Search Results (45)

The study investigated the diversity and ecology of Myxomycetes (Amoebozoa) along a vegetation gradient in the Cuzco department, Peru, spanning altitudes from 2500 to 4700 m. Field collections were carried out at six sites distributed across three distinct vegetation formations: non-Amazonian Forest, paramo, and high Andean zones with and without vegetation cover. The collected material was analyzed through direct observation, cultivation in moist chambers, and morphological identification, resulting in the record of 18 species, including three new records for Peru (Diderma circumdissilens, Licea tenera, and Perichaena luteola). Species richness was higher at lower altitudes and in environments with greater substrate availability, such as dead branches and mosses, but declined under extreme environmental conditions, particularly at high elevations. Principal component analysis revealed differences in community composition among the environments, associated with environmental variables and substrate types. The results highlight that the Peruvian Andes harbor a significant biodiversity of Myxomycetes, including species adapted to high-altitude conditions, reinforcing the importance of conservation and further study of these extreme ecosystems. We conclude that high mountain environments serve as biodiversity hotspots, and that future studies, including molecular techniques, are essential to understanding the distribution and adaptation of these organisms in the Andean environments. Full article

The species of the Bufonidae family exhibit a great diversity of habitats, diurnal or nocturnal habits, a complex evolutionary history, and a wide distribution, which makes this group suitable for morphological studies. In this work, we aimed to identify the existence of morphological patterns related to the habitat use and diurnal or nocturnal habits of Bufonidae in the Brazilian Amazon. To achieve this, we studied the morphological measurements of 210 specimens from three zoological collections and characterized the type of habitat and diurnality/nocturnality of the species. The morphological patterns and habitat use were investigated through principal component analysis (PCA) and multiple correspondence analysis (MCA), respectively. The evaluation of the relationships between morphological variation, habitat use, and diurnality/nocturnality was performed via redundancy analysis (RDA). Accordingly, Amazonian bufonids were divided into three morphological groups associated with different vegetation types and environments, demonstrating that body size is closely linked to diurnal or nocturnal life habits and habitat. Species with large body sizes are associated to anthropized areas, while intermediate and smaller species are associated with primary forests. Full article

Climate change and landscape fragmentation have made fires the primary drivers of forest degradation in Southern Amazonia. Understanding their impacts is crucial for informing public conservation policies. In this study, we assessed the effects of repeated fires on trees with a diameter ≥10 cm across three distinct vegetation types in this threatened region: Amazonian successional forest (SF), transitional forest (TF), and ombrophilous forest (OF). Two anthropogenic fires affected all three vegetation types in consecutive years. We hypothesized that SF would be the least impacted due to its more open structure and the presence of fire-adapted savanna (Cerrado) species. As expected, SF experienced the lowest tree mortality rate (9.1%). However, both TF and OF were heavily affected, with mortality rates of 28.0% and 29.7%, respectively. Despite SF’s apparent fire resilience, all vegetation types experienced a significant net loss of species and individuals. These results indicate a fire-induced degradation stage in both TF and OF, characterized by reduced species diversity and structural integrity. Our findings suggest that recurrent fires may trigger irreversible vegetation shifts and broader ecosystem tipping points across the Amazonian frontier. Full article

Fire is a key ecological driver in tropical savannas, yet its effects on plant biodiversity remain understudied in Amazonian savannas. This study investigates how fire recurrence influences taxonomic and functional diversity in savanna ecosystems in northeastern Amazonia. We conducted vegetation surveys across five phytophysiognomies in Amapá State, Brazil, and compiled trait data for 226 plant species. Generalized Additive Mixed Models (GAMMs) were used to evaluate the relationships between fire frequency and diversity metrics across five landscape scales. The results showed that taxonomic diversity—particularly Shannon diversity—exhibited a unimodal response to fire recurrence, with peak diversity occurring at intermediate fire frequencies. Abundance increased with fire frequency, indicating potential dominance by fire-tolerant species. Functional diversity responded more subtly: functional richness and dispersion showed weak, non-linear associations with fire, while functional evenness remained stable. These findings suggest that recurrent fire can reduce taxonomic diversity without strongly altering functional structure, possibly due to functional redundancy among species. The use of multiscale models revealed that biodiversity–fire relationships vary with spatial context. In conclusion, this study highlights the moderate resilience of Amazonian savannas to fire recurrence and emphasizes the need to incorporate these ecosystems into fire management plans in climate change scenarios. Full article

