Journal articles on the topic 'Amazonian slope'

In northern South America, an extensive tropical lowland runs 5,000 km from the Atlantic coast to the foot of the Andes. The slope is gentle until about 500 m where the eastern Andes rise abruptly. The lowland supports Amazonia, which is the most extensive tract of tropical rainforest on the planet. Most of its boundaries are well defined, but the boundary between Amazonia and the forest of the eastern slopes of the Andes has not been clearly defined. To determine for avifauna whether Amazonia is restricted to the lowland of northern South America or whether it also extends up into the eastern slopes of the Andes, different types of data were used. The results indicate that Amazonia may be restricted to the lowland that extends from the Atlantic coast to the foot of the Andes, up to about 500 m. Consequently, the number of bird species strictly endemic to Amazonia would be 290. Comparison with the distribution of vegetation on the eastern slopes of the Andes also suggests that Amazonia as a biome may be restricted to the lowland that extends from the Atlantic coast to the foot of the Andes, up to about 500 m.

Four new species of Lispinus from the premontane forest of the eastern slope of the Peruvian Andes are described and records of all other Lispinus species from Peru are given. The new species are: L. blandus, L. minimus, L. speciosus, and L. peruanus. A key to the known 21 Peruvian species is provided, habitat information is summarized and geographical distribution of species is discussed. The following six types of zoogeographic distribution can be differentiated for the Peruvian Lispinus species: endemic, eastern Andean, lowland Amazonian, Circum-Amazonian, northern Southand Central-American, and Pan-Neotropical.

AbstractWe report the first record of the rare Koepcke’s spear-nosed bat Gardnerycteris koepckeae collected outside of Peru, based on morphological and cytochrome b data. The species was found at the National Natural Park Alto Fragua Indi-Wasi, Department of Caquetá, Colombia. This record extended the species distribution 1400 km north from the northernmost known locality in Huanhuachayo, Ayacucho, Peru. This finding suggests that G. koepckeae is distributed over middle elevations along the eastern slope of the Andean-Amazonia foothills in Peru and Colombia, similar to other Phyllostomid bats, such as Vampyressa melissa and Lonchophylla handleyi. We reviewed the threatened category of G. koepckeae, currently categorized as Data Deficient (DD), according to the International Union for Conservation of Nature (IUCN), but considered as Endangered (EN) in recent papers. Based on this new record, we suggest that the species should be included in future assessments as Near Threatened (NT) or Vulnerable (VU) based on its wider distribution along the Andean-Amazonian foothills of Colombia, Ecuador and Peru, and probably the Orinoco slope of the Andes of Colombia and Venezuela.

Abstract. Podzol-ferralsol soil systems cover great areas in Amazonia and in other equatorial regions, they are an end-member of old equatorial landscape evolution, are frequently associated with kaolin deposits and store and export large amounts of carbon. Their biogeochemistry was usually inferred from soil mineralogy and from spring or river water properties. This paper presents a database for groundwaters sampled in situ in a typical podzol-ferralsol soil catena from the Alto Rio Negro region, Brazil; the sampling periods allowed to sample under high- and low-level water-table conditions. The compositions of the groundwaters percolating the soil system are consistent with the currently observed mineral and organic paragenesis. The acidity and the site density of the dissolved organic matter (DOM) produced and circulating in the podzol white sand horizons are similar to what was observed in acid podzolic temperate zone. The aggressiveness of the white sand groundwater with regard to secondary minerals favours the podzol development at the expense of the ferralsolic or kaolin material. Some DOM is able to percolate in depth through clayey material with concentrations up to 9.7 mgC l−1 (4.0 on average). This DOM is characterized by high site densities indicating a large proportion of small carboxylic acids. In the deep kaolin and in the ferralsolic horizons, the Si and Al content of the groundwater is controlled by gibbsite and kaolinite precipitation/dissolution and by quartz dissolution. The mobility of Fe, mainly transported as Fe2+, is sensitive to small variations in EH. The bleaching of the deep kaolin at the upper part of the slopes is favoured by the high content of small carboxylic compounds and by the redox conditions of the solutions issuing from the podzolic horizons. The transfer of Al and Fe result in the precipitation of Al-nodules in slope horizons and of Fe-oxides in the upper downslope horizon. It can be inferred that thick bleached kaolin are likely everywhere presently active giant podzols are close to a slope gradient sufficient to allow deep percolation of groundwater.

Four Ecuadorian species in Calathea series Nudiscapae (Petersen) Schumann s.l. are described as new. Calathea tinalandia occurs on the Pacific slope of the Cordillera in Pichincha and Esmeraldas provinces, while C. lanicaulis, C. anderssonii, and C. clivorum occur in northeastern Ecuador in the Amazonian lowlands of Napo and Pastaza provinces.

The aim of this study was to assess precipitation (P) and actual evapotranspiration (ET) by analyzing data from in situ stations compared with remote sensing products. Climate Hazards Center InfraRed Precipitation (CHIRP) and Climate Prediction Center morphing technique (CMORPH) were used for P and Operational Simplified Surface Energy Balance (SSEBop) was used for ET. The P in situ data for six stations were also compared to a reference station in the city. ET was analyzed for a single in situ station. The region chosen for this study was the Metropolitan Area of Belem (MAB), close to the estuary of the Amazon River and the mouth of the Tocantins River. Belem is the rainiest state capital in Brazil, which causes a myriad of challenges for the local population. The assessment was performed using the statistical metrics root-mean-square error (RMSE), normalized root-mean-square error (NRMSE), mean bias error (MBE), coefficient of determination (R2), regression slope, and Nash–Sutcliffe coefficient (NS). For the reference station, the automatic and conventional CHIRP and CMORPH results, in mm/month, were as follows: automatic CHIRP: RMSE = 93.3, NRMSE = 0.32, MBE = −33.54, R2 = 0.7048, Slope = 0.945, NS = 0.5668; CMORPH: RMSE = 195.93, NRMSE = 0.37, MBE = −52.86, R2 = 0.6731, Slope = 0.93, NS = 0.4344; conventional station CHIRP: RMSE = 94.87, NRMSE = 0.32, MBE = −33.54, R2 = 0.7048, Slope = 0.945, NS = 0.5668; CMORPH: RMSE = 105.58, NRMSE = 0.38, MBE = −59.46 R2 = 0.7728, Slope = 1.007, NS = 0.4308. In the MAB region, ET ranges on average between 83 mm/month in the Amazonian summer and 112 mm/month in the Amazonian winter. This work concludes that, although CMORPH has a coarser resolution than CHIRP for the MAB at a monthly resolution, both remote sensing products were reliable. SSEBop also showed acceptable performance. For analyses of the consistency of precipitation time series, these products could provide more accurate information. The present study validates P and ET from remote sensing products with station data in the rain-dominated urban MAB.

Purpose: this work aims to analyze the factors that contributed to the intensification of erosion in the Amazon region of Buriticupu (MA) and discuss possible forms of mitigation and control. Methods: urban area of the municipality was characterized and data on soil, pedology, relief, slope, use and occupation, economic activities developed, as well as satellite images, were collected. This information was used to analyze indicators of natural erosion processes, as well as the influence of human activities. Possible mitigation and control solutions were discussed. Results and discussion: it was found that several aspects contribute to the development of erosion phenomena in the region, such as soil type, slope and hydrology. In the case of the municipality under study, geoenvironmental factors favor the development of gullies. However, the main force has been the action of man in modifying the landscape and weakening the soil. It is understood that it is necessary to implement articulated biogeoengineering strategies, such as controlling the slope and stability of slopes, the water flow regime, plant restoration and environmental education strategies. With this, we can be successful in mitigating the phenomenon and preserving the landscape. Implications of the research: it is urgent to develop shared management measures between federated entities, organized civil society and the local population to map and regulate sustainable development, especially in Amazonian regions. Originality/value: in some Amazonian regions, as in the case of the municipality of Buriticupu (MA), the advancement of agricultural activities and urban development, associated with climate change, have significantly influenced the emergence and advancement of gullies, which can promote the disappearance of the built environment. These gullies are treated as more advanced soil erosion phenomena, serious and difficult to control and remediate. Although erosion is a problem that affects many regions in Brazil, there are still few studies that aim to investigate the causes of its appearance and the discussion about possible solutions applied to gullies in the Amazon region is unprecedented. Agricultural development has accelerated soil degradation and is an urgent problem to be debated.

SummaryWe documented the geographical distributions and habitat selection of Neotropical migrants in South America along a successional gradient in the lowlands of Amazonian Peru, and along elevational gradients in the Andes of south-eastern Peru and of eastern and western Ecuador. Most of the 30 species of northern migrants that regularly winter in South America appear to be concentrated in the western edge of the Amazon basin and on the lower slopes (2,000 m) of the Andes. Migrants in a lowland site were documented more often in early successional habitats than in primary forest, and no species were confined to mature forest habitats. The number of species and relative abundance of migrants in primary forest, however, increased with elevation up to about 1,200 m and decreased above that elevation. Several species (Contopus borealis, Dendroica cerulea and Wilsonia canadensis) were largely confined to primary forest in the 1,000-2,000 m elevational zones in both Peru and Ecuador. Migrants on the western slope of the Ecuadorean Andes included several species that primarily winter further north. In general, the species richness of migrants and residents was inversely correlated, both on a biogeographical and a local scale. Migratory birds are most likely to be adversely affected by deforestation of the lower slopes of the Andes, which is proceeding at a rapid pace. The impact of human alterations of Amazonian forests will be greater on resident than on migratory birds. The loss of mid-successional lowland forests, however, might have a negative effect on several species.

