Homegardens on Amazonian Dark Earths,Non-anthropogenic Upland,and Floodplain Soils along the Brazilian Middle Madeira River Exhibit Diverging Agrobiodiversity<Superscript>1</Superscript>

Homegardens on Amazonian Dark Earths, Non-anthropogenic Upland, and Floodplain Soils along the Brazilian Middle Madeira River Exhibit Diverging Agrobiodiversity. We test the hypothesis that the agrobiodiversity associated with homegardens on three different soils—upland Amazonian Dark Earths (ADE) and Oxisols (OX), and Fluvent Entisols (FL)—commonly found along the middle Madeira River in the municipality of Manicoré, Amazonas State, Brazil, is different due to the contrasting biotic, abiotic, and cultural settings specific to each of these soils. Using data from interviews with 63 farmers about food and utility species, we compare structural and floristic characteristics of homegarden agrobiodiversity. The density of individuals is higher on ADE than on the other soils (mean ± standard deviation: 715 ± 363 on ADE, 474 ± 283 on OX, 642 ± 399 on FL). ADE and OX have higher species richness (28.2 ± 5.6 on ADE, 25 ± 3.7on OX, 23.6 ± 5 on FL), while ADE and FL have a greater degree of domestication (2 ± 0.6 on ADE, 1.3 ± 0.5 on OX, 2.3 ± 0.6 on FL). ADE and OX have greater proportions of richness, density, and coverage composed of South American species, while FL has greater proportions of richness and density composed of Old World species. ADE has higher proportions of density and coverage of Mesoamerican species. Floristic composition is also different between soils: ADE occupies an intermediate position, composed of species associated with each of the other soil types and species that are most common on ADE. These differences in agrobiodiversity emerge through the interaction of human agency, plant responses, and the unique properties of soils in relation to socioeconomic and historical trajectories over time.     

Anthropogenic impact of mercury accumulation in fish from the Rio Madeira and Rio Negro rivers (Amazonia)

Fish is an important concentrator of mono-methyl mercury and the main route to human contamination. We compared fish Hg bioaccumulation (within similar weight ranges) in two Amazonian river habitats during high-water seasons. The Rio Madeira has been greatly impacted by agriculture, alluvial gold extraction, and a hydroelectric reservoir, whereas the Rio Negro is much less affected by these human activities. The species at the top of the food web, Hoplias malabaricus (piscivorous; 80-668 ng Hg/g) and Cichla spp. (piscivorous; 42–747 ng Hg/g) showed the highest range of Hg concentrations. Nonpiscivorous species with comparable weight range, such as Potamorhina latior (detritivorous; 20–157 ng Hg/g) and Myleus torquatus (herbivorous; 2–182 ng Hg/g), had lower Hg concentrations. Triportheus elongatus (omnivorous; 5–350 ng Hg/g), with the lowest weight range, also showed a low range of Hg concentrations. Despite the Rio Madeira's higher sediment load as well as environmental impacts (deforestation, agriculture, hydroelectric reservoir, and alluvial gold mining) on natural Hg release, fish Hg bioaccumulation was no different between the two river habitats for nonpiscivorous species. In this small observational study only the species at the top of the food web (M. torquatus, Cichla spp, T. elongatus) showed higher mean Hg concentrations in the Rio Madeira than the dominantly wilderness habitat of the Rio Negro.     

Xavante Ritual Hunting: Anthropogenic Fire,Reciprocity, and Collective Landscape Management in the Brazilian Cerrado

Conservation attention to indigenous hunting with fire in the cerrado largely focuses on sustainability as construed in scientific terms rather than according to indigenous points of view. Towards the goal of reframing the debate in terms more congruent with indigenous perspectives, I address how the Xavante (A’uw?) view ritualized and collective hunting, including hunting with fire, as indispensable means of acquiring gifts by which to celebrate important events, express feelings of respect and gratitude towards others, promote positive social values among male youth, and maintain the group’s ethnic identity. In particular, ritualized exchanges of game meat are necessary and culturally appropriate means of expressing esteem for others at some of life’s most important moments. For the Xavante, the social imperative to give and receive gifts of meat during weddings and initiation ceremonies motivates efforts to maintain the collective hunting with fire tradition in a manner that ensures its long term environmental viability.     