The growing interest in sustainable raw materials has led to a significant rise in demand for Amazonian vegetable oils, such as pracaxi (Pentaclethra macroloba (Willd.) Kuntze) and patauá (Oenocarpus bataua). This study examines the patterns of their usage in scientific publications between 2010 and 2023, emphasizing their potential in three key areas: food, cosmetics, and mineral processing. The methodology employed is the Systematic Literature Network Analysis (SLNA), which integrates Systematic Literature Review (SLR) with Bibliographic Network Analysis. We identified sixty-one scientific articles from the Scopus database, with 32 meeting the criteria for Bibliometric Analysis. Using the VOSviewer program (version 1.6.20), we performed a keyword co-occurrence analysis to create bibliometric maps. These maps provided a clear depiction of the main research areas and how they have evolved over time in relation to these oilseeds. To complement the descriptive analyses, the Bibliometrix R package (version 4.4.1) was used to extract bibliographic information. This methodology effectively identifies emerging research sectors and provides a solid foundation for future studies on the Amazon bioeconomy. Full article

Metamorphosis is central to Indigenous Amazonian cosmologies, which often posit a period in the past when transformations from one being into another proliferated. This time gave way to the relative stability of the present that always runs the risk of going back to an ongoing process of transmutation. In this article, I highlight the significance of plants in Amerindian ontologies of becoming as catalysts of metamorphic movements through their entheogenic effects, through their curative properties and as the ancestors and teachers of humans. Beyond being the facilitators of other entities’ transformations and the virtual grandparents of all beings, plants are also masters of metamorphosis, displaying much more plasticity in adapting to their surroundings than animals. I argue that contemporary Amazonian women’s poetry translates the multiple transformations of vegetal life into literary form. In many Amazonian Indigenous communities, women have traditionally been the ones responsible for plant cultivation, while, in Western societies, women are often associated to certain parts of plants, such as flowers, and to nature as a whole. In the article, I analyze the poetry of Colombian author Anastasia Candre Yamacuri (1962–2014) and Peruvian writer Ana Varela Tafur (1963-), who emphasize the metamorphic potential of plants and the ontology of becoming at play in Amazonia. I contend that women’s writing on plants reflects evolving views on both plants’ and women’s roles in Amazonian societies, marked by rapid social transformation and environmental destruction. Full article

The expansion of anthropogenic activities drives changes in the composition, structure, and spatial configuration of natural landscapes, influencing both the taxonomic and functional diversity of bird communities. This pattern is evident in the Colombian Amazon, where agricultural and livestock expansion has altered ecological dynamics, avifaunal assemblages, and the provision of regulating ecosystem services. This study analyzed the influence of agroforestry (cocoa-based agroforestry systems—SAFc) and silvopastoral systems (SSP) on the functional diversity of birds and their potential impact on ecosystem services in eight productive landscape mosaics within the Colombian Amazon. Each mosaic consisted of a 1 km² grid, within which seven types of vegetation cover were classified, and seven landscape metrics were calculated. Bird communities were surveyed through visual observations and mist-net captures, during which functional traits were measured. Additionally, functional guilds were assigned to each species based on a literature review. Five multidimensional indices of functional diversity were computed, along with community-weighted means per guild. A total of 218 bird species were recorded across both land-use systems. Bird richness, abundance, and functional diversity—as well as the composition of functional guilds—varied according to vegetation cover. Functional diversity increased in mosaics containing closed vegetation patches with symmetrical configurations. Variations in functional guilds were linked to low functional redundancy, which may also lead to differences in the provision of regulating ecosystem services such as biological pest control and seed dispersal—both of which are critical for the regeneration and connectivity of productive rural landscapes. In conclusion, functional diversity contributes to the resilience of bird communities in landscapes with Amazonian agroforestry and silvopastoral systems, highlighting the need for landscape management that promotes structural heterogeneity to sustain regulating ecosystem services and ecological connectivity. Full article

