Search Results (2,089)

Abstract: Forest types correspond to differences in structural characteristics and species composition that influence biomass and biodiversity values, which are essential measurements for ecological monitoring and management. However, differentiating forest types in tropical regions remains a challenge. This study aimed to improve forest type extent mapping by combining structural information from discrete full-waveform LiDAR returns with multitemporal images. This study was conducted in a tropical forest region over complex terrain in north-eastern Tanzania. First, structural classes were generated by applying time-series clustering algorithms. The results showed four different structural clusters corresponding to forest types, montane–humid forest, montane–dry forest, submontane forest, and non-forest, when using the Kshape algorithm. Kshape considers the shape of the full-sequence LiDAR waveform, requiring little preprocessing. Despite the overlap amongst the original clusters, the averages of structural characteristics were significantly different across all but five metrics. The labeled clusters were then further refined and used as training data to generate a wall-to-wall forest cover type map by classifying biannual images. The highest-performing model was a KNN model with 13 spectral and 3 terrain features achieving 81.7% accuracy. The patterns in the distributions of forest types provide better information from which to adapt forest management, particularly in forest–non-forest transitional zones. Full article

Girdling is a crucial technique for promoting the close-to-nature transformation of plantation forests in Hainan Tropical Rainforest National Park (HNNP). It has shown effectiveness in aspects such as community structure and biodiversity restoration. However, its impacts on ecological functions like eco-hydrology still require further in-depth investigation. This study analyzes the impact of girdling on the eco-hydrological indices of three plantations—Acacia mangium, Pinus caribaea, and Cunninghamia lanceolata—through field investigations and laboratory tests. The data was evaluated using a game theory combination weighting-cloud model. The results show that the eco-hydrological indicators of leaf litter in A. mangium increased by 5.77% while those of P. caribaea and C. lanceolata decreased by 11.86% and 5.29%, respectively. Soil bulk density decreased slightly across all plantations while total porosity increased, with A. mangium showing the highest increase of 20.31%. Organic carbon content increased by 76.81% in A. mangium and 7.24% in C. lanceolata, whereas it decreased in P. caribaea. Saturated hydraulic conductivity increased by 33.32% in P. caribaea and 20.91% in A. mangium but decreased in C. lanceolata. Based on the cloud model, the eco-hydrological function of A. mangium improved from ‘medium’ to ‘good’, while that of P. caribaea and C. lanceolata declined towards the ‘poor’ level. In summary, during the process of close-to-nature transformation of tropical rainforests, girdling is an effective method to enhance the ecohydrological functions of broadleaf planted forests. However, for coniferous species, the ecohydrological functions of the planted forests weaken in the short term following the transformation. Full article

This study evaluates the mycoremediation potential of wild mushroom species from Chiapas, Mexico, specifically for high copper concentrations. Nine fungal carpophores were collected from tropical forests near coffee plantations. The morphological characteristics of the fungal strains and fruiting bodies were analyzed. Each specimen was identified through sequencing using the ITS₁ and ITS₄ primers. The ability to tolerate different concentrations of copper was evaluated by determining the fungal mycelial growth inhibition potential. Copper bioaccumulation by the fungi was quantified using biosorption assays with atomic absorption spectrophotometry. The enzymatic activity of laccase, lignin peroxidase, and manganese peroxidase from the fungal species was also determined in the presence of copper. Phylogenetic analysis identified the fungal species as Agaricus bisporus, A. subrufescens, Calvatia fragilis, Ganoderma coffeatum, G. lucidum, Pleurotus djmor, P. floridanus, Trametes elegans, and T. versicolor, all classified within the Agaromycetes class. The nine fungal species exhibited varying abilities to tolerate Cu²⁺ concentrations from 30 to 100 mg L⁻¹. At 30 and 60 mg L⁻¹ Cu²⁺, the G. lucidum H14-35 strain demonstrated the highest biosorption capacity, reaching 76.97%. Overall, the mushrooms in this study showed strong Cu²⁺ tolerance and biosorption, making them promising biomaterials for remediating copper-contaminated soils. Full article

