Amazon eastern

Prior to the eastern adventures of Linschoeten and Tradescant, the sailors of Columbus had discovered the natives of Central America playing with lumps of natural mbber. These were obtained, like gutta percha, by coagulation from a latex the first recorded reference to natural mbber was in Valdes La historia natural y general de las Indies, published in Seville (1535-1557). In 1731 la Condamine, leading an expedition on behalf of the French government to study the shape of the earth, sent back from the Amazon basin mbber-coated cloth prepared by native tribes and used in the manufacture of waterproof shoes and flexible bottles. 

Figure 3. An undisturbed primary tropical rainforest in the eastern Amazon Basin, Brazil. Although these forests only comprise 7% of the earth s surface, they contain as much as 40% of all species and are significant global C sinks.

As shown in Figure 14.8, kaolinite concentrations are highest in tropical and equatorial latitudes, particiflarly off the western coasts of North Africa and Australia (>40%) and the northeastern coasts of Australia and South America (30%). The first two are the result of aeolian transport by the Trade Winds from the Saharan and Australian deserts, respectively. The other two are the result of river input from the eastern Australian continent and the Amazon River. 

The earliest available preparations, made as infusions and concentrated to a syrup by the native people, were designated as calabash (gourd), tubo- (bamboo), or pot (clay pot) curare depending upon the containers in which the drug was packaged. Curare is obtained from the upper regions of the Amazon river, the Orinoco basin, and the eastern slopes of the Ecuadorian plateau. The term curare is derived from the Indian name (woorari, urari) for poison (Grollman, 1962). 

The significant investment made in superficial roots by trees of Amazon forests is a clear indication of the importance of nutrient recycling from organic pools at the soil surface. However, research from the central and eastern Amazon has shown that trees in seasonally dry forests also have roots extending to at least 18 m depth (Nepstad et al. 1994). While the main function of these roots appears to be the uptake of deep soil water and groundwater, there is also potential for these roots to access deeper nutrient pools in the soil column. Nepstad et al. (this volume) elaborate on this issue by demonstrating that secondary forests growing in the eastern Amazon have P and K nutrient needs that cannot be satisfied by available stocks in the... 

Regarding Amazon deforestation, the largest deforestation rates are observed in southwestern and eastern Amazonia, the so-called Deforestation Arc. The Instituto Nacional de Pesquisas Espaciais (INPE) of Brazil developed the Deforestation Project (in Portuguese, PRODES Programa de Monitoramento de Desflorestamento na Amazonia) based on LANDSAT images for... 

A comparison of C budgets for forests and pastures in the eastern Amazon was made by Trumbore et al. (1995). In a reformed and fertilized pasture of Brachiaria brizantha, they estimated gains, relative to forest soil C stocks, of over 20 tons soil C ha 1 in the top 1 m of soil and a loss of about 0.5 tons C ha i in the 1-8 m soil depth interval during the first 5 years following pasture... 

Seasonality of precipitation is also an important factor controlling N trace gas emissions from Amazonian soils. At Paragominas in the highly seasonal eastern Amazon, N2O is the most important N gas during the wet season when diffusivity is restricted, thus favoring the more reduced N gas form (Table 6.8). During the dry season, the more oxidized NO form is the dominant N gas emitted. Differences in total N gas emissions among land uses is controlled by N availability as indicated by net N mineralization and net nitrification (Table... 

In spite of the lessons from Jari, other large scale plantation development plans continue in the Brazilian Amazon. If developed, the Grande Carajas Program would consume large areas of tropical forest in the eastern Amazon in order to obtain charcoal for the smelting of pig-iron from the Carajas mines. The area of Eucalyptus plantation to produce the required amount of charcoal would be over 700,000 ha-more than 10 times the area of E. deglupta already cultivated in the Jari Project (Feamside 1989). 

Fearnside, P. M. 1989. The charcoal of Carajas a threat to the forests of Brazil s eastern Amazon region. Ambio 18 141-143. 

Little direct evidence of deep root uptake of nutrients is available in the Amazon or elsewhere. Within our eastern Amazonian research site at the Fazenda Vitoria in Paragominas, Para, however, we have made measurements of soil and vegetation that help us bound estimates of the potential for deep root uptake of nutrients by secondary forests. Specifically, we have (1) estimated... 

Koutika, L., F. Bartoli, F. Andreux, C. C. Cerri, G. Buitin, T. Chone, and R. Philippy. 1997. Organic matter dynamics and aggregation in soils under rain forest and pastures of increasing age in the eastern Amazon Basin. Geoderma 76 87-112. 

Uhl, C., and J. B. Kauffman. 1990. Deforestation, fire susceptibility and potential tree responses to fire in the eastern Amazon. Ecology 71(2) 437-449. 

Mattos, M. M., and C. Uhl. 1994. Economic and ecological perspectives on ranching in the Eastern Amazon. World Development 22 145-158. 

Uhl, C., and R. Buschbacher. 1985. A disturbing synergism between cattle ranch burning and selective tree harvesting in the Eastern Amazon. Biotropica 17 265-268. 

At the confluence of the Japura and Solimoes rivers, two forest sites of Mamiraua are described by Ayres (1993) with respect to the influence of inundation period on species composition. From the western Amazon there are inventories from the Rio Uyacali (Marmillod 1982), Rio Jurua (Campbell et al. 1992) and Rio Napo (Balsev et al. 1987), and in the eastern Amazon there are inventories from the Rio Guama (Pires and Koury 1959) and the Rio Xingu (Campbell et al. 1986). An overview of sample size, number of species and stems of these inventories is given on Table 13.5. 

On nonflooded sites in Amazonia, species richness increases from east to west, from 87 species ha i near Belem (Black et al. 1950) to over 179 species ha near Manaus (Prance et al. 1976) and more than 200 species in Ecuador (Balslev et al. 1987). Gentry (1982, 1990) explained species richness generally increases as annual precipitation increases. However in the same direction diversity increases in the floodplain forests from 53 species per ha in Para (Pires and Koury 1959) to over 135 species in Mamiraua (Ayres 1993) to 149 species at the Rio Napo (Balslev et al. 1987). The human influence on species composition in floodplain forests is a poorly investigated factor however, forests of the eastern Amazon have been exposed to deforestation and severe exploitation for longer times than western forests. In the varzea of the Solimoes river, selective logging nearly caused the extinction of... 

Nixon et al. (1996) have compiled N and P data for many of the watersheds and estuaries feeding the North Atlantic Ocean. In many of the watersheds of eastern North America, the input of N from anthropogenic atmospheric supply and sewage is a considerable fraction of the total input. This is not the case for the Amazon shelf, where atmospheric and sewage inputs are small relative to riverine input and upwelling. For the embayments and estuaries of the North Atlantic, Nixon et al. (1996) observed a significant correlation between %P exported and the mean freshwater replacement time. During the AmasSeds cruises the freshwater... 

In the Amazon Basin there are two different rainfall regimes — in the central part and a portion of the western area of the Basin there is a definite dry period, but in the eastern and western end of the Basin there... 

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