Riparian Environments Research Articles

Phytophthora alni Infection Reinforces the Defense Reactions in Alnus glutinosa - Frankia Roots to the Detriment of Nodules

Alnus glutinosa, able to establish symbiosis with mutualistic bacteria of the genus Frankia, is one of the main species in European riparian environments, where it performs numerous biological and socio-economic functions. However, riparian ecosystems face a growing threat from Phytophthora alni, a highly aggressive waterborne pathogen causing severe dieback in A. glutinosa. To date, the tripartite interaction between the host plant, the symbiont Frankia and the pathogen remains unexplored but is critical for understanding how pathogen-induced stress influences the nodule molecular machinery and so on the host-symbiont metabolism. In the present study, we aimed to explore for the first time how P. alni affects the overall molecular processes of Alnus glutinosa – Frankia nodules, with a special focus on unraveling the spatial expression of defense mechanisms within these tissues. We conducted a laboratory experiment based on P. alni infection of young A. glutinosa seedlings nodulated with Frankia alni ACN14a, non-infected or infected with the pathogen P. alni. Multi-omics analyses were carried out on nodules (N) and associated roots (AR) of the same plant in order to underline the impact on the nodule molecular processes (i.e. N/AR markers) when the host plant is infected compared to non-infected plants. Our results revealed that P. alni infection modified the molecular nodule processes and induced reprograming of defense-related markers by a shift in associated roots to the detriment of nodules. These findings suggest that A. glutinosa reinforces locally its immune responses in roots but moderates this activation in nodule to preserve its Frankia symbiont.

A leap in scale for invasive species management: a medium‐scale beaver eradication pilot project

AbstractIn 1946, 20 beavers (Castor canadensis) were introduced in Tierra del Fuego, Argentina, and over the last 70 years, the population has expanded, severely affecting riparian environments. In 2008, Argentina and Chile agreed to restore the environments affected by beavers through their eradication. The objectives of this paper were to assess the trapping effort and cost required to remove beavers, and to determine the factors that influence capture success. The study was conducted over 7 pilot areas in the Argentine part of Tierra del Fuego. Ten trappers using body‐grip traps, snares, and shooting carried out an eradication pilot project between October 2015 and June 2018. Trappers acted in 505 colonies, performing 9,751 trapping episodes, and capturing 1,012 beavers. In the mountain range zone, trappers needed on average 23 trapping episodes/km of watercourse. Capture success was best explained by trap placement and trap type. We estimated a required investment of 31 million US dollars over 17 years for a full beaver eradication in the Argentine part of Tierra del Fuego. We concluded that by using mainly body‐grip traps, eradication is feasible and it allows trapping in neighboring colonies simultaneously, without the need to check traps daily. Traps should be set preferably on dams, dams should be broken only after the first captures, and trappers should be trained to capture all individuals.

Implementation of complementary methods for bat sampling in a karstic landscape in central–northern Guatemala, Central America

The use of complementary sampling methods for bats is recommended to improve inventories of species. Here we performed direct and indirect sampling in caves, in the main river, and in various forest vegetation covers in a karst landscape in central–northern Guatemala. We determined efficiency and complementarity between methods. Using mist nets and with an effort of 2,670 m²h, we captured 296 individuals of 19 species. Using ultrasonic microphones and after 71 hours of recording, we obtained 1,598 effective files of 16 species/sonotypes. Using a harp trap and after 79 hours of operation, we captured 939 individuals of 12 species. In total, we report 34 species/sonotypes. Regarding the percentage of species richness sampled, according to an extrapolation to double the sampling effort, this varied between 69.8 % and 91.5 %, which we consider satisfactory. The percentages of complementarity between methods were over 70 %, notably high between mist nets and ultrasonic microphones (91 %). To date in Guatemala, inventories have been incomplete, mainly because they are biased by the use of mist nets and the capture of bats of the Phyllostomidae family. Training and implementation of non–extensively used methods such as acoustic detection is needed to improve our knowledge about this taxonomic group and provide fundamental information for conservation strategies. Dataset published through GBIF (DOI: 10.15470/3vcvof). Key words: Harp trap, Karstic caves, Lanquín, Mist nets, Riparian environments, Ultrasonic microphones