Abstract The present study aims to compare the allometry and wood density of Goupia glabra Aubl. (Goupiaceae) in two different terra-firme sites in Amazonian forest. A total of 65 trees ≥ 10 cm DBH was sampled in both sites, with 39 trees in Nova Olinda do Norte (NOlinda, near the Amazon River) and 29 trees in Apuí (near the southern edge of the Amazon forest). Except for the relationship between DBH (diameter at breast height) and Ht (total height), allometric relationships for G.glabra differed significantly between sites. Apuí had lower intercept and greater slope for log10 (DBH) versus log10 (Hs – stem height), and, conversely, greater intercept and lower slope for log10 (DBH) versus log10 (Ch – crown height). The slope differed significantly between the sites for DBH versus Cd (crown diameter), with greater slope found for NOlinda. Mean basic wood density in Apuí was 8.8% lower than in NOlinda. Our findings highlight the variation in adaptive strategy of G. glabra due to environmental differences between sites. This is probably because of different canopy-understory light gradients, which result in differentiation of resource allocation between vertical and horizontal growth, which, in turn, affects mechanical support related to wood density. We also hypothesize that differences in soil fertility and disturbance regimes between sites may act concomitantly with light.

Soil-landscape relationships in natural environments can provide helpful insights into soil suitability and limitations and necessary changes regarding agricultural land use and management. The objective of this work was to verify soil variations along a sandstone-gneiss lithological toposequence in the western Amazonian region of Brazil. Within this topolithosequence, the following soil profiles were sampled: CAMBISSOLO HÁPLICO (Dystric Leptic Cambisol), NEOSSOLO REGOLÍTICO (Cambic, Lithic, Leptosol), NEOSSOLO QUARTZARÊNICO (Dystric Regosol), PLINTOSSOLO PÉTRICO (Petric, Plinthosol), and ARGISSOLO AMARELO (Chromic, Abruptic, Acrisol). These profiles were located on the following slope segments: interfluve (P1), convex creep slope (P2), transportational midslope (P3), colluvial footslope (P4), and alluvial toeslope (P5). Soil analyses included physical and chemical attributes. The influence of the landscape on soil attributes was evaluated through randomness test, run charts, Pearson correlation, and Tukey test at a 5% significance level. Soil chemical properties were more sensitive to slope-related variations, with increased chemical quality in P2 for both horizons. Soil organic matter proved to be crucial for improving the chemical and physical quality of sandstone soils.

Ophiocaryon nicolasii, from the “Camino de los Andaquíes,” in the Amazonian slope of the Eastern Cordillera of Colombia, Caquetá department, is described and illustrated and its morphological relationships with other similar Ophiocaryon species are discussed. This new species is a small tree from the foothills to montane forest (500–1000 m). Morphologically it is related to O. manausense (W.A. Rodrigues) Barneby, but it differs by: smaller leaves, petioles, petiolules, and inflorescences; leaflets with 8–16 secondary veins; leaflets, bracteoles, staminodes and ovary with different shape; margins of sepals erose. Information about the Andakí region and its ancestral inhabitants is presented. An updated key to the species of Ophiocaryon is provided.

AbstractHerbaceous plants are often under-studied in tropical forests, despite their high density and diversity, and little is known about the factors that influence their distribution at microscales. In a 25-ha plot in lowland Amazonian rain forest in Yasuní National Park, Ecuador, we censused six species of Heliconia (Heliconiaceae) in a stratified random manner across three topographic habitat types. We observed distribution patterns consistent with habitat filtering. Overall, more individuals occurred in the valley (N = 979) and slope (N = 847) compared with the ridge (N = 571) habitat. At the species level, Heliconia stricta (N = 1135), H. spathocircinata (N = 309) and H. ortotricha (N = 36) all had higher abundance in the valley and slope than ridge. Further, H. vellerigera (N = 20) was completely absent from the ridge. Conversely, H. velutina (N = 903) was most common in the drier ridge habitat. The two most common species (H. stricta and H. velutina) had a reciprocal or negative co-occurrence pattern and occurred preferentially in valley versus ridge habitats. These results suggest that taxa within this family have different adaptations to the wetter valley versus the drier ridge and that habitat partitioning contributes to coexistence.

Abstract The major biodiversity on the planet is present in coastal and oceanic environments, despite this, on the northern continental shelf of Brazil, data on most of the marine groups still are deficient, especially in areas deeper than 20 m and in the continental slope area. This lack of data is aggravated by high fisheries exploitation, which causes a decline in large, abundant populations, even leading them to threat of extinction. Among that marine biodiversity, no group has a larger morphological variety than crustaceans. In this scenario, knowledge about the local biodiversity, its richness and seasonality, is essential for a qualified fisheries management. The Amazon continental shelf has one of the largest shrimp fisheries in the country, and due to the ecological and economic importance that crustaceans have in the region, a detailed study on their diversity is necessary. In this article, we use data collected in the Revizee Program. We identified 91 species: crabs (32.97%), shrimp (28.57%), anomurans (10.99%), soft crabs (10.99%), lobsters (9.89%), stomatopods (4.40%) and isopods (2.20%). The State of Amapá had fewer species () compared to Pará (). The data analysis shows there is a lack of knowledge about the real biodiversity present on the Amazon continental shelf.

Abstract. The podzol-ferralsol soil systems, which cover great areas of Amazonia and other equatorial regions, are frequently associated with kaolin deposits and store and export large amounts of carbon. Although natural organic matter (NOM) plays a key role in their dynamics, little is known about their biogeochemistry. In order to assess the specific role of dissolved organic matter (DOM) on NOM storage in deep horizons and to determine possible relationships between kaolin formation and DOM properties, we studied the groundwater composition of a typical podzol-ferralsol soil catena from the Alto Rio Negro region, Brazil. Groundwater was sampled using tension-free lysimeters placed according to soil morphology. DOC, EH, pH, and dissolved Si, Al3+, Fe2+, and Fe3+ were analyzed for all samples and values are given in a database. Quantification of other dissolved ions, small carboxylic acids and SUVA254 index and acid-base microtitration was achieved on selected samples. Part of the DOM produced by the hydromorphic podzols is directly exported to the blackwater streams; another part percolates at greater depth, and more than 90% of it adsorbs in the Bh-Bhs horizons, allowing carbon storage at depth. Humic substances are preferentially adsorbed with regard to small carboxylic compounds. With regard to kaolin genesis, kaolinite precipitation is favored by Al release from NOM mineralization within the Bh-Bhs and kaolin bleaching is ensured by iron reduction due to acidity and relatively low EH. Fe2+ mobility can be related to small EH variations and enhanced by the significant concentration of small carboxylic acids. The long-term result of these processes is the thickening of the kaolin, and it can be inferred that kaolin is likely to occur where active, giant podzols are close to a slope gradient sufficient enough to lower the deep water table.

The study was carried out on the gallery forest of the Bacaba stream situated in the Municipal Ecological Reserve ‘Mário Viana’ (14°43′S, 52°21′W) in Nova Xavantina, Eastern Mato Grosso, Brazil. Three sections of the gallery (upper, middle and lower) running downstream and differing in slope were surveyed by stratified sampling. Fortyseven nested 10m × 10m plots were analysed in each section, giving a total sampling area of 1.41ha overall. All trees or lianas ≥ 15cm girth at breast height were recorded and a total of 129 species belonging to 105 genera and 47 families were found. Diversity was high, with the Shannon index ranging from 3.84 nats/individual in the lower section to 4.08 in the middle section. The most important families (IVI) were Caesalpiniaceae (upper and middle sections) and Arecaceae (lower section), and the most important species were Diospyros obovata (upper section), Hymenaea courbaril var. stilbocarpa (middle section) and Mauritia flexuosa (lower section). Morisita and Sørensen indices of similarity were calculated. The floristic composition was complex and included species in common with a number of Brazilian forest types and with cerrado (savanna), as well as many widespread species, but stronger links with Amazonian forests could be detected. This is to be expected since the area lies in the ecotonal zone of the cerrado and Amazonian forest biomes and the Bacaba stream itself is a tributary of the Mortes–Araguaia–Amazon river system.

ABSTRACT In Amazonian terra-firme non inundated forests, local floristic composition and species occurrence are explained by water availability as determined by topographic conditions. Topographic complexity can render these conditions quite variable across the landscape and the effects on plant ecological responses are difficult to document. We used a set of topographically defined hydrological metrics to evaluate community composition and single-species responses of four plant groups [pteridophytes (ferns and lycophytes), Melastomataceae, palms (Arecaceae) and Zingiberales] to topographic conditions in the middle Juruá River region, in western Brazilian Amazonia. The area spans two geological formations (Içá and Solimões) with contrasting topography. River terraces are also found along the main rivers in the area. Local topographic conditions were approximated by height above the nearest drainage (HAND), slope, and Strahler´s drainage order, all obtained from a SRTM digital elevation model (DEM). Data were analyzed using linear and generalized linear mixed models and regression trees. HAND was most successful in explaining floristic composition for all plant groups, except for Melastomataceae, and was more important in the hilly Içá formation than in the Solimões. Individual occurrences of 57% species were predicted by at least one of the topographic variables, suggesting a marked habitat specialization along topographic gradients. For these species, response models using SRTM-DEM-derived variables gave similar results than models using field-measured topography only. Our results suggest that topographical variables estimated from remote sensing can be used to predict local variation in the structure of plant communities in tropical forests.