Recent studies have incorporated tidal elevation into hydrological models, yet they have not focused on simulating or evaluating tidal processes within these frameworks. Integrating tidal dynamics improves the representation of terrestrial–coastal interactions, including groundwater fluctuations, vegetation dynamics, and sediment transport. This study evaluates the capability of MOHID-Land, a physically based hydrological model, to simulate macro-tidal conditions in an Amazonian estuary. MOHID-Land enables tidal simulation by incorporating water-level time series as boundary conditions. A sensitivity analysis was conducted to (i) evaluate two global tidal models as boundary conditions; (ii) verify the impact of hydrological processes on water levels; and (iii) assess the effect of different bathymetries on water dynamics. The model effectively simulated tidal oscillations with good accuracy across eight tidal stations, although the inner stations required improved bathymetry. The Reference, Atmosphere, Porous Media and Vegetation (AtPmVg), and Finite Element Solution (FES) version 2014 (FES2014) simulations yielded similar water levels and goodness-of-fit metrics. While MOHID-Land is robust, and water level modeling is insensitive to meteorological, soil, or vegetation parameters, the model is highly sensitive to bathymetry. This study enhances the understanding of the applicability of hydrological models in terrestrial–coastal modeling. Full article

With few measurement sites and a great need to validate satellite data to characterize the exchange of energy and carbon fluxes in tropical forest areas, quantified by the Net Ecosystem Exchange (NEE) and associated with phenological measurements, there is an increasing need for studies aimed at characterizing the Amazonian environment in its biosphere–atmosphere interaction, considering the accelerated deforestation in recent years. Using data from a flux measurement tower in the Caxiuanã-PA forest (2005–2008), climatic data, CO₂ exchange estimated by eddy covariance, as well as Gross Primary Productivity (GPP) data and satellite vegetation indices (from MODIS), this work aimed to describe the site’s energy, climatic and carbon cycle flux patterns, correlating its gross primary productivity with satellite vegetation indices. The results found were: (1) marked seasonality of climatic variables and energy flows, with evapotranspiration and air temperature on the site following the annual march of solar radiation and precipitation; (2) energy fluxes in phase and dependent on available energy; (3) the site as a carbon sink (−569.7 ± 444.9 gC m⁻² year⁻¹), with intensity varying according to the site’s annual water availability; (4) low correlation between productivity data and vegetation indices, corroborating data in the literature on these variables in this type of ecosystem. The results show the importance of preserving this type of environment for the mitigation of global warming and the need to improve satellite estimates for this region. NDVI and EVI patterns follow radiative availability, as does LAI, but without direct capture related to GPP data, which correlates better with satellite data only in the months with the highest LAI. The results show the significant difference at a point measurement to a satellite interpolation, presenting how important preserving any type of environment is, even related to its size, for the global climate balance, and also the need to improve satellite estimates for smaller areas. Full article

The Ecuadorian Amazon holds more biodiversity than most other places on Earth. Palms are a particularly dominant component of the vegetation; however, it remains unknown to what degree the pattern has persisted through time. Here, we investigate the persistence of palm dominance through time and the degree to which past human activities (e.g., fire, cultivation, and forest opening) have affected changes in palm abundances across five regions of the Ecuadorian Amazon. We analyzed soil cores (40–80 cm depth) from each region for charcoal (evidence of past fire) and phytoliths (evidence of past vegetation change). The timings of fires (based on ¹⁴C radiocarbon dates), the occurrence, recurrence, and number of fires (based on charcoal presence and abundance in samples), and the amount of change in palm abundances (based on phytoliths) varied within and between the studied regions. The charcoal and phytolith results indicate the presence of low levels of past human activity at all sites. Our results show that patterns of modern palm hyperdominance found in Amazonian forests have not been persistent through time, and that even low levels of past human activities can affect palm abundance. Full article