Ecological Environment Assessment System in River–Riparian Areas Based on a Protocol for Hydromorphological Quality Evaluation

This paper aims to propose a method for the evaluation of the hydromorphological quality of a river and its riparian areas using three essential components: morphological characterization, river connectivity, and vegetation coverage. The method has been applied to the Tordera river in Catalonia, Spain. The general goal is to establish a riparian environment assessment tool by proposing parameters for each of the three mentioned aspects. This approach relies on data collection and evaluation with a simple computational procedure for eliminating subjectivity in the weighting and classification of evaluation levels. In the proposed methodology, the weights of the indicators are determined by the Distance Correlation-Based CRITIC (D-CRITIC) method, and the results are integrated using the Coupling Coordination Degree Model (CCDM). The proposed methodology quantifies assessment parameters and analyzes the environmental problems faced by riparian zones and rivers through the parameters and the results of the CCDM and thus can be used as a basis for proposing methods to improve the ecological situation. The results can be used for the enhancement of the coordination between the development of riparian resources and the requirements of ecosystem protection and utilization, and they can be used to promote the healthy development of ecological environments and the effective use of riparian resources.

Miconiagaragoana - Melastomataceae: A new rheophytic species from the eastern Andes of Colombia.

A new species, Miconiagaragoana, from riparian environments of the northern Cordillera Oriental of Colombia, is described. This is the second species exclusive to rheophytic conditions that grows in the Andean forest in Colombia and is characterized by the presence of stellate-lepidote trichomes on young structures and inflorescences, terminal inflorescences, 4-merous (rarely 5-merous) flowers, oblong-subulate anthers with an apical pore and 2-locular ovary. The differences with other rheophytic species occurring in Colombia are noted and it is argued that it is related to other Andean species with bluish-green ripe fruits such as M.squamulosa and M.symplocoidea. This new species is so far known only from Colombia and its threat category is suggested as Critically Endangered" (CR).

Exploring the distribution pattern of native and alien forests and their woody species diversity in a small Mediterranean city

Recent studies have explored the ecological relationship between native urban forests and self-sown non-native forests in large cities and metropolises but further research efforts dedicated to analyzing this relationship in small cities are still needed. To improve our understanding of the ecology of urban native and alien forests in Mediterranean small cities, we analyzed the woody species richness, the community-weight mean of moisture and nitrogen ecological indicators, and soil disturbance indicators in the main urban wood types of the city of Campobasso (Italy), as well as their spatial distribution pattern across a gradient of cover and aggregation of green areas. The study showed that both native oak forests and Robinia pseudoacacia forests contributed to the maintenance of woody species richness. If we exclude the riparian environment, R. pseudoacacia forests occupied small marginal patches, tolerating soil disturbance and a high disturbance frequency, thus occupying habitats where the native oak forests could not grow. Conversely, R. pseudoacacia forests shared the ecological niche with the native riparian forests, which calls for action to prevent the spread of this alien species along river banks. Our results highlighted that urban remnant forests should be considered important assets for the planning and upkeep of urban green areas.

Windthrow in riparian buffers affects the water quality of freshwater ecosystems in the eastern Canadian boreal forest

Despite the wide application of riparian buffers in the managed boreal forest, their long-term effectiveness as freshwater protection tools remains unknown. Here, we evaluate windthrow incidence in riparian buffers in the eastern Canadian boreal forest and determine the effect of windthrow on the water quality index of the adjacent freshwater ecosystems. We studied 40 sites—20 riparian buffers, aged 10 to 20 years after harvesting and 20 control sites within intact riparian environments—distributed among clay and sandy (esker) soils and black spruce (Picea mariana) and jack pine (Pinus banksiana) stands. We observed more windthrow in the harvested stands (36%) relative to the control sites (16%), regardless of substrate and species. We determined that the most important factors explaining windthrow were exposition, harvesting, aquatic environment size, and stand characteristics. These factors drive wind exposure, speed, and force, which determine post-harvest windthrow risk. Furthermore, windthrow negatively affected the water quality index of the adjacent aquatic systems, i.e., greater windthrow decreased the protective effect of the riparian buffer. We recommend increasing the use of partial harvest near riparian environments and adapting riparian buffers to site conditions to ensure the long-term protection of adjacent freshwater ecosystems.

