Southwestern Amazon Region Research Articles

Analysis of environmental variables and deforestation in the amazon using logistical regression models.

In this study, we applied a multivariate logistic regression model to identify deforested areas and evaluate the current effects on environmental variables in the Brazilian state of Rondônia, located in the southwestern Amazon region using data from the MODIS/Terra sensor. The variables albedo, temperature, evapotranspiration, vegetation index, and gross primary productivity were analyzed from 2000 to 2022, with surface type data from the PRODES project as the dependent variable. The accuracy of the models was evaluated by the parameters area under the curve (AUC), pseudo R2, and Akaike information criterion, in addition to statistical tests. The results indicated that deforested areas had higher albedo (25%) and higher surface temperatures (3.2°C) compared to forested areas. There was a significant reduction of the EVI (16%), indicating water stress, and a decrease in GPP (18%) and ETr (23%) due to the loss of plant biomass. The most precise model (91.6%) included only surface temperature and albedo, providing important information about the environmental impacts of deforestation in humid tropical regions.

New fossil anhingids from the upper Acre River (Late Miocene of southwestern Amazon).

Four extant species of anhingids are found worldwide, all belonging to a single genus (Anhinga). However, the fossil record reveals a much greater diversity of this group in the past. The oldest known anhingids date back to the upper Oligocene period in Australia, but during the Miocene epoch in South America, they achieved their most remarkable diversity. This study describes newly discovered anhingid fossils from the Late Miocene period in South America. These fossils were extracted from the Acre conglomerate member, part of the Upper Miocene deposits in the southwestern Amazon region. The described fossils consist of two fragments of pelvic girdles, two femora, and two vertebrae belonging to a giant anhingid (Macranhinga sp.), as well as a vertebra from Anhinga minuta, the smallest of all darters. The examination of these fossils suggests the presence of potentially three distinct anhingid taxa within the same locality. The environment in which the conglomerate deposits were formed was ecologically complex. It is likely that these three species coexisted within the same ecosystem but avoided direct competition for food and reproductive sites by not fully exploiting their fundamental niche.

Variations in the Odonata Assemblages: How Do the Dry Season and Water Bodies Influence Them?

Diverse abiotic and biotic factors drive the ecological variation of communities across spatial and temporal dimensions. Within the Amazonian landscape, various freshwater environments exhibit distinct physicochemical characteristics. Thus, our study delved into the fluctuations of Odonata assemblages amidst distinct water bodies within Amazonia, encompassing two distinct climatic seasons. Comparative analysis was conducted on Odonata species diversity and assemblage composition across a blackwater pond, a lake, and a stream, spanning the initiation and culmination of the dry season in the southwestern Amazon region in Peru. Our methodology involved capturing adult Odonata using entomological nets on three separate occasions between 11:00 and 14:00h for each water body in May (beginning of the dry season) and October (end of the dry season) of 2018. We also evaluated the influence of temperature, precipitation, and percent cloud cover on the abundance and richness of adult Odonata. Species richness and composition differed among the three water bodies in both periods of the dry season. No effect of the dry season periods on species richness and abundance was observed. However, except in the oxbow lake, the more abundant species were substituted to the end of the dry season. Our study highlights the influence of water body types on Odonata species diversity and composition. The effects of the sampling period during the dry season may not be immediately apparent in conventional diversity metrics, such as species richness and abundance. Instead, its effects manifest predominantly in the relative abundance of the species that compose these assemblages.

Growing Coffea canephora in agroforestry systems with Brazilian firetree, Brazil nut, and teak

