Aspectos fitogeográficos do Brasil : áreas e características no passado e no presente

Resumo

With the object of taking yet another step towards obtaining a better knowledge of the natural areas of Brazil, the characteristics of each, and consequently of a better use to be made of the land, the Author stresses that the overall pictures summing up the phytogeographical situation in this country have long ceased to correspond to reality.

            An initial survey was made of existing works, and a criticism of them covering almost 10 years led to an accumulation of valuable elements.

            Furthermore, in the course of more than 14 years, the Author himself has made numerous trips to gather first-hand observations in nearly all the Units of the Federation with the exception only of the states of Santa Catarina and Piauí and the Federal territory of Rio Branco.

            Finally, the third process is based on air-photo survey, an examination of the flight strips of the American Air Force and L.A.S.A. (Levantamentos Aerojotogramétricos S.A.) providing a facility that preceding authors did not enjoy.

            Likewise the indispensable collaboration of the scientific institutions, amongst others the Botanical Garden, the Forest Service, the National Pine Institute and National Geography Council, made for a high degree of accuracy in the data.

            The first major necessity was to fix epochs, for this work proposes to give two views of the country: present and past, the latter being dated by the arrival of the first white man in Brazil, i. e. the discovery of the country.

            The Author rejects the concepts of primacy, original, secondary, etc., commonly applied to vegetation, considering that they admit of conflicting interpretations. He is this in favour of the concept of primitive vegetation (at the time of the Discover: XVIth Century), with remains lasting until our days, and the vegetation altered by men (fixed at the two-year period 1958-1959; XXth Century).

            Objectively he has divided the great plant formations into forest type, savannah type, transitional forest-savannah type and scrub forest (in Portuguese: florestal, campestre, cerrado and caatinga). Having recognized these four broad. categories, each of which admits of considerable variation, the author raises them to the level of existing climax communities.

            A map was organized of existing vegetation (XXth Century), and then work was begun on the map of primitive vegetation (XVIth Century). With the aid of these two maps, percentages were calculated and, transformed into square kilometer, they provide an overall view of the phytogeographic situation in Brazil. To furnish an even better knowledge of the subject, the situation of the major plant formations at the present time is given, as well as the comparative situation between altered and unaltered vegetation and the situation of land use in Brazil, by means of a comparison between areas under crops, pasture and untilled forest.