Abstract Understanding and conserving wetland vegetation requires a unified framework for classifying plants adapted to aquatic environments. Numerous taxonomic, limnological, and ecological studies have endeavored to establish such a framework. From Eugenius Warming's pioneering work to the latest classifications, this paper provides a historical overview of the various terms, concepts, and criteria used to categorize these plants, considering environmental factors, evolutionary relationships, and functional traits. The biological forms associated with adaptations to flooding, including floating and submerged species, offer valuable insights into the diverse life strategies of aquatic plants within the land-water continuum. This review thoroughly examines the definition of amphibious plants, a complex group that reflects the diversity of landscapes in which they occur, often resulting in sampling biases over time. These plants, reliant on water to complete their life cycle, are adapted to fluctuating water levels typical of waterway margins and exhibit phenotypic plasticity in response to varying degrees of soil water saturation. Finally, we discuss key considerations for sampling techniques to better investigate amphibious plants, such as sampling in different seasons and analyzing hydrological fluctuations in the studied region.

Ecological niche modeling (ENM) is widely used to predict species distributions and support biodiversity conservation under environmental change, yet its application to Amazonian wetland plants has not been systematically synthesized. We conducted a systematic review following the PRISMA 2020 guidelines to evaluate methodological approaches, environmental predictors, model performance, and research gaps. Literature searches were performed in Web of Science, Scopus, and Consensus (as a complementary AI-assisted academic search platform), yielding 1789 records, of which 48 met the eligibility criteria. Correlative models predominated, with MaxEnt, Random Forest, and ensemble frameworks being the most frequently applied algorithms. Across studies, integrating hydrological and edaphic predictors consistently improved model performance and ecological realism compared with climate-only approaches. Future climate projections indicated greater vulnerability for habitat-specialist species, whereas western Amazonia and the Andean foothills were repeatedly identified as potential climatic refugia. Major limitations included geographically biased occurrence records, limited high-resolution environmental datasets, and the underrepresentation of several Amazonian wetland ecosystems. Overall, the evidence indicates that reliable ENMs for Amazonian wetlands require integrating climatic, hydrological, and edaphic drivers rather than relying solely on macroclimate. Future research should prioritize geographically representative sampling, improved environmental datasets, transparent workflows, and process-informed modeling to strengthen ecological forecasting and conservation planning under climate and land-use change.

Heavy metal contamination of freshwater systems represents a persistent environmental challenge due to metal toxicity, non-biodegradability, and bioaccumulation potential. This study compared the phytoremediation performance of Eichhornia crassipes, Pistia stratiotes, and Chrysopogon zizanioides for the removal of chromium (Cr), copper (Cu), cadmium (Cd), and lead (Pb) from contaminated water under controlled conditions. Plants were exposed to aqueous solutions containing 5 mg L−1 of the four metals for 45 days. Metal concentrations in roots and shoots were determined by wavelength-dispersive X-ray fluorescence, translocation factor (TF), bioconcentration factor (BCF), and removal efficiency (RE) were calculated. TF values (0.02–2.90) varied across species, metals, and experimental conditions, indicating a general tendency for metal retention in roots, although translocation to shoots occurred in several cases. BCF values (0.04–87.55) were significantly influenced by species, exposure time, and treatment (p < 0.05), with P. stratiotes showing higher accumulation under specific conditions (Cu = 87.55; Pb = 44.56). In contrast, RE showed high variability (−616.21 to 72.72%) and no significant differences among experimental factors. Overall, the results demonstrate context-dependent variation in metal uptake and translocation, highlighting the potential of aquatic macrophytes as low-cost alternatives for the treatment of metal-contaminated wastewater systems.

Floodplain forests in central Amazonia are structured along a marked flooding gradient that influences species distribution, performance, and survival. This study evaluated the demographic structure, survival, and growth responses of two co-occurring tree species across contrasting v & aacute;rzea environments differing in inundation regimes. Field surveys quantified seedlings, juveniles, and adults in low- and high-floodplain forests, while a field experiment assessed survival and growth under conditions with and without interspecific interaction. Repeated-measures ANOVA revealed that temporal variation and forest type significantly affected growth parameters, with species-specific responses to flooding intensity. In the field experiment, mortality of Crateva tapia L. differed significantly among treatments (chi(2) = 24.96, p < 0.001), with the highest mortality observed in high-v & aacute;rzea (up to 75% under interspecific interaction), while Hura crepitans L. showed 100% survival across all treatments. Non-parametric analyses detected no significant treatment effects on selected morphological traits. The results support the stress-gradient hypothesis, suggesting that plant-plant interactions may shift along the flooding gradient, with facilitative processes becoming more relevant under higher stress conditions. Overall, differential flood tolerance appears to be a key driver of habitat preference and population structure in these Amazonian wetlands.