Full-waveform LiDAR (FWF) offers a promising advantage over other technologies to represent the vertical canopy structure of secondary successions in the Amazon region, as the waveform encapsulates the properties of all elements intercepting the emitted beam. In this study, we investigated modifications in the vertical structure of the Amazonian secondary successions across the vegetation gradient from early to advanced stages of vegetation regrowth. The analysis was performed over two distinct climatic regions (Drier and Wetter), designated using the Maximum Cumulative Water Deficit (MCWD). The study area was covered by 309 sample plots distributed along 25 LiDAR transects. The plots were grouped into three successional stages (early—SS1; intermediate—SS2; advanced—SS3). Mature Forest (MF) was used as a reference of comparison. A total of 14 FWF LiDAR metrics from four categories of analysis (Height, Peaks, Understory and Gaussian Decomposition) were extracted using the Waveform LiDAR for Forestry eXtraction (WoLFeX) software (v1.1.1). In addition to examining the variation in these metrics across different successional stages, we calculated their Relative Recovery (RR) with vegetation regrowth, and evaluated their ability to discriminate successional stages using Random Forest (RF). The results showed significant differences in FWF metrics across the successional stages, and within and between sample plots and regions. The Drier region generally exhibited more pronounced differences between successional stages and lower FWF metric values compared to the Wetter region, mainly in the category of height, peaks, and Gaussian decomposition. Furthermore, the Drier region displayed a lower relative recovery of metrics in the early years of succession, compared to the areas of MF, eventually reaching rates akin to those of the Wetter region as succession progressed. Canopy height metrics such as Waveform distance (WD), and Gaussian Decomposition metrics such as Bottom of canopy (BC), Bottom of canopy distance (BCD) and Canopy distance (CD), related to the height of the lower forest stratum, were the most important attributes in discriminating successional stages in both analyzed regions. However, the Drier region exhibited superior discrimination between successional stages, achieving a weighted F1-score of 0.80 compared to 0.73 in the Wetter region. When comparing the metrics from SS in different stages to MF, our findings underscore that secondary forests achieve substantial relative recovery of FWF metrics within the initial 10 years after land abandonment. Regions with potentially slower relative recovery (e.g., Drier regions) may require longer-term planning to ensure success in providing full potential ecosystem services in the Amazon. Full article

The characteristics of South American biomass burning (BB) aerosols transported over northern and central Argentina were investigated from July to December 2019. This period was chosen due to the high aerosol optical depth values found in the region and because simultaneously intensive biomass burning took place over the Amazon. More specifically, a combination of remote sensing observations with simulated air parcel back trajectories was used to link the optical and physical properties of three BB aerosol events that affected Pilar Observatory (PO, Argentina, 31°41′S, 63°53′W, 338 m above sea level), with low-level atmospheric circulation patterns and with types of vegetation burned in specific fire regions. The lidar observations at the PO site were used for the first time to characterize the vertical extent and structure of BB aerosol plumes as well as their connection with the planetary boundary layer, and dust particles. Based mainly on the air-parcel trajectories, a local transport regime and a long transport regime were identified. We found that in all the BB aerosol event cases studied in this paper, light-absorbing fine-mode aerosols were detected, resulting mainly from a mixture of aging smoke and dust particles. In the remote transport regime, the main sources of the BB aerosols reaching PO were associated with Amazonian rainforest wildfires. These aerosols were transported into northern and central Argentina within a strong low-level jet circulation. During the local transport regime, the BB aerosols were linked with closer fires related to tropical forests, cropland, grassland, and scrub/shrubland vegetation types in southeastern South America. Moreover, aerosols carried by the remote transport regime were associated with a high aerosol loading and enhanced aging and relatively smaller particle sizes, while aerosols associated with the local transport pattern were consistently less affected by the aging effect and showed larger sizes and low aerosol loading. Full article

