Area and Age of Secondary Forests in Brazilian Amazonia 1978–2002: An Empirical Estimate

In quantifying the carbon budget of the Amazon region, temporal estimates of the extent and age of regenerating tropical forests are fundamental. However, retrieving such information from remote-sensing data is difficult, largely because of spectral similarities between different successional stages and variations in the reflectance of forests following different pathways of regeneration. In this study, secondary-forest dynamics in Brazilian Amazonia were modeled for the 1978–2002 period to determine area and age on a grid basis. We modeled the area, age, and age class distribution of secondary forests using empirical relationships with the percentage of remaining primary forest, as determined from large-area remote-sensing campaigns (the Pathfinder and Prodes projects). The statistical models were calibrated using detailed maps of secondary-forest age generated for seven sites in the Brazilian Legal Amazon. The area–age distribution was then specified from mean age by a distribution assumption. Over the period 1978–2002, secondary-forest area was shown to have increased from 29,000 to 161,000 km² (that is, by a factor of 5). The mean age increased from 4.4 to 4.8 years. We generated a time series of secondary-forest area fractions and successional stages that provides wall-to-wall coverage of the Brazilian Amazon at a spatial resolution of 0.1 decimal degrees (approximately 11 km). Validation against reference data yielded root mean squared errors of 8% of the total area for estimate of secondary-forest area and 2.4 years for mean secondary-forest age. Using this approach, we provide the first published update on the state of secondary forests in Amazonia since the early 1990s and a time series of secondary-forest area over the 25-year period.     

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.     

A Matter of Scale: Historical and Environmental Factors Structure Anuran Assemblages from the Upper Madeira River,Amazonia

Biogeographical history and current ecological interactions have usually been addressed separately to explain the spatial distribution of patterns of biodiversity. In this study, we evaluated the integrated effects of biogeographical and environmental factors in structuring the diurnal amphibian anuran assemblages of the upper Madeira River, southwestern Amazonia. We used a sampling design involving 98 standardized units, distributed across seven locations covering both banks of the river's course in the state of Rondônia, Brazil. We conducted searches for frogs in three campaigns between February 2010 and February 2011, aiming to: (1) evaluate the effect of the Madeira River as a biogeographic barrier at the species‐assemblage level, and (2) test the influence of seven environmental variables (vegetation structure, vegetation cover, soil nutrients, soil structure, slope, elevation, and distance from the river bank) on the spatial structure of the frog assemblages, separately on each riverbank. Thirteen species of diurnal frogs were recorded, six of which were restricted to one of the river margins. Multivariate analysis of variance indicated a significant effect of the river as a barrier. Multiple regression analyses suggested that the environmental variables structuring frog assemblages differ on either side of the river. We found that both historical elements (on a regional scale) and environmental factors (at a local scale) shaped the occurrence and distribution of frog species in the study area.     

Science,Knowledge and Belief. On Local Understandings of Weather and Climate Change in Amazonia

This article explores different modes of understanding such atmospheric phenomena that in English are described as ‘weather’ and ‘climate’ applying Norman Fairclough’s critical discourse analysis. In consequence, focus is not on the physical phenomena as such but on ontological differences as reflected in expressions and practices pertaining to indigenous Matsigenka people and migrants from the Andean highlands to the tropical lowlands, centring on their respective interaction both with each other and, more generally, with the social, natural and supernatural dimensions of the environment. Adhering to ideals of modernity and modern science, the Andean migrants employ the climate change discourse as an indication upon social advancement to promote and legitimize their superiority over the allegedly backward and irrational Matsigenka to whom the climate discourse makes little sense. The climate change discourse thus serves here as a means of environmental colonialism in order to turn Matsigenka people into proper citizens.     