Leucaena leucocephala is a nitrogen-fixing legume widely used in agroforestry systems, although its invasive potential poses increasing risks to wetlands and riparian ecosystems. This systematic review synthesizes current knowledge on the ecological mechanisms, environmental stressors, and management strategies associated with the invasion of L. leucocephala in humid tropical environments. Following PRISMA guidelines, 60 studies retrieved from Scopus, Web of Science, and Consensus were qualitatively analyzed. The results indicate that invasion success is strongly associated with environmental disturbances and stress conditions, particularly drought stress, altered hydrological regimes, fire occurrence, and land-use change, which reduce ecosystem resistance and facilitate species establishment. Key invasion mechanisms include high seed production, persistent soil seed banks, rapid growth, allelopathic effects, and strong resprouting capacity, leading to suppression of native vegetation and structural simplification of plant communities. Integrated management strategies combining mechanical and chemical control with active revegetation consistently showed higher effectiveness than isolated approaches. The evidence further suggests that climate-related stressors may intensify invasion dynamics and increase ecosystem vulnerability under future climate scenarios. Despite recent advances, important knowledge gaps remain regarding long-term ecosystem functioning, hydrological feedback, and adaptive management in invaded wetlands.

Urbanization alters the hydrological and structural functioning of tropical urban streams, influencing organic matter transport and retention processes. This study investigated leaf litter retention dynamics in the Bindá Stream in central Amazonia. A six-month leaf release experiment (100 leaves per 12 trial; 1200 leaves total) was conducted alongside hydrological monitoring and floristic surveys of riparian vegetation (adult and regeneration strata). Leaf retention remained consistently low (<33%) across sampling periods. Generalized linear models indicated that flow velocity and discharge were the primary predictors of retention probability, with higher hydrodynamic intensity significantly reducing in-stream storage. Riparian vegetation exhibited moderate structural complexity (Shannon H' = 1.80; Structural Complexity Index = 3.80), yet limited channel roughness and physical obstructions constrained retention efficiency. Anthropogenic debris locally increased retention, but represents a structurally altered retention mechanism. Hydrodynamic forcing, rather than precipitation totals alone, governed organic matter transport dynamics. Reduced retention capacity suggests limited buffering of downstream material export under high-flow conditions. Although direct water-quality or epidemiological indicators were not measured, findings align with ecohydrological frameworks linking structural simplification and flow flashiness to diminished ecosystem regulation. These results inform riparian restoration and urban stormwater management strategies aimed at enhancing ecosystem regulation and water-quality buffering in tropical cities.

Amazonian white-sand forests (campinarana) are highly specialized ecosystems characterized by nutrient-poor sandy soils and pronounced seasonal variation in water availability. Plant species inhabiting these environments are exposed to alternating periods of water deficit and soil saturation, which may strongly constrain recruitment and early establishment. Aldina heterophylla is an endemic tree species specialist in these habitats. This study evaluated seed germination, biomass allocation, anatomical traits, and early seedling responses of A. heterophylla under contrasting water regimes: control, partial flooding, and drought. Seedling performance was assessed after 50 and 100 days of treatment. After 50 days, flooded seedlings showed significantly greater root biomass than control plants, indicating short-term plastic adjustment to saturated soils. However, prolonged flooding induced chlorosis, necrosis, leaf abscission, and partial mortality. In contrast, drought-stressed seedlings developed leaf senescence but maintained 100% survival throughout the experiment. Morphological and physiological traits varied significantly over time among treatments, particularly leaf number, height, and chlorophyll dynamics. The results indicate that A. heterophylla seedlings are more tolerant to water deficit than to prolonged flooding, although they display adaptive responses to temporary soil saturation. These findings improve understanding of regeneration processes in Amazonian white-sand ecosystems and provide relevant information for conservation planning under increasing climatic extremes.