On the African continent, Picrodendraceae are represented by four genera. Their intracontinental paleophytogeographic histories and paleoecological aspects are obscured by the lack of pre-Miocene fossils. For this study, late Eocene sediments from Kenya were investigated. The sample was prepared in the laboratory, and its organic residue was screened for pollen. We extracted fossil Picrodendraceae pollen and investigated the grains using light and scanning electron microscopy. Based on the pollen morphology, the grains were assigned to Hyaenanche. This genus is currently confined to a small area within the Cape Province, South Africa. There, the plants grow as shrubs and small trees at an elevation between 60 and 800 m, on rocky substrate, as part of open fynbos vegetation, and under a dry climate with hot summers and limited precipitation. The sedimentary context and the associated palynoflora suggest that during the Eocene of Kenya, Hyaenanche was part of lowland coastal vegetation in Eastern Africa. There, the plants grew under fully humid to winter-dry tropical climates as part of landwards margins of mangroves, seasonally inundated floodplain forests, or coastal forests. Our study shows that when evaluating paleoecological aspects of relict monotypic plants, their extant closely related genera and their fossil records need to be considered. Full article

Mutualisms characterized by reciprocal benefits between species are a fundamental relationship of tropical ecosystems. Ant Gardens (AGs) represent an interesting ant-plant mutualism, involving specialized interactions between vascular epiphytes and ants. While this relationship has been extensively studied in various tropical regions, the available information on Peruvian ecosystems is limited. The objective of this study was to identify the ant and epiphyte species that constitute AGs. From February 2023 to January 2024, a study was conducted on two 50 × 10 m transects within the Mauritia flexuosa peat swamp forest, located within the Water Association Aguajal Renacal del Alto Mayo (ADECARAM) Tingana in San Martín, Peru. A total of 69 ant gardens were documented, comprising 18 phorophyte species, 19 epiphyte species, and three ant species. The results demonstrated that neither the height nor the diameter at breast height (DBH) of phorophytes exhibited a statistically significant correlation with the number of AGs per host. However, a positive correlation was observed between the length and width of the AGs and the number of ants per AG. The findings of this study contribute to the understanding of AG mutualism in Peruvian ecosystems. Full article

Background: Bees rely on plants for nutrition and reproduction, making the preservation of natural areas crucial as pollinator reservoirs. Seasonal tropical dry forests are among the richest habitats for bees, but only 27% of their original extent remains in Mexico. In contrast, temperate forests harbor fewer bee species and face high deforestation rates, with 40% of their area converted to other land uses. This study aimed to estimate the α and β diversities of wild bees and compare bee–plant interaction networks between these two vegetation types. Methods: Wild bees and their interactions with plants were monitored for one year in four sites within the Área de Protección de Flora y Fauna Sierra de Quila. Two sites corresponded to seasonal tropical dry forest and two to temperate forest. α and β diversity, connectance, nestedness, web asymmetry, and niche overlap were analyzed. Results: Sierra de Quila harbors high bee diversity, with 155 species in tropical dry forest and 103 in temperate forest. Species turnover between vegetation types was high, although nine species used floral resources in both forests, connecting the interaction networks. Conclusions: Sierra de Quila diverse habitats promote high bee diversity, with niche partitioning and low connectance facilitating coexistence across different vegetation types. Full article

A total of 96 strains of Nostocales (Cyanobacteria) were established from the phyllosphere of the laurel forests in the Canary Islands (Spain) and the Azores (Portugal) using enrichment media lacking combined nitrogen. The strains were characterized by light microscopy and SSU rRNA gene comparisons. Morphologically, most strains belonged to two different morphotypes, termed “Nostoc-type” and “Tolypothrix-type”. Molecular phylogenetic analysis of 527 SSU rRNA gene sequences of cyanobacteria (95 sequences established during this study plus 392 sequences from Nostocales and 40 sequences from non-heterocyte-forming cyanobacteria retrieved from the databases) revealed that none of the SSU rRNA gene sequences from the phyllosphere of the laurel forests was identical to a database sequence. In addition, the genetic diversity of the isolated strains was high, with 42 different genotypes (44% of the sequences) recognized. Among the new genotypes were also terrestrial members of the genus Nodularia as well as members of the genus Brasilonema. It is concluded that heterocyte-forming cyanobacteria represent a component of the phyllosphere that is still largely undersampled in subtropical/tropical forests. Full article