We analyze the structure of diameter, richness, and diversity of the forests in the upper limit of the great Amazon basin located in the Ecuadorian territory of the Cordilleras del Cóndor and Cutucú. Our hypothesis was that the forests of the eastern mountain ranges are not homogeneous, but rather present differences in their structure, richness, and floristic diversity. Our main objective was to classify the types of forests based on the characteristics of the diameter structure and the species composition of the Amazonian forests of the eastern mountain ranges in southern Ecuador, and we determined the influence of critical edaphic, environmental, and geomorphological factors, For this we installed eight permanent plots of one hectare in homogeneous and well preserved forest stands, four plots in the province of Zamora Chinchipe and four in the province of Morona Santiago. We identified and measured all trees >10 cm at chest height and for each plot, soil samples, as well as environmental and slope data were taken. We performed an non-metric multidimensional scaling analysis (NMDS) analysis to evaluate changes in climatic and geomorphological gradients, and used the CCA analysis to assess the relationship between the composition of the species at the plot level and the edapho-climatic variables. Finally, we modeled the change in diversity ad species (Fisher’s alpha) in relation to climatic, altitudinal, and geomorphological gradients using a GLM. We determined the existence of two different types of forest, the first called Terra Firme, characterized by the presence of a greater number of species and individuals per plot as compared to the second type of forest called Tepuy or Sandstone forest. Species richness was negatively correlated with the phosphorus content of the soil and the pH, annual average temperature, annual rainfall, and altitude. Terra Firme forests, settled in more stable and nutrient-rich climatic areas, were more diverse and Sandstone forests are poor in nutrients and develop in areas with greater seasonality.

A long pollen record is derived from sediments of a lake dammed behind a low moraine of the last glaciation at 3°S latitude in the Ecuadorian Andes and is compared with a glacial age pollen record from the Amazon rainforest immediately below. Lake Surucucho (Llaviucu) lies at 3180 m on the Amazonian flank of the Andes and above the glacial age pollen record from San Juan Bosco at 970 m. The Surucucho pollen record is interpreted as showing treeless vegetation in glacial times, advance of treeline in late-glacial time, and Holocene development of modern Andean forests. Combining the Surucucho and San Juan Bosco records shows that Andean vegetation was affected by glacial cooling at all elevations. Vegetation did not move up and down slope as belts. Rather, plant associations were reformed as temperature-sensitive species found different centers of distribution with changing temperature.

We investigated the effects of landscape features and forest structure on the avian community at the Reserva Florestal Adolpho Ducke near Manaus, in the Brazilian Amazon. We sampled the landscape and forest in 72 50 × 50 m plots systematically distributed in the reserve, covering an area of 6,400 ha. The avifauna was sampled using mist nets and acoustic surveys near the plots. We found no significant relationships between landscape features and forest components in the plots and the number of bird species and individuals sampled. Results of Principal Coordinate Analyses, however, showed that bird species composition changes along a topographic gradient (plateau-slope-valley), and also in relation to leaf litter depth and distance to forest streams. We also found compositional differences in the avian community on the eastern and western water basins that compose the reserve. Our results suggest that although most bird species occur throughout the reserve, many species track differences in the landscape and the forest structure.

Abstract. The main objective of this paper is to review the usefulness of altimetric data in ungauged or very poorly monitored basin. It is shown that altimetric measurements can be combined with a single in-situ gauge to derive a reliable stage-discharge relationship upstream from the gauge. The Caqueta River in the Colombian Amazon Basin was selected to simulate a poorly monitored basin. Thus it was possible to derive the stage-discharge relationship for 13 "virtual gauge stations'' defined at river crossing with radar altimetric ground tracks. Stage measurements are derived from altimetric data following the methodology developed by Leon et al. (2006). Discharge is modeled using PROGUM – a flow routing model based on the Muskingum Cunge (M-C) approach considering a diffusion-cum-dynamic wave propagation (Leon et al., 2006) using a single gauge located downstream from the basin under study. Rating curve parameters at virtual stations are estimated by fitting with a power law the temporal series of water surface altitude derived from satellite measurements and the modelled discharges. The methodology allows the ellipsoidal height of effective zero flow to be estimated. This parameter is a good proxy of the mean water depth from which the bottom slope of the reaches can be computed. Validation has been conducted by comparing the results with stages and discharges measured at five other gauges available on the Caqueta basin. Outflow errors range from 10% to 20% between the upper basin and the lower basin, respectively. Mean absolute differences less than 1.10 m between estimated equivalent water depth and measured water depth indicates the reliability of the proposed method. Finally, a 1.2×10−4 mm−1 mean bottom slope has been obtained for the 730 km long reach of the Caqueta main stream considered.

ABSTRACT Very few studies have been devoted to understanding the digital terrain model (DTM) creation for Amazon forests. DTM has a special and important role when airborne laser scanning is used to estimate vegetation biomass. We examined the influence of pulse density, spatial resolution, filter algorithms, vegetation density and slope on the DTM quality. Three Amazonian forested areas were surveyed with airborne laser scanning, and each original point cloud was reduced targeting to 20, 15, 10, 8, 6, 4, 2, 1, 0.75, 0.5 and 0.25 pulses per square meter based on a random resampling process. The DTM from resampled clouds was compared with the reference DTM produced from the original LiDAR data by calculating the deviation pixel by pixel and summarizing it through the root mean square error (RMSE). The DTM from resampled clouds were also evaluated considering the level of agreement with the reference DTM. Our study showed a clear trade-off between the return density and the horizontal resolution. Higher forest canopy density demanded higher return density or lower DTM resolution.

The Amazon region can be seen as an immensity of natural resources of all types. However, its diverse ecosystems are fragile, especially its different soil types. Because of the constant and accelerated urbanization of its spaces, several negative externalities occur, such as the silting of miniature river courses, known as streams. In this sense, this study aimed to present a proposal to treat and act to contain the degradation of Igarapé da Vovó and recover the areas surrounding it. To this end, it proposes a corrective intervention using low-impact technology (LID) due to the absence of a water energy dissipation device in the drain outlets. The proposal aims to obtain the results that the area adapts to the techniques used significantly, reducing runoff, eliminating erosion, increasing the volume of the basin, and reducing silting. The purpose is that this action can ensure that the spring increases its water capacity, becoming a successful reference for sustainable intervention in solving siltation and slope erosion in a fragment of Amazonian urban forest.

Abstract. The realistic representation of aerosol–cloud interactions is of primary importance for accurate climate model projections. The investigation of these interactions in strongly contrasting clean and polluted atmospheric conditions in the Amazon region has been one of the motivations for several field campaigns, including the airborne “Aerosol, Cloud, Precipitation, and Radiation Interactions and Dynamics of Convective Cloud Systems–Cloud Processes of the Main Precipitation Systems in Brazil: A Contribution to Cloud Resolving Modeling and to the GPM (Global Precipitation Measurement) (ACRIDICON-CHUVA)” campaign based in Manaus, Brazil, in September 2014. In this work we combine in situ and remotely sensed aerosol, cloud, and atmospheric radiation data collected during ACRIDICON-CHUVA with regional, online-coupled chemistry-transport simulations to evaluate the model's ability to represent the indirect effects of biomass burning aerosol on cloud microphysical and optical properties (droplet number concentration and effective radius). We found agreement between the modeled and observed median cloud droplet number concentration (CDNC) for low values of CDNC, i.e., low levels of pollution. In general, a linear relationship between modeled and observed CDNC with a slope of 0.3 was found, which implies a systematic underestimation of modeled CDNC when compared to measurements. Variability in cloud condensation nuclei (CCN) number concentrations was also underestimated, and cloud droplet effective radii (reff) were overestimated by the model. Modeled effective radius profiles began to saturate around 500 CCN cm−3 at cloud base, indicating an upper limit for the model sensitivity well below CCN concentrations reached during the burning season in the Amazon Basin. Additional CCN emitted from local fires did not cause a notable change in modeled cloud droplet effective radii. Finally, we also evaluate a parameterization of CDNC at cloud base using more readily available cloud microphysical properties, showing that we are able to derive CDNC at cloud base from cloud-side remote-sensing observations.

