Maria Teresa Fernandez Piedade

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.

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.

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.

Seed dispersal by fish (ichthyochory) plays a key role in the structure of Amazonian floodplain forests. The hydrological regime creates broad variability in flooding depth and duration, and as a result, the tree species richness increases as the flooding depth and duration decrease. This flooding gradient leads to habitats, such as low várzea (LV) and high várzea (HV) forests, corresponding to flood durations of 50–230 and ≤ 50 days year ⁻¹ , respectively. Our study evaluated the fruit consumption by fish and the seed dispersal potential along the flood gradient. We tested the hypothesis that the role of fish as seed dispersers varies between LV and HV and that the seed dispersal network is modular and nested. We expect to find a greater contribution of fish to seed dispersal in LV forests. Based on fish collections from Paciência Island and a literature review, we identified 40 fish species that consumed fruits and seeds of 188 tree species in Amazon floodplains. Of these, 114 tree species were recorded on Paciência Island or in other floristic inventories along the flood gradient in várzea forests. When we considered only the tree species with distribution restricted to each forest type (LV or HV), the species richness of fruits and seeds consumed by fish was greater in LV forest. The ichthyochory network showed a significant nested structure. Although most forest inventories have found greater tree species richness in the HV, our study highlights the importance of fish consumption of fruit and seeds in LV forests.

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 várzea 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 (χ² = 24.96, p < 0.001), with the highest mortality observed in high-várzea (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.

This study investigates the edaphic-hydrological gradients of riparian zones in the Falsino River basin, Eastern Amazon. We defined 21 sampling units based on water body order (2nd to 4th) to capture edaphic and hydrological variation. Maximum river level values (MRL) were represented using limnimetric rulers as proxy of flood pulse intensity, and physicochemical analysis was performed on 378 soil samples. The topographic measurements by Global Positioning System (GPS) and Shuttle Radar Topography Mission (SRTM) quantified basin levels and the results were compared. Results reveal a clear spatial pattern, with MRL increasing with tributary order and decreasing elevation. Flood pulse intensity strongly influenced soil texture and acidity, while variables such as organic matter and phosphorus were weakly associated. The inverse relationship between elevation and MRL highlights the topographic control on hydrological dynamics, although elevation alone did not explain most soil variations. Both GPS and SRTM showed strong agreement, validating their use in low-relief Amazonian landscapes. Sample plot delimitation along the basin’s longitudinal profile facilitated the evaluation of abiotic attribute relationships. This research provides novel insights into how hydro-topographic interactions shape riparian soil properties, offering a practical framework for hydropedological assessments in remote tropical basins.

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.

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.

February 2, World Wetlands Day, highlights the vital role of wetlands in biodiversity, climate regulation, food systems and human livelihoods. Although they cover a small fraction of Earth's surface, wetlands provide a disproportionate share of ecosystem services and mitigate climate change through carbon sequestration. Yet, over one‐third of global wetlands have been lost in recent decades, weakening their ability to buffer climate extremes. Despite advances under frameworks such as the Ramsar Convention, protection remains fragmented and insufficient. We argue that effective conservation requires large‐scale financial mechanisms and propose initiating discussions toward a Wetlands Forever Facility to enable integrated, equitable investments.