs were detected for the measured leaf and thorn traits, including 16 major QTLs with a PVE ≥ 8%. Collectively, this study identified stable genetic loci for important morphological traits and provides a valuable theoretical foundation for marker-assisted selection and genetic improvement of ornamental traits in Bougainvillea. Full article