Interactions between rainfall, deforestation and fires during recent years in the Brazilian Amazonia

Understanding the interplay between climate and land-use dynamics is a fundamental concern for assessing the vulnerability of Amazonia to climate change. In this study, we analyse satellite-derived monthly and annual time series of rainfall, fires and deforestation to explicitly quantify the seasonal patterns and relationships between these three variables, with a particular focus on the Amazonian drought of 2005. Our results demonstrate a marked seasonality with one peak per year for all variables analysed, except deforestation. For the annual cycle, we found correlations above 90% with a time lag between variables. Deforestation and fires reach the highest values three and six months, respectively, after the peak of the rainy season. The cumulative number of hot pixels was linearly related to the size of the area deforested annually from 1998 to 2004 (r2=0.84, p=0.004). During the 2005 drought, the number of hot pixels increased 43% in relation to the expected value for a similar deforested area (approx. 19000km2). We demonstrated that anthropogenic forcing, such as land-use change, is decisive in determining the seasonality and annual patterns of fire occurrence. Moreover, droughts can significantly increase the number of fires in the region even with decreased deforestation rates. We may expect that the ongoing deforestation, currently based on slash and burn procedures, and the use of fires for land management in Amazonia will intensify the impact of droughts associated with natural climate variability or human-induced climate change and, therefore, a large area of forest edge will be under increased risk of fires.     

Selenium Levels in the Whole Blood of Children and Teenagers from Two Riparian Communities at the Madeira River Basin in the Western Brazilian Amazon

Selenium (Se) is an essential micronutrient that exerts multiple functions in the organism, and both its deficiency and excess can cause health impairments. Thus, it is important to monitor its levels in the population, especially in vulnerable groups, such as children from the Brazilian Amazon region, where there is a lack of information in this regard. The aim of this research was to study Se levels in the whole blood of children and teenagers (5–16 years old) from two riparian communities at the Madeira River (Cuniã RESEX and Belmont). Se level variations related to the communities’ location, seasonality, diet, and body mass index (BMI) were assessed. Blood samples were collected in both communities for Se determinations, using ICP-MS and hemogram analyses, during May and September of 2011. Food frequency questionnaires were applied to assess consumption rates of specific food items. Non-parametric tests and linear multiple regressions were applied in the data analyses. Median Se levels were significantly higher during May (Cuniã RESEX 149 μg L^?1; Belmont 85 μg L^?1) compared to September (Cuniã RESEX 79 μg L^?1; Belmont 53 μg L^?1). No significant differences were found between the communities regarding BMI measurements and anemia prevalence. However, Se blood levels were significantly higher at the Cuniã RESEX compared to Belmont. In addition, the former showed higher fish and Brazil nut intakes, which may be the main Se sources for this community. These results contribute to a better understanding of Se reference levels for children and teenagers of Western Amazon riparian communities.     

Rhizobial Populations in Soils from Natural Acacia senegal and Acacia nilotica Forests in Mauritania and the Senegal River Valley

Eighty-two strains of rhizobia were isolated from soils taken from several sites in Mauritania and Senegal. These soil samples were collected from natural stands of Acacia nilotica and Acacia senegal. The soils from Mauritania were less rich in native rhizobia than the soils from Senegal. The strains were characterized using polymerase chain reaction–restriction fragment length polymorphism and by sequencing the rDNA 16S–23S intergenic spacer region (IGS). They were sorted into seven IGS groups. These groups were not associated with the geographical origin of the strains or with the host-plant species at the site where the soils were collected. Most of the strains were in three of the IGS groups (I, IV, and V). One representative strain from each IGS group was sequenced and showed that the strains were from the genus Mesorhizobium. IGS groups I, IV, and VI were close to the species M. plurifarium (AF34563), IGS groups IIand III were close to the species Mesorhizobium sp. (AF510360), IGS group V was close to the species Mesorhizobium sp. (AF510366), and IGS group VII was close to Mesorhizobium sp. (AF510346).     