We describe a new species of Stenocercus from an interandean valley of the upper Río Huallaga on the Amazonian slope of central Peru (Región Huánuco), at an elevation of 1700–1900 m. The new species differs from other Stenocercus, except S. boettgeri, S. haenschi, S. humeralis, and S. varius, by the combination of the following characters: presence of granular scales on the posterior surface of the thighs, enlarged vertebrals, three caudal whorls per autotomic segment, a medially complete antegular fold, non-spinose caudals, and by males lacking a black transverse band on the ventral surface of the neck. However, the new Stenocercus differs from these, with the exception of S. humeralis, by having more scales around the midbody (104–107, =105.66) than S. boettgeri (79–104, Mean= 88.61), S. haenschi (57–64, Mean=60.50), and S. varius (74–88, Mean=82.35); and from S. humeralis by having the scales in the frontonasal region nearly equal in size to the scales in the occipitoparietal region, while in S. humeralis the scales on the frontonasal region are twice or three times longer than the scales on the occipitoparietal region.

Abstract:Despite its high plant diversity, the Amazon forest is dominated by a limited number of highly abundant, oligarchic tree and liana species. The high diversity can be related to specific habitat requirements in many of the less common species, but fewer studies have investigated the characteristics of the dominant species. To test how environmental variation may contribute to the success of dominant species we investigated whether the vital rates of the abundant liana Machaerium cuspidatum is sensitive to canopy height, topographic steepness, vegetation density, soil components and floristic composition across an Ecuadorian Amazon forest. The population was inventoried in 1998 and in 2009. Plants were divided into seedling-sized individuals, non-climbers and climbers. Out of 448 seedling-sized plants 421 died, 539 of 732 non-climbers died, and 107 of 198 climbers died. There was weak positive effect of dense understorey on the relative growth rate of climbers. The mortality of seedling-sized plants was higher in areas with intermediate slope, but for larger plants mortality was not related to environmental variation. The limited sensitivity of the vital rates to environmental gradients in the area suggests that ecological generalism contributes to the success of this dominant Amazonian liana.

Liparis altomayoënsissp. nov. is described, illustrated, and tentatively assigned to the Neotropical section Decumbentes on the basis of its branching, prostrate rhizomes and upright stems bearing several leaves. Vegetatively, the new species is distinguished by its short, upward stems bearing 3–6 leaves, these with undulate, translucent margins and reticulate, prominent veining on the upper surface. Florally, it is distinctive in the labellum with fleshy basal one-half provided with a central, rounded cavity limited on each side by a prominent, bilobulate ridge and apically by a lunate ridge, and membranaceous, trilobulate apical one-half deflexed ca. 90°. In contrast with other species of section Decumbentes, in which fruit formation is infrequent, in L. altomayoënsis a high proportion (⁓50–100%) of flowers develop into a fruit; in some flowers the pollinaria rotate and contact the stigma, apparently resulting in at least facultative self-pollination. The main differences among the six species of L. section Decumbentes hitherto known are contrasted in a dichotomous key. The new species is known only from three populations located in the Bosque de Protección Alto Mayo, on the Amazonian slope of the Andes in northeastern Peru but appears to be under no foreseeable threats.

Abstract:Understanding how wood decomposition varies spatially at the mesoscale (between 1-ha plots) may improve carbon flux estimates in Amazonian forests. An experiment was carried out to test the influence of soil, slope, above-ground tree live biomass (biomass), fine-litter mass and characteristics of neighbouring trees on the variation of wood decomposition between 1-ha plots in four species of tropical trees that vary in wood density (Manilkara huberi – 0.86 g cm−3, Couratari guianensis – 0.54 g cm−3, Hura crepitans – 0.32 g cm−3 and Parkia pendula – 0.29 g cm−3). A wood sample from each species (30 × 5 × 2.5 cm) was placed in each of 71 plots within 64 km2 of terra firme tropical moist forest in Reserva Florestal Adolpho Ducke. One year later, samples were collected and weighed. The effects of specificity of decomposers was measured by the association of decomposition with the wood density and with the taxonomic group of the nearest tree with dbh ≥30 cm. Wood decomposition was independent of soil (texture and nutrients), slope, biomass and fine-litter mass at the mesoscale, except for C. guianensis, which showed greater decomposition in locations with greater biomass. Decomposition was also independent of wood density and taxonomic group of nearby large trees. In general, none of the variables was useful as a predictor of wood decomposition at the scale larger than 1 ha. Thus, the use of models that include soil and topography to improve estimates of carbon flux are limited because wood decomposition does not follow similar mesoscale patterns to that of biomass and fine-litter decomposition. Also, the results indicate that wood decomposition is more likely to be associated with generalist decomposers than with specialists associated with neighbouring trees.

Soil respiration plays a significant role in the carbon cycle of Amazonian rainforests. Measurements of soil respiration have only been carried out in few places in the Amazon. This study investigated the effects of the method of ring insertion in the soil as well as of rainfall and spatial distribution on CO2 emission in the central Amazon region. The ring insertion effect increased the soil emission about 13-20% for sandy and loamy soils during the firsts 4-7 hours, respectively. After rainfall events below 2 mm, the soil respiration did not change, but for rainfall greater than 3 mm, after 2 hours there was a decrease in soil temperature and respiration of about 10-34% for the loamy and sand soils, with emissions returning to normal after around 15-18 hours. The size of the measurement areas and the spatial distribution of soil respiration were better estimated using the Shuttle Radar Topographic Mission (SRTM) data. The Campina reserve is a mosaic of bare soil, stunted heath forest-SHF and tall heath forest-THF. The estimated total average CO2 emissions from the area was 3.08±0.8 µmol CO2 m-2 s-1. The Cuieiras reserve is another mosaic of plateau, slope, Campinarana and riparian forests and the total average emission from the area was 3.82±0.76 µmol CO2 m-2 s-1. We also found that the main control factor of the soil respiration was soil temperature, with 90% explained by regression analysis. Automated soil respiration datasets are a good tool to improve the technique and increase the reliability of measurements to allow a better understanding of all possible factors driven by soil respiration processes.

Abstract. Two simulations with a regional climate model are analyzed for climatic changes between the late 20th century and a pre-industrial period over central and southern South America. The model simulations have been forced with large-scale boundary data from the global simulation performed with a coupled atmosphere-ocean general circulation model. The regional simulations have been carried out on a 0.44° × 0.44° grid (approx. 50 km × 50 km horizontal resolution). The differences in the external forcings are related to a changed greenhouse gas content of the atmosphere, being higher in the present-day simulation. For validation purposes the climate model is analyzed using a five year long simulation between 1993 and 1997 forced with re-analysis data. The climate model reproduces the main climatic features reasonably well, especially when comparing model output co-located with observational station data. However, the comparison between observed and simulated climate is hampered by the sparse meteorological station network in South America. The present-day simulation is compared with the pre-industrial simulation for atmospheric fields of near-surface temperatures, precipitation, sea level pressure and zonal wind. Higher temperatures in the present-day simulation are evident over entire South America, mostly pronounced over the southern region of the Andes Mountains and the Parana basin. During southern winter the higher temperatures prevail over the entire continent, with largest differences over the central Andes Mountains and the Amazonian basin. Precipitation differences show a more heterogeneous pattern, especially over tropical regions. This might be explained by changes in convective processes acting on small scales. During southern summer wetter conditions are evident over the Amazonian and Parana basin in the present-day simulation. Precipitation increases are evident over Patagonia together with decreases to the north along the western slope of the Andes Mountains. During southern winter also a dipole pattern along the Andes Mountains with wetter conditions over the southern parts and drier conditions over the central parts is evident. An interesting feature relates to precipitation changes with changing sign within a few 10th of kilometers along the southern parts of the Andes mountain chain. This pattern can be explained by changes in large-scale circulation related to latitudinal changes of the extratropical southern hemispheric westerlies.

Populations in the genus Pyriglena Cabanis, 1847, commonly known as fire-eyes, are patchily distributed in central South America from the Pacific slope of the Andes to the Atlantic Forest of Brazil. Pyriglena populations are currently placed into 12 taxa, only five of which are not isolated from their neighbors by distance, a high mountain range, or a major river. In the Thamnophilidae, taxonomic decisions regarding such allopatric populations have primarily rested on differences in vocalizations, thought not to be learned and to play a key role in the speciation process. When we examined Pyriglena vocalizations in this context, the outcomes revealed substantial diversity in their calls, rather than their songs. They commonly delivered four different types of calls, unusual although not unprecedented in thamnophilids. Diversity in calls rather than songs underscores the need to consider all vocalizations in taxonomic studies. The outcomes support the continued recognition of the White-shouldered Fire-eye Pyriglena leucoptera (Vieillot) and Fringe-backed Fire-eye Pyriglena atra (Swainson) as distinct species, and indicate that, in addition, the currently constituted Pyriglena leuconota should be considered three species: the Western Fire-eye Pyriglena maura (Ménétries); the Tapajos Fire-eye Pyriglena similis Zimmer; and the East Amazonian Fire-eye Pyriglena leuconota (von Spix). We also identify taxonomic uncertainties regarding subspecies that require acquisition of additional data and further analysis.