Planting coffee in agroforestry systems (AFSs) provides diverse advantages to farmers interested in producing environmental services, such as increased local biodiversity, reduction in soil erosion, improvement in water infiltration into the soil, and regulation of climate extremes. It can also be economically attractive due to the possibility of serving alternative markets that have higher and more stable prices for coffees integrated into alternative systems and the generation of products complementary to coffee. This study aimed to evaluate the effects of different planting densities of three forest species on the composition of AFSs with coffee plants under the conditions of the southwestern Amazon region. The study was conducted from November 2014 to June 2021 in the experimental field of Embrapa in Ouro Preto do Oeste, RO, Brazil. The coffee plants were intercropped with three forest species: i) Brazilian firetree (Schizolobium parahyba var. amazonicum), ii) Brazil nut (Bertholletia excelsa), and iii) teak (Tectona grandis). The treatments used in each experiment were four plant densities of plants: zero (coffee plants only, in full sun), 111 plants ha−1 (10 × 9 m), 222 plants ha−1 (10 × 4.5 m), and 444 plants ha−1 (5 × 4.5 m). The experiments were conducted in a split-plot arrangement, with plots consisting of plant densities and subplots consisting of harvest periods (crop seasons). The experimental design was completely randomized, with nine replications. The part of the plot used for data collection consisted of one planted row with 12 coffee plants. The average and accumulated productivities of coffe plants were evaluated over five harvests (2017-2021). Afforestation of the coffee field with Brazilian firetree plants reduces the mean yield and cumulative yield of C. canephora ‘Conilon’ in the first five commercial crop years. Brazil nut and teak planted at densities of up to 222 trees per hectare did not lead to a reduction in the mean and cumulative yield of coffee plants.

Sex trafficking by consent? Andean padrinazgo, illegal mining in Amazonia, and state intervention

AbstractRising gold prices have led to the expansion of illegal gold mining in Peru's southwestern Amazon region. This is accompanied by an increase in sex trafficking of Indigenous girls and women from the southern Andes. This article focuses on the emerging economic and cultural connections that span Andean and Amazonian mining and sex trafficking migration in the region. The notion of precarity is applied to assess victims’ agency within a racialized, neoliberal, informal labor market at the fringes of global capitalism. In tracing the trajectory of trafficked adolescents from highlands to lowlands and, in some cases, into state‐run shelters, the role of padrinazgo (patronage of godparents) is explored. It is argued that trafficked subjects’ choices are circumscribed by padrinazgo‐type relationships with traffickers, according to which they pursue a “preferred precarity” across competing existential, vocational, and subjective states.

Population Development of Bean Weevils (Coleoptera: Chrysomelidae: Bruchinae) in Landrace Varieties of Cowpeas and Common Beans

Bean weevils (Coleoptera: Chrysomelidae: Bruchinae) are responsible for large quantity losses of cowpea (Vigna unguiculata (L.) Walp.; Fabaceae) and common bean (Phaseolus vulgaris L.; Fabaceae). The magnitude of damage is related to the grains’ varietal susceptibility. The objective of this study was to determine the population development rates of Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae) in 4 landrace varieties of cowpea (var. ‘UFAC-B01,’ ‘UFAC-MV01,’ ‘UFAC-MG01,’ and ‘UFAC-Q01’), as well as the population development rates of Zabrotes subfasciatus (Boheman) (Coleoptera: Chrysomelidae) in 4 landrace varieties of common bean (var. ‘UFAC-G01,’ ‘UFAC-M01,’ ‘UFAC-P01,’ and ‘UFAC-R01’). We determined the population development rates of the weevils in each variety. The weight of 100 grains (g) and the percentage of grain weight loss were measured, and correlations between these variables were analyzed. The statistical design was completely randomized, with 4 replications. Varieties UFAC-Q01 (cowpea) and UFAC-R01 (common bean) showed lower insect population development rates than other varieties. Although variations were found in the weight of 100 grains and grain weight loss, no significant correlations with bean weevil population development were observed. The cowpea and common bean landrace varieties from the southwestern Amazon region are important sources of resistance to bean weevils. The UFAC-Q01 cowpea variety and the UFAC-R01 common bean variety showed lower susceptibility to C. maculatus and Z. subfasciatus, respectively. Resumo Os bruquideos (Coleoptera: Chrysomelidae: Bruchinae) sao responsaveis por elevadas perdas na qualidade do caupi (Vigna unguiculata (L.) Walp.; Fabaceae) e feijao comum (Phaseolus vulgaris L.; Fabaceae), sendo que a magnitude dos danos esta relacionados a susceptibilidade varietal dos graos. O objetivo desta investigacao foi determinar as taxas de desenvolvimento populacional de Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae) em quarto variedades crioulas de caupi (var. ‘UFAC-B01,’ ‘UFAC-MV01,’ ‘UFAC-MG01,’ e ‘UFAC-Q01’), bem como a a taxa de desenvolvimento populacional de Zabrotes subfasciatus (Boheman) (Coleoptera: Chrysomelidae) em quarto variedades crioulas de feijao comum (vbean weevilsar. ‘UFAC-G01,’ ‘UFAC-M01,’ ‘UFAC-P01,’ e ‘UFAC-R01’). Foram realizados bioensaios para determinar as taxas de desenvolvimento populacional dos bruquideos em cada variedade, e avaliou-se a massa de 100 graos (g), perda de massa (%) e foram realizadas analises de correlacao entre estes fatores. O delineamento estatistico foi inteiramente casualizado com quatro repeticoes. As variedades UFAC-Q01 e UFAC-R01 de caupi e feijao comum, respectivamente, apresentaram menores taxas de desenvolvimento populacional, comparando-se com as demais variedades. Embora tenha havido variacao da massa de 100 graos, perda de massa, nao foram constadas correlacoes significativamente com o desenvolvimento populacional dos bruquideos. As variedades landraces de caupi e feijao comum, oriundos da Amazonia Sul-Ocideltal, constituem importantes fontes de resistencia para bruquideos, sendo que as variedades UFAC-Q01 e UFAC-R01 de caupi e feijao comum apresentaram menor susceptibilidade ao ataque de C. maculatus e Z. subfasciatus. Key Words: Vigna unguiculata; Phaseolus vulgaris; varietal susceptibility; storage; bruchids View this article in BioOne

