Eastern Amazon Region Research Articles

As políticas federais e reconfigurações espaciais na Amazônia

This paper analyzes the social and spatial repercussions of federal policies designed for the Brazilian Eastern Amazon region, in the 20th century. Initially, the paper examines the attempts to re-establish, at a regional level, the dynamics of the rubber production. The new policies developed implemented after the military coup of 1964 and the new policies for the region, adopted after the military regime, as well as the new institutional approach are also analyzed. We conclude with the distribution of federal policies in two large groups, according to their strategy principles: one based on the efficiency of state intervention in the development processes, and another based in the efficiency of the market forces.

The relationship between pasture degradation and soil properties in the Brazilian amazon: a case study

Abstract Pasture degradation is one of the greatest problems related to land use in the Amazon region, forcing farmers to open new forest areas. Many studies have identified the causes and the factors involved in this degradation process, in an attempt to reverse the situation. The purpose of this study was to examine the relationship between pasture degradation and some soil properties, to try to identify the most significant soil features in the degradation process. A cattle raising farm in the eastern Amazon region, with pastures of different ages and degrees of degradation, was used as the site for this study: a primary forest area, PN; three Guinea grass (Panicum maximum Jacq.) pastures in an increasingly degraded sequence—P1, P2 and P3; one Gamba grass (Andropogon gayanus Kunth) pasture following an extremely degraded Guinea grass pasture, P4. Aboveground phytomass data showed differences between the pastures, reflecting initially observed degradation levels. Grass biomass decreased sharply from P1 to P2 and disappeared at P3. Pasture recovery with Gamba grass at P4 was very successful, with grass biomass higher than P1 and weed biomass smaller than P2 and P3. Root biomass also decreased with pasture degradation. Soil bulk density increased with pasture decrease at the topsoil layer. Results from the soil chemical analysis showed that there were no signs of decrease in organic carbon and total nitrogen after the forest was transformed into pasture. In all pastures, degraded or not, the soil pH, the sum of bases and the saturation degree were higher than in the forest soil. The extractable phosphorus content, lower in forest soil, remained quite stable in pasture soils, but it could become a limiting factor for the maintenance of Guinea grass. Results indicated that pasture degradation does not seem to be directly related to the modification of the chemical features of soils.

Prevalência de genótipos e de mutantes pré-core A-1896 do vírus da hepatite B e suas implicações na hepatite crônica, em uma população da Amazônia oriental

Hepatitis B virus (HBV) infection presents itself with a variety of clinical manifestations. The present work aims to describe the prevalence of HBV genotypes and the occurrence of precore mutation A-1896 in a population group of the Eastern Amazon region of Brazil and to correlate them with the clinical presentation of chronic HBV infection. 51 HBsAg carriers (HBV-DNA positive) were selected and divided into three groups: A (14 asymptomatic subjects), B (20 HBeAg positive symptomatic patients) and C (17 HBeAg negative symptomatic patients). Using an automa ed DNA sequencer ABI model 377 by sequencing for determined of genotypes and precore mutation. The results showed that the genotype A was the most commonly found (81.1%, 89.5% and 93.7% in groups A, B and C, respectively) and precore mutation A-1896 was described in 11.5% (3/26) of group A subjects. Genotype A of HBV was the most prevalent (89.1%) and low occurrence of precore mutation A-1896, both not associate with the worst outcome of the chronic infection of HBV.

Clinical trial of two antivenoms for the treatment of Bothrops and Lachesis bites in the north eastern Amazon region of Brazil

The efficacies of specific Bothrops atrox- Lachesis and standard Bothrops- Lachesis antivenoms were compared in the north eastern Amazon region of Brazil. The main aim was to investigate whether a specific antivenom raised against the venom of B. atrox, the most important Amazon snake species from a medical point of view, was necessary for the treatment of patients in this region. Seventy-four patients with local and systemic effects of envenoming by Bothrops or Lachesis snakes were randomly allocated to receive either specific ( n=38) or standard ( n=36) antivenoms. In 46 cases (24 in the standard antivenom group, 22 in the other) the snake was identified either by enzyme immunoassay or by examination of the dead snake, as B. atrox in 45, L. muta in one. Patients were similar in all clinical and epidemiological respects before treatment. Results indicated that both antivenoms were equally effective in reversing all signs of envenoming detected both clinically and in the laboratory. Venom-induced haemostatic abnormalities were resolved within 24 h after the start of antivenom therapy in most patients. The extent of local complications, such as local skin necrosis and secondary infection, was similar in both groups. There were no deaths. The incidence of early anaphylactic reactions was 18% and 19%, respectively for specific and standard antivenoms; none was life-threatening. Measurement of serum venom concentrations by enzyme immunoassay (EIA) confirmed that both antivenoms cleared venom antigenaemia effectively. EIA also revealed that one patient had been bitten by Lachesis muta, although the clinical features in this case were not distinctive.