Copper Sorption Behavior of Selected Soils of the Oasis in the Middle Reaches of Heihe River Basin,China

The mobility and bioavailability of copper (Cu) depends on the Cu sorption capacity of soil and also on the chemical form of Cu in soils. Laboratory batch experiments were carried out to study the sorption and distribution of Cu in nine soils differing in their physicochemical properties from the oasis in the middle reaches of Heihe river basin, China: desert soil (S-1), agricultural soils (S-2, S-3, S-8, and S-9), marshland soil (S-4), and hungriness shrub soils (S-5 and S-6). Copper sorption behavior was studied using the sorption isotherm and sequential extraction procedure. In general, the sorption capacity for Cu decreased in the order: S-4 > S-9 > S-2 > S-8 > S-3 > S-6 > S-5 > S-7 > S-1. The correlation results suggest that soils with higher CEC, silt, clay, CaCO3, and organic matter will retain Cu more strongly and in greater amounts than soils that are sandy with lower CEC, CaCO3, and organic matter. pH is not an important impact factor to Cu sorption in experimental soil samples because pH in soils used in this study had a narrow range. The distribution of sorbed Cu varied between nine soils studied and depended on both soil properties and initial added Cu concentration. There are significant differences in the distribution of Cu in each soil with the increase of initial Cu concentration. The predominance of Cu associated with the available fraction, which was over 50% of the total sorbed Cu in most cases, indicates that the change of geochemical conditions might promote the release of Cu back into soil solution thus impacting organisms in the soils. The added Cu has also the tendencies to locate in the residual fraction, which was larger than 5% of the total amount extracted from the four fractions in most soils.     

Selenium and mercury concentrations in some fish species of the Madeira River, Amazon Basin, Brazil

Samples of 7 species of piscivorous, omnivorous, and herbivorous fish caught at 12 different sites on the Madeira River, Amazon Basin, were analyzed for selenium and mercury. Selenium was determined by anodic stripping voltammetry and mercury by cold vapor atomic absorption spectrophotometry. The means for selenium concentrations ranged from 0.49 to 3.11 nmol/g and for mercury from 0.41 to 6.66 nmol/g depending on the fish species. The molar ratios of Hg:Se increased according to the fish trophic level. Piscivorous species had the highest mean ratio (4.0) and herbivorous species the lowest (0.9). There was a positive and statistically significant correlation between selenium and mercury concentrations for the herbivorous species (r = 0.716;p = 0.0088) not seen for omnivororus and piscivorous species (r = -0.2032;p = 0.3407). These findings are significant for the fish-eating population of the Madeira River because the ingestion of mercury would always be in excess of selenium.     

Restoration of Tropical Moist Forests on Bauxite-Mined Lands in the Brazilian Amazon

We evaluated forest structure and composition in 9- to 13-year-old stands established on a bauxite-mined site at Trombetas (Pará), Brazil, using four different reforestation techniques following initial site preparation and topsoil replacement. These techniques included reliance on natural forest regeneration, mixed commercial species plantings of mostly exotic timber trees, direct seeding with mostly native early successional tree species, and mixed native species plantings of more than 70 tree species (the current operational restoration treatment at this site). Replicated fixed-radius plots in each treatment and in undisturbed primary forest were used to quantify the canopy and understory structure and the abundance and diversity of all vascular plant species. Treatment comparisons considered regeneration density, species richness and diversity for all floristic categories, and, for trees and shrubs, the relative contribution of initial planting and subsequent regeneration from soil seed banks and seed inputs from nearby primary forests. With the possible exception of the stands of mixed commercial species, which were superior to all others in terms of tree basal-area development but relatively poor in species richness, all treatments were structurally and floristically diverse, with a high probability of long-term restoration success. Of these, the mixed native species plantings appeared to be at least risk of arrested succession due to the dominance of a broader range of tree species of different successional stages or expected life spans. In all treatments, several locally important families of primary forest trees (Annonaceae, Chrysobalanaceae, Lauraceae, Palmae and Sapotaceae) were markedly underrepresented due to a combination of poor survival of initial plantings and limitations on seed dispersal from the surrounding primary forest.     