Retained organic matter is the primary energy source for aquatic biota in forested ecosystems, serving as an indicator of ecosystem integrity through the retention of allochthonous inputs. The composition and seasonal dynamics of riparian vegetation directly influence the quantity and quality of this essential resource. This study evaluated the leaf retention capacity of the urbanized Bindá Stream, located in central Amazonia (Manaus, Brazil). Leaf release and capture experiments were conducted monthly over a six-month period (November 2017 to April 2018) along a 30-meter reach, with two replicates per month (n = 12). Riparian plant species richness was also surveyed. During each trial, depth, width, flow velocity, discharge, and the proportion of physical obstacles were recorded. The Bindá Stream showed low leaf retention capacity, with less than 33% of the leaves retained. Across the study period, depth ranged from 0.22 to 0.38 m, flow velocity from 0.27 to 0.45 m s⁻¹, channel width from 2.87 to 3.48 m, and discharge from 0.24 to 0.46 m³ s⁻¹. These hydrological variations influenced retention rates, as shown by leaf transport curves. The low retention capacity reflects poor conservation status resulting from significant anthropogenic impacts. Combined with water pollution, this limitation in organic matter retention weakens aquatic food webs by reducing resource availability for aquatic organisms. Our findings underscore the urgent need for further studies and ecological restoration efforts in Manaus’ urban streams to safeguard their ecological integrity and ecosystem functions.

ABSTRACT Amazonian várzea floodplains (approximately 450,000 km²) are dynamic ecosystems where tree species must adapt to seasonal flooding. In this context, germination patterns and the type and composition of seed reserves (lipids, soluble sugars, proteins) are critical for seedling establishment. This exploratory study examined seed biometry, reserve composition, and germination performance in eight common tree species from high- and low-várzea environments: Guazuma ulmifolia, Hura crepitans, Pseudobombax munguba, Nectandra amazonum, Zygia latifolia, Handroanthus barbatus, Macrolobium acaciifolium, and Crateva tapia, aiming to contribute to the understanding of functional strategies in tropical flooded areas. Considerable interspecific variation in seed size (length: 0.31-38.03 mm; width: 0.40-36.59 mm) and reserve content was found. Hura crepitans and P. munguba had the highest lipid levels, while H. barbatus showed elevated concentrations of soluble sugars and proteins. The highest germination rates were observed in H. barbatus, C. tapia, and P. munguba, whereas Z. latifolia and N. amazonum germinated more slowly. Despite the limited number of species and sites, patterns suggest that low-várzea species invest more in reserves and germinate more slowly, consistent with a resource-conserving strategy for early-establishment. High-várzea species showed less consistent patterns, indicating the need for broader studies. Reserve composition helps explain adaptive germination responses to flooding, evidencing the complexity of these strategies. Our results provide a basis for understanding functional diversity and guide research and restoration actions in these ecosystems.

BACKGROUND AND AIMS:The climate crisis is reshaping ecosystems globally, with wetlands, including veredas in the Brazilian Cerrado, among the most vulnerable. Despite their ecological importance, the response of vereda species to climate change remains unclear. This study assessed potential shifts in the distribution of 24 key species under two climate scenarios (SSP2-4.5 and SSP5-8.5) for the period 2061-2080 to understand the impacts on this ecosystem. METHODS:We downloaded 19 bioclimatic variables at a 30 arc-second resolution from the WorldClim database. To avoid multicollinearity, variable selection was performed using Variance Inflation Factor. Future projections were based on the MPI-ESM1-2-HR General Circulation Model. Species distribution models (SDMs) were built using the 'biomod2' R package, incorporating nine algorithms. Model evaluation was conducted using True Skill Statistic and Receiver Operating Characteristic metrics to ensure robust predictions. KEY RESULTS:Models demonstrated high reliability, with mean sensitivity (86.83 ± 10.03) and specificity (87.59 ± 7.45). Among 24 species, 13 showed loss of suitable areas under at least one climate scenario, with northeastern Cerrado projected to experience the greatest losses, and expansions occurring along the southern Cerrado-Atlantic Forest border. Desmoscelis villosa showed the greatest losses (-25.86% in SSP2; -25.98% in SSP5), while Xyris tortula exhibited significant gains. Overlap of climatically suitable areas decreased by 1.46% (SSP2) and 0.45% (SSP5), indicating potential range shifts and fragmentation under future scenarios. CONCLUSIONS:Our study highlights that climate change is likely to reshape the distribution of vereda wetland species, with most experiencing a loss of suitable areas. This is particularly concerning given the ecological importance of veredas as biodiversity hotspots and hydrological regulators within the Cerrado. Integrating climate change projections with land-use and conservation strategies will be critical to mitigating these impacts and safeguarding the unique biodiversity of this ecosystem.