Isopods Cymothoidae ectoparasites of fish from the Amazon.

Most freshwater species of Cymothoidae are distributed in South America. They have mainly been recorded in the eastern and western regions of the Amazon River basin. However, in this ecosystem, the biodiversity of this group may be greater if the entire Amazon basin is considered. In this regard, the aim of the present study was to provide an updated list of isopod species of the family Cymothoidae that are found in fish in the Brazilian Amazon region and to report on new fish host occurrences and expanded geographical distributions for cymothoid isopods that parasitize fish in the southwestern Brazilian Amazon region. The parasites found in fish specimens were collected, fixed and identified later. We found eight species of Cymothoidae parasitizing different host fish species in the southwestern Amazon region. However, we found 14 species of Cymothoidae throughout the Brazilian Amazon region. Three additional species are thus reported here, which increases the number of species of Cymothoidae in this region to 17. These additional species are also new records for Brazil. Therefore, this study has contribute to expand the knowledge about the distribution and diversity of Cymothoidae in the Amazon basin.

English

No-tillage is an agricultural system that is proposed as a sustainable soil management system. This paper aims to evaluate the short-term effects of cover crops on a no-tillage system, by assessing a number of physical and chemical attributes of soil of the Brazilian Amazon region. The experiment was carried out in a typical Ferralsol under a no-tillage system from March to December, 2014. A randomized block design, with four replicates was used. The performance and effects of fourteen cover crops (Cajanus cajan, Canavalia ensiformis, Crotalaria juncea, Crotalaria ochroleuca, Crotalaria spectabilis, Stizolobium aterrima, Stizolobium cinereum, Pennisetum glaucum, Sorghum bicolor, Sorghum sudanense, Urochloa brizanha cv. Xaraes, Urochloa brizantha cv. Piata and Urochloa ruziziensis and Zea mays) and fallow (control treatment) on the soil quality were assessed. The cover crops were sown in the off season in April 2014, before the summer crop (maize). The levels of P, K, Ca2+, Mg2+, Al3+, H+Al, saturation by aluminum, sum of bases, organic matter, pH and resistance to soil penetration were evaluated following the end of the cover crops growth. Some near-surface soil attributes were affected by the cover crops. Urochloa species improved the levels of potassium in the soil at depths up to 5 cm below the surface. The highest penetration resistance was observed in the superficial layer between 12 and 16 cm deep, with penetration resistance values varying between 2472 and 2912 kPa. The Urochloa exhibited satisfactory agronomic performance when grown under a simulated crop livestock integration system. It is concluded that the use of cover crops in a no-till system has the potential to improve the chemical quality of soil in the Southwestern Amazon region. Key words: No-tillage, ecological intensification, sustainability, Rondonia, green manure.

