Amazon forest

Neill, C., Piccolo, M. C., Melillo, J. M., Steudler, P. A., Ceni, C. C. (1999). Nitrogen dynamics in Amazon forest and pasture soils measured by 15N pool dilution. Soil Biology Biochemistry, 31, 567-572. 

Fig. 9. GC-MS TIC traces for silylated total extracts of soil, river sediment and aerosol samples (a) Amazon Forest soil (Manaus, Brazil) (b) almond orchard agricultural field soil (CA, USA) (c) Harney River sediment in Everglades National Park (FL, USA), and (d) Gosan Island (Korea) aerosol during Asian dust event (April 27—28, 2001). Numbers refer to carbon chain length of homologous series ( = rj-alkane, o = rj-alkanol, A = rj-alkanoic acid, DHA = dehydroabietic acid, ik = isoprenoid ketone, S = sitosterol). 

Needless to say, any ecosystem offers a rich variety of chemical ecology stories to discover. For example, on an excursion in the Amazon forest one can be sure to encounter many fascinating chemical relationships between organisms. Here I start with three examples concerning birds. 

Clearly, the fate of the Amazon and the implications of its fate to the overall Earth system are topics of enormous scientific and popular interest. While there is little disagreement that the complete destruction of Amazon forests would be catastrophic, what about partial deforestation of the region How much, and which parts, of the Amazon can be converted to sustainable human land... 

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... 

Production of roots on top of the mineral soil has been explained as a consequence of the low nutrient availability in Amazon forests (Herrera et al. 1978, Cuevas and Medina 1983, Medina and Cuevas 1989). Vertical root distribution results from differential nutrient availability in the soil profile (Berish 1982, Berish and Ewel 1988). Shallow rooted systems may be a result of litter and soil organic matter production and decomposition rates in systems where nutrient input from litter exceeds that of nutrient release by soil weathering, as is the case of Ca, Mg, and P in terra firme forests (Medina and Cuevas 1989). In the Middle Caqueta region of Colombia, for example, Ca and Mg concentrations in the L and F layers are between 15 and 20 times higher than in the mineral soil (Duivenvoorden and Lips 1995). 

Buschbacher, R. J. 1984. Changes in productivity and nutrient cycling following conversion of Amazon forest to pasmre. PhD Thesis, University of Georgia, Athens, GA. 

Cuevas, E., and E. Medina. 1990. Phosphorus/nitrogen interactions in adjacent Amazon forests with contrasting soils and water availability." In Phosphorus Cycles in Terrestrial and Aquatic Ecosystems, eds. H. Tiessen, D. Lopez-Hernandez, and I.H. Salcedo (Proc. SCOPE-UNEP Regional Workshop 3 South and Central America. Saskatchewan Institute of Pedology. Saskatoon, Canada), pp. 83-94. 

One of the difficulties in getting information on research already carried out in Brazil is that the dissertations of graduate students in the universities are seldom published in indexed journals. There has been no attempt to compare the cerrados with other savannas in South America, other continents, or Amazon forests because the information available from the cerrados on quantitative aspects of nutrient cycling in natural ecosystems is very meager (Baruch et al. 1996). There are several important studies reported from the Amazon region on nutrient concentrations in plants, litter decomposition, and hydrological cycles over the last couple of... 

Moraes, J. F., B. Volkoff, C. C. Cerri, and M. Bemoux. 1996. "Soil properties under Amazon forest and changes due to pasture installation in Rondonia, Brazil." Geoderma... 

Serrao, E. A. S., and J. M. Toledo. 1990. The search for sustainability in Amazonian pasmres." In Alternatives to Deforestation Steps Toward Sustainable Utilization of Amazon Forests, ed. A. B. Anderson (Columbia University Press, New York), pp. 195-214. 

Yamazaki, S, A. Takelani, K. Fujita, C. P. t sques, and T. Ikeda, 1990. Ecology of Hypsipyla gmndella and its seasonal changes in population density in Peruvian Amazon forest. Japan Agricultural Research Quarterly 24 2,149-155. 

One of the largest problems in quantifying the carbon stock of Amazon forest is the difficulty of obtaining a reliable estimate of... 

Indirect methods, based on allometric inference, from measurements of the diameter at breast height (DBH) and the height of the trees to obtain wood volumes, is the main method adopted to estimate biomass in the Amazon. Forest biomass estimates are made through regression analysis, where several fitting curves are tested to obtain an ideal model that can be applied to the trees. These models are calibrated by direct weighing of the biomass from a subsample of trees (see for example, Jordan and Uhl 1978, Higuchi et al. 1994, Brown et al. 1995), and could also include other compartments besides trees, such as vines or understory. Indirect methods are broadly adopted in the forestry industry to evaluate the volume of commercial wood. 

Fearnside, P. M. 1985. Brazil s Amazon forest and the global carbon problem. Interciencia 10(4) 179-186. 

Fearnside, P. M. 1996. Amazonian deforestation and global warming Carbon stocks in vegetation replacing Brazil s Amazon forest. Forest Ecology and Management 80 21-34. 

The floristic composition of floodplain forests is described by several forest inventories covering the complete Amazon basin. Detailed information is available from central Amazon forests in the vicinity of Manaus with inventories of about 17 ha of varzea forest from the Ilha de Marchantaria, Costa do Marrecao, and Costa do Barroso (Worbes 1983, 1986, Revilla 1991, Worbes et al. 1992, Klinge et al. 1995) and from igapo forests (Keel and Prance 1979, Revilla 1981, Worbes... 

Clearly, local conditions, such as tree species, the number of trees per unit area and the average intensity of the precipitation will affect the proportions. Thus in the Amazon forest in the region of San Carlos, Venezuela, Jordan and Heuveldop (1981) found 87% throughfall and 8% stem flow, while only 5% of precipitation was intercepted. 

Table 4 - Transit time of rainwater in Amazon forest soil determined by 8 O (Leopold et al., 1982a).

These species are distributed over five main types of biomas the cerrado savannahs, the Mata Atlantica rain forest, the Amazon forest, pantanal wetlands, and caatinga semiarid scrublands, as can be seen in Fig. (1). In spite of all this wealth, the first two are among the ecosystems regarded as hotspots in South America [5]. 

In a similar way, an ethnopharmacological survey among the Caboclos of the Jau National Park, in the Amazon forest, showed that every formula may present from one up to six ingredients (parts of plants and/or animals) [51]. 

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