Length–weight relationships of fish from Madeira River,Brazilian Amazon,before the construction of hydropower plants

Length–weight relationships (LWRs) are presented for 112 freshwater fish species representing 23 families and five orders captured in the Madeira River, the largest white‐water river tributary of the Amazon River. The allometry coefficient (b) of the LWR (Wt = aSL^b) ranged from 2.446 to 3.856 with a median value of 3.102. Eight new LWR records are presented for Amazonian species as information for FishBase. LWRs in the present study provide historical data on a and b coefficients prior to the damming of the Madeira River in November 2011, allowing comparison estimates of predicted future population parameters as influenced by human intervention.     

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.     

Seed Dispersal Modes of the Sandstone Plateau Vegetation of the Middle Caquetá River Region,Colombian Amazonia1

We characterized the dispersal spectra and phenology of 298 vascular plant species of the sandstone plateaus of Colombian Amazonia. Dispersal modes were determined by the morphology of dispersion units, personal observations on fruit consumption, and an extensive literature review. We obtained the number of species per dispersal mode for the sandstone plateaus and for two recognized vegetation types: open‐herbaceous vegetation and low forest‐shrub vegetation. Dispersal modes were assigned to 295 plant species. Animals dispersed the highest percentage of species (46.6%), while the percentage of autochorous and anemochorous species was 29.4 and 23 percent, respectively. The dispersal spectrum of the low forest‐shrub vegetation type, based on the coverage of every species, showed that percentages of anemochorous (40.2%) and zoochorous species (37.8%) were similar. Autochory was the most important seed dispersal mode of the open‐herbaceous vegetation (60%). Birds were the principal group of potential dispersers (58.9%) of zoochorous species and reptiles the least important. We found two marked fruiting peaks, one from the end of the dry season to the beginning of the wet season and the second one from the beginning to the middle of the dry season. Our results showed that besides the differences in the vegetation structure and floristic composition between the sandstone plateaus and the adjacent tall forest, there also exist differences in the dispersal spectra and the fruiting rhythms.     

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.     

起测径对南盘江流域次生林中枯立木空间结构的影响

树木大小是林分的基础属性,反映个体在森林生态系统过程中扮演的角色和地位。作者于2016-2018年在中国西南地区南盘江流域松栎混交林中建立3块永久性标准固定样地(A、B、C),并用双相关函数g(r)、标记相关函数kmm(r)、标记变差函数γ(r)和k-邻体距离分布函数Dk(r)分析不同大小枯立木的空间结构特征,以揭示林分水平上枯立木的大小和空间结构之间的关系。结果显示:(1)枯立木的起测径(minimum measured diameter,mmd)越小,小尺度上(r=0~5 m)的分布格局趋向聚集状态,但随着起测径的增大(mmd=5~8 cm),随机分布格局几乎占据每个尺度(r=0~20 m)。(2)当起测径等于1~2 cm时,枯立木的大小在小尺度上(r=0~1 m)接近聚集分布,除此之外它一直保持随机分布。(3)当起测径≤4 cm时,枯立木的树种分布集中;反之,它在每个尺度上越接近或成为随机状态。(4)当起测径由1 cm增大至8 cm时,r=0~10 m之内相邻木的株数减少且距离增加,其变化程度受到林分株数的影响。研究表明,枯立木的起测径与其分布格局类型、标记特征以及距离分布紧密相关,暗示同种小树易呈团块死亡,而大径的枯立木偏向随机分布;对比分析枯死木的空间结构需使用统一的起测径标准。     

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).     

浦阳江中上游河谷盆地乡土景观研究

由流域水系冲击作用形成的河谷盆地往往具有较为封闭的地域环境,人与环境的相互作用将其转化为独特的乡土景观。以浙江省浦阳江中上游河谷盆地乡土景观为研究对象,依据人与自然的互动关系,将研究区分为湖区和畈区2种景观类型,同时基于风景园林学的视角,分别从自然基底、农田水利体系、聚落体系层面阐述2种景观类型的构成要素和空间格局特征,并通过典型的聚落样本进一步揭示了各系统层之间的相互关系以及乡土景观格局与乡土景观过程的耦合关系机制。     

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.     

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.     

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.     

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.