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Showing papers by "Amazon.com published in 1990"


Journal ArticleDOI
01 Jun 1990-Nature
TL;DR: In this article, a detailed map of botanical collection density is used to identify the true concentrations of plant endemism, which is important for selecting priority conservation areas to guarantee preservation of unique species.
Abstract: HERBARIUM specimen collecting in the Brazilian Amazon has been concentrated in widely scattered collecting centres associated with some proposed centres of substrate-independent endemism1–3, suggesting that these may be sampling artefacts. Furthermore, many Amazonian plant species are uncommon, so the more intensely a local flora is studied, the more it will seem to be unique. This weakens the botanical argument for a dry Pleistocene Amazon4 and the associated forest refuge theory for the origin of Amazonian plant diversity1–3, because modern endemism centres are used as evidence to define past isolated forest patches—sites of allopatric speciation in a supposedly dry climate (Fig. 1). With a detailed map of botanical collection density, it is possible to recognize the true concentrations of plant endemism, which is important for selecting priority conservation areas to guarantee preservation of unique species.

360 citations


Journal ArticleDOI
Philip M. Fearnside1
TL;DR: In this article, a best estimate of the cumulative area of forest cleared through 1988 as 345 × 103 km2 (including old clearings), or 8.2% of the 4 × 106 km2 forested portion of the legal Amazon region was given.
Abstract: Examination of the often contradictory estimates of the rate and extent of deforestation in Brazilian Amazonia leads to a ‘best estimate’ of the cumulative area of forest cleared through 1988 as 345 × 103 km2 (including old clearings), or 8.2% of the 4 × 106 km2 forested portion of Brasil's 5 × 106 km2 ‘Legal Amazon’ region.

93 citations


Book ChapterDOI
Philip M. Fearnside1
01 Jan 1990
TL;DR: A large-scale human-initiated burning of grasslands could be expected to affect both the 165,000 km2 of humid savannas of present-day Amazonia (such as those in Roraima in the Humaita area of the state of Amazonas) and the limit between the forest and the central Brazilian scrubland as discussed by the authors.
Abstract: Fire has long played an important role in the formation of vegetation types in Amazonia. During the Pleistocene, a large part of Amazonia was covered by grassland, with forest confined to small refugia (the number, size, and evolutionary importance of which are the subject of controversy) (Prance 1982). This period coincided with the arrival of the first humans in the area. Fires started by precolumbian human groups would have slowed the progress of recolonization of the grasslands by forest (e.g., Budowski 1956). Human-initiated burning of grasslands could be expected to affect both the 165,000 km2 of humid savannas of present-day Amazonia (such as those in Roraima in the Humaita area of the state of Amazonas) and the limit between the forest and the cerrado or central Brazilian scrubland. Charcoal in the soil of the lavrados (“natural” grasslands) of Roraima indicate large-scale burning about 1000 years B.P. (Sternberg 1968).

80 citations


Journal ArticleDOI
Philip M. Fearnside1
TL;DR: National decision makers frequently view rainiorest settlement as a solution to the problems of other regions undergoing population growth, land tenure concentration, environmental degradation, agricultural mechanization and population displacement by development projects.
Abstract: Tropical rainiorest areas are rapidly being settled as a result of continued growth of local populations, spontaneous migration from non-rainiorest areas and planned settlement projects undertaken by governments. National decision makers frequently view rainiorest settlement as a solution to the problems of other regions undergoing population growth, land tenure concentration, environmental degradation, agricultural mechanization and population displacement by development projects. Natural habitats are replaced by settlements that often cannot support the density of population expected of them. Inappropriate assumptions can lead to estimates that are orders of magnitude too high, such as an FAO calculation that Brazil could support over seven billion people if Amazonia were converted to intensive agriculture. Inadequate information on human carrying capacity allows planners to foster unrealistic expectations.

24 citations