Micorrizas arbusculares y endófitos septados en tres especies de Thelypteridaceae de ambientes riparios de las Yungas (Tucumán, Argentina)

Background and aims: The status of the presence of arbuscular mycorrhizal fungi (AMF) in lycophytes and ferns has been analysed in 11% of them. This work aims to characterise and quantify the AMF colonisation and to characterise septate endophytes present on the roots of the Thelypteridaceae: Amauropelta jujuyensis, A. nubicola, and Pelazoneuron patens. M&M: Ten individuals per species were collected in August 2022. Conventional staining and techniques were used to estimate colonisation. Results: The root of Amauropelta jujuyensis, A. nubicola, and Pelazoneuron patens showed AMF with Arum and Paris morphological types simultaneously. The hyphal colonization showed no significant difference among species, arbuscular colonization was significantly higher in A. jujuyensis, while vesicular colonization was considerably higher in A. nubicola. In addition, septate endophytes were evident in the species of the genus Amauropelta. Conclusion: The association of AMF and other fungal endophytes with the native Argentine Thelypteridaceae Amauropelta jujuyensis, A. nubicola, and Pelazoneuron patens is evidenced for the first time in riparian environments of the Yungas. The coexistence of Arum and Paris morphological types in the three studied fern species is demonstrated.

Generating 3D Models for UAV-Based Detection of Riparian PET Plastic Bottle Waste: Integrating Local Social Media and InstantMesh

In recent years, waste pollution has become a severe threat to riparian environments worldwide. Along with the advancement of deep learning (DL) algorithms (i.e., object detection models), related techniques have become useful for practical applications. This work attempts to develop a data generation approach to generate datasets for small target recognition, especially for recognition in remote sensing images. A relevant point is that similarity between data used for model training and data used for testing is crucially important for object detection model performance. Therefore, obtaining training data with high similarity to the monitored objects is a key objective of this study. Currently, Artificial Intelligence Generated Content (AIGC), such as single target objects generated by Luma AI, is a promising data source for DL-based object detection models. However, most of the training data supporting the generated results are not from Japan. Consequently, the generated data are less similar to monitored objects in Japan, having, for example, different label colors, shapes, and designs. For this study, the authors developed a data generation approach by combining social media (Clean-Up Okayama) and single-image-based 3D model generation algorithms (e.g., InstantMesh) to provide a reliable reference for future generations of localized data. The trained YOLOv8 model in this research, obtained from the S2PS (Similar to Practical Situation) AIGC dataset, produced encouraging results (high F1 scores, approximately 0.9) in scenario-controlled UAV-based riparian PET bottle waste identification tasks. The results of this study show the potential of AIGC to supplement or replace real-world data collection and reduce the on-site work load.

Rapid Assessment of Riparian Vegetation at Calyawan River, Barangay Andap, Municipality of New Bataan, Davao de Oro Province, Philippines