Increasing biodiversity in highly diverse plant communities can jointly increase ecosystem function and ecosystem vulnerability. This paradox requires further attention. This study analyzed the functional response of plant communities to above- and below-ground parameters along the chronosequence (degraded pastures (DP), early forests (EF), intermediate forests (IF), and old-growth forests (OF)) in two highly fragmented landscapes of the Colombian Amazon as an estimate of the level of functional vulnerability. Three sets of functional attributes were evaluated: (i) functional composition based on the community-weighted mean (CWM) of five traits; (ii) functional diversity based on the multi-trait indices and functional dispersion (FDis) of each individual trait; and (iii) the functional vulnerability at the community-level and species-level. The individual traits did not show a clear pattern along the chronosequence. However, the trend indicated an increase in the values of resource conservation traits with the age of abandonment. The functional response of the community did not vary between landscapes. Between DP and OF, there was a significant increase in functional diversity and a decrease in functional redundancy, which increased community-level vulnerability. Consequently, the more vulnerable species were observed in the IF and OF plots. In addition, a decrease in environmental parameters, such as penetration resistance, bulk density and Ca content, and an increase in slope, precipitation, electric conductivity, pH, clay, organic material, and P and N contents increased the vulnerability. We elucidated the need for secondary forest management in terms of conservation and restoration to maintain the capacity to respond to changing environmental conditions in highly fragmented landscapes in the Andean–Amazonian transition.

ABSTRACT The soil carbon under Amazonian forests has an important roles in global changing, making information on the soil content and depths of these stocks are considerable interest in efforts to quantify soil carbon emissions to the atmosphere.This study quantified the content and soil organic carbon stock under primary forest up to 2 m depth, at different topographic positions, at Cuieiras Biological Reserve, Manaus/ ZF2, km 34, in the Central Amazon, evaluating the soil attributes that may influence the permanence of soil carbon. Soil samples were collected along a transect of 850 m on topographic gradient Oxisol (plateau), Ultisol (slope) and Spodosol (valley). The stocks of soil carbon were obtained by multiplying the carbon content, soil bulk density and trickiness of soil layers. The watershed was delimited by using STRM and IKONOS images and the carbon contend obtained in the transects was extrapolated as a way to evaluate the potential for carbon stocks in an area of 2678.68 ha. The total SOC was greater in Oxisol followed by Spodosol and Ultisol. It was found direct correlations between the SOC and soil physical attributes. Among the clay soils (Oxisol and Ultisol), the largest stocks of carbon were observed in Oxisol at both the transect (90 to 175.5 Mg C ha-1) as the level of watershed (100.2 to 195.2 Mg C ha-1). The carbon stocks under sandy soil (Spodosol) was greater to clay soils along the transect (160-241 Mg C ha-1) and near them in the Watershed (96.90 to 146.01 Mg C ha-1).

Abstract. Recent extreme events in the Amazon River basin and the vulnerability of local population motivate the development of hydrological forecast systems using process based models for this region. In this direction, the knowledge of the source of errors in hydrological forecast systems may guide the choice on improving model structure, model forcings or developing data assimilation systems for estimation of initial model states. We evaluate the relative importance of hydrologic initial conditions and model meteorological forcings errors (precipitation) as sources of stream flow forecast uncertainty in the Amazon River basin. We used a hindcast approach that compares Ensemble Streamflow Prediction (ESP) and a reverse Ensemble Streamflow Prediction (reverse-ESP). Simulations were performed using the physically-based and distributed hydrological model MGB-IPH, comprising surface energy and water balance, soil water, river and floodplain hydrodynamics processes. The model was forced using TRMM 3B42 precipitation estimates. Results show that uncertainty on initial conditions plays an important role for discharge predictability, even for large lead times (∼1 to 3 months) on main Amazonian Rivers. Initial conditions of surface waters state variables are the major source of hydrological forecast uncertainty, mainly in rivers with low slope and large floodplains. Initial conditions of groundwater state variables are important, mostly during low flow period and in the southeast part of the Amazon where lithology and the strong rainfall seasonality with a marked dry season may be the explaining factors. Analyses indicate that hydrological forecasts based on a hydrological model forced with historical meteorological data and optimal initial conditions may be feasible. Also, development of data assimilation methods is encouraged for this region.

Abstract. Recent extreme events in the Amazon River basin and the vulnerability of local population motivate the development of hydrological forecast systems (HFSs) using process based models for this region. In this direction, the knowledge of the source of errors in HFSs may guide the choice on improving model structure, model forcings or developing data assimilation (DA) systems for estimation of initial model states. We evaluate the relative importance of hydrologic initial conditions (ICs) and model meteorological forcings (MFs) errors (precisely precipitation) as sources of stream flow forecast uncertainty in the Amazon River basin. We used a hindcast approach developed by Wood and Lettenmaier (2008) that contrasts Ensemble Streamflow Prediction (ESP) and a reverse Ensemble Streamflow Prediction (reverse-ESP). Simulations were performed using the physically-based and distributed hydrological model MGB-IPH, comprising surface energy and water balance, soil water, river and floodplain hydrodynamics processes. Model was forced using TRMM 3B42 precipitation estimates. Results show that uncertainty on initial conditions play an important role for discharge predictability even for large lead times (~1 to 3 months) on main Amazonian Rivers. ICs of surface waters state variables are the major source of hydrological forecast uncertainty, mainly in rivers with low slope and large floodplains. ICs of groundwater state variables are important mostly during low flow period and southeast part of the Amazon, where lithology and the strong rainfall seasonality with a marked dry season may be the explaining factors. Analyses indicate that hydrological forecasts based on a hydrological model forced with historical meteorological data and optimal initial conditions, may be feasible. Also, development of DA methods is encouraged for this region.

The Horned Toad, Rhinella ceratophrys, is widely distributed in the northwestern part of the Amazon region. It is known from Venezuela by only a single juvenile from the base of Cerro Marahuaca, Amazonas state. Herein we report four additional specimens from Venezuela: three juveniles also from Cerro Marahuaca, and a subadult female from the southern slopes of Cerro La Neblina, at the southern border of Amazonas state. The specimen from Cerro La Neblina extends the species distribution to the extreme south of Venezuelan Amazonia, 307 km south of Marahuaca, and it represents the southeasternmost record of the species. We also confirm the presence of R. ceratophrys in Brazil based on voucher specimens, and present an updated distribution map.

Mapping plant species at the regional scale to provide information for ecologists and forest managers is a challenge for the remote sensing community. Here, we use a deep learning algorithm called U-net and very high-resolution multispectral images (0.5 m) from GeoEye satellite to identify, segment and map canopy palms over ∼3000 km 2 of Amazonian forest. The map was used to analyse the spatial distribution of canopy palm trees and its relation to human disturbance and edaphic conditions. The overall accuracy of the map was 95.5% and the F1-score was 0.7. Canopy palm trees covered 6.4% of the forest canopy and were distributed in more than two million patches that can represent one or more individuals. The density of canopy palms is affected by human disturbance. The post-disturbance density in secondary forests seems to be related to the type of disturbance, being higher in abandoned pasture areas and lower in forests that have been cut once and abandoned. Additionally, analysis of palm trees’ distribution shows that their abundance is controlled naturally by local soil water content, avoiding both flooded and waterlogged areas near rivers and dry areas on the top of the hills. They show two preferential habitats, in the low elevation above the large rivers, and in the slope directly below the hill tops. Overall, their distribution over the region indicates a relatively pristine landscape, albeit within a forest that is critically endangered because of its location between two deforestation fronts and because of illegal cutting. New tree species distribution data, such as the map of all adult canopy palms produced in this work, are urgently needed to support Amazon species inventory and to understand their distribution and diversity.

Tropical forests play an important role as a reservoir of carbon and biodiversity, specifically forests in the Brazilian Amazon. However, the last decades have been marked by important changes in the Amazon, particularly those associated with climatic extremes. Quantifying the variability of rainfall patterns, hence, is essential for understanding changes and impacts of climate upon this ecosystem. The aim of this study was to analyse spatiotemporal trends in rainfall along the Brazilian Legal Amazon between 1998 and 2015. For this purpose, rainfall data derived from the Tropical Rainfall Measuring Mission satellite (TRMM) and nonparametric statistical methods, such as Mann–Kendall and Sen’s Slope, were used. Through this approach, some patterns were identified. No evidence of significant rainfall trends (p ≤ 0.05) for annual or monthly (except for September, which showed a significant negative trend) averages was found. However, significant monthly negative rainfall anomalies were found in 1998, 2005, 2010, and 2015, and positive in 1999, 2000, 2004, 2009, and 2013. The annual pixel-by-pixel analysis showed that 92.3% of the Brazilian Amazon had no rainfall trend during the period analysed, 4.2% had significant negative trends (p ≤ 0.05), and another 3.5% had significant positive trends (p ≤ 0.05). Despite no clear temporal rainfall trends for most of the Amazon had negative trends for September, corresponding to the peak of dry season in the majority of the region, and negative rainfall anomalies found in 22% of the years analysed, which indicate that water-dependent ecological processes may be negatively affected. Moreover, these processes may be under increased risk of disruption resulting from other drought-related events, such as wildfires, which are expect to be intensified by rainfall reduction during the Amazonian dry season.