Tropical ferns are underrepresented in demographic studies, despite their ecological importance in forest ecosystems. This study investigates the mortality rates of terrestrial ferns along an elevational gradient (500–4000 m a.s.l.) in Ecuador, focusing on relationships with environmental variables, community characteristics, and plant size. Over two years (2009–2011), 3213 individuals representing 88 species were monitored in 22 permanent plots across eight elevations. Mortality rates, calculated as the percentage of individuals lost annually, averaged 0.87%, with a hump-shaped trend along the gradient and a significant negative relationship with temperature. Mortality rates were positively correlated with species richness and fern density, suggesting competition may influence community structure. Larger individuals exhibited higher mortality rates, likely due to greater resource demands and exposure to environmental stressors. These findings emphasize the interplay of abiotic factors, such as elevation and temperature, and biotic interactions, including competition and herbivory, in shaping fern population dynamics. The low mortality rates observed reflect population stability, potentially linked to unique life history traits, such as extended generation times. This study provides critical insights into the demographic strategies of tropical ferns and underscores the need for long-term research to better understand their responses to environmental and biotic pressures. Full article

This study examines CH₄ and N₂O fluxes during the dry season in two distinct areas of the Pantanal: Barranco Alto Farm (BAF), dominated by grasslands, and Passo da Lontra (PL), a forested region. As climate change increases the occurrence of droughts, understanding greenhouse gas (GHG) fluxes in tropical wetlands during dry periods is crucial. Using static chambers, CH₄ and N₂O emissions were measured from soils and tree stems in both regions, with additional measurements from grass in BAF. Contrary to expectations, PL—characterized by clayey soils—had sandy mud samples that retained less water, promoting oxic conditions and methane uptake, making it a CH₄ sink. Meanwhile, BAF’s sandy, well-drained soils exhibited minimal CH₄ fluxes, with negligible methane uptake or emissions. N₂O fluxes were generally higher in BAF, particularly from tree stems, indicating significant interactions between soil type, moisture, and vegetation. These findings highlight the pivotal roles of soil texture and aeration in GHG emissions, suggesting that well-drained, sandy soils in tropical wetlands may not always enhance methane oxidation. This underscores the importance of continuous GHG monitoring in the Pantanal to refine climate change mitigation strategies. Full article

For tropical rainforest regions with dense vegetation cover, the development of effective large-scale soil mapping methods is crucial to improve soil management practices to replace the time-consuming and laborious conventional approaches. While machine learning (ML) algorithms demonstrate superior predictability of soil properties over linear models, their practical and automated application for predicting soil properties using remote sensing data requires further assessment. Therefore, this study aims to integrate Unmanned Aerial Vehicles (UAVs)-based hyperspectral images and Light Detection and Ranging (LiDAR) points to predict the soil properties indirectly in two tropical rainforest mountains (Diaoluo and Limu) in Hainan Province, China. A total of 175 features, including texture features, vegetation indices, and forest parameters, were extracted from two study sites. Six ML models, Partial Least Squares Regression (PLSR), Random Forest (RF), Adaptive Boosting (AdaBoost), Gradient Boosting Decision Trees (GBDT), Extreme Gradient Boosting (XGBoost), and Multilayer Perceptron (MLP), were constructed to predict soil properties, including soil acidity (pH), total nitrogen (TN), soil organic carbon (SOC), and total phosphorus (TP). To enhance model performance, a Bayesian optimization algorithm (BOA) was introduced to obtain optimal model hyperparameters. The results showed that compared with the default parameter tuning method, BOA always improved models’ performances in predicting soil properties, achieving average R² improvements of 202.93%, 121.48%, 8.90%, and 38.41% for soil pH, SOC, TN, and TP, respectively. In general, BOA effectively determined the complex interactions between hyperparameters and prediction features, leading to an improved model performance of ML methods compared to default parameter tuning models. The GBDT model generally outperformed other ML methods in predicting the soil pH and TN, while the XGBoost model achieved the highest prediction accuracy for SOC and TP. The fusion of hyperspectral images and LiDAR data resulted in better prediction of soil properties compared to using each single data source. The models utilizing the integration of features derived from hyperspectral images and LiDAR data outperformed those relying on one single data source. In summary, this study highlights the promising combination of UAV-based hyperspectral images with LiDAR data points to advance digital soil property mapping in forested areas, achieving large-scale soil management and monitoring. Full article