Soil Seed Bank Phytosociology in No-Tillage Systems in the Southwestern Amazon Region

Understanding the ecological dynamics of weed populations in no-tillage systems is important to establish strategies for integrated weed control capable of increasing agroecosystem sustainability. This study sought to evaluate the effect of succession systems on the seed bank in a no-tillage system. The effects of fifteen succession systems, composed of seven grasses, seven Leguminosae, and a fallow condition, were evaluated on the seed bank at two soil depths (0 to 10 and 10 to 20 cm). The species found in the seed bank were quantified and identified by species and family. The precision of sampling, density, dominance, the indices of diversity of Simpson and Shannon-Weiner; index of sustainability; analysis of groupings of dissimilarities; and the value of importance of each species were calculated. High weed diversity was observed; 29 species were counted, including members of 12 different families. The highest expression of weeds was observed at soil depths of 0 to 10 cm. The Simpson and Shannon-Weiner coefficients indicated high diversity in both systems of succession. The index of sustainability did not indicate significant alterations in the different systems of succession. The coefficients of confenetic correlation were 0.74% and 0.82% for the 0 - 10 and the 10 - 20 cm soil depths respectively. It is concluded that there is a high diversity of weeds in the agroecosystems of Amazonia, and different cover crops promote modifications in the community and expression of the weeds’ seed bank.

Use of plant oils from the southwestern Amazon for the control of maize weevil

The purpose of this study was to evaluate the insecticidal potential of oils obtained from plant species endemic to the southwestern Amazon region against the maize weevil (Sitophilus zeamais Motschulsky). We evaluated the mortality of insects treated with 11 plant oils. After the discriminant assays, concentration–mortality bioassays were conducted to evaluate the toxicity of each oil. The insects were treated with the oils, and mortality was assessed after 24 h. Each assay was performed in four replicates. The LC50 of the oils against S. zeamais ranged between 53.35% and 65.22% for the oils obtained from Astrocaryum aculeatum Meyer, Copaifera spp., Carapa guianensis Aublet, Oenocarpus bataua Mart., Mauritia flexuosa L,. and Orbignya phalerata Mart. These oils exhibited consistency in their toxic activity and emerged as potential alternatives to be implemented in integrated pest management programs for stored product pests. The results of this investigation identified several plant species in the Amazonian flora with potential insecticidal properties.

The Ethnic Life of Missionaries: Early Inculturation Theology in Mato Grosso, Brazil (1952-1990)

From the early 1950s to the mid-1970s, missionaries from several congregations in the southwestern Amazon region of Brazil, notably a group of young Jesuits, developed an avant la lettre radical brand of inculturation theology, based on close relations with academic anthropology and cultural relativism. By the 1990s, this “type” of inculturation became one of the missionary norms in the region; it was also instrumental in the creation and orientation of the Indigenist Missionary Council, the main missionary organization in Brazil. I explore the trajectories of three inculturation theology Jesuits who asserted the need to protect indigenous cultures, including their shamanic rituals.

Cloud condensation nuclei from biomass burning during the Amazonian dry-to-wet transition season

Aircraft measurements of cloud condensation nuclei (CCN) during the Large-Scale Biosphere–Atmosphere Experiment in Amazonia (LBA) were conducted over the Southwestern Amazon region in September–October 2002, to emphasize the dry-to-wet transition season. The CCN concentrations were measured for values within the range 0.1–1.0% of supersaturation. The CCN concentration inside the boundary layer revealed a general decreasing trend during the transition from the end of the dry season to the onset of the wet season. Clean and polluted areas showed large differences. The differences were not so strong at high levels in the troposphere and there was evidence supporting the semi-direct aerosol effect in suppressing convection through the evaporation of clouds by aerosol absorption. The measurements also showed a diurnal cycle following biomass burning activity. Although biomass burning was the most important source of CCN, it was seen as a source of relatively efficient CCN, since the increase was significant only at high supersaturations.