Plants cope with the environment by displaying large phenotypic variation. Two spectra of global plant form and function have been identified: a size spectrum from small to tall species with increasing stem tissue density, leaf size, and seed mass; a leaf economics spectrum reflecting slow to fast returns on investments in leaf nutrients and carbon. When species assemble to communities it is assumed that these spectra are filtered by the environment to produce community level functional composition. It is unknown what are the main drivers for community functional composition in a large area such as Amazonia. We use 13 functional traits, including wood density, seed mass, leaf characteristics, breeding system, nectar production, fruit type, and root characteristics of 812 tree genera (5211 species), and find that they describe two main axes found at the global scale. At community level, the first axis captures not only the 'fast-slow spectrum', but also most size-related traits. Climate and disturbance explain a minor part of this variance compared to soil fertility. Forests on poor soils differ largely in terms of trait values from those on rich soils. Trait composition and soil fertility exert a strong influence on forest functioning: biomass and relative biomass production.

Recent evidence suggests that the ecological footprints of pre-Columbian Indigenous peoples in Amazonia persist in modern forests. Ecological impacts resulting from European colonization c. 1550 CE and the Amazonian Rubber Boom c. 1850 to 1920 CE are largely unexplored but could be important additive influences on forest structure and tree species composition. Using environmental niche models, we show the highest probabilities of pre-Columbian and colonial occupation sites, and hence human-induced ecological influences, occurred in forests along rivers. In many areas, the predicted pre-Columbian and colonial distributions overlap spatially with the potential for superimposed ecological influences. Environmental gradients are known to structure Amazonian vegetation composition, but they are also strong predictors of past human influence, both spatially and temporally. Our comparisons of model outputs with relative abundances of Amazonian tree species suggest that pre-Columbian and colonial-period ecological legacies are associated with modern forest composition.

Considerando que a dispersão de sementes é um processo ecológico essencial para a regeneração florestal e que grandes frugívoros, como Tapirus terrestris, têm papel central na manutenção da diversidade vegetal amazônica, este estudo buscou avaliar os serviços ecossistêmicos de frugivoria e dispersão realizados por essa espécie na Reserva de Desenvolvimento Sustentável do Uatumã. Objetivou-se identificar, por meio da análise de fezes, as espécies consumidas, quantificar sementes intactas e predadas e analisar possíveis variações sazonais no consumo. Foram coletadas 22 amostras fecais em áreas de baixios de terra firme, campinarana e ramais, durante a estação seca de 2016 e a chuvosa de 2017, as quais foram triadas. Observou-se que T. terrestris consumiu predominantemente material vegetal não reprodutivo, mas 714 sementes de cinco espécies foram registradas. Sacoglottis guianensis representou cerca de 80% das sementes consumidas. Houve aumento do número de amostras e da quantidade de sementes no período chuvoso, indicando maior disponibilidade de frutos. Os pesos de sementes intactas e predadas foram semelhantes, sugerindo que a espécie atua tanto como dispersora quanto como predadora. Conclui-se que T. terrestris desempenha importante função ecológica na região, apresentando dieta oportunista e variações sazonais marcantes, além de registrar pela primeira vez Endopleura uchi em sua dieta local.