Alpinia oxyphylla Miq. is an important undergrowth species in southern China. The fruits of A. oxyphylla are recognized as one of “the four famous south medicines” and are also used in the production of preserved fruit. However, as non-medicinal parts, their stems and leaves are unutilized. In order to promote resource recycling, the chemical components of such stems and leaves were investigated, and we evaluated their melanin inhibitory potential through DPPH and ABTS radical scavenging, tyrosinase inhibition, and melanin production inhibition in B16 cells. Five new compounds, aloxy A (1), kaempferol 3-O-α-L-rhamnosyl-(1 → 2)-(3″,4″-diacetyl-β-D-glucuronate methyl ester) (2), quercetin 3-O-α-L-rhamnosyl-(1 → 2)-(3″,4″-diacetyl-β-D-glucuronate methyl ester) (3), kaempferol 3-O-α-L-rhamnosyl-(1 → 3)-(4″-acetyl-β-D-glucuronate methyl ester) (4), and kaempferol 3-O-α-L-rhamnosyl-(1 → 2)-(3″-acetyl-β-D-glucuronate methyl ester) (5), and seventeen known ones (6–22) were isolated and identified from the stems and leaves of A. oxyphylla. Among these compounds, 19 compounds presented tyrosinase inhibitory activities, among which aloxy A (1), hexahydrocurcumin (7), gingerenone A (8) and 4,4′-dimethoxy-3′-hydroxy-7,9′:7′,9-diepoxylignan-3-O-β-D-glucopyranoside (22) showed strong inhibitory activity, with IC₅₀ values between 6.26 ± 0.42 and 22.04 ± 1.09 μM, lower than the positive control (Kojic acid, IC₅₀ = 37.22 ± 1.64 μM). A total of 15 compounds exhibited varying degrees of DPPH and ABTS radical scavenging activities. In addition, 1, 2, and 7 showed melanin production inhibition activity in B16 cells, and the effects presented as concentration-dependent. The above results indicate that the stems and leaves of A. oxyphylla are rich with phenolic compounds, and display tyrosinase inhibition and antioxidant activities, which could lead to potential applications related to melanin production inhibition such as in the development of cosmetics. Full article

Pollen rain studies are rare in arid and semi-arid regions worldwide. Interpretations related to the dynamics of plant communities and possible paleoclimatic changes in these areas face significant limitations due to this lack of data. The global biome of Seasonally Dry Tropical Forests and Shrublands (SDTFS) is represented in Northeast Brazil by the caatinga, which is composed of xerophytic vegetation. This study aimed to generate information about the pollen rain in this area and to understand its relationship with species flowering, pollination syndromes, life forms, and climatic aspects. A caatinga area in Canudos, Bahia, Brazil (09°54′ S 39°07′ W), was selected for this purpose. Artificial pollen collectors were installed and exchanged monthly over two years for palynological analyses of the collected material, using standard palynological techniques. A total of 124 pollen types were identified, with approximately 8823 pollen grains deposited per cm² over the two years. Several vegetation components were represented in the pollen rain, reflecting local plant diversity, life forms, and physiognomies. A positive relationship was observed between increased temperature and pollen production from trees and shrubs, and new pollen types were associated with indicator species of caatinga vegetation. Full article