Empirical Determination of Political Cultures as a Basis for Effective Coordination of Forest Management Systems

To design viable strategies to implement sustainable forest management, tools are needed that allow the understanding and management of the driving forces behind conflicting opinions and divergent solutions. The approach of Thompson et al. (1990) to cultural theory--because of its descriptive power--may be an ideal basis to create such tools. The possibility of determining empirically the cultural bias of the actors and groups involved is fundamental to this approach. We conducted a pilot study in the eastern Amazon region to explore the possibility of characterizing individuals according to the four types of political culture defined by Thompson et al. The findings indicated that the empirical classification of individuals is possible but complex. A relation between the types of political cultures and perceptions of sustainable forest management was observed. A systematic elaboration of adequate indicators and assessment methods is crucial in exploring the potential of transferring the theoretical approach into practice.

The urban market of Açaí fruit ( Euterpe oleracea Mart.) and rural land use change: Ethnographic insights into the role of price and land tenure constraining agricultural choices in the Amazon estuary

This paper examines the recent development of the acai fruit economy in regional Amazonian urban markets (as a staple food) and more recently among national and international consumers (as a fashion food) and the consequences for agroforestry intensification by Caboclo communities in the Amazon estuary. The paper is based on long-term ethnographic research and field experiments; the acai fruit economy is discussed from agricultural, social, and economic perspectives; attention is given to its historical development, the structure of acai fruit production, its agents, the relationship among themselves and the urban market. Decadal price performance is presented for acai fruit and acai transportation costs and compared to major agropastoral products for the Eastern Amazon region. Dominant views about the ‘economic rationality’ of rural producers' decision-making are discussed. Acai fruit has performed as well as and in some cases surpassed most agro-pastoral products of the Northern region. Economic returns for producers reflect linkages between price signals from urban markets, harvesting decision, and land tenure condition of the producer. Urban markets for the fruit is expanding and bringing new participants to the acai fruit economy further conditioning the ability of rural producers to take advantage of external markets for forest products. Discussion of factors conditioning agricultural development and integration between urban and rural areas conclude the article.

A case of gynandromorphism in Amblyomma oblongoguttatum (Acari: Ixodidae).

During a survey conducted from August to November 1998 to ticks associated with dogs in the rural area of Uruará, in the state of Para, Eastern Amazon region of Brazil, we collected one gynandromorph specimen out of 18 Amblyomma oblongoguttatum Koch specimens collected from dogs. It is a perfect bipartite gynandromorph, reported in this species for the first time.

Carbon storage and root penetration in deep soils under small-farmer land-use systems in the Eastern Amazon region, Brazil.

The north-east of Para state in the Eastern Amazon of Brazil was settled over 100 years ago. Today the region is an agricultural landscape with variously-aged secondary vegetation and fields with annual cultures, plantation crops and pastures. The effect of these different land covers on carbon sequestration as well as on water and nutrient extraction remain subject of debate. Therefore, we assessed the importance of land use on soil carbon stocks by measuring various C fractions and root biomass (0–6 m) in slash-and-burn systems and (semi-) permanent cultures. An extensive root system down to at least 6 m depth was present under various secondary vegetation stands and slashed and burned fields recently taken into cultivation as well as under a primary forest. Shallower rooting patterns were evident under (permanent) oil palm (4.5 m) and (semi-permanent) passion fruit plantations (2.5 m). Carbon storage in soils of traditional slash-and-burn agriculture up to 6 m depth (185 t ha-1) was not significantly lower than under a primary forest (196 t ha-1) but declined significantly under (semi-) permanent cultures (to 146–167 t ha-1). Compared to above-ground C losses, soil C losses due to slash-and-burn agriculture may thus be small. This is an argument for maintaining the secondary vegetation as part of the agricultural land-use system, as the root system of its trees is conserved and thus C is sequestered also at greater depth.

Fire-free alternatives to slash-and-burn for shifting cultivation in the eastern Amazon region: the role of fertilizers

