Limites Meridionais e orientais da área de ocorrência da floresta amazônica em território brasileiro

Abstract

            The determination of the southern and eastern limits of the area in which the amazonic forest occurs, within the Brazilian borders, constitutes the principal objective of the present paper

            This said delimitation was required by the "Comissão Especial do Plano de Valorização da Amazônia" (Special Commission for the Reclamation Plan of Amazônia), of the "Câmara Federal de Deputados" (Federal Chamber of Deputies), which had decided, by means of a project of law, that the area occupied by the forest or amazonic hilea, within Brazilian territory, would be the region in which the above mentioned "Plano de Valorização" (Reclamation Plan) should be executed, according to the 199 th article of the Brazilian Constitution of 1946

            This criterion was choosed due to the fact that the area occupied by the hilea corresponds to the one occupied by the amazonic region itself, and, furthermore, because that vegetal formation practically conditions the various forms of economic activities which are characteristic of the amazonic region

            The limits of the above mentioned area were obtained through the interpretation of trimetrogon aerial photographs taken by the American Air Force, cartographic as well as bibliographic research, reconnaissance flights and field trips

            These said limits represent a schematic line separating the areas of either continuous or discontinuous occurrence of the hilean forest, with the areas of predominant occurrence of the characteristic formations of the Brazilian regions denominated "Centro-Oeste" (Central-West) and "Nordeste-Ocidental" (Western Northeast), and they constitute, finally, a simplified line which represents the innumerable reentrances originated by the frequent interpenetrations of those mentioned regional formations, in their multiple and varied contacts

            These limits are also intended to correct the ones presented by a number of authors since the beginning of the last century, and to serve as a base or element of comparison to a more precise delimitation which may happen to be made in the future

            The delimitation which is now presented does not represent rigorously the one of the geographic region commonly refereed to as Amazônia, but it can be regarded, nowadays, as a contribution to a more accurate determination of the geography areas covered by the regions: "Norte" (North), "Centro-Oeste" (Central-West) and 'Nordeste" (Northeast) of Brazil and, furthermore, as a contribution to a better understanding of the regional geography of the South American continent, particularly in what concerns to the area covered by the Amazonian type of climate, of which the hilean forest constitutes an expressive reflex

            The present paper, due to the methods and procedures adopted to obtain the identification of the forest, results of a phytophysiognomic study

            The area of the Brazilian territory where, as stated, the amazonic forest occurs, is calculated in 4 161 482 square kilometers, corresponding to 48,87% of the total area of Brasil.

            The density of the population within this area is very low (only 0,6 inhabitants per square kilometer) and it is the greatest demographic empty space of the country Its economy is predominantly based in collecting native products of the forest and in reduced and incipient agricultural and cattle-grazing activities; due to its large extension, this area is the greatest under-developed space in south America

            The three monographs which accompany this paper as an annex, complete the same; one of them represents an up to date source of data for the knowledge of the geographic distribution of the botanical species which constitute the amazonic hilea within the State of Maranhão, and the second, a contribution to the study of the history of Phytogeography in Brazil; the last, a commentary in which the author explains the reasons why the delimitation herein presented by the "Conselho Nacional de Geografia" (National Council of Geography) was not adopted for the execution of the Reclamation Plan for the amazonic region.