The presence of green areas in urbanized cities is crucial to reduce the negative impacts of urbanization. However, these areas can influence the signal quality of IoT devices that use wireless communication, such as LoRa technology. Vegetation attenuates electromagnetic waves, interfering with the data transmission between IoT devices, resulting in the need for signal propagation modeling, which considers the effect of vegetation on its propagation. In this context, this research was conducted at the Federal University of Pará, using measurements in a wooded environment composed of the Pau-Mulato species, typical of the Amazon. Two machine learning-based propagation models, GRNN and MLPNN, were developed to consider the effect of Amazonian trees on propagation, analyzing different factors, such as the transmitter’s height relative to the trunk, the beginning of foliage, and the middle of the tree canopy, as well as the LoRa spreading factor (SF) 12, and the co-polarization of the transmitter and receiver antennas. The proposed models demonstrated higher accuracy, achieving values of root mean square error (RMSE) of $3.86$ dB and standard deviation (SD) of $3.8614$ dB, respectively, compared to existing empirical models like CI, FI, Early ITU-R, COST235, Weissberger, and FITU-R. The significance of this study lies in its potential to boost wireless communications in wooded environments. Furthermore, this research contributes to enhancing more efficient and robust LoRa networks for applications in agriculture, environmental monitoring, and smart urban infrastructure. Full article

Organogels have importance for topical applications because they can be used to deliver drugs in a controlled and prolonged fashion. These are materials consisting of a three-dimensional network of organic molecules dispersed in a solvent. Recent studies have demonstrated that the solvent could be replaced by oils from non-conventional biologic sources. There is a diversity of not-explored species in the Amazon that are promising sources of vegetable oils with a promising composition. This study developed an organogel with buriti (Mauritia flexuosa L.f) and cacay (Caryodendron orinocense Karst.) oils, using cetostearyl alcohol as an organogelator due to its compatibility, stability, security, affordability, and it is readily available. The oils were characterized, and the organogels were synthesized by studying their crystal evolution and oil-binding capacity. The microstructure was evaluated with polarized light microscopy, fractal dimension, FTIR spectroscopy, XRD, and thermal and rheological analyses. It was found that the critical gelation concentration was higher for cacay oil as it possessed a higher amount of polyunsaturated triacylglycerols. The crystals of the buriti organogel had a smaller lamellar shape, a greater surface area, and physical and thermal stability; although, it presented a slower crystal evolution due to the low number of minor compounds and a greater number of saturated triacylglycerols. The polar fraction of the organogelators as well as triacylglycerol and minor polar compounds are important in forming crystallization nuclei. The study showed that Amazonian oils in crystallization processes form microstructures with differentiating physicochemical properties. Full article

The database on water quality in Amazonian rivers located in unplanned urbanized regions along the Brazilian Amazon Coast is still quite limited. This study addresses these concerns, and the tested hypothesis was that the water quality of the Cereja River has deteriorated in recent years, despite the efforts of government authorities to mitigate anthropogenic impacts. To assess changes in water quality, seven campaigns were conducted, collecting data at six fixed points during two different periods. High-resolution satellite images were used to document unplanned occupation. Unfortunately, the number of houses along the Cereja River has increased, in violation of the law. This has contributed to the river’s intense trophic condition, lower dissolved oxygen concentrations, higher concentrations of pathogenic bacteria, and loss of vegetation cover. According to national water quality standards, the Cereja is unsuitable for any human use. This is in stark contrast to the scenario a few decades ago when the river was used for leisure, fishing, and other activities. The results obtained confirm the initial hypothesis and can support potential management strategies and decision-making by authorities. The observed scenario can be extrapolated to other rivers located in urban areas in the Amazon region that have similarly regrettably experienced relatively uncontrolled growth. Full article