Aims: The aim of this study was to examine the vegetation found along the riverbanks of the Calyawan River in Barangay Andap, Municipality of New Bataan, Province of Davao de Oro, Philippines using the transect walk method. The goals were to determine the variety and abundance of the flora along the riverbank, evaluate the conservation status of the discovered plant species, and suggest measures for safeguarding and preserving the riparian environment. Study Design: The study employed a transect walk method to carry out an initial survey of the riparian vegetation. A 1-kilometer transect was conducted along the riverbanks of the Calyawan River to gather qualitative and quantiatative measurements of plant diversity. The evaluation took place on December 20, 2022. This approach facilitated a quick and systematic examination of the vegetation along the riverbanks. Place and Duration: The study was carried out on the riverbanks of the Calyawan River in Barangay Andap, Municipality of New Bataan, Province of Davao de Oro. The fieldwork was conducted on December 20, 2022. The region can be reached by using the Compostela-Montevista-Mati Boundary Road. Methodology: The transect walk approach was employed to record the riparian flora during the survey. Plant species were identified and photographed, but no tangible plant specimens were collected. The obtained data encompassed the identification of fern and angiosperm taxa and families encountered along the transect. The conservation status assessments were conducted using the pre-existing classifications of the species. Results: A rapid assessment revealed the presence of 49 distinct genera of ferns and angiosperm plants belonging to 30 different families along the transect. Out of these, 74% of the riparian plant genera that were identified were found to be endemic to the region. The assessment of the riparian plants' conservation status indicated that 37% were classed as vulnerable, 30% as least concern, 22% as other threatened species, 10% as endangered, and 1% were not categorized. Although the sample time was short, these findings emphasize the abundance and importance of the riparian flora in terms of conservation. Conclusion: The initial study conducted along the riverbanks of Calyawan River indicated a notable variety of plants that grow along the river, with a large number of species that are unique to that area. Many identified plants have a conservation status that emphasizes the necessity for heightened sampling efforts and monitoring in order to gain a more comprehensive understanding of and safeguard this rich ecosystem. Considering the clear human-induced stresses on the forest fragments in the region, it is advisable to enhance and broaden conservation efforts in order to protect the riparian vegetation and guarantee its ongoing existence.

Seasonal dynamics of soil ecosystems in the riparian zones of the Three Gorges Reservoir, China

Riparian soils, together with vegetation, play a crucial role in supporting biodiversity and driving biogeochemical processes within river ecosystems. Conservation of riparian soils and artificial planting are essential for river ecosystem recovery following land degradation. Researchers focus on examining soil nutrients, microbial biomass, and organic acid metabolism in the interactions between plants and soil along riverbanks. However, the seasonal responses of riparian soils to artificial plantations have been infrequently reported in the existing literature. This study investigates the influence of seasonal variations on soil conditions and the growth of artificially planted species in the riparian zones of the Three Gorges Dam Reservoir (TGDR) in China. The species sampled include Cynodon dactylon, Hemarthria altissima, and Salix matsudana. These species provide valuable insight into soil properties along riparian zones, assessing interactions across different seasons: T1 (spring), T2 (summer), and T3 (autumn). The results demonstrated significant seasonal changes in soil organic matter, ammonium nitrogen, nitrate nitrogen, and other indicators between T1 and T3. Apart from invertase activity in H. altissima soil, enzyme activity peaked during T1. Dominant soil bacteria were examined using high-throughput 16S rDNA sequencing, revealing that the available bacteria belong to 62 phyla and 211 classes. Among the most abundant were Proteobacteria and Actinobacteria, averaging over 60 % across all soil samples. Principal component analyses accounted for 62.81 % (T1), 50.57 % (T2), and 54.08 % (T3) of the variation observed in the study, indicating that soil properties were predominantly influenced by the different seasonal phases, assuming all other factors remained constant. Pearson correlation analysis (p < 0.05) identified strong positive correlations between physical properties and all three plant species during T1 (r ≤ 0.94), as well as significant negative correlations with bacterial communities in T2 and T3 (r ≤ −1.00). These findings suggest that the selected plant species are well-suited to cultivation in the riparian zone of the TGDR. This study enhances our understanding of seasonal dynamics in riparian environments, offering practical insights into their management.

Can Multiscale Thermal Infrared Imaging Help Validate and Monitor Water Stress in Alluvial Forests?