To estimate the potential and realized carbon emission reductions from implementation of reduced-impact logging (RIL) in Indonesia, we compiled logging emissions data from 15 concessions in Kalimantan and 10 from the Papuan provinces. Committed emissions data were collected for harvested timber as well as from collateral damage caused by felling, skidding, and clearing for haul roads and log yards. Emissions expressed as mean ± standard error per cubic meter of timber harvested, per area harvested, and per Mg of timber harvested (i.e., the ‘Carbon Impact Factor’) were 1.30 ± 0.15 Mg C m⁻³, 27.52 ± 4.44 Mg C ha⁻¹, and 6.88 ± 0.84 Mg Mg⁻¹, respectively. Among the sampled concessions, felling, hauling, and skidding caused 18–86%, 2–48%, and 6–75% of these emissions, respectively. Potential emission reductions calculated as the difference between observed emissions and those of the five best-performing concessions are 0.67 ± 0.15 Mg C m⁻³, 21.11 ± 4.38 Mg C ha⁻¹, and 4.20 ± 0.83 Mg Mg⁻¹, which represents reductions of 51%, 76%, and 61%, respectively. Extrapolating these estimates to all of Indonesia using average log production data from 2018 to 2021 results in an estimated annual emissions reduction of 14.47 Tg CO₂ from full adoption of RIL, which is 2.9% of Indonesia’s nationally determined contribution (NDC) from the forestry sector. Full article

Ensuring the sustainability of forests is among the priority measures to be taken against the decline in biodiversity, which is among the world’s increasingly common concerns. This study investigated whether sustainable forest management processes are considering wildlife conservation objectives. Ten forest management processes were categorized and then analyzed for whether wildlife conservation is adequately considered. The wildlife data were grouped into four categories, with the most common being the protection of biodiversity and wildlife trade. The satisfaction level obtained according to the scoring method used was determined as the criterion of success in wildlife conservation. According to the scoring method applied, the overall success was found to be 50%. It was determined that a standard should be developed regarding the economic value of wildlife fauna and flora species and that this issue should be included in sustainable forest management strategies. Only 20 of 116 total sustainable forest management criteria considered wildlife. The African Timber Organization process, which has the most member countries, was identified as the process with the lowest number of wildlife criteria, at 2%, while the International Tropical Timber Organization process was found to have the most wildlife protection criteria at 20%. The conservation success rates for the two processes of which Türkiye is a member were also found to be quite low. It is concluded that there is a need to strengthen the place of wildlife, one of the most important living components for forests, in SFM processes both for Türkiye and internationally. The results obtained were evaluated both in terms of international criteria and practices in Türkiye. It is also recommended that future international meetings include wildlife health and diversity as a separate criterion when determining sustainable methods. Full article

This study investigates the application of Phased Array Corrosion Mapping (PACM) as a non-destructive testing (NDT) method for detecting and monitoring corrosion growth on hot stainless steel (SS) surfaces, specifically focusing on SS 304 and SS 316. Conducted across a temperature range of 30 °C to 250 °C, the research evaluates the effectiveness of PACM in high-temperature environments typical of the petrochemical industry. Experiments were conducted using specimens with machined slots and flat-bottom holes (FBHs) to simulate corrosion defects. The results demonstrate that PACM effectively detects and maps corrosion indicators, with color-coded C-scan data facilitating easy interpretation. Temperature variations significantly influenced ultrasound signal characteristics, leading to observable changes in FBH indications, particularly at elevated temperatures. Increased ultrasound attenuation necessitated adjustments in decibel settings to maintain accuracy. SS 304 and SS 316 exhibited distinct responses to temperature changes, with SS 316 showing higher dB values and unique signal behaviors, including increased scattering and noise echoes at elevated temperatures. Detected depths for slots and FBHs correlated closely with designed depths, with deviations generally less than 0.5 mm; however, some instances showed deviations exceeding 2 mm, underscoring the need for careful interpretation. At temperatures above 230 °C, the disbanding of probe elements led to weak or absent signals, complicating data interpretation and requiring adjustments in testing protocols. This study highlights the feasibility and effectiveness of PACM for corrosion detection on hot SS surfaces, providing critical insights into material behavior under thermal conditions. Future research should include physical examination of samples using Scanning Electron Microscopy (SEM) to validate and enhance the reliability of the findings. The integration of non-contact NDT methods and optimization of calibration techniques are essential for improving PACM performance at elevated temperatures. Full article