The natural organization of Brazilian inter-and subtropical landscapes

Abstract

(Original1y published in lU Simpósio sobre o Cerrado, 1971, Editora B1ücher and Editora da Universidade de São Paulo, as A organização natural das paisagens inter e subtropicais brasileiras. Translated by P. E. Vanzo1ini, revised by Thomas R. Fairchild.) 1 1NTRODUCTION Present conditions are rather favorable to the development of interdisciplinary studies of the organization of Brazilian inter-and subtropical landscapes. Among such conditions are the easy access to the diverse physiographical and ecological regions, the very large number of aerial photographs that are available, and a perrnissive attitude toward the formation of interdisciplinary teams. The theme in itself is attractive, as the display of Brazilian inter-and subtropical landscapes is markedly original within the tropical world. Although most of the country is subject to the conflicting influences of Nature and Man, there still exist fairly favorable conditions for the characterization of natural spaces, in an objetive attempt to reconstruct their primary organization. 1twill perhaps be the task of the present generation of Brazilian researchers to document this issue in the literature on earth and life sciences in Brazil. From the beginning I want to stress that it is by alI means convenient to intensify studies on the functioning and organization of Brazilian landscapes, taking into account regional and local conjunctures resulting from anthropic actions. Undoubtedly the analysis of the interference of processes, predatory actions, and harmful aggressions-unconsciously brought about by man-is just as important for the app1ication of scientific principIes as the effort to understand the ecological conditions of less disturbed areas. Prehistoric man in Brazil seems to have caused little disturbance to the inter-and subtropicallandscapes. The unified evolution of the most diverse landscapes in Tropical America during the last 10,000 years included the aboriginals as one additional element in the global development of the landscapes. It was the contrary of what succeeded in Africa, where a Recent fauna of gigantic animaIs, and human groups over 500,000 years old caused telling changes in some landscapes. It seems to me that the development of Brazilian intertropical landscapes was on the whole more harmonious, better integrated and balanced than what happened on the other side of the Atlantic Oceano 2 THE GREAT BRAZ1LIAN' LANDSCAPE DOMA1NS Six great landscape and macro-ecological domains are at present recognized in Brazil. Four of them are intertropical, occupying over 7.5 million km2; the other two, subtropical, are noticeably smalIer, adding up to a little more than 0.5 milIion km2• The great domains, defined by vegetational and morphoclimatic features of great spatial extent and generality, include landscape pattems of sub-regional character and eventual enclaves of extraneous landscapes, recurrent vegetational features related primarily to other domains. On the other hand, peculiarities of compartmentation, sedimentary strata of paleoclimatic significance, and paleozoological and paleobotanical records show that, during the Quatemary, these domains did not always exhibit the features and distribution evident at the time of arrival of the first Europeans. " 1n sum, the domais are: Domain of the forested Amazonian lowlands. A markedly zonal, equatorial to sub-equatorial area. First order extent of over 2.5 milIion km2• Labyrinthine (Rio Amazonas) or meandrous (main tributaries) floodplains, tabuleiros (Editor 's note: low sedimentary plateaus, tablelands) with convex slopes, and low rounded hills with convex slopes (E.n.: half-orange hills) on the margins of the Amazonian sedimentary basin; residual relief in the form of sugarloaves that may have been inselbergs more than once during the Quaternary; discrete Neogene pediplanation and pedimentation levels; terraces supported by graveI beds or lateritic crusts; blackwater rivers in autochthonous drainage areas, drainage thoroughly perennial. Domain of the semi-arid inter-plateau 57