ABSTRACTAlluvial forests are sensitive to drought induced by climate change and exacerbated by altered flow regimes. Our ability to detect and map their sensitivity to drought is crucial to evaluate the effects of climate change and adjust management practices. Therefore, we explore the potential of multiscale thermal infrared imagery (TIR) to diagnose their sensitivity to droughts. In summer 2022, we sampled leaves and phloem on Populus nigra trees from two sites with contrasted hydrological connectivity along the Ain River (France) to investigate the seasonality of water stress and act as ground truth for airborne TIR images. To map forest sensitivity to drought, we used TIR data from four airborne campaigns and Landsat archives over a larger spatial and temporal extent. Field data showed that stress conditions were reached for both sites but were higher in the site with lower groundwater connectivity, which was also the case for individual tree crown temperatures. At the forest plot scale, canopy temperature was linked to forest connectivity for two of four TIR campaigns, with higher values in the more degraded reaches. Landsat data were used to locate the areas of the riparian forest impacted by a historical drought event and monitor their recovery and proved useful to identify trends. TIR data showed promising results to help detect and map tree water stress in riparian environments. However, stress is not detected in all TIR campaigns, demonstrating that one‐shot TIR acquisitions alone are not enough to diagnose stress and complementary in‐field eco‐physiological measurements are necessary.

Early Cretaceous dinosaur, bird and turtle tracks from the Lanzhou-Minhe Basin, Gansu Province, Northwest China

The Early Cretaceous avian ichnofauna of Laurasia, particularly in East Asia, is remarkably abundant. The northwestern region of China is the most productive area for bird tracks. Recently, four avian-dominated track sites have been discovered in the Cretaceous Lanzhou-Minhe Basin of Gansu, where the shorebird track Koreanaornis, the ankylopollexian track Caririchinium and the turtle track Chelonipus occur. The Kongjiasi site yields a new type of the fluvio-lacustrine Chelonipus ichnocoenosis related to birds, which was previously defined to include only non-avian theropods and turtles. The site is associated with a waterfront foraging site of a Cretaceous shorebird which might be due to the invertebrate-rich substrate. The sole association of both bird and other theropod tracks with Chelonipus ichnocoenosis may indicate a difference in the appetite of avian and non-avian theropods for littoral foraging sites. And a review of the global turtle track-related ichnofauna and ichnocoenosis may offer new insights into the qualitative speculation of palaeobathymetry in riparian environments.

Global sensitivity analysis with deep learning-based surrogate models for unraveling key parameters and processes governing redox zonation in riparian zone

The riparian zone constitutes an intricate redox environment, giving rise to distinct redox zones characterized by dissolved oxygen (DO), nitrate, manganese dioxide (Mn (IV)), iron hydroxide (Fe(III)), and sulfate. Processes encompassing river fluctuation, groundwater flow, microbial growth and death, as well as solute reactive transport, exert substantial influences on the spatiotemporal zonation of these redox zones in the riparian zone. Nonetheless, understanding remains elusive regarding how these processes govern the thickness of these zones. In this study, we built a one-dimensional (1-D) model which is adapted from Zhu et al. (2023) that integrates these processes to simulate the temporal variation of the thicknesses of different redox zones in riparian zone. Sobol’s sensitivity analysis method and the hierarchical sensitivity analysis framework based on Bayesian Networks (BNs) were then employed to quantify the sensitivities of the 17 selected parameters and the four generalized processes governing redox zonation, respectively. To mitigate the computational costs, multi-layer perceptron (MLP) was employed to establish the surrogate models, efficiently predicting model outputs for sensitivity analysis. The results of sensitivity analysis highlight the groundwater flow and reactive transport processes as the most important processes affecting thickness variations of the redox zones. Parameters such as the initial hydraulic conductivity (Ks0) and DOC concentration (CDOC) play a predominant role in governing the thickness variations. Parameters linked to river fluctuation and microbe growth processes exhibit very limited effects on redox zonation. These findings offer valuable insights into the factors controlling redox zones in the riparian environment.