Dissolved organic matter (DOM) is a crucial component of continental aquatic ecosystems. It plays a vital role in the carbon cycle by serving as a significant source and reservoir of carbon in water. DOM provides energy and nutrients to organisms, affecting primary productivity, organic composition, and the food chain. This study presents empirical bio-optical models for estimating the absorption of colored dissolved organic matter (aCDOM) in the Negro River using in situ remote sensing reflectance (Rrs) data. Physical–chemical data (TSS, DOC, and POC) and optical data (aCDOM and Rrs) were collected from the Negro River, its tributaries, and lakes and empirical relationships between aCDOM at 440 nm, single band, and the ratio bands of Rrs were assessed. The analysis of spectral slope shows no statistically significant correlations with DOC concentration or aCDOM absorption coefficient. However, strong relationships were observed between DOC and aCDOM (R2 = 0.72), aCDOM and Rrs at 650 nm (R2 > 0.80 and RMSE < 1.75 m−1), as well as aCDOM and the green/red band ratio (R2 > 0.80 and RMSE < 2.30 m−1). aCDOM displayed large spatial and temporal variations, varying from 1.9 up to 20.1 m−1, with higher values in rivers of the upper course of the Negro basin and lower values in rivers with total solids suspended > 10 mg·L−1. Environmental factors that influence the production of dissolved organic matter include soil type, dense forest cover, high precipitation, and low erosion rates. This study demonstrated that aCDOM can serve as an indicator of DOC, and Rrs can serve as an indicator of aCDOM in the Negro basin. Our findings offer a starting point for future research on the optical properties of Amazonian black-water rivers.

The purpose of this work was to analyze the geomorphology of the Tarumã-Açú basin according to morphometric, slope, topographical parameters to understand the current dynamics of the basin geomorphological. Morphometric analysis indicated a low tendency to erosion in the Basin. The flat slope is located near the mouth of the Tarumã-Açú river and the largest slopes indicate terraces and dividers and most of the basin is characterized by small and medium hills (3-20 %). The basin has a strong structural control represented by a Strike-Slip Fault that controls the Tarumã-Açú River and the tributaries of left bank have lineaments and parallelism that may indicate tectonic control (dip-slip faults?) in an en enchelon system. It is also noted that the basin underwent tectonic tilting to the west, possibly indicating tectonic influence during the Cenozoic.

Abstract. This paper investigates the physical and chemical characteristics of aerosols at ground level at a site heavily impacted by biomass burning. The site is located near Porto Velho, Rondônia, in the Southwestern part of the Brazilian Amazon forest, and was selected for the deployment of a large suite of instruments, among them an Aerosol Chemical Speciation Monitor. Our measurements were made during the South American Biomass Burning Analysis (SAMBBA) field experiment, which consisted of a combination of aircraft and ground based measurements over Brazil, aiming to investigate the impacts of biomass burning emissions on climate, air quality, and numerical weather prediction over South America. The campaign took place during the dry season and the transition to the wet season in September/October 2012. During most of the campaign, the site was impacted by regional biomass burning pollution (average CO mixing ratio of 0.6 ppm), occasionally superimposed by intense (up to 2 ppm of CO), freshly emitted biomass burning plumes. Aerosol number concentrations ranged from ∼1000 cm−3 to peaks of up to 35 000 cm−3 during biomass burning (BB) events, corresponding to an average submicron mass mean concentrations of 13.7 μg m−3 and peak concentrations close to 100 μg m−3. Organic aerosol strongly dominated the submicron non-refractory composition, with an average concentration of 11.4 μg m−3. The inorganic species, NH4, SO4, NO3, and Cl, were observed on average at concentrations of 0.44, 0.34, 0.19, and 0.01 μg m−3, respectively. Equivalent Black Carbon (BCe) ranged from 0.2 to 5.5 μg m−3, with an average concentration of 1.3 μg m−3. During BB peaks, organics accounted for over 90% of total mass (submicron non-refractory plus BCe), among the highest values described in the literature. We examined the ageing of Biomass Burning Organic Aerosol (BBOA) using the changes in the H : C and O : C ratios, and found that throughout most of the aerosol processing (O : C ≅ 0.25 to O : C ≅ 0.6), no remarkable change is observed in the H : C ratio (∼1.35). Such a result contrasts strongly with previous observations of chemical ageing of both urban and Amazonian biogenic aerosols. At higher levels of processing (O : C>0.6), the H : C ratio changes with a H : C / O : C slope of −0.5, possibly due to the development of a combination of BB (H : C / O : C slope = 0) and biogenic (H : C / O : C slope = −1) OA. An analysis of the ΔOA / ΔCO mass ratios yields very little enhancement in the OA loading with atmospheric processing, consistent with previous observations. These results indicate that negligible Secondary Organic Aerosol (SOA) formation occurs throughout the observed BB plume processing, or that SOA formation is almost entirely balanced by OA volatilization. Positive Matrix Factorization of the organic aerosol spectra resulted in three factors: Fresh BBOA, Aged BBOA and Low-Volatility Oxygenated Organic Aerosol (LV-OOA). Analysis of the diurnal patterns and correlation with external markers indicates that during the first part of the campaign OA concentrations are impacted by local fire plumes with some chemical processing occurring in the near-surface layer. During the second part of the campaign, long-range transport of BB plumes above the surface layer, as well as potential SOAs formed aloft, dominates OA concentrations at our ground-based sampling site. This manuscript describes the first ground-based deployment of aerosol mass spectrometry at a site heavily impacted by biomass burning in the Amazon region, allowing a deeper understanding of aerosol life cycle in this important ecosystem.

Abstract. This paper investigates the physical and chemical characteristics of aerosols at ground level at a site heavily impacted by biomass burning. The site is located near Porto Velho, Rondônia, in the southwestern part of the Brazilian Amazon rainforest, and was selected for the deployment of a large suite of instruments, among them an Aerosol Chemical Speciation Monitor. Our measurements were made during the South American Biomass Burning Analysis (SAMBBA) field experiment, which consisted of a combination of aircraft and ground-based measurements over Brazil, aimed to investigate the impacts of biomass burning emissions on climate, air quality, and numerical weather prediction over South America. The campaign took place during the dry season and the transition to the wet season in September/October 2012. During most of the campaign, the site was impacted by regional biomass burning pollution (average CO mixing ratio of 0.6 ppm), occasionally superimposed by intense (up to 2 ppm of CO), freshly emitted biomass burning plumes. Aerosol number concentrations ranged from ~1000 cm−3 to peaks of up to 35 000 cm−3 (during biomass burning (BB) events, corresponding to an average submicron mass mean concentrations of 13.7 μg m−3 and peak concentrations close to 100 μg m−3. Organic aerosol strongly dominated the submicron non-refractory composition, with an average concentration of 11.4 μg m−3. The inorganic species, NH4, SO4, NO3, and Cl, were observed, on average, at concentrations of 0.44, 0.34, 0.19, and 0.01 μg m−3, respectively. Equivalent black carbon (BCe) ranged from 0.2 to 5.5 μg m−3, with an average concentration of 1.3 μg m−3. During BB peaks, organics accounted for over 90% of total mass (submicron non-refractory plus BCe), among the highest values described in the literature. We examined the ageing of biomass burning organic aerosol (BBOA) using the changes in the H : C and O : C ratios, and found that throughout most of the aerosol processing (O : C ≅ 0.25 to O : C ≅ 0.6), no remarkable change is observed in the H : C ratio (~1.35). Such a result contrasts strongly with previous observations of chemical ageing of both urban and Amazonian biogenic aerosols. At higher levels of processing (O : C > 0.6), the H : C ratio changes with a H : C / O : C slope of −0.5, possibly due to the development of a combination of BB (H : C / O : C slope = 0) and biogenic (H : C /O :C slope =−1) organic aerosol (OA). An analysis of the ΔOA /ΔCO mass ratios yields very little enhancement in the OA loading with atmospheric processing, consistent with previous observations. These results indicate that negligible secondary organic aerosol (SOA) formation occurs throughout the observed BB plume processing, or that SOA formation is almost entirely balanced by OA volatilization. Positive matrix factorization (PMF) of the organic aerosol spectra resulted in three factors: fresh BBOA, aged BBOA, and low-volatility oxygenated organic aerosol (LV-OOA). Analysis of the diurnal patterns and correlation with external markers indicates that during the first part of the campaign, OA concentrations are impacted by local fire plumes with some chemical processing occurring in the near-surface layer. During the second part of the campaign, long-range transport of BB plumes above the surface layer, as well as potential SOAs formed aloft, dominates OA concentrations at our ground-based sampling site. This manuscript describes the first ground-based deployment of the aerosol mass spectrometry at a site heavily impacted by biomass burning in the Amazon region, allowing a deeper understanding of aerosol life cycle in this important ecosystem.