Forest fires in slash-and-burn agriculture rank high in the list of environmental concerns. The objective of this study in Pará State, Brazil, was to evaluate fire-free alternatives to burning of the slashed fallow vegetation for crop production in the humid tropics. Burning, mulching and incorporation of fallow biomass were compared in two successive cropping periods with rice, cowpea and cassava, with and without NPK fertilizer. In the traditional system, with slash-and-burn technology and without fertilizer, the shortening of the fallow period from 10 to 4 years caused a reduction of 30% only in the rice yields of the first cropping period. In the second cropping period, rice yields were lower in the area with 10 years of fallowing and similar with the shorter fallowed area when compared to the first season. Cowpea did not show any differences, whereas cassava yields decreased from the first to the second cropping period in both fallow situations. When fertilizers were applied, fallow periods beyond 4 years and doubled cropping periods appeared to have little effect on yields. Transforming the fallow vegetation into wood chips instead of slash burning reduced rice yields in the first cropping period 47 and 80% after 4 and 10 years of fallowing, respectively, and made cowpea production impossible after 10 years of fallowing. Cassava yields were not affected by fire-free land preparation. Application of fertilizers raised yields from around 0.7 t ha −1 to over 2 t ha −1 for rice, and from around 0.2 t ha −1 or less to around 1.5 t ha −1 for cowpea. Fertilizer use was essential to obtain acceptable yields for the two crops under fire-free land preparation. Residual fertilizer doubled cassava yields. Comparing the two successive cropping periods, rice and cowpea yields increased, on average, 47 and 27%, respectively, in the second cropping period, irrespective of fallow age, but with fertilizer application. Over the entire cropping period, use of fertilizer led to a greater exploitation of soil N and K but not of P. The risk of soil degradation due to intensified cropping by shortened fallow or prolonged cropping periods is considered low, provided that sufficient plant material and nutrients are supplied to the soil by fire-free land preparation and fertilization.

Response of secondary vegetation in Eastern Amazonia to relaxed nutrient availability constraints

This study evaluated the effect of nutrient application on the regrowth dynamics of secondary fallow vegetation in an intensely exploited shifting cultivation area in the eastern Amazon region of Brazil. The importance of N, P, K, Ca, Mg, S and a mixture of micronutrients was tested in a minus-one-trial by comparison with a full complement of nutrients and unfertilized control plots. Fertilizers were applied three times during the experiment and their effects were monitored over a period of 2 1/2 years. Prior to the second fertilization, one third of each experimental plot was cleared of the vegetation cover and planted in maize, prior to the third fertilizer application these subplots were planted in sorghum. Biomass of maize and sorghum were used to indicate nutrient constraints and fertilizing effects due to the different treatments. Both crops were limited by P- and N-availability, with greater responses to P. The initial fertilization did not affect the biomass accumulation of the secondary vegetation during the first 15 months, but two additional applications significantly increased biomass in the complete fertilizer treatment compared to the unfertilized control. Biomass accumulation was primarily P-limited, N-limitation was apparent but not significant. The remaining nutrients did not affect plant growth. Fertilization favored production of nutrient-rich leaves. Application of readily available nutrients gave grasses a competitive edge over slower reacting woody vegetation. Fertilization also caused significant shifts in the contribution of woody species to biomass accumulation, as could be demonstrated for two prominent pioneer tree species. Growth response to fertilization as well as the primary limiting nutrient varied among seven dominant species monitored in the secondary vegetation. We conclude that growth of tropical secondary vegetation can be nutrient limited and it might respond significantly to additional nutrients by increasing biomass production.

The “Grande Carajás Project” Reason and passion

Abstract The “Grande Caraja's Project” is not only the most important industrial project in the history of Brazil, it is also a project with far reaching international consequences. The mining of a number of raw materials will directly affect world mineral markets and the industrialization of the Eastern Amazon region may have ecological effects far beyond the borders of Brazil. A debate on the Program is not only crucial for the economic, political and social future of Brazil, it's an important element in the general discussion on “third world” industrialization and development.

Why Brazil?

Abstract Abstract The second part of our series on the major mining areas of the world will focus on Brazil. We publish a very extensive material on the state owned mining conglomerate, Companhia Vale do Rio Doce and on the “Grande Caraja's Program” for industrialization of the Eastern Amazon region. These articles analyse, from a Brazilian perspective, the efforts of this “third world” country to gain control over its natural resources and the struggle to formulate a national development policy. The following editorial introduction, looks at Brazil “from the outside”, trying to asses its role in the global struggle for minerals and the contradictions of its present export oriented resource policies.

Minor element geochemistry of the Paragominas bauxite, Brazil

The Paragominas bauxite deposit in the eastern Amazon region lies within the Maranhao basin and appears to have developed in late Tertiary and early Quaternary sediments. The bauxitic zone extends over at least 100,000 hectares. In the area sampled for this study, the average thickness is 2.2 + or - .1 m. Estimated reserves are in excess of 10 9 metric tons.Spark source mass spectroscopy was used to determine the concentrations of 56 elements in samples from one profile. Concentrations are compared to the available corresponding information from other bauxite deposits and to crustal abundances.The elements (F, S, Cl, Sc, V, Ga, Ge, Se, Nb, Cd, In, La, Sm, Gd, Tb, Ho, Er, Tm, Yb, Pb, U) with concentrations similar to those in the earth9s crust number approximately the same as those (Cr, Co, Ni, Cu, Zn, Br, Rb, Sr, Y, Ag, Cs, Ba, Ce, Pr, Nd, Eu) whose levels are depleted. Enriched elements (B, As, Zr, Mo, Sn, Sb, I, Hf, Th, Bi) include those having refractory oxides and those exhibiting biological affinity.