Plastic litter assessment of the riverbanks of Pulot River and its tributary in Sofronio Española, Palawan Island, Philippines

Rivers are essential sources of plastic litter in the marine environment. Recently, the Philippines was reported as the biggest polluter of plastic litter from riverine sources. However, the riverine plastic litter's origin has been less established. In this study, we determined the density, composition, and accumulation of plastic litter on the riversides of Pulot River and its tributary in Palawan Island, Philippines. We also identified the possible sources of plastic litter. Results showed that the plastic litter density was highest at the river edge during the first sampling period. Litter densities for the predefined zones and sampling periods all showed no significant differences. The most dominant plastic litter types were food packaging and plastic bags, followed by toiletries. ‘Others’ consisted of multilayers, mixed, and plastics accounted for the most abundant polymer types. We identified the residents in the vicinity illegally dumping litter, for there were small illegal dumping sites along the river. These results suggest the urgent need for better waste policy implementation measures to protect the riparian environments and reduce the input of riverine plastic litter into the marine environment to ensure river resource sustainability.

Geopedological influence on the wood anatomy of Gymnanthes klotzschiana (Euphorbiaceae) in a subtropical riparian forest, in Southern Brazil

The wood anatomy of Gymnanthes klotzschiana was studied, to assess whether there are variations in the secondary xylem under different geopedological conditions. The species is dominant in subtropical alluvial forests and can be established in different ecological conditions, especially regarding soil water regime. Wood samples were collected in the plain of the Iguaçu River, in Paraná, Brazil, encompassing three geopedological conditions: gleysol, fluvisol and psamment, characterized by varying degrees of water saturation, ranging from very poorly drained to heavily drained. Considerable intraspecific variations were found in the xylem in response to geopedological conditions. Most of the variation occurs in attributes related to the biomechanical and hydraulic functions (e.g. fibers and vessels), with cells smaller in gleysol, larger in fluvisol and intermediate in psamment. For some variables, the xylem has similar responses in conditions of water deficit and permanent water saturation, indicating a probable influence of physiological drought. The phenotypic plasticity of the species explains its high adaptability to the selective and variable conditions of riparian environments. The study contributes to understanding the species’ ecological responses, highlighting its relevance as a keystone species in the dynamic and fragile ecosystems of the floodplains, fundamental for the maintenance of many ecosystem services.

Riparian forests: a temporal analysis of their ecological status in urban river systems of the Andean Patagonia, Chubut, Argentina

Abstract Streams and rivers are ecosystems strongly impacted by changes associated with urbanization, which cause ecological degradation of their banks and the deterioration in water quality. Assessing the ecological state of riverbanks and proposing measures to mitigate their degradation are priorities. This study aimed to evaluate the quality of riparian forests in three urban river systems with different population densities and to analyze changes over a temporal scale. The pre-urban, urban and post-urban sections of the rivers were analyzed. The Quality Index of Riparian Forests for Andean Patagonian rivers (QBRp) was used. This index assesses four riverbank attributes: vegetation cover, vegetation structure, cover quality and degree of naturalness of the river channel. In all cases, pre-urban sections showed the highest QBRp values, indicating good quality riverbanks. The application of the index at different times allowed the identification of temporal changes in the ecological quality of the riverbanks, both in general and regarding individual components. A general trend of stability or improvement in the ecological quality of the riverbanks was recorded in peri-urban sections; meanwhile, urban and one post-urban sections displayed a decrease in quality, a condition related to modifications in the structure and quality of vegetation and the loss of the river channel naturalness. Urban areas with medium-high population density were associated with poor quality riverbanks. The QBRp index enables the assessment of how urbanization affects diverse aspects of riparian quality over time and supports the development of concrete actions for the effective management of these riparian environments.

Influência de um corredor fluvial na variação de elementos climáticos: O caso da Cidade de Neuquén (Argentina)

This paper aimed to compare the behavior of climatic elements and extreme thermal events between two landscape units of the city of Neuquén, Argentina, for the period 2013-2020. The study involved daily data of minimum temperature (Tmin), maximum temperature (Tmax), and relative humidity (RH) obtained from the meteorological stations "Neuquén Aero" (NA) and "Paseo de la Costa" (PC), referring to the valley (peri-urban area) and the fluvial corridor (riparian environment) respectively. The influence of the riverbank on the daily Tmin and Tmax during Heat Waves (HW) and Cold Waves (CW) in the valley was analyzed using the methodology of the National Meteorological Service. The mean Tmax (Tmin), at annual, seasonal, and monthly resolutions, were lower (higher) in PC. The mean RH values were higher in NA. During the HW, a regulatory effect was exhibited regarding the number of days that the threshold values were exceeded consecutively in the fluvial littoral.