Abstract Context. - Many ferralsols and podzols from central Amazon were developed by a long-time pedogenesis over a sandy-clay Cretaceous sediment which mainly consists of kaolinite and quartz [Lucas et al., 1996]. The soils progressively range from clayey microaggregate ferralsols on the plateaux associated with tropical forests, to podzols at the bottom of thalwegs and in some small declivities of the largest plateaux associated with forests of smaller trees or open savannahs [Chauvel et al., 1987; Bravard, 1988; Lucas, 1989; Cornu, 1995]. Their moisture properties are different from those of temperate soils [Arruda et al., 1987; van den Berg et al., 1997; Tomasella et al., 2000]. Methods. - To quantify the moisture properties, mercury injection porosimetry (MIP) seems to be an adequate method [Vachier et al., 1979]. It is easy to use and enables accurate investigation of the major part of the porosity spectrum. We used a Carlo-Erba 2000 which enabled 12 to 20 measurements for pore entry radii from 4 nm to 0.1 mm. It requires dried (here, air-then oven-drying), centimetre-sized samples. The drying of the sample, the large pressures of Hg used, the different surface properties of soil components in presence of water or Hg, may induce discrepancies between MIP data and water desorption measurements, particularly if the organic matter (OM) is abundant. We compared MIP and water desorption data, and established pedotransfer functions to estimate the water desorption curve from MIP data and OM content. Water desorption was performed with a pressure membrane equipment, which allows us to investigate pores with entry radii from 0.1 μm to 0.5 mm [AFNOR, 1996a], on decimetric samples. We also used water desorption data obtained in situ in other studies from similar sites [Tomasella and Hodnett, 1996]. For some depths, drying under controlled atmosphere [AFNOR, 1996a] enabled us to investigate pores with entry radii down to 1.5 nm. The total pore volume was determined on the same dry or humid sample (volume 100 cm3) by cylinder measurement or using the paraffin method [AFNOR, 1996b], in order to determine the volume of large pores. Organic carbon mass ratio (C) data are from Bravard [1988] and Cornu [1995]; a C value of 1 % corresponds to a volume ratio of organic matter to solid soil of 4.8 to 6 %. Notations. - We classified each pore class from its pore size (r), deduced from pressure data with the Laplace law (r is the entry radius for cylindrical pore model or the entry width for slit-shaped pore model): - nanopores (r &lt; 4 nm) and cryptopores (4 nm &lt; r &lt; 0.1 μm) are residual pores, containing residual water that roots cannot extract. It moves by evaporation in dry conditions; - micropores (0.1 μm &lt; r &lt; 10 μm) contain bioavailable water; - mesopores (10 μm &lt; r &lt; 0.1 mm) and macropores (0.1 mm &lt; r) are determinant for hydraulic conductivity, from which water drain in some hours (mesopores) or seconds (macropores) after the rain. We described their abundance in terms of volume, in order to better quantify their geometrical structure, and took as a reference the volume of dry solid matter in the soil, because the total soil volume is not constant (it depends on moisture content). Then we used the partial void ratio (u) for MIP, the water ratio (n) or the air ratio (a) for water desorption, and the fluid ratio (e) for total porosity: \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \[\mathit{u}=\frac{\mathit{V}_{\mathit{viod}}}{\mathit{V}_{\mathit{solid}}},\ \mathit{n}=\ \frac{\mathit{V}_{\mathit{w}}}{\mathit{V_{solid}}},\mathit{a}=\frac{\mathit{V_{air}}}{\mathit{V_{solid}}},\mathit{e_{humid}}=\ \frac{\mathit{V_{w}}+\mathit{V_{air}}}{\mathit{V_{solid}}}\ and\ \mathit{e_{dry}}=\ \frac{\mathit{V_{air}}}{\mathit{V_{solid}}}=\ \frac{\mathit{V_{void}}\ +\ \mathit{V_{Hg}}}{\mathit{V_{solid}}}\] \end{document} MIP and water desorption give directly the values of ucrypto, umicro, umeso, nres, nmicro, nmeso. Total pore volume measurements give ehumid and edry. We must be aware that the maximum water content remains below the fluid content, because of residual air: air bubbles trapped during wetting (we tried to minimize this effect by a progressive, two-week-long wetting), air linked to hydrophobic soil organic surfaces, and air in non-connected pores (not here). Residual air can thus be neglected for MIP, and for the water desorption of samples without organic matter. By subtraction, we obtain: \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \begin{eqnarray*}&&(\mathit{n_{macro}}\ +\ \mathit{a_{res}})\ =\ \mathit{e_{humide}}\ {-}\ \mathit{n_{res}}\ {-}\ \mathit{n_{micro}}\ {-}\ \mathit{n_{meso}}{\ }{\ }and\\&&(\mathit{u_{macro}}\ +\ \mathit{u_{nano}})\ =\ \mathit{e_{dry}}\ {-}\ \mathit{u_{crypto}}\ {-}\ \mathit{y_{micro}}\ {-}\ \mathit{u_{meso}}.\end{eqnarray*} \end{document} We can extrapolate the ratio of dry nanopores (unano) with reasonable accuracy because its value is anyway very low. For the ferralsols between 1.1 and 1.7 m depth, (umacro + unano) ≤0.03. We added a small triangle to the left of the porosity spectrum, in order to have unano = 0.01 at 1.4 m depth for the ferralsol. Then unano ranges from 0.002 for the podzol to 0.02 for the ferralsol above 0.7 m depth. All the porosity spectra we obtained had very few small micropores. Two porosity domains can thus be defined: textural porosity below 0.25 μm pore size, and structural porosity above. We described these two domains using their logarithmic average pore entry radii (rtext or rstruct) and their lobe width λ,. These parameters were defined by fitting an Ahuja and Schwartzendruber curve [1972] (often named a symmetric, m = 1, van Genuchten curve [van Genuchten, 1980]): \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathit{u}\ =\ \frac{\mathit{u_{text}}}{1+(\mathit{r_{text}}/\mathit{r})^{{\nu}_{\mathit{text}}}}\) \end{document} then \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathit{u}=\ \mathit{u_{text}}+\frac{\mathit{u_{struct}}}{1+(\mathit{r_{struct}}/\mathit{r})^{{\nu}_{\mathit{struct}}}}\) \end{document} and it is the same for n. [Log(rtext) − λtext;Log(rtext)+ λtext] is the interval gathering half of textural porosity, with λtext = Log3/νtext and it is the same for structural porosity. We set ustruct from e measurements, to give it a physical meaning, and introduced it as a value of associated with the 1mm pore size during the fitting, so that all curves approach their asymptotic value for about the same pore size. Results on porosity spectra. - The carbon content declines with depth, with a local maximum in the Bh horizon for the podzols (fig. 4). Ferralsols have a high residual porosity and average meso- and macroporosities (fig. 2 and 5), podzols have basically high meso- and macroporosities (figs 3 and 6), and transition soils are intermediate. For ferralsols and transition soils, named clayey soils here, all porosity classes have typical variations with depth: maximum at the surface; local minimum at a compacted horizon at 0.13 to 0.3 m (ferralsol) or 0.4 to 0.6 m (transition soil); local maximum for meso- and macroporosity, at the « termites’ horizon » at 0.4–0.6 m (ferralsol) or 0.8–1.2 m (transition soil); constant values for residual porosity below a depth of 1.2 m, and decreasing values for the other porosity classes. The average textural pore size increases vertically from the surface to the depth, with a local minimum at the compacted level, and laterally from ferralsols to podzols (fig. 7 and 10). Interpretation. - Residual porosity is correlated to clay content and textural pore size is correlated to the kaolinite particle size (unpublished work). The compacted level, named biological plough pan [Chauvel et al., 1987], may be due to a gravitational accumulation of the finest kaolinites from the above horizons, at the foot of the highly pedoturbated level. Low microporosity is linked to a very low silt and fine sand content, typical of tropical soils. Meso-and macroporosities are due to a clay microaggregation for clayey soils, and to the coarse sand fabric for the podzol. Microaggregation of clay is enhanced near the surface by root or ant pedoturbation, and at depth by termit pedoturbation, and maybe lateral water flows on the slope. Dispersion. - The dispersion of the values is low for a depth between 0.7 and 1.5 m, which is due to a homogeneous kaolinitic plasma. The dispersion increases with pore size, surface proximity for depth 0.7 m, or the increasing depth below 1.5 m. Near the topsoil, this is due to the heterogeneous biological activity, giving an heterogeneous soil structure. In horizons below 1.5 m, the causes are micronodules, localised water flows, and insufficient root pedoturbation. Therefore, we took more samples near the surface, we quantified soil shrinkage from the same sample before and after drying, we gave a higher statistical weight to data from 0.7 to 1.5 m depth in regressions, and smoothed values with depth (table IV). Comparison of results on dry or humid samples Total poral volume. - The shrinkage of the ferralsols samples decreases with depth. On the contrary, the shrinkage of podzol samples increases with depth (fig 5, 6 and table I). Residual porosity and microporosity. - OM presence is correlated to a decrease in the residual and micro- porosity given by MIP, compared to water desorption data. For soil samples with a low organic matter content, MIP gives a lower residual porosity especially for fine clays and a higher microporosity (table I). We could establish one pedotransfer function for all the soils studied here by taking into account the average textural pore size (table II and fig- 8). Meso- and macroporosity. — Through drying, mesoporosity increases for clayey soils and shrinks for podzol. These changes are more important for deep than for shallow horizons. Through drying, macroporosity increases, except for deep horizons of clayey soils (fig. 5,6; tables I, III). Textural porosity of ferralsols and transition soils. - The progressive vertical and lateral variation of MIP data gives reliability to a comparison with the two points where the textural porosity of humid samples was measured. MIP gives a higher pore size (roughly doubled, see table II) and a lower textural lobe width (roughly halved), compared to water desorption data. Structural porosity. - Our measurements on dry samples, compared to water desorption data, give simultaneous variations of three parameters, average structural pore size, structural lobe width, and macropores/mesopores volume ratio: an increase for the upper horizons of clayey soils or the deep horizons of podzol, a low change for the upper podzol horizons, and a decrease for the deeper horizons of clayey soils (fig. 9 and 10). However, the dispersion on these parameters is too high to predict them for humid samples from our data on dry samples. In order to parameterise the water desorption curve, we propose to apply equations of table I to subdivisions of micro- and mesoporosity, sharing out the organic matter influence between these subdivisions to get a precise water desorption curve, that can then be parameterised [Bastet, 1999]. Interpretation. - Hysteresis and pore geometry effects could not explain differences between water desorption and MIP, as in both cases the non-wetting fluid (air or Hg) enters pore space, and the same pore geometrical model was applied. The contact angle used in the Laplace law may change with the soil composition, especially with OM content for water desorption (hydrophobicity). Then we may have overestimated humid pore sizes at shallow horizons. Correcting this would enhance the discrepancies observed here. Some phenomena are not taken into account in the Laplace law: compression of porosity during MIP [Penumadu and Dean, 2000], or water physiosorption on mineral surfaces during water desorption [Tuller et al, 1999]. The first phenomenon causes the Laplace law to overestimate dry pore sizes (for r &lt; 2 μm), the second causes it to overestimate humid nanoporosity. Both explain that MIP gives a higher microporosity, a higher textural pore size, a lower residual porosity. The drying of samples causes porosity shrinkage, diminishing pore volumes and pore sizes. Then some macropores of clayey soils could turn into mesopores. However, the shrinkage at a given scale may cause the opening of the porosity at a higher scale, with cracking. Thus, the shrinkage of residual porosity can explain the increase of microporosity for all horizons, the increase of mesoporosity for clayey horizons, and the increase of macroporosity (eye-visible cracks), for shallow clayey horizons. The shrinkage of podzol mesoporosity can explain the increase of its macroporosity as well. The amount of shrinkage due to drying, or compression during MIP depends on soil OM content and type, soil structure and soil texture. Soil texture could explain a smaller shrinkage of total porosity for podzol than ferralsol, for shallow horizons: the lentil-shaped kaolinites, depending on their relative positions, are more likely to occupy a variable volume than the quartz grains, round-shaped with cavities. Soil structure is determined by its pedogenesis: eluviation/illuviation, pedoturbation. The unexpected large shrinkage for deep podzol seems to be due to a loose structure, inherited from eluviation of clay. Pedoturbation, together with OM presence, may either create porosity, or seal or compact porosity [Sokolowska and Sokolowski, 1998 ; Chauvel et al., 1999]. They may create a new porosity likely to shrink in clayey soils and on the contrary they may consolidate the loose structure of podzols. Conclusion. - We established pedotransfer functions to define the water desorption curve from MIP, organic carbon content, and bulk density (table I and II). These functions can be used for soils with the following characteristics, thus for most tropical soils: - negligible fine clay (&lt; 0.2 μm) content, in order to enable the extrapolation of nanopore volume from MIP, without needing nitrogen desorption [Bruand and Prost, 1987]; - soils mainly composed of kaolinite and quartz. The organic carbon content has little influence on the humic podzol studied here, so the equations established here are pertinent for other podzols. These pedotransfer functions give information on the structure of these soils : - residual and micro- porosities modify between MIP and water desorption, according to the organic carbon content and the texture of clay (given by the average textural pore size), with the same law for all soils; - mesoporosity changes according to two different types of structure : (1) clay microaggregates for clayey soils, (2) sandy fabric for podzol, loose at depth due to eluviation of parent clay, consolidated near the surface by pedoturbation; - total porosity follows, with an attenuation, the changes in the MO-linked porosity and in the porosity linked to soil structuring particles, that is the residual porosity for clayey soils, and the mesoporosity for podzols; - macroporosity, in reality as in the equations, compensates for the difference. This method could be tested on soils with other granulometry, mineralogy, or higher OM content. This work was supported by IRD and the PEGI and PROSE programs, we thank Max Sarrazin for his technical collaboration and the reviewers for their critical reading.

Peruvian species of Magnolia were not included in major treatments of the Peruvian flora until the last decade, following revisions of Dugandiodendron and Talauma for the Neotropics published by Lozano-Contreras in 1994 (Pennington et al. 2004, Ulloa et al. 2004) when M. amazonica (Ducke, 1925: 11) Govaerts (1996: 25) and M. rimachii, (Lozano, 1994: 105) Govaerts (1996: 39), two lowland Amazonian species, were included. Subsequently, new species of Magnolia were described from the eastern humid montane and lowland forests in northern and central Peru (Dillon & Sanchez 2009, Vázquez-García et al. 2012). The new species reported here is described for the humid forests of the eastern Andean slopes of central Peru. Following the classification proposed by Figlar & Nooteboom (2004), this species belong to genus Magnolia subgenus Magnolia section Talauma subsection Talauma because of stipule adnation to petioles, circumscissile dehiscence of fruits and absence of a filamentous appendage in the stamen connective.

AbstractThe clay fraction of soils from a toposequence developed on a sandy clay Tertiary sediment in the Brazilian Amazonia was studied. Clayey Acrorthox located at the upper part of the sequence have transformed progressively into sandy Tropohumods down the slope. Along the slope important chemical and mineralogical changes linked to modifications in the weathering conditions were observed. In the Acrorthox the hydrolysis process largely prevails and the clay fraction is composed mainly of Fe-rich kaolinite. Fe and Al amorphous compounds become increasingly abundant along the slope. In the Spodosols, hydrolysis and acidocomplexolysis processes have both been effective, and the clay fractions contain not only more gibbsite, but also amorphous materials which are particularly abundant in the Bh horizons.

We describe four new species of Piper from the Amazonian slopes of the northern Andes. Piper hoyoscardozii is distinguished from similar climbing species, P. dryadum and P. flagellicuspe, by its longer peduncles. The Amazonian species Piper indiwasii is distinguished from P. scutilimbum from Panama and northern Colombia by the narrowly spatulate leaf base extension. Piper nokaidoyitau is characterised by the presence of larger leaves and longer spikes than similar species, P. anonifolium and P. hostmannianum. Finally, P. velae is characterised by cordulate leaf bases in all nodes, petioles 0.8–1.5 cm long and pubescent fruits, which easily distinguish it from the related species, P. holdridgeanum.

A new species of Euptychiina butterfly, Splendeuptychia mercedes n. sp. is described from the Amazonian region and Eastern Andean slopes of Peru. The morphology, distribution and conservation status of the new species are described and discussed.

Distribution of birds is dynamic. Understanding, documentation and appropriate use of new records are essential, especially when managing threatened species. Here we present novel data regarding new distributional records for 17 bird species along the Amazonian slopes of the eastern Ecuadorian Andes. The new records fill gaps on our knowledge in the distribution, both in latitude and altitude.

The family Centrolenidae contains about 148 species (Frost 2009), 11 genera and two subfamilies, distributed from southern Mexico to Panama, through the Andes from Venezuela to Bolivia, with species in the Amazon and Orinoco river basins, the Guiana Shield region, and the Atlantic forests of southeastern Brazil and northeastern Argentina (Guayasamin et al. 2009). The subfamily Centroleninae contains nine genera (Centrolene, Chimerella, Cochranella, Espadarana, Nymphargus, Rulyrana, Sachatamia, Teratohyla, and Vitreorana; Guayasamin et al. 2009). In spite of the high diversity in this subfamily, only the larvae of 15 species are well known (Centrolene altitudinale, C. daidaleum, C. geckoideum, C. hesperium, C. venezuelense, Cochranella granulosa, Espadarana andinum, E. prosoblepon, Teratohyla midas, T. pulverata, T. spinosa, Vitreorana castroviejoi, V. eurygnatha, V. helenae, and V. uranoscopa - Starret 1960; Duellman 1978; Heyer 1985; Cadle & McDiarmid 1990; Mijares-Urrutia 1990; Rada de Matinez 1990; Rueda-Almonacid 1994; Hoffmann 2004; Señaris & Ayarzagüena 2005; Rada et al. 2007). Thirteen of them are associated with Amazonian forests or forested slopes of the Andes (Frost 2009). The tadpole of Vitreorana oyampiensis (=Cochranella oyampiensis) has not been formally described; it was mentioned briefly (diagrammatic drawings and larval color notes) in Hero´s tadpole identification key from Central Amazonia (Hero 1990). In this paper we describe the tadpoles of V. oyampiensis and also provide comments on the spawning sites, clutch size, breeding periods and development site of tadpoles.

SummaryThe rare and threatened Long-wattled Umbrellabird Cephalopterus penduliger inhabits the canopy and mid-storey level of humid to wet foothill and montane forests (150–1,800 m)of the Andean slopes of south-west Colombia and western Ecuador. Here we report on male activity pattern and display behaviour observed at one of two leks recently discovered in the vicinity of Playa de Oro, Rio Santiago, Esmeraldas Province, north-west Ecuador. Courtship behaviour of C. penduliger is compared with the Central American and Amazonian congeners (Bare-necked Umbrellabird C. glabricollis and Amazonian Umbrellabird C. ornatus). The lek of C. penduliger was active during the whole study period (February 1997 to January 1998), but both lek structure and daytime activity pattern changed markedly within the observation period.