A modelagem de nicho ecológico (ENM – Ecological Niche Modeling) consolidou-se como uma ferramenta relevante para prever a distribuição de espécies frente a alterações climáticas e pressões antrópicas. Sua aplicação em espécies associadas a áreas úmidas nos Neotrópicos tem crescido, dada a alta biodiversidade e vulnerabilidade desses ecossistemas. Este trabalho revisa avanços metodológicos recentes na modelagem de espécies de áreas úmidas neotropicais, com foco na inclusão de variáveis edáficas e hidrológicas, fatores bióticos e dados genéticos. A partir de uma revisão narrativa de 50 estudos publicados entre 2017 e 2024, identificaram-se quatro eixos principais: (i) uso de dados edáficos e climáticos; (ii) estratégias para espécies pouco amostradas; (iii) integração de fatores bióticos; e (iv) maior amplitude de nicho hidrológico em espécies amazônicas. Apesar de modelos como MaxEnt, GAM e SVM alcançarem alta acurácia (AUC > 0,9), persistem desafios como viés amostral e ausência de validação empírica. A integração de dados de sensoriamento remoto, atributos funcionais e informações genéticas melhora significativamente a robustez dos modelos. Além de sua relevância preditiva, os ENMs emergem como ferramentas fundamentais para promover a conservação e o uso sustentável de áreas úmidas, contribuindo para a gestão ambiental baseada em evidências. Conclui-se que, embora promissores, os ENMs demandam avanços na qualidade dos dados e abordagens multivariadas para apoiar estratégias de conservação em áreas úmidas tropicais.

A dinâmica hidrológica sazonal dos rios amazônicos, caracterizada por fases terrestre e aquática ao longo do ano, exerce forte influência sobre o estabelecimento e o crescimento da vegetação marginal. Tanto o excesso de água durante a fase aquática quanto sua limitação na fase terrestre configuram condições altamente estressantes para as plantas. Neste estudo foi avaliado o crescimento de plântulas de duas espécies arbóreas de áreas férteis da várzea amazônica, Pseudobombax munguba (Mart. & Zucc.) Dugand e Vitex cymosa Bertero ex Spreng, submetidas a diferentes regimes hídricos. As plântulas, obtidas de sementes coletadas nos frutos das espécies na natureza, foram expostas por seis meses a três tratamentos: controle, inundação parcial e seca. As variáveis altura, diâmetro do coleto e número de folhas foram avaliadas mensalmente ao longo de 180 dias, e, ao final do experimento, foi determinada a biomassa das plantas. P. munguba apresentou maior incremento em altura e diâmetro que V. cymosa, com crescimento estimulado tanto pela inundação parcial quanto pela seca. Em ambas as espécies, observou-se redução do número de folhas ao longo do experimento. O incremento de biomassa foi significativamente afetado apenas nas raízes de P. munguba, e no caule e biomassa total de V. cymosa, com maiores valores no tratamento de inundação parcial. Os resultados evidenciam estratégias contrastantes de resposta ao estresse hídrico, associadas ao estágio sucessional das espécies: P. munguba, espécie pioneira, apresentou crescimento mais rápido, enquanto V. cymosa, espécie secundária, exibiu crescimento mais conservativo sob condições de estresse. Esses achados indicam que alterações no regime hidrológico podem impactar o metabolismo e a distribuição das espécies arbóreas nas áreas alagáveis amazônicas.

Unlike most rivers globally, nearly all lowland Amazonian rivers have unregulated flow, supporting seasonally flooded floodplain forests. Floodplain forests harbor a unique tree species assemblage adapted to flooding and specialized fauna, including fruit-eating fish that migrate seasonally into floodplains, favoring expansive floodplain areas. Frugivorous fish are forest-dependent fauna critical to forest regeneration via seed dispersal and support commercial and artisanal fisheries. We implemented linear mixed effects models to investigate drivers of species richness among specialized frugivorous fishes across the ~6,000,000 km 2 Amazon Basin, analyzing 29 species from 9 families (10,058 occurrences). Floodplain predictors per subbasin included floodplain forest extent, tree species richness (309,540 occurrences for 2,506 species), water biogeochemistry, flood duration, and elevation, with river order controlling for longitudinal positioning along the river network. We observed heterogeneous patterns of frugivorous fish species richness, which were positively correlated with floodplain forest extent, tree species richness, and flood duration. The natural hydrological regime facilitates fish access to flooded forests and controls fruit production. Thus, the ability of Amazonian floodplain ecosystems to support frugivorous fish assemblages hinges on extensive and diverse seasonally flooded forests. Given the low functional redundancy in fish seed dispersal networks, diverse frugivorous fish assemblages disperse and maintain diverse forests; vice versa, diverse forests maintain more fish species, underscoring the critically important taxonomic interdependencies that embody Amazonian ecosystems. Effective management strategies must acknowledge that access to diverse and hydrologically functional floodplain forests is essential to ensure the long-term survival of frugivorous fish and, in turn, the long-term sustainability of floodplain forests.