Impact of biomass burning aerosols on precipitation in the Amazon: A modeling case study

A study of the potential role of aerosols in modifying clouds and precipitation is presented using a numerical atmospheric model. Measurements of cloud condensation nuclei (CCN) and cloud size distribution properties taken in the southwestern Amazon region during the transition from dry to wet seasons were used as guidelines to define the microphysical parameters for the simulations. Numerical simulations were carried out using the Brazilian Development on Regional Atmospheric Modeling System, and the results presented considerable sensitivity to changes in these parameters. High CCN concentrations, typical of polluted days, were found to result in increases or decreases in total precipitation, depending on the level of pollution used as a reference, showing a complexity that parallels the aerosol‐precipitation interaction. Our results show that on the grids evaluated, higher CCN concentrations reduced low‐to‐moderate rainfall rates and increased high rainfall rates. The principal consequence of the increased pollution was a change from a warm to a cold rain process, which affected the maximum and overall mean accumulated precipitation. Under polluted conditions, cloud cover diminished, allowing greater amounts of solar radiation to reach the surface. Aerosol absorption of radiation in the lower layers of the atmosphere delayed convective evolution but produced higher maximum rainfall rates due to increased instability. In addition, the intensity of the surface sensible heat flux, as well as that of the latent heat flux, was reduced by the lower temperature difference between surface and air, producing greater energy stores at the surface.

Carbon sequestration in agricultural soils in the Cerrado region of the Brazilian Amazon

The introduction of crop management practices after conversion of Amazon Cerrado into cropland influences soil C stocks and has direct and indirect consequences on greenhouse gases (GHG) emissions. The aim of this study was to quantify soil C sequestration, through the evaluation of the changes in C stocks, as well as the GHG fluxes (N 2O and CH 4) during the process of conversion of Cerrado into agricultural land in the southwestern Amazon region, comparing no-tillage (NT) and conventional tillage (CT) systems. We collected samples from soils and made gas flux measurements in July 2004 (the dry season) and in January 2005 (the wet season) at six areas: Cerrado, CT cultivated with rice for 1 year (1CT) and 2 years (2CT), and NT cultivated with soybean for 1 year (1NT), 2 years (2NT) and 3 years (3NT), in each case after a 2-year period of rice under CT. Soil samples were analyzed in both seasons for total organic C and bulk density. The soil C stocks, corrected for a mass of soil equivalent to the 0–30-cm layer under Cerrado, indicated that soils under NT had generally higher C storage compared to native Cerrado and CT soils. The annual C accumulation rate in the conversion of rice under CT into soybean under NT was 0.38 Mg ha −1 year −1. Although CO 2 emissions were not used in the C sequestration estimates to avoid double counting, we did include the fluxes of this gas in our discussion. In the wet season, CO 2 emissions were twice as high as in the dry season and the highest N 2O emissions occurred under the NT system. There were no CH 4 emissions to the atmosphere (negative fluxes) and there were no significant seasonal variations. When N 2O and CH 4 emissions in C-equivalent were subtracted (assuming that the measurements made on 4 days were representative of the whole year), the soil C sequestration rate of the conversion of rice under CT into soybean under NT was 0.23 Mg ha −1 year −1. Although there were positive soil C sequestration rates, our results do not present data regarding the full C balance in soil management changes in the Amazon Cerrado.