Distribution and trophodynamics of substituted diphenylamine antioxidants and benzotriazole UV stabilizers in a freshwater ecosystem and the adjacent riparian environment.

Substituted diphenylamine antioxidants (SDPAs) and benzotriazole UV stabilizers (BZT-UVs) are industrial additives of emerging environmental concern. However, little is known about their environmental fate and bioaccumulation. This study investigated the concentrations of SDPAs and BZT-UVs in the water, sediment and biota samples in the freshwater ecosystem and adjacent riparian environment using Hamilton Harbour in the Great Lakes of North America as a study site. The bioaccumulation factors and trophodynamics of these contaminants were studied using field-collected samples. Eight target SDPAs and two BZT-UVs (2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (UV234) and 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (UV328)) were frequently detected in the sediment, water and biota samples. UV328 showed significantly greater concentrations in water (0.28-2.8 ng L-1) and sediment (8.3-48 ng g-1, dry weight) than other target contaminants, implying greater contamination of UV328 in Hamilton Harbour. SDPAs exhibited trophic dilution in species living in the water, whereas UV234 was biomagnified in the same samples. No clear trophodynamic trend was found for UV328 for water-respiring species. Air-breathing invertebrates had higher concentrations of both SDPAs and BZT-UVs than water-respiring invertebrates, and biomagnification was observed particularly for adult dragonflies. These results suggest that the trophodynamics of SDPAs and BZT-UVs vary depending on whether the food web is terrestrial or aquatic. Future research should investigate the occurrence and partitioning of SDPAs and BZT-UVs in the air-water interface and evaluate the toxicities of these contaminants in air-breathing species.

Soil-landscape-vegetation relationships in grassland-forest boundaries, and possible applications in ecological restoration

Edaphic influence on plant distribution is essential to community ecology studies, and for vegetation management and restoration in grasslands-forest ecosystems. Pampa biome is a subtropical grassland with high floristic diversity and with an important role in food production in South America, including tree plantations where recent changes in land use soil has been questioned about the impacts on water consumption, soil degradation and potential biodiversity loss. We assessed the relationship of soil physical, chemical and morphological properties with forest and grassland species occurrence, to improve our understanding of soil and landscapes with grasslands-forest mosaics, and contribute to ecological restoration in the biome. Soil physical and chemical properties were determined in different toposequences localized in two forest farms in southern Brazil, both covered with grassland and native forest use. Natural fertility of the studied soils was highest in the lowlands, along with highest moisture and lowest toxic aluminum content. Soil saturated hydraulic conductivity was highest in the summit and backslope soils, influenced by coarser fractions in the granulometry. Soil bulk density, total porosity, microporosity, macroporosity, saturated hydraulic conductivity field capacity, permanent wilting point and available water content, influenced by sand, silt and clay contents, varied among soils and landscape and contributed to vegetation diversity. Some of the plant species occupied specific soils and landscapes. The greatest vegetation frequency was of grassland species (Poaceae and Asteraceae) in both study sites. Grassland-forest area has forest individuals in the middle of the grassland and riparian, while in grassland area the riparian vegetation is composed naturally by grassland. Forest fragments expanded in grassland-forest area during the 15 years prior to our study, but in the grassland area there were no changes in the phyto-physiognomy, demonstrating that the vegetation of grassland occurs naturally in the riparian environment. This study highlights that many of sites covered naturally by grassland, in the Pampa biome, should be protected from disruptive activities and/or recovered with species endemic to the ecosystem, without necessarily by forest enrichment as usually recommended for restoration activities.