Ecological and Biological Features of Soils in Fir Forests Defoliated by the Siberian Moth in the Southern Taiga Subzone of Middle Siberia

Experimental data are analyzed that concern the effect of zoogenic debris on the properties of soddy deep podzolic soils and raw-humus brown soils characteristic of southern taiga forests in the Yenisei region of Siberia. It is shown that the influence of excrements of Siberian moth larvae on the soil microflora lasts for two or, at most, three growing seasons. Zoogenic plant debris falling on the ground surface during tree stand defoliation is a short-acting but powerful stimulant of biological activity in the litter; hence, it has a considerable effect on soil properties. This effect is enhanced by changes in ecological conditions that occur upon defoliation. The influence of the cenotic factor on biogenic soil properties is manifested more strongly in the organogenic horizons. The communities of microorganisms involved in the nitrogen and carbon cycles are dominated by prototrophic forms in the normal fir forest and by pedotrophic forms in the forest defoliated by pests.     

Succession of Ephemeral Secondary Forests and Their Limited Role for the Conservation of Floristic Diversity in a Human-Modified Tropical Landscape

Both local- and landscape-scale processes drive succession of secondary forests in human-modified tropical landscapes. Nonetheless, until recently successional changes in composition and diversity have been predominantly studied at the patch level. Here, we used a unique dataset with 45 randomly selected sites across a mixed-use tropical landscape in central Panama to study forest succession simultaneously on local and landscape scales and across both life stages (seedling, sapling, juvenile and adult trees) and life forms (shrubs, trees, lianas, and palms). To understand the potential of these secondary forests to conserve tree species diversity, we also evaluated the diversity of species that can persist as viable metapopulations in a dynamic patchwork of short-lived successional forests, using different assumptions about the average relative size at reproductive maturity. We found a deterministic shift in the diversity and composition of the local plant communities as well as the metacommunity, driven by variation in the rate at which species recruited into and disappeared from the secondary forests across the landscape. Our results indicate that dispersal limitation and the successional niche operate simultaneously and shape successional dynamics of the metacommunity of these early secondary forests. A high diversity of plant species across the metacommunity of early secondary forests shows a potential for restoration of diverse forests through natural succession, when trees and fragments of older forests are maintained in the agricultural matrix and land is abandoned or set aside for a long period of time. On the other hand, during the first 32 years the number of species with mature-sized individuals was a relatively small and strongly biased sub-sample of the total species pool. This implies that ephemeral secondary forests have a limited role in the long-term conservation of tree species diversity in human-modified tropical landscapes.     

Tropical Fossil Caviomorph Rodents from the Southwestern Brazilian Amazonia in the Context of the South American Faunas: Systematics,Biochronology, and Paleobiogeography

The fossil-bearing stratigraphic sections of the Solimões Formation (southwestern Brazilian Amazonia) are exposed mainly along the Juruá, Purus, and Acre rivers, and in road cuts. These deposits have provided fossils of the four main lineages of Caviomorpha – Cavioidea, Erethizontoidea, Octodontoidea, and Chinchilloidea, contributing to the understanding on the evolution of tropical Neogene rodents. Herein, our knowledge about fossil rodents from this region is reviewed. New specimens are recorded, including taxa mentioned for this region for the first time, such as basal cavioids, Dolichotinae, Caviodon (Hydrochoeridae), and Drytomomys (Dinomyidae). Unfortunately, the deposits have no absolute ages, and based on palynological data and the biochronology of several taxa (mainly mammals), the encompassed fauna has been constrained to the late Miocene. However, some rodent lineages recorded here seem to be more related to older faunas, from the middle Miocene and Paleogene. Regarding the biogeographic and paleoenvironmental affinities, most of the Neogene rodents from the Acre region show more similarities to those from the Entre Rios, Argentina, and Urumaco, Venezuela, where wet environments were present during Neogene times. An increase in prospecting along southwestern Amazonian rivers looking for rodents (among other vertebrates) associated with methods to better constrain the ages of these faunal assemblages will contribute to a better understanding of the evolution of the tropical rodents as well as the stratigraphy and age of that portion of the basin.     