Temporal nutrient variation in soil and vegetation of post-forest pastures as a function of soil order, pasture age, and management, Rondônia, Brazil

Abstract Understanding pasture degradation processes is key for sustainable development in the Amazon region. Pasture degradation can be indexed by pasture nutritional status, which is impacted by environmental and human related factors. Most studies of the biogeochemistry of Amazonian pastures have been restricted to highly acidic soils with little focus on how management affects pasture biogeochemistry. We investigated soil physical and chemical properties and grass nutrients under different edaphic conditions and management practices in Rondonia state, in the southwestern Amazon region. Our objectives were to analyze the impacts of soil order, pasture age, and pasture management on soil fertility, bulk density and plant nutrients, in order to understand sustainability needs for the future of this region. We sampled 17 study sites on Oxisols, Ultisols, and Alfisols. The pasture age classes we used consisted of 6–10, 11–15, and >16 years including forest as the control. We also evaluated the impact of beef and dairy management strategies on pastures installed on Ultisols. Pastures on Alfisols showed the highest soil P, Ca, and base saturation, properties that decreased gradually after 5 years of pasture installation. In contrast, pastures on Oxisols showed low and stable levels of nutrients regardless of age. Foliar nutrient concentrations appear to be influenced by edaphic conditions. Soil P and foliar P concentration were highly correlated. In general, pasture age was a poor indicator of soil fertility and foliar chemistry because of high variability among pastures belonging to the same soil order. In terms of the impacts of pasture management, we did not observe significant differences in soil or foliar properties in pasture used for beef and dairy on Ultisols.

Size distribution and hygroscopic properties of aerosol particles from dry-season biomass burning in Amazonia

Abstract. Aerosol particle number size distributions and hygroscopic properties were measured at a pasture site in the southwestern Amazon region (Rondonia). The measurements were performed 11 September-14 November 2002 as part of LBA-SMOCC (Large scale Biosphere atmosphere experiment in Amazonia - SMOke aerosols, Clouds, rainfall and Climate), and cover the later part of the dry season (with heavy biomass burning), a transition period, and the onset of the wet period. Particle number size distributions were measured with a DMPS (Differential Mobility Particle Sizer, 3-850nm) and an APS (Aerodynamic Particle Sizer), extending the distributions up to 3.3 µm in diameter. An H-TDMA (Hygroscopic Tandem Differential Mobility Analyzer) measured the hygroscopic diameter growth factors (Gf) at 90% relative humidity (RH), for particles with dry diameters (dp) between 20-440 nm, and at several occasions RH scans (30-90% RH) were performed for 165nm particles. These data provide the most extensive characterization of Amazonian biomass burning aerosol, with respect to particle number size distributions and hygroscopic properties, presented until now. The evolution of the convective boundary layer over the course of the day causes a distinct diel variation in the aerosol physical properties, which was used to get information about the properties of the aerosol at higher altitudes. The number size distributions averaged over the three defined time periods showed three modes; a nucleation mode with geometrical median diameters (GMD) of ~12 nm, an Aitken mode (GMD=61-92 nm) and an accumulation mode (GMD=128-190 nm). The two larger modes were shifted towards larger GMD with increasing influence from biomass burning. The hygroscopic growth at 90% RH revealed a somewhat external mixture with two groups of particles; here denoted nearly hydrophobic (Gf~1.09 for 100 nm particles) and moderately hygroscopic (Gf~1.26). While the hygroscopic growth factors were surprisingly similar over the periods, the number fraction of particles belonging to each hygroscopic group varied more, with the dry period aerosol being more dominated by nearly hydrophobic particles. As a result the total particle water uptake rose going into the cleaner period. The fraction of moderately hygroscopic particles was consistently larger for particles in the accumulation mode compared to the Aitken mode for all periods. Scanning the H-TDMA over RH (30-90% RH) showed no deliquescence behavior. A parameterization of both Gf(RH) and Gf(dp), is given.

Daytime Cycle of Low-Level Clouds and the Tropical Convective Boundary Layer in Southwestern Amazonia