A contaminação por metais pesados em riachos urbanos da Amazônia representa uma ameaça crescente à qualidade da água e à saúde pública. Este estudo avaliou a toxicidade do cobre (Cu) e o potencial de fitorremediação da macrófita aquática Pistia stratiotes L. (Araceae), espécie amplamente distribuída em ecossistemas amazônicos. O experimento foi conduzido em casa de vegetação do INPA (Manaus-AM), utilizando sete concentrações de cobre (0; 2,5; 5; 10; 20; 40 e 80 mg L⁻¹) com 10 repetições cada. Foi avaliada a biomassa fresca e seca das folhas e raízes, além da mortalidade após 30 dias de exposição. Observou-se redução significativa da biomassa foliar e radicular a partir de 5 mg L⁻¹, com inibição total do crescimento e mortalidade de 100% das plantas em 80 mg L⁻¹. A dose letal média (DL₅₀) foi estimada em 37,03 mg L⁻¹ (IC95% = 20,75–60,11 mg L⁻¹). Os resultados indicam que P. stratiotes apresenta sensibilidade a concentrações elevadas de cobre, mas tolerância suficiente para ser utilizada como espécie indicadora e agente fitorremediador em corpos hídricos contaminados da região amazônica. A aplicação dessa espécie em sistemas de tratamento naturais pode representar uma alternativa de baixo custo e eficiente para mitigação de poluição por metais pesados.

Fish species characteristics and supply of food resources in Amazonian floodplain forests probably shape the trophic structure and composition of the fish community; however, this dynamic has rarely been studied in the context of trophic networks. In this study, we hypothesized that the main forces that structure the trophic web of the fish community present in two blackwater forests are the supply of resources of allochthonous origin and species characteristics, such as body size and abundance of individuals. Interactions assembly was explored and analyzed, and we tested whether fish body size, number of individuals, trophic category, and use of different food resources affect the structure of the trophic network. Out of 771 fish individuals, 30 species consumed food divided into eight categories: animal remains, plant remains, fish, flowers, invertebrates (terrestrial and aquatic), leaves, fruit pulp, and seeds. We found a network that is modular and highly specialized. Conversely, the network is structured by low connectance and nestedness. The supply of compositional items from riparian vegetation provided a multifunctional network formed by different layers represented mainly by herbivorous and frugivorous guilds. Our results also show that food web centrality is influenced by fish size and abundance. Overall, we suggest that the seasonal food supply of flooded forests and the size and abundance of fish species shape the structure of Amazonian food webs. We reinforce the importance of lateral connectivity in low productivity environments, such as blackwater floodplain forests. We provide insights into the coexistence of fish communities and their functional role.

This study aimed to identify the number of vascular epiphytes endemic to the Amazon forest, estimate the distribution of 20 endemic vascular epiphytes (EVEs) using species distribution modeling (SDMs), and examine their potential occurrence inside and outside Amazonian Protected Areas (PAs) to predict potential habitats and conservation strategies. The study was carried out in the Amazon rainforest, focusing on PAs and their interactions with the distribution of EVEs. We used four primary sources of biodiversity data (GBIF, Kew Herbarium, Species Link, and Amazon inventories) to uncover the composition of endemic epiphytes. Fifteen EVEs were selected based on occurrence records from at least 17 locations. The research used a large dataset of epiphyte collections, eight modeling algorithms, and 34 environmental variables to generate consensus maps that identify suitable habitats for EVEs. The main results indicated that most EVEs have suitable areas concentrated along the edges of the Amazon rainforest, especially on the slopes of the Andes, with limited suitability in central and eastern Amazonia. The largest areas of suitability for the 20 model species were greater in unprotected areas (79%) than in protected areas (76.5%). The overlap between suitable areas and PAs highlights the importance of these areas in protecting EVEs. However, the significant presence of habitats outside PAs requires management strategies that go beyond their boundaries. The findings offer critical insights for biodiversity conservation and for planning actions to safeguard the diversity of Amazonian epiphytes in the face of increasing pressures.