Occurrence of Cephalonomia stephanoderis Betrem (Hymenoptera: Bethylidae) in coffee plantations of the Brazilian Amazonia

Adults of Cephalonomia stephanoderis Betrem were detected (in November 2003) during the sampling of Coffea canephora Pierre ex A. Froehner berries damaged by Hypothenemus hampei Ferrari (Coleoptera: Scolytidae) in Ouro Preto D'Oeste - Rond?nia, Brazil (10 degrees 45'S and 62 degrees 15'W). From January to July 2004, the parasitoid was monthly sampled in 200 berries damaged by H. hampei. Probably, C. stephanoderis can already exert some parasitism pressure at the coffee berry borer population. The occurrence of this parasitoid in natural conditions points out to another alternative for the biological control of the H. hampei in Rond?nia. This is the first record of C. stephanoderis in coffee plantations of the Brazilian Amazonia.     

Landscapes of Power and Identity: Comparative Histories in the Sonoran Desert and the Forests of Amazonia from Colony to Republic

Landscapes of Power and Identity: Comparative Histories in the Sonoran Desert and the Forests of Amazonia from Colony to Republic . Cynthia Radding. Durham, NC: Duke University Press, 2005. 431 pp.     

<Emphasis Type="Italic">Caboclo</Emphasis> Horticulture and Amazonian Dark Earths along the Middle Madeira River,Brazil

This article examines the relationship between Amazonian Dark Earths (ADE) and Caboclo horticultural knowledge and practice along the middle Madeira River (the biggest whitewater tributary of the Amazon) in the municipality of Manicoré, Amazonas State, Brazil. ADE are fertile anthropogenic (human-made) soils that are found in many areas of the Amazon region. The formation of ADE is a legacy of Amerindian settlement patterns, mostly during the late pre-Columbian period (2000–500 bp). The primary users of ADE in the Central Amazon today are Caboclos, traditional Amazonian people of heterogeneous origins. The multi-sited ethnography presented here demonstrates that Caboclos have developed a repertoire of local knowledge surrounding the cultivation of their staple crop, bitter manioc, in these soils. This revolves around a local theory of “weakness” and “strength” used to describe different sets of bitter manioc landrace traits and their responses to planting in different kinds of soil and fallow ages. This local theory has developed in the context of a regional historical ecology that has enabled the conservation and generation of such horticultural knowledge. I conclude that these notions of strength and weakness shape divergent loci of bitter manioc genetic traits and co-evolutionary dynamics between people and plants in the cultivation of bitter manioc in different soil types.     

Effect of biomass on assemblages of large mammals in a seasonally dry forest in the Brazilian Amazonia

Aiming to understand the relationship between body mass and abundance, a community of middle-sized and larger mammals was studied in a seasonally dry forest in the far north of the Brazilian Amazonia. Diurnal and nocturnal surveys were carried out by the line-transect method along a 10-km transect. Data were collected on density, biomass, use of forest types, forest strata, diet and feeding strategies by the mammals. Biomass explained animal abundance better than did body mass across the two forest types: Terra Firme forest and mixed forest. There was a statistically significant positive relationship between the biomass of all the 33 mammals studied and group density, as well as between biomass and group size, in both forests. When terrestrial and arboreal mammals, and also different feeding guilds were considered separately, they exhibited very similar results, where biomass alone was positively associated with group density and group size. The slope of the relationships between body mass and group density, body mass and group size, biomass and group density, and biomass and group size varied considerably, with significant scatter around the regression line. Food and food competition shaped the relationship between animal mass and abundance, and this relationship can even vary widely between assemblages. As a result of competition for the available resources, group density increased with increasing biomass.