Abstract During the wet season in the southwestern Amazon region, daytime water transport out of the atmospheric mixed layer into the deeper atmosphere is shown to depend upon cloud amounts and types and synoptic-scale velocity fields. Interactions among clouds, convective conditions, and subcloud-layer properties were estimated for two dominant flow regimes observed during the 1999 Tropical Rainfall Measuring Mission component of the Brazilian Large-Scale Biosphere–Atmosphere (TRMM-LBA) field campaign. During daytime the cloud and subcloud layers were coupled by radiative, convective, and precipitation processes. The properties of cloud and subcloud layers varied according to the different convective influences of easterly versus westerly lower-tropospheric flows. The most pronounced flow-regime effects on composite cloud cycles occurred under persistent lower-tropospheric flows, which produced strong convective cloud growth with a near absence of low-level stratiform clouds, minimal cumulative attenuation of incoming solar irradiance (∼25%), rapid daytime mixed-layer growth (>100 m h−1), and boundary layer drying (0.22 g kg−1 h−1), high convective velocities (>1.5 m s−1), high surface buoyancy flux (>200 W m−2), and high latent heat flux (600 W m−2) into cloud layer. In contrast, persistent westerly flows were less convective, showing a strong morning presence of low-level stratiform genera (>0.9 cloud amount), greater cumulative attenuation of incoming solar irradiance (∼47%), slower mixed-layer growth (<50 m h−1) with a slight tendency for mixed-layer moistening, and a delayed peak in the low-level cumuliform cloud cycle (2000 versus 1700 UTC). The results reported in this article indicate that numerical models need to account for cloud amounts and types when estimating water vapor transport to the cloud layer.

Characteristics of the Amazonian mesoscale convective systems observed from satellite and radar during the WETAMC/LBA experiment

An objective tracking of mesoscale convective systems (MCSs) observed in full‐resolution Geostationary Operational Environmental Satellite (GOES) satellite images has been applied during the Wet Season Atmospheric Mesoscale Campaign/Large‐Scale Biosphere–Atmosphere (WETAMC/LBA) experiment in Amazonia from January to February 1999 to document the characteristics of the convective cloud organization in the southwestern Amazon region. The same tracking methodology was also applied to the National Aeronautical Space Administration (NASA) Tropical Ocean Global Atmosphere (TOGA) C‐Band radar data in order to estimate the propagation of the convective rain cells from constant altitude plan position indicators (CAPPI) at a height of 2 km. The convective activity showed two different patterns named Easterly and Westerly regimes according to the wind flow in the 700–850‐hPa layer. During the Easterly regime, MCSs and rain cells had closely related propagations. MCS as well as rain cell propagations were associated mostly to the midlevel mean flow. During the Westerly regime, the propagations of both MCSs and rain cells were much more disorganized, there was no clear relationship with the mean atmospheric flow at any level, although the rain cells have a slight tendency to propagate eastward, and the low‐level rain cells propagated quite independently of the high‐level cloud cover. MCS initiations were mostly driven by topography, that is, high escarpment and relatively high elevation.

Stable carbon isotope ratio of tree leaves, boles and fine litter in a tropical forest in Rondônia, Brazil.

Leaves of 208 trees were collected for isotopic analysis together with wood from 36 tree boles and 18 samples of fine litter from a terra-firme forest located at Samuel Ecological Reserve, Rondônia State, in the southwestern Amazon region. The range of δ13C values in leaves was from -28 to -36‰, with an average (±1 SD) of -32.1 ± 1.5‰, which was more negative than the δ13C values of bole samples (-28.4 ± 2.0‰) and fine litter (-28.7 ± 2.0‰). These values are within the range found for tropical and subtropical forests. Pooling the δ13C values for leaf samples from trees of the same height gave averages which were positively correlated with plant height at a highly significant level, with a slope of 0.06 and an intercept of -33.3‰ and a correlation coefficient r 2=0.70 (P<0.001).

Aotus from the southwestern Amazon region is geographically and chromosomally intermediate betweenA. azarae boliviensis andA. infulatus

We described the karyotypes detected in 23Aotus specimens captured on Southwestern Amazon region (63°30'W, 9°00'S). This region should be occupied byA. nigriceps. However, the animals described here have a fur pattern and a karyotypes similar to those ofA. azarae boliviensis andA. infulatus. The females presented 50 chromosomes and the males 49 as a consequence of fusion between the chromosome Y and an autosome. This sample presented polymorphisms of G- and C-banding and NOR-staining. These animals are karyotypically intermediate betweenA. a. boliviensis andA. infulatus. The taxonomy and karyotypic evolution of these taxa are discussed.