The Semi-arid Domain of the Northeast of Brazil

Abstract

In the backlands of the easternmost corner of South America, where the continent forms a large convex bulge projected into the South Atlantic , in latitudes ranging from 2° to 16° south of the Equator, a unique set of tropical landscapes are found. Its singularity derives not from the lushness of the vegetation or large river systems, but from being one of the few sub-equatorial dryland regions of the world. The scenery of the semi-arid core of the Northeast of Brazil is one dominated by vast rocky pediments interspersed with Proterozoic crystalline massifs and elevated basins forming table-like plateaus. The vegetation of the region, named caatinga —literally white forest—by its native Tupi peoples, is largely deciduous and singularly adapted to the harsh semi-arid conditions and thin soils. The climate of the drylands of Brazil displays an interannual variation of rainfall only comparable to that of deserts. Precipitation is largely dependent on the faulty southward migration of the ITCZ (Intertropical Convergence Zone ), and areas of increased aridity develop to the leeside the flat-topped plateaus and rocky massifs that dot the otherwise level topography of the region. Land use practices dominated by cattle ranching, since the first contact with Europeans in the early sixteenth century, have converted large areas into degraded rangelands and created six expanding nuclei of desertification. Lately, commercial scale irrigated agriculture has been introduced along the major rivers’ floodplains, such as the São Francisco , the only exotic perennial stream to cross the area. Being largely focused on tropical fruit production to supply the international market demands, irrigated farmland has created jobs and raised environmental concerns over the issues soils salinization and overall expansion of land degradation.

Os sertões, terra ignota.

(The backlands, unknown land)